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What changed in Spero Therapeutics, Inc.'s 10-K — 2024 vs 2025

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Paragraph-level year-over-year comparison of Spero Therapeutics, Inc.'s 2024 and 2025 10-K annual filings, covering the Business, Risk Factors, Legal Proceedings, Cybersecurity, MD&A and Market Risk sections. Every new, removed and edited paragraph is highlighted side-by-side so you can see exactly what management changed in the 2025 report.

+765 added−784 removedSource: 10-K (2026-03-26) vs 10-K (2025-03-27)

Top changes in Spero Therapeutics, Inc.'s 2025 10-K

765 paragraphs added · 784 removed · 476 edited across 8 sections

Item 1. Business

Business — how the company describes what it does

133 edited+131 added−176 removed225 unchanged
Biggest changeFailure to comply with the applicable U.S. requirements at any time during the product development process, approval process or after approval, may subject an applicant to a variety of administrative or judicial sanctions, such as the FDA’s refusal to approve pending NDAs, withdrawal of an approval, imposition of a clinical hold, issuance of warning letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, refusals of government contracts, restitution, disgorgement or civil and/or criminal penalties. 19 The process required by the FDA before a drug may be marketed in the United States generally involves the following: • completion of preclinical laboratory tests, animal studies and formulation studies in compliance with GLPs and other applicable regulations; • submission to the FDA of an IND which must become effective before human clinical trials may begin; • approval by an independent institutional review board (“IRB”) before each trial may be initiated; • performance of adequate and well-controlled human clinical trials in accordance with good clinical practices (“GCPs”) to establish the safety and efficacy of the proposed drug product for each indication; • submission to the FDA of an NDA and payment of user fees; • satisfactory completion of an FDA advisory committee review, if applicable; • satisfactory completion of an FDA pre-approval inspection of the manufacturing facility or facilities at which the product is produced to assess compliance with current good manufacturing practices (“cGMPs”) and to assure that the facilities, methods and controls are adequate to preserve the drug’s identity, strength, quality and purity; • satisfactory completion of audits of clinical trial sites conducted by FDA to assure compliance with GCPs and the integrity of clinical data; and • FDA review and approval of the NDA.
Biggest changeThe process required by the FDA before a drug may be marketed in the United States generally involves the following: • completion of preclinical laboratory tests, animal studies and formulation studies in compliance with Good Laboratory Practices (“GLPs”) and other applicable regulations; • submission to the FDA of an IND which must become effective before human clinical trials may begin; • approval by an independent institutional review board (“IRB”) before each trial may be initiated; • performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practices (“GCPs”) to establish the safety and efficacy of the proposed drug product for each indication; • submission to the FDA of an NDA and payment of user fees under the PDUFA; • satisfactory completion of an FDA advisory committee review, if applicable; • satisfactory completion of an FDA pre-approval inspection of the manufacturing facility or facilities at which the product is produced to assess compliance with current Good Manufacturing Practices (“cGMPs”) and to assure that the facilities, methods and controls are adequate to preserve the drug’s identity, strength, quality and purity; • satisfactory completion of audits of clinical trial sites conducted by FDA to assure compliance with GCPs and the integrity of clinical data; and • FDA review and approval of the NDA; and • compliance with any post-approval requirements, including the potential requirement to implement a Risk Evaluation and Mitigation Strategy (“REMS”) and the potential requirement to conduct any post-approval studies required by the FDA.
The table below reflects resistance rates in the United States in the community and hospital settings. cUTIs in the United States 2024 E. coli Resistance Rates to Fluoroquinolones 2019-2022 E. coli Resistance Rates to Fluoroquinolones 2013-2014 E. coli Resistance Rates to Fluoroquinolones 2000-2004 E. coli Resistance Rates to Fluoroquinolones Community Setting 21.6% 21.5% 11.7% 0% Hospital Setting 44.3% 37.9% 34.5% 3.5% In addition, the FDA has issued several warnings against the use of fluoroquinolones in certain patients and determined that fluoroquinolones should be reserved for use in patients with these conditions who have no alternative treatment options; safety warnings in the labeling of fluoroquinolone class products have been further strengthened over the past several years.
The table below reflects resistance rates in the United States in the community and hospital settings. cUTIs in the United States 2024 E. coli Resistance Rates to Fluoroquinolones 2019-2022 E. coli Resistance Rates to Fluoroquinolones 2013-2014 E. coli Resistance Rates to Fluoroquinolones 2000-2004 E. coli Resistance Rates to Fluoroquinolones Community Setting 21.6% 21.5% 11.7% 0% Hospital Setting 44.3% 37.9% 34.5% 3.5% 5 In addition, the FDA has issued several warnings against the use of fluoroquinolones in certain patients and determined that fluoroquinolones should be reserved for use in patients with these conditions who have no alternative treatment options; safety warnings in the labeling of fluoroquinolone class products have been further strengthened over the past several years.
In addition, we have entered into license agreements (described below) pursuant to which we have granted certain development, manufacturing and commercialization rights with respect to certain of our product candidates. Tebipenem HBr Agreements GSK License Agreement On November 7, 2022, we closed the transactions contemplated by the GSK License Agreement, which was entered into on September 21, 2022.
In 7 addition, we have entered into license agreements (described below) pursuant to which we have granted certain development, manufacturing and commercialization rights with respect to certain of our product candidates. Tebipenem HBr Agreements GSK License Agreement On November 7, 2022, we closed the transactions contemplated by the GSK License Agreement, which was entered into on September 21, 2022.
Similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation; 33 • The Physician Payments Sunshine Act, enacted as part of the ACA, among other things, imposes reporting requirements on manufacturers of FDA-approved drugs, devices, biologics and medical supplies covered by Medicare or Medicaid to report, on an annual basis, to CMS information related to payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain advanced non-physician health care practitioners and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members; • HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act (“HITECH”) and their respective implementing regulations impose specified requirements relating to the privacy and security of individually identifiable health information that is protected under HIPAA, called “protected health information” or “PHI”.
Similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation; • The Physician Payments Sunshine Act, enacted as part of the ACA, among other things, imposes reporting requirements on manufacturers of FDA-approved drugs, devices, biologics and medical supplies covered by Medicare or Medicaid to report, on an annual basis, to CMS information related to payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain advanced non-physician health care practitioners and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members; • HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act (“HITECH”) and their respective implementing regulations impose specified requirements relating to the privacy and security of individually identifiable health information that is protected under HIPAA, called “protected health information” or “PHI”.
In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the civil False Claims Act; • The federal civil and criminal false claims laws, including the civil False Claims Act, and civil monetary penalty laws, prohibit, among other things, knowingly presenting or causing the presentation of a false, fictitious or fraudulent claim for payment to the U.S. government, knowingly making, using, or causing to be made or used a false record or statement material to a false or fraudulent claim to the U.S. government, or from knowingly making a false statement to avoid, decrease or conceal an obligation to pay money to the U.S. government.
In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the civil False Claims Act; • The federal civil and criminal false claims laws, including the civil False Claims Act, and civil monetary penalty laws, prohibit, among other things, knowingly presenting or causing the presentation of a false, fictitious or fraudulent claim for payment to the U.S. government, knowingly making, using, or causing to be made or used a false record or statement 30 material to a false or fraudulent claim to the U.S. government, or from knowingly making a false statement to avoid, decrease or conceal an obligation to pay money to the U.S. government.
Under the terms of the Original Everest License Agreement, we granted Everest an exclusive license to develop, manufacture and commercialize SPR206 or products that contain SPR206 (“Everest Licensed Products”) in Greater China (which includes Mainland China, Hong Kong and Macau), South Korea and certain Southeast Asian countries, collectively referred to as the “Everest Territory.” We retained development, manufacturing and commercialization rights with respect to SPR206 and Everest Licensed Products in the rest of the world and also retained the right to develop or manufacture SPR206 and Everest Licensed Products in the Everest Territory for use outside the Everest Territory.
Under the terms of the Original Everest License Agreement, we granted Everest an exclusive license to develop, manufacture and commercialize SPR206 or products 10 that contain SPR206 (“Everest Licensed Products”) in Greater China (which includes Mainland China, Hong Kong and Macau), South Korea and certain Southeast Asian countries, collectively referred to as the “Everest Territory.” We retained development, manufacturing and commercialization rights with respect to SPR206 and Everest Licensed Products in the rest of the world and also retained the right to develop or manufacture SPR206 and Everest Licensed Products in the Everest Territory for use outside the Everest Territory.
Individual states in the United States have also increasingly passed legislation and implemented regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In December 2020, the U.S.
Individual states in the United States have also increasingly passed legislation and implemented regulations designed to control pharmaceutical product 27 pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In December 2020, the U.S.
The FTC followed that action in November 2023 by publicly calling out over 100 “improper” patent listings made by ten large pharmaceutical companies and initiating an FDA administrative process with respect to those patents. The controversy regarding the 27 appropriateness of listing such patents has led to numerous lawsuits alleging anticompetitive conduct by biopharmaceutical companies.
The FTC followed that action in November 2023 by publicly calling out over 100 “improper” patent listings made by ten large pharmaceutical companies and initiating an FDA administrative process with respect to those patents. The controversy regarding the appropriateness of listing such patents has led to numerous lawsuits alleging anticompetitive conduct by biopharmaceutical companies.
To ensure cGMP and GCP compliance by its employees and third-party contractors, an applicant may incur significant expenditure of time, money and effort in the areas of training, record keeping, production and quality control. The FDA generally accepts data from foreign clinical trials in support of an NDA if the trials were conducted under an IND.
To ensure cGMP and GCP compliance by its employees and third-party contractors, an applicant may incur significant expenditure of time, money and effort in the areas of training, record keeping, 18 production and quality control. The FDA generally accepts data from foreign clinical trials in support of an NDA if the trials were conducted under an IND.
Under the terms of the Pfizer License Agreement, we received no other upfront payments but are eligible to receive up to $80.0 million in development and sales milestones, and we may also receive high single-digit to low double-digit royalties on net sales of SPR206 in the Pfizer Territory. Achievement of these payments cannot be guaranteed.
Under the terms of the Pfizer License Agreement, we received no other upfront payments but are eligible to receive up to $80.0 million in development and sales milestones, and we may also receive high single-digit to low double-digit royalties on net sales of SPR206 in the Pfizer Territory. Achievement of these payments cannot be 11 guaranteed.
Potency is commonly expressed as the minimum inhibitory concentration (“MIC”) in µg/mL or mg/L, which is the lowest concentration of drug needed to inhibit bacterial growth. Antibiotics with lower MICs are considered to be more potent. 4 • Resistance . Antibiotic resistance refers to the inability of an antibiotic to effectively control bacterial growth.
Potency is commonly expressed as the minimum inhibitory concentration (“MIC”) in µg/mL or mg/L, which is the lowest concentration of drug needed to inhibit bacterial growth. Antibiotics with lower MICs are considered to be more potent. • Resistance . Antibiotic resistance refers to the inability of an antibiotic to effectively control bacterial growth.
To the extent that our consultants, contractors, or collaborators use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting trade secrets, know-how, and inventions. 18 Competition The biopharmaceutical industry is characterized by intense competition and rapid innovation.
To the extent that our consultants, contractors, or collaborators use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting trade secrets, know-how, and inventions. Competition The biopharmaceutical industry is characterized by intense competition and rapid innovation.
The processes for obtaining regulatory approvals in the United States and in foreign countries, along with subsequent compliance with applicable statutes and regulations, require the expenditure of substantial time and financial resources. United States Government Regulation In the United States, the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act (“FDCA”) and implementing regulations.
The processes for obtaining regulatory approvals in the United States and in foreign countries and jurisdictions, along with subsequent compliance with applicable statutes and regulations, require the expenditure of substantial time and financial resources. United States Government Regulation In the United States, the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act (“FDCA”) and implementing regulations.
Post-Approval Requirements Drugs manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to recordkeeping, periodic reporting, product sampling and distribution, 25 advertising and promotion and reporting of adverse experiences with the product.
Post-Approval Requirements Drugs manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to recordkeeping, periodic reporting, product sampling and distribution, advertising and promotion and reporting of adverse experiences with the product.
After approval is granted, the FDA may withdraw the approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. In addition, FDA regulations require that products be manufactured in specific approved facilities and in accordance with cGMPs.
After approval is granted, the FDA may withdraw the approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. 21 In addition, FDA regulations require that products be manufactured in specific approved facilities and in accordance with cGMPs.
With Meiji, we have established a joint development committee for the management of the development of tebipenem HBr, including any joint, cross-territory studies that may be undertaken by the parties, if any. In addition, the parties have established a joint commercialization committee to coordinate information sharing relative to the commercialization of tebipenem HBr.
With Meiji, we have 9 established a joint development committee for the management of the development of tebipenem HBr, including any joint, cross-territory studies that may be undertaken by the parties, if any. In addition, the parties have established a joint commercialization committee to coordinate information sharing relative to the commercialization of tebipenem HBr.
Decreases in third-party reimbursement for our product candidates or a decision by a third-party payor to not cover our product candidates could reduce physician usage of the product candidate and have a material adverse effect on our sales, results of operations and financial condition.
Decreases in third-party reimbursement for any our product candidates or a decision by a third-party payor to not cover any of our product candidates could reduce physician usage of the product candidate and have a material adverse effect on our sales, results of operations and financial condition.
The aim of this Directive is to ensure that pricing and reimbursement mechanisms established in the EU Member States are transparent and objective, do not hinder the free movement of and trade in medicinal products in the EU, and do not hinder, 32 prevent or distort competition on the market.
The aim of this Directive is to ensure that pricing and reimbursement mechanisms established in the EU Member States are transparent and objective, do not hinder the free movement of and trade in medicinal products in the EU, and do not hinder, prevent or distort competition on the market.
Antibiotics that are effective against a wide variety of bacteria are considered to be broad-spectrum, while those that act upon a limited number of bacteria are considered to be narrow-spectrum. • Potency . Potency refers to the amount of antibiotic required to kill or inhibit growth of bacteria in vitro .
Antibiotics that are effective against a wide variety of bacteria are considered to be broad-spectrum, while those that act upon a limited number of bacteria are considered to be narrow-spectrum. 4 • Potency . Potency refers to the amount of antibiotic required to kill or inhibit growth of bacteria in vitro .
The action plan must include the sponsor’s diversity goals for enrollment, as well as a rationale for the goals and a description of how the sponsor will meet them. Sponsors must submit a diversity action plan to the FDA by the time the sponsor submits the relevant clinical trial protocol to the FDA for review.
The action plan must include the sponsor’s diversity goals for enrollment, as well as a rationale for the goals and a description of how the sponsor will meet them. Sponsors must submit a DAP to the FDA by the time the sponsor submits the relevant clinical trial protocol to the FDA for review.
In the United States, a patent’s term may be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the USPTO in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over an earlier-filed patent.
In the United States, a patent’s term may be lengthened by patent term adjustment, which compensates a patentee for administrative 13 delays by the USPTO in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over an earlier-filed patent.
Manufacturing We do not own or operate manufacturing facilities for the production of any of our product candidates, nor do we have plans to develop our own manufacturing operations in the foreseeable future.
Manufacturing We do not own or operate manufacturing facilities for the production of any existing or future product candidates, nor do we have plans to develop our own manufacturing operations in the foreseeable future.
Congress include the: Pioneering Antimicrobial Subscriptions to End Upsurging Resistance (“PASTEUR”) Act that would direct large federal payments for critical need antimicrobials and the Developing an Innovative Strategy for Antimicrobial Resistant Microorganisms (DISARM) Act that would provide for separate market-rate payments for antimicrobials used in hospital settings; as well as additional funding streams provided in pandemic response efforts linked to the coronavirus.
Congress include the: Pioneering Antimicrobial Subscriptions to End Upsurging Resistance (“PASTEUR”) Act that would direct large federal payments for critical need antimicrobials and the Developing an Innovative Strategy for Antimicrobial Resistant Microorganisms (“DISARM”) Act that would provide for separate market-rate payments for antimicrobials used in hospital settings; as well as additional funding streams provided in pandemic response efforts linked to the coronavirus.
Tebipenem HBr Key Attributes Tebipenem HBr is designed to be the first broad-spectrum oral carbapenem-class antibiotic to treat cUTI, including pyelonephritis caused by certain microorganisms in adults who have limited oral treatment options. Unlike other carbapenems on the U.S. market, which are only available as IV-administered infusions, tebipenem HBr is an orally administered tablet.
Tebipenem HBr Key Attributes Tebipenem HBr is designed to be the first oral carbapenem-class antibiotic to treat cUTI, including pyelonephritis caused by certain microorganisms in adults who have limited oral treatment options. Unlike other carbapenems on the U.S. market, which are only available as IV-administered infusions, tebipenem HBr is an orally administered tablet.
We also rely on the know-how and continuing technological innovation to develop and maintain our proprietary position. Spero-Owned Intellectual Property Relating to Compounds Under Development We have patent applications directed to the composition of matter, formulation and/or use of tebipenem HBr, SPR720 and SPR206 pending in the United States, Europe, Japan and other countries.
We also rely on the know-how and continuing technological innovation to develop and maintain our proprietary position. Spero-Owned Intellectual Property Relating to Compounds Under Development We have both issued and pending patent applications directed to the composition of matter, formulation and/or use of tebipenem HBr, SPR720 and SPR206 pending in the United States, Europe, Japan and other countries.
Concurrent with the GSK License Agreement, an affiliate of GSK purchased 7,450,000 shares of our common stock at a purchase price of $1.20805 per share for an aggregate purchase price of $9.0 million. Under the License Agreement, we are responsible for the execution and costs of the follow-up Phase 3 clinical trial of tebipenem HBr.
Concurrent with the GSK License Agreement, an affiliate of GSK purchased 7,450,000 shares of our common stock at a purchase price of $1.20805 per share for an aggregate purchase price of $9.0 million. Under the GSK License Agreement, we were responsible for the execution and costs of the follow-up Phase 3 clinical trial of tebipenem HBr.
The awards are subject to termination for convenience at any time by the granting government agency, and the granting government agency is not obligated to provide funding to us beyond the base period amounts from Congressionally approved annual appropriations. These awards are structured in the following manner: • BARDA award to support the further clinical development of tebipenem HBr.
The awards are subject to termination for convenience at any time by the granting government agency, and the granting government agency is not obligated to provide funding to us beyond the base period amounts from Congressionally approved annual appropriations. These awards are structured in the following manner: 12 BARDA award to support the clinical development of tebipenem HBr.
SPR206 Agreements Cantab Agreements In June 2016, we entered into a stock purchase agreement (the “Cantab Agreement”) with Pro Bono Bio PLC, a corporation organized under the laws of England, and its affiliates, including PBB Distributions Limited (“PBB”), Cantab Anti-Infectives Ltd. (“CAI”) and New Pharma License Holdings Limited (“NPLH”).
SPR206 Agreements Cantab Agreements In June 2016, we entered into a stock purchase agreement (the “Cantab Agreement”) with Pro Bono Bio PLC, a corporation organized under the laws of England, and its affiliates, including PBB Distributions Limited (“PBB”), Cantab Anti-Infectives Ltd. and New Pharma License Holdings Limited.
Ongoing Clinical Trials On July 31, 2023, we announced that we received written agreement from the FDA, under a Special Protocol Assessment (“SPA”), on the design and size of PIVOT-PO, a pivotal Phase 3 clinical trial of tebipenem HBr in patients with cUTI, including acute pyelonephritis (“AP”).
Completed Clinical Trials PIVOT-PO On July 31, 2023, we announced that we received written agreement from the FDA, under a Special Protocol Assessment (“SPA”), on the design and size of PIVOT-PO, a pivotal Phase 3 clinical trial of tebipenem HBr in patients with cUTI, including acute pyelonephritis (“AP”).
We are responsible for all costs related to developing and obtaining regulatory approval of SPR206 and Pfizer Licensed Products in the Pfizer Territory, with a focus on the European market, and are obligated to use commercially reasonable efforts, including to achieve certain specified diligence milestones within agreed-upon periods.
We were responsible for all costs related to developing and obtaining regulatory approval of SPR206 and Pfizer Licensed Products in the Pfizer Territory, with a focus on the European market, and were obligated to use commercially reasonable efforts, including to achieve certain specified diligence milestones within agreed-upon periods.
While drugs such astrimethoprim/ sulfamethoxazole and fluoroquinolones (levofloxacin, ciprofloxacin) have been the primary oral options for treatment of UTIs caused by Gram-negative organisms, nearly 30% to 35% of UTIs are caused by resistant bacteria, which has led to increased use of IV-administered therapeutics such as carbapenems.
While drugs such as trimethoprim / sulfamethoxazole and fluoroquinolones (levofloxacin, ciprofloxacin) have been the primary oral options for treatment of UTIs caused by Gram-negative organisms, nearly 30% to 35% of UTIs are caused by resistant bacteria, which has led to increased use of IV-administered therapeutics such as carbapenems.
Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting drug reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, or evidence of safety and effectiveness in a new subpopulation.
Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting product reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, and evidence of safety and effectiveness in a new subpopulation.
The review team then issues a recommendation, and a senior FDA official makes a decision. 23 A CRL indicates that the review cycle of the application is complete, and the application will not be approved in its present form.
The review team then issues a recommendation, and a senior FDA official makes a decision. 19 A CRL indicates that the review cycle of the application is complete, and the application will not be approved in its present form.
For instance, more than 40% of E. coli isolates with trimethoprim/sulfamethoxazole resistance were co-resistant to levofloxacin. While current UTI treatment guidelines published by the Infectious Diseases Society of America identify fluoroquinolones as an appropriate empirical therapy option, this recommendation is contingent on local resistance rates being less than 10%.
For instance, more than 40% of Escherichia coli (“E. coli”) isolates with trimethoprim/sulfamethoxazole resistance were co-resistant to levofloxacin. While current UTI treatment guidelines published by the Infectious Diseases Society of America identify fluoroquinolones as an appropriate empirical therapy option, this recommendation is contingent on local resistance rates being less than 10%.
The primary efficacy endpoint will be overall response (composite of clinical cure plus microbiological eradication) at the test-of-cure visit. The primary analysis for the trial will be an assessment of non-inferiority (“NI”) in the microbiological intention-to-treat population, based on a 10% NI margin.
The primary efficacy endpoint was overall response (composite of clinical cure plus microbiological eradication) at the test-of-cure visit. The primary analysis for the trial was an assessment of non-inferiority (“NI”) in the microbiological intention-to-treat population, based on a 10% NI margin.
According to the CDC, Gram-negative pathogens are particularly worrisome because they are increasingly developing resistance to currently used drugs. In 2019, the CDC designated antibiotic-resistant Gram-negative bacteria such as carbapenem-resistant Acinetobacter baumannii (“CRAB”), MDR Pseudomonas aeruginosa (“MDR PA”), carbapenem-resistant Enterobacterales (“CRE”), and extended-spectrum-β-lactamase (“ESBL”)-producing Enterobacterales as urgent or serious threats.
According to the CDC, Gram-negative pathogens are particularly worrisome because they are increasingly developing resistance to currently used drugs. In 2019, the CDC designated antibiotic-resistant Gram-negative bacteria such as carbapenem-resistant Acinetobacter baumannii (“CRAB”), multi-drug resistant (“MDR”) Pseudomonas aeruginosa (“MDR PA”), carbapenem-resistant Enterobacterales (“CRE”), and extended-spectrum-β-lactamase (“ESBL”)-producing Enterobacterales as urgent or serious threats.
We will also be responsible for providing and paying for the clinical supply of tebipenem HBr while GSK will be responsible for the costs of the commercial supply of tebipenem HBr. A joint development committee has been established between GSK and us to coordinate and review development activities for tebipenem HBr in the United States.
Additionally, we were responsible for providing and paying for the clinical supply of tebipenem HBr while GSK will be responsible for the costs of the commercial supply of tebipenem HBr. A joint development committee has been established between GSK and us to coordinate and review development activities for tebipenem HBr in the United States.
In general, state Medicaid programs are required to cover drugs of manufacturers that have entered into a Medicaid Drug Rebate Agreement, although such drugs may be subject to prior authorization or other utilization controls. The U.S.
In general, state Medicaid programs are required to cover drugs of manufacturers that have entered into a Medicaid Drug Rebate Agreement, although such drugs may be subject to prior authorization or other utilization controls.
The data do not need to show the product to be effective in the pediatric population studied; rather, the additional protection is granted if the pediatric clinical trial is deemed to have fairly responded to the FDA’s Written Request.
The data does not need to show the product to be effective in the 25 pediatric population studied; rather, the additional protection is granted if the pediatric clinical trial is deemed to have fairly responded to the FDA’s Written Request.
In addition, in the event that GSK has the right to terminate the GSK License Agreement due to a material breach by us, GSK may elect not to terminate the GSK License Agreement and in lieu thereof may assume the responsibility and expense of development of tebipenem HBr in the United States, in which event GSK’s obligation to make further development payments to us 13 (including unpaid installments of any earned milestone payments) would cease, and/or to reduce all subsequent commercial and sales milestone payments and royalty payments otherwise due by GSK to us under the GSK License Agreement by 50%.
In addition, in the event that GSK has the right to terminate the GSK License Agreement due to a material breach by us, GSK may elect not to terminate the GSK License Agreement and in lieu thereof may assume the responsibility and expense of development of tebipenem HBr in the United States, in which event GSK’s obligation to make further development payments to us would cease, and/or to reduce all subsequent commercial and sales milestone payments and royalty payments otherwise due by GSK to us under the GSK License Agreement by 50%.
PIVOT-PO is a global, randomized, double-blind, pivotal Phase 3 clinical trial of oral tebipenem HBr vs. IV imipenem cilastatin, in hospitalized adult patients with cUTI/AP. Patients will be randomized 1:1 to receive tebipenem HBr (600 mg) orally every six hours, or imipenem cilastatin (500 mg) IV every six hours, for a total of seven to ten days.
PIVOT-PO was a global, randomized, double-blind, pivotal Phase 3 clinical trial of oral tebipenem HBr vs. IV imipenem cilastatin, in hospitalized adult patients with cUTI/AP. Patients were randomized 1:1 to receive tebipenem HBr (600 mg) orally every six hours, or imipenem cilastatin (500 mg) IV every six hours, for a total of seven to ten days.
However, the high rates of fluoroquinolone-resistant Escherichia coli (“E. coli”) found in the United States today in the community and hospital settings, as shown in the table below, would suggest that there is a need for an antibiotic that is effective against fluoroquinolone-resistant infections.
However, the high rates of fluoroquinolone-resistant E. coli found in the United States today in the community and hospital settings, as shown in the table below, would suggest that there is a need for an antibiotic that is effective against fluoroquinolone-resistant infections.
Whether or not we obtain FDA approval for a product, we must obtain approval by the comparable regulatory authorities of foreign countries or economic areas, such as the European Union (“EU”) and Australia, before we may commence clinical trials or market products in those countries or areas.
Whether or not we obtain FDA approval for a product, we must obtain approval by the comparable regulatory authorities of foreign countries or economic areas, such as the EU and Australia, before we may commence clinical trials or market products in those countries or areas.
The information contained in our website is not intended to be a part of this filing. 35
The information contained in our website is not intended to be a part of this filing. 32
Phase 3 clinical trials usually involve a larger number of participants than a Phase 2 clinical trial. Congress recently amended the FDCA to require sponsors of a Phase 3 clinical trial, or other “pivotal study” of a new drug to support marketing authorization, and to design and submit a diversity action plan for such clinical trial.
Phase 3 clinical trials usually involve a larger number of participants than a Phase 2 clinical trial. In December 2022, Congress amended the FDCA to require sponsors of a Phase 3 clinical trial, or other “pivotal study” of a new drug to support marketing authorization, and to design and submit a diversity action plan (“DAP”) for such clinical trial.
The PDUFA time clock begins on the FDA receipt date except for eligible products (i.e., new molecular entity (“NME”) NDAs and original biologics license applications (“BLAs”)). For these applications, the PDUFA time clock begins 60 days after the application receipt date if the application is filed; however, the review timeline for all applications begins on the day of submission.
The PDUFA time clock begins on the FDA receipt date except for eligible products (i.e., new molecular entity (“NME”) NDAs and original new drug applications (“NDAs”)). For these applications, the PDUFA time clock begins 60 days after the application receipt date if the application is filed; however, the review timeline for all applications begins on the day of submission.
Finally, the development of new treatment methods for the diseases we are targeting could render our product candidates non-competitive or obsolete.
Finally, the development of new treatment methods for the diseases we are targeting could render our existing and future product candidates non-competitive or obsolete.
The FDA may not grant approval on a timely basis, or at all. The FDA also may require submission of a Risk Evaluation and Mitigation Strategy (“REMS”) if it determines that a REMS is necessary to ensure that the benefits of the product outweigh its risks and to assure the safe use of the product.
The FDA may not grant approval on a timely basis, or at all. The FDA also may require submission of a REMS if it determines that a REMS is necessary to ensure that the benefits of the product outweigh its risks and to assure the safe use of the product.
HITECH also increased the civil and criminal penalties that may be imposed against covered entities, business associates and third parties who acquire PHI unlawfully, and gave state attorneys general new authority to file civil actions for damages or injunctions in federal courts to enforce HIPAA and seek attorney’s fees and costs associated with pursuing federal civil actions; • State and federal consumer protection laws, including the Federal Trade Commission Act, the Washington My Health, My Data Act, and other state privacy laws in Nevada and Connecticut govern the collection, use, disclosure and protection of health and other personal information and could apply to our operations and the operations of our collaborators; and • Analogous state laws and regulations, such as state anti-kickback and false claims laws which may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors, including private insurers; state laws which require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government in addition to requiring drug and therapeutic biologics manufacturers to report information related to payments to physicians and other healthcare providers or marketing expenditures and pricing information; state and local laws which require the registration of pharmaceutical sales representatives; and state laws and non-U.S. laws and regulations that govern the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways, thus complicating compliance efforts.
HITECH also increased the civil and criminal penalties that may be imposed against covered entities, business associates and third parties who acquire PHI unlawfully, and gave state attorneys general new authority to file civil actions for damages or injunctions in federal courts to enforce HIPAA and seek attorney’s fees and costs associated with pursuing federal civil actions; State and federal consumer protection laws, including the Federal Trade Commission Act, the Washington My Health, My Data Act, and other state privacy laws in Nevada and Connecticut govern the collection, use, disclosure and protection of health and other personal information and could apply to our operations and the operations of our collaborators; and • Analogous state laws and regulations, such as state anti-kickback and false claims laws which may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors, including private insurers; state laws which require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government in addition to requiring drug and therapeutic biologics manufacturers to report information related to payments to physicians and other healthcare providers or marketing expenditures and pricing information; state and local laws which require the registration of pharmaceutical sales representatives; and state laws and non-U.S. laws and regulations that govern the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways, thus complicating compliance efforts. 31 Antimicrobial Policy Efforts to respond to the growth of antimicrobial resistance (“AMR”) have taken various forms, from non-dilutive financing of discovery, research, and development to proposals to reward innovation and enhance reimbursement.
GSK is responsible for the execution and costs of any additional further development, including additional Phase 3 trials, regulatory filings and commercialization activities for tebipenem HBr in the GSK Territory.
We were responsible for the execution and costs of the Phase 3 clinical trial of tebipenem HBr. GSK is responsible for the execution and costs of any additional further development, including additional Phase 3 trials, regulatory filings and commercialization activities for tebipenem HBr in the GSK Territory.
Everest Medicines License Agreement On January 4, 2019, we, through NPLH, entered into a license agreement (the “Original Everest License Agreement”) with Everest, which Original Everest License Agreement also included an option granted by our wholly-owned subsidiary, Spero Potentiator, Inc., a Delaware corporation.
Everest Medicines License Agreement On January 4, 2019, we, through our wholly owned subsidiary New Pharma License Holdings Limited (“NPLH”), entered into a license agreement (the “Original Everest License Agreement”) with Everest, which Original Everest License Agreement also included an option granted by our wholly-owned subsidiary, Spero Potentiator, Inc., a Delaware corporation.
Under the Ensuring Innovation Act, which was signed into law in April 2021, the FDA must publish action packages summarizing its decisions to approve new drugs within 30 days of approval of such products. To date, CRLs are not publicly available documents.
Under the Ensuring Innovation Act, which was signed into law in April 2021, the FDA must publish action packages summarizing its decisions to approve new drugs within 30 days of approval of such products.
The Centers for Disease Control and Prevention (“CDC”) estimates that the annual impact of antibiotic-resistant infections on the U.S. economy is $20–$35 billion in direct health care costs. Both Gram-positive and Gram-negative pathogens harbor resistance mechanisms and contribute to the global threat.
The Centers for Disease Control and Prevention (“CDC”) estimates that the annual impact of antibiotic-resistant infections on the U.S. economy is at least $20 billion annually in excess direct health care costs, with an additional $35 billion in lost productivity. Both Gram-positive and Gram-negative pathogens harbor resistance mechanisms and contribute to the global threat.
Tebipenem HBr Oral Carbapenem (Tebipenem Pivoxil Hydrobromide) Our tebipenem HBr program contains one issued and three pending United States patent applications, and 40 issued and 30 pending foreign patent applications covering novel solid forms of tebipenem pivoxil hydrobromide and novel pharmaceutical formulations of tebipenem pivoxil hydrobromide as of December 31, 2024, all wholly owned by us.
Tebipenem HBr Oral Carbapenem (Tebipenem Pivoxil Hydrobromide) Our tebipenem HBr program contains multiple issued patents and pending United States patent applications, and issued patents and pending foreign patent applications covering novel solid forms of tebipenem pivoxil hydrobromide and novel pharmaceutical formulations of tebipenem pivoxil hydrobromide as of December 31, 2025, all wholly owned by us.
The issued foreign patents are issued in Australia, Brazil, Canada, the Eurasian Patent Office (“EAPO”), which includes Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Turkmenistan, Indonesia, Israel, Japan, Mexico, New Zealand, South Korea, and South Africa.
Foreign patents are issued in Australia, Brazil, Canada, the Eurasian Patent Office (which includes Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Turkmenistan) Indonesia, Israel, Japan, Mexico, New Zealand, South Korea, and South Africa. Foreign patent applications are pending in Australia, Canada, China, Egypt, India, the Philippines, and Thailand.
We received the first installment payment of $23.8 million for such development milestone in February 2024, the second installment payment of $23.8 million in August 2024 and the third installment payment of $23.8 million in February 2025. The final installment payment of $23.8 million is expected to be received in the third quarter of 2025.
We received the first installment payment of $23.8 million for such development milestone in the first quarter of 2024, the second installment payment in the third quarter of 2024, the third installment payment in the first quarter of 2025 and we received the final development milestone installment in the third quarter of 2025.
Under the terms of the Pfizer License Agreement, we granted Pfizer an exclusive royalty-bearing license to develop, manufacture and commercialize SPR206 or products that contain SPR206 (the “Pfizer Licensed Products”) globally with some territorial exceptions (the “Pfizer Territory”).
Under the terms of the Pfizer License Agreement, we granted Pfizer an exclusive royalty-bearing license to develop, manufacture and commercialize SPR206 or products that contain SPR206 (the “Pfizer Licensed Products”) globally with some territorial exceptions (the “Pfizer Territory”). The Pfizer Territory excludes the United States and the Asian markets previously licensed to Everest in the Everest Territory.
Individual states in the United States have increasingly passed legislation and implemented regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.
At the state level, individual states are increasingly aggressive in passing legislation and implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.
While data showed antimicrobial activity associated with SPR720, the analysis did not show sufficient separation from placebo and highlighted potential dose limiting safety issues in patients dosed at 1,000 mg orally once daily, including three cases of reversible grade 3 hepatotoxicity.
While data showed antimicrobial activity associated with SPR720, the analysis did not show sufficient separation from placebo and highlighted potential dose limiting safety issues in patients dosed at 1,000 mg orally once daily, including three cases of reversible grade 3 hepatotoxicity. After assessing next steps for SPR720, we announced that we ceased development of SPR720 in November 2025.
The FDA may request additional information rather than accept an application for filing. In this event, the application must be resubmitted with additional information. The resubmitted application is also subject to review before the FDA accepts it for filing. Review of NDAs After the submission is accepted for filing, the FDA begins an in-depth substantive review of the application.
The FDA may request additional information rather than accept an application for filing. In this event, the application must be resubmitted with additional information. The resubmitted application is also subject to review before the FDA accepts it for filing.
Randomization is stratified by age, baseline diagnosis (cUTI or AP), and the presence or absence of urinary tract instrumentation. In December 2023, we commenced enrollment in PIVOT-PO. The pre-planned interim analysis of PIVOT-PO is expected to be completed in the second quarter of 2025.
Randomization was stratified by age, baseline diagnosis (cUTI or AP), and the presence or absence of urinary tract instrumentation. 6 In December 2023, we commenced enrollment in PIVOT-PO. The pre-planned interim analysis of PIVOT-PO was completed in May 2025.
We currently rely on a limited number of third-party contract manufacturers for all of our required raw materials, drug substance, and finished drug product for our preclinical research and clinical trials. We currently employ internal resources to manage our manufacturing. We currently have two suppliers for tebipenem HBr’s active pharmaceutical ingredient.
We have historically relied on a limited number of third-party contract manufacturers for all of our required raw materials, drug substance, and finished drug product for our preclinical research and clinical trials. We currently employ internal resources to manage our manufacturing.
Item 1. B usiness. Overview We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases caused by multi-drug resistant (“MDR”) bacterial infections with high unmet need.
Item 1. B usiness. Overview We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases with high unmet need.
A joint development committee was established between Pfizer and us to coordinate and review the development, manufacturing and commercialization plans with respect to Pfizer Licensed Products in the Pfizer Territory. Pfizer is responsible for commercializing SPR206 and the Licensed Products in the Pfizer Territory.
A joint development committee was established between Pfizer and us to coordinate and review the development, manufacturing and commercialization plans with respect to Pfizer Licensed Products in the Pfizer Territory. Pfizer was responsible for commercializing SPR206 and the Licensed Products in the Pfizer Territory. In March 2025, we notified Pfizer of our decision to cease development of SPR206.
The government has recently begun enforcing these registration and results reporting requirements against non-compliant clinical trial sponsors. 20 Human clinical trials are typically conducted in three sequential phases, which may overlap or be combined: Phase 1 : The drug is initially introduced into healthy human subjects or patients with the target disease or condition and tested for safety, dosage tolerance, ADME and, if possible, to gain an early indication of its effectiveness.
Human clinical trials are typically conducted in three sequential phases, which may overlap or be combined: Phase 1 : The drug is initially introduced into healthy human subjects or patients with the target disease or condition and tested for safety, dosage tolerance, ADME and, if possible, to gain an early indication of its effectiveness.
In February 2019, we were granted QIDP designation for SPR720 capsule for oral use for the treatment of lung infections caused by nontuberculous mycobacteria and for the treatment of lung infections caused by Mycobacterium TB . 28 In addition to the expedited review benefits for which a QIDP-designated drug candidate may be eligible, such a drug that is approved for the use for which the QIDP designation was granted will receive a five-year extension to any non-patent marketing exclusivity period for which the drug qualified upon approval, such as five-year NCE exclusivity, three-year new clinical data exclusivity, seven-year orphan exclusivity, or six-month pediatric exclusivity.
In addition to the expedited review benefits for which a QIDP-designated drug candidate may be eligible, such a drug that is approved for the use for which the QIDP designation was granted will receive a five-year extension to any non-patent marketing exclusivity period for which the drug qualified upon approval, such as five-year NCE exclusivity, three-year new clinical data exclusivity, seven-year orphan exclusivity, or six-month pediatric exclusivity.
Nonetheless, from a practical perspective, a sponsor’s failure to follow the FDA’s recommendations for design of a clinical program may put the program at significant risk of failure. 21 Acceptance of NDAs Assuming successful completion of the required clinical testing, the results of the nonclinical studies and clinical trials, along with information relating to the product’s chemistry, manufacturing, controls, safety updates, patent information, abuse information and proposed labeling, are submitted to the FDA as part of an application requesting approval to market the product candidate for one or more indications.
Acceptance of NDAs Assuming successful completion of the required clinical testing, the results of the nonclinical studies and clinical trials, along with information relating to the product’s chemistry, manufacturing, controls, safety updates, patent information, abuse information and proposed labeling, are submitted to the FDA as part of an application requesting approval to market the product candidate for one or more indications.
The Pfizer Territory excludes the United States and the Asian markets previously licensed to Everest in the Everest Territory. 15 In connection with the Pfizer Purchase Agreement, Pfizer purchased 2,362,348 shares of our common stock at a price of $16.93 per share for a total investment of $40.0 million.
In connection with the Pfizer Purchase Agreement, Pfizer purchased 2,362,348 shares of our common stock at a price of $16.93 per share for a total investment of $40.0 million.
As a result, submission of an IND may not result in the FDA allowing clinical trials to commence. A clinical hold may occur at any time during the life of an IND and may affect one or more specific studies or all studies conducted under the IND.
A clinical hold may occur at any time during the life of an IND and may affect one or more specific studies or all studies conducted under the IND.
Qualified Infectious Disease Product Exclusivity Under the GAIN Act, the FDA may designate a qualified product as a QIDP.
Qualified Infectious Disease Product Exclusivity Under the Generating Antibiotic Incentives Now (“GAIN”) Act, the FDA may designate a qualified product as a QIDP.
The growing challenges, caused by limited effective oral treatment options for cUTI and pyelonephritis and the increasing resistance rates amongst uropathogens, place a significant burden on both patients and the healthcare system, in terms of recurrent infections, hospitalizations, and cost.
The growing challenges, including the increasing resistance rates amongst uropathogens, place a significant burden on both patients and the healthcare system, in terms of recurrent infections, hospitalizations, and cost.
The FDA may grant a waiver for some or all of the requirements for a diversity action plan. If the FDA objects to a sponsor’s diversity action plan or otherwise requires significant changes to be made, it could delay initiation of the relevant clinical trial.
The FDA may grant a waiver for some or all of the requirements for a DAP. If the FDA objects to a sponsor’s DAP or otherwise requires significant changes to be made, it could delay initiation of the relevant clinical trial. In June 2024, the FDA issued draft guidance outlining the general requirements for DAPs.
Data may come from company-sponsored clinical trials intended to test the safety and efficacy of a product’s use or from a number of alternative sources, including studies initiated by investigators. To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety and efficacy of a drug product.
Data may come from company-sponsored clinical trials intended to test the safety and efficacy of a product’s use or from a number of alternative sources, including studies initiated by investigators.
Scrutiny of the accelerated approval pathway is likely to continue and may lead to legislative and/or administrative changes in the future. Special Protocol Assessment A company may reach an agreement with FDA under the SPA process as to the required design and size of clinical trials intended to form the primary basis of an efficacy claim.
Special Protocol Assessment A company may reach an agreement with FDA under the SPA process as to the required design and size of clinical trials intended to form the primary basis of an efficacy claim.
Post-approval trials, sometimes referred to as “Phase 4” clinical trials, may be conducted after initial marketing approval. These trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication. In certain instances, FDA may mandate the performance of Phase 4 clinical trials.
In addition, the FDA issued final guidance outlining recommendations for the implementation of decentralized clinical trials. Post-approval trials, sometimes referred to as “Phase 4” clinical trials, may be conducted after initial marketing approval. These trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication.
The FDA will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and are adequate to assure consistent production of the product within required specifications.
The FDA will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and are adequate to assure consistent production of the product within required specifications. Moreover, the FDA will review a sponsor’s financial relationship with the principal investigators who conducted the clinical trials in support of the NDA.
Under the terms of the GSK License Agreement, we are entitled to receive a $95.0 million development milestone that is payable in four equal semiannual installments.
In December 2023, we commenced enrollment in PIVOT-PO with its first patient, first visit. Under the terms of the GSK License Agreement, we were entitled to receive a $95.0 million development milestone that is payable in four equal semiannual installments.
Under the Orphan Drug Act, the FDA may grant orphan drug designation to a drug intended to treat a rare disease or condition, which is generally a disease or condition that affects either (i) fewer than 200,000 individuals in the United States, or (ii) more than 200,000 individuals in the United States and for which there is no reasonable expectation that the cost of developing and making available in the United States a drug for this type of disease or condition will be recovered from sales in the United States for that drug.
This so-called GAIN exclusivity extension is not available to a QIDP-designated drug that has previously received the five-year extension period, such as when an applicant is seeking approval for a new indication or new strength of an FDA-approved and commercially marketed drug. 24 Orphan Drug Designation and Exclusivity Under the Orphan Drug Act, the FDA may grant orphan drug designation to a drug intended to treat a rare disease or condition, which is generally a disease or condition that affects either (i) fewer than 200,000 individuals in the United States, or (ii) more than 200,000 individuals in the United States and for which there is no reasonable expectation that the cost of developing and making available in the United States a drug for this type of disease or condition will be recovered from sales in the United States for that drug.
The FDA also may inspect the sponsor and one or more clinical trial sites to assure compliance with IND and GCP requirements and the integrity of the clinical data submitted to the FDA.
If so, the FDA may exclude data from the clinical trial site in connection with its determination of safety and efficacy of the investigational product. The FDA also may inspect the sponsor and one or more clinical trial sites to assure compliance with IND and GCP requirements and the integrity of the clinical data submitted to the FDA.
Under the terms of the GSK License Agreement, we received an upfront payment of $66.0 million for GSK to secure rights to the medicine, and GSK also invested $9.0 million in our common stock. 12 In July 2023, we received written agreement from the FDA, under a SPA, on the design and size of PIVOT-PO, a pivotal Phase 3 clinical trial of tebipenem HBr in patients with cUTI, including AP.
In July 2023, we received written agreement from the FDA, under a SPA, on the design and size of PIVOT-PO, a pivotal Phase 3 clinical trial of tebipenem HBr in patients with cUTI, including AP. Under the terms of the GSK License Agreement, we received a $30.0 million development milestone payment during the third quarter of 2023.

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Item 1A. Risk Factors

Risk Factors — what could go wrong, per management

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Biggest changeAlthough we have decided to discontinue further development of SPR206 and are exploring strategic options, including potential out-licensing, to maximize the value for the program and allow us to leverage the expertise of strategic partners and have suspended our current development efforts with respect to the SPR720 oral program, although we continue to evaluate other potential paths forward as the remaining data are collected and analyzed, our business remains heavily dependent on the successful development, regulatory approval, and, if approved, commercialization of tebipenem HBr and other future product candidates.
Biggest changeAlthough we decided to cease further development of SPR206 and SPR720, our business remains heavily dependent on the successful development, regulatory approval, and, if approved, commercialization of tebipenem HBr and any future product candidates. We cannot be certain that any product candidate will receive regulatory approval or will be successfully commercialized even if it receives regulatory approval.
In the case of our clinical trials, results may differ on the basis of the type of bacteria with which patients are infected. We cannot make assurances that any clinical trials that we may conduct will demonstrate consistent or adequate efficacy and safety to obtain regulatory approval to market our product candidates.
In the case of our clinical trials, results may differ on the basis of the type of bacteria with which patients are infected. We cannot make assurances that any clinical trials that we may conduct will demonstrate consistent or adequate efficacy and safety to obtain regulatory approval to market any product candidates.
Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize our product candidates, which may harm our business and results of operations.
Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize any product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize any product candidates, which may harm our business and results of operations.
If unexpected adverse events occur in any of our ongoing or planned clinical trials, we may need to abandon development of our product candidates, or limit development to lower doses or to certain uses or subpopulations in which the undesirable side effects or other unfavorable characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective.
If unexpected adverse events occur in any of our ongoing or planned clinical trials, we may need to abandon development of any product candidates, or limit development to lower doses or to certain uses or subpopulations in which the undesirable side effects or other unfavorable characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective.
Any failure of any of our product candidates that obtains regulatory approval to achieve market acceptance or commercial success would adversely affect our business prospects.
Any failure of any product candidates that obtains regulatory approval to achieve market acceptance or commercial success would adversely affect our business prospects.
We face an inherent risk of product liability claims as a result of the clinical testing of our product candidates despite obtaining appropriate informed consents from our clinical trial participants. We will face an even greater risk if we obtain marketing approval for and commercially sell any of our product candidates.
We face an inherent risk of product liability claims as a result of the clinical testing of any product candidates despite obtaining appropriate informed consents from our clinical trial participants. We will face an even greater risk if we obtain marketing approval for and commercially sell any product candidates.
Regardless of the merits or eventual outcome, liability claims may result in: • reduced resources for our management to pursue our business strategy; • decreased demand for our product candidates or products that we may develop; • injury to our reputation and significant negative media attention; • withdrawal of clinical trial participants; • initiation of investigations by regulators; • product recalls, withdrawals or labeling, marketing or promotional restrictions; • significant costs to defend resulting litigation; • substantial monetary awards to trial participants or patients; • loss of revenue; and • the inability to commercialize any products that we may develop.
Regardless of the merits or eventual outcome, liability claims may result in: • reduced resources for our management to pursue our business strategy; • decreased demand for any product candidates or products that we may develop; • injury to our reputation and significant negative media attention; • withdrawal of clinical trial participants; • initiation of investigations by regulators; • product recalls, withdrawals or labeling, marketing or promotional restrictions; • significant costs to defend resulting litigation; • substantial monetary awards to trial participants or patients; • loss of revenue; and • the inability to commercialize any products that we may develop.
To the extent that any disruption or cybersecurity incident results in a loss of or damage to our data or applications, or inappropriate disclosure or theft of confidential or proprietary information, in addition to incurring liability, the further development of our product candidates could be delayed or our competitive position could be compromised.
To the extent that any disruption or cybersecurity incident results in a loss of or damage to our data or applications, or inappropriate disclosure or theft of confidential or proprietary information, in addition to incurring liability, the further development of any of our product candidates could be delayed or our competitive position could be compromised.
The FDA or any foreign regulatory bodies can delay, limit or deny approval of our product candidates or require us to conduct additional nonclinical or clinical testing or abandon a program for many reasons, including: • the FDA or the applicable foreign regulatory agency’s disagreement with the design or implementation of our clinical trials; • negative or ambiguous results from our clinical trials or results that may not meet the level of statistical significance required by the FDA or comparable foreign regulatory agencies for approval; • serious and unexpected drug-related side effects experienced by participants in our clinical trials or by individuals using drugs similar to our product candidates; • our inability to demonstrate to the satisfaction of the FDA or the applicable foreign regulatory body that our product candidates are safe and effective for the proposed indication; • the FDA’s or the applicable foreign regulatory agency’s disagreement with the interpretation of data from nonclinical studies or clinical trials; • our inability to demonstrate the clinical and other benefits of our product candidates outweigh any safety or other perceived risks; • the FDA’s or the applicable foreign regulatory agency’s requirement for additional nonclinical studies or clinical trials; • the FDA’s or the applicable foreign regulatory agency’s disagreement regarding the formulation, labeling and/or the specifications for our product candidates; or • the potential for approval policies or regulations of the FDA or the applicable foreign regulatory agencies to significantly change in a manner rendering our clinical data insufficient for approval.
The FDA or any foreign regulatory bodies can delay, limit or deny approval of any of our product candidates or require us to conduct additional nonclinical or clinical testing or abandon a program for many reasons, including: • the FDA or the applicable foreign regulatory agency’s disagreement with the design or implementation of our clinical trials; • negative or ambiguous results from our clinical trials or results that may not meet the level of statistical significance required by the FDA or comparable foreign regulatory agencies for approval; • serious and unexpected drug-related side effects experienced by participants in our clinical trials or by individuals using drugs similar to any of our product candidates; • our inability to demonstrate to the satisfaction of the FDA or the applicable foreign regulatory body that any of our product candidates are safe and effective for the proposed indication; • the FDA’s or the applicable foreign regulatory agency’s disagreement with the interpretation of data from nonclinical studies or clinical trials; • our inability to demonstrate the clinical and other benefits of any of our product candidates outweigh any safety or other perceived risks; • the FDA’s or the applicable foreign regulatory agency’s requirement for additional nonclinical studies or clinical trials; • the FDA’s or the applicable foreign regulatory agency’s disagreement regarding the formulation, labeling and/or the specifications for any of our product candidates; or • the potential for approval policies or regulations of the FDA or the applicable foreign regulatory agencies to significantly change in a manner rendering our clinical data insufficient for approval.
Recently enacted and future policies and legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our product candidates and may affect the reimbursement made for any product candidate for which we receive marketing approval.
Recently enacted and future policies and legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize any of our product candidates and may affect the reimbursement made for any product candidate for which we receive marketing approval.
We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand for our product candidates or additional pricing pressures.
We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand for any of our product candidates or additional pricing pressures.
Unstable global economic and political conditions, including economic uncertainty tied to volatility in interest rates and inflation, credit and financial market instability, and uncertainty related to ongoing geopolitical conflicts, could adversely affect our business, financial condition, stock price and ability to raise capital.
Unstable global economic and political conditions, including economic uncertainty tied to volatility in interest rates and inflation, credit and financial market instability, and uncertainty related to ongoing geopolitical conflicts, could adversely affect our business, financial condition, stock price and ability to raise capital.
Even if we are able to obtain approval for commercialization of a product candidate in a foreign country, we will be subject to additional risks related to international business operations, including: • potentially reduced protection for intellectual property rights; • the potential for so-called parallel importing, which is what happens when a local seller, faced with high or higher local prices, opts to import goods from a foreign market (with low or lower prices) rather than buying them locally; • unexpected changes in tariffs, trade barriers and regulatory requirements; • economic weakness, including inflation, or political instability in particular foreign economies and markets; • workforce uncertainty in countries where labor unrest is more common than in the United States; 69 • production shortages resulting from any events affecting a product candidate and/or finished drug product supply or manufacturing capabilities abroad; • business interruptions resulting from geo-political conflicts, including war and terrorism, health epidemics or natural disasters, including earthquakes, hurricanes, typhoons, floods and fires; and • failure to comply with Office of Foreign Asset Control rules and regulations and the Foreign Corrupt Practices Act.
Even if we are able to obtain approval for commercialization of a product candidate in a foreign country, we will be subject to additional risks related to international business operations, including: • potentially reduced protection for intellectual property rights; • the potential for so-called parallel importing, which is what happens when a local seller, faced with high or higher local prices, opts to import goods from a foreign market (with low or lower prices) rather than buying them locally; • unexpected changes in tariffs, trade barriers and regulatory requirements; • economic weakness, including inflation, or political instability in particular foreign economies and markets; • workforce uncertainty in countries where labor unrest is more common than in the United States; • production shortages resulting from any events affecting a product candidate and/or finished drug product supply or manufacturing capabilities abroad; • business interruptions resulting from geo-political conflicts, including war and terrorism, health epidemics or natural disasters, including earthquakes, hurricanes, typhoons, floods and fires; and • failure to comply with Office of Foreign Asset Control rules and regulations and the Foreign Corrupt Practices Act.
The degree of market acceptance of any product candidate for which we receive approval depends on a number of factors, including: • the efficacy and safety of the product candidate as demonstrated in clinical trials; • relative convenience and ease of administration; 40 • the clinical indications for which the product candidate is approved; • the potential and perceived advantages and disadvantages of the product candidates, including cost and clinical benefit relative to alternative treatments; • the willingness of physicians to prescribe the product and of the target patient population to try new therapies; • the willingness of hospital pharmacy directors to purchase the product for their formularies; • acceptance by physicians, patients, operators of hospitals and treatment facilities and parties responsible for coverage and reimbursement of the product; • the availability of coverage and adequate reimbursement by third-party payors and government authorities; • the effectiveness of our sales and marketing efforts; • the strength of marketing and distribution support; • limitations or warnings, including distribution or use restrictions, contained in the product’s approved labeling or an approved REMS; • whether the product is designated under physician treatment guidelines as a first-line therapy or as a second- or third-line therapy for particular infections; • the approval of other new products for the same indications; • the timing of market introduction of the approved product as well as competitive products; • adverse publicity about the product or favorable publicity about competitive products; • the emergence of bacterial resistance to the product; and • the rate at which resistance to other drugs in the target infections grows.
The degree of market acceptance of any product candidate for which we receive approval depends on a number of factors, including: • the efficacy and safety of the product candidate as demonstrated in clinical trials; • relative convenience and ease of administration; • the clinical indications for which the product candidate is approved; • the potential and perceived advantages and disadvantages of the product candidates, including cost and clinical benefit relative to alternative treatments; • the willingness of physicians to prescribe the product and of the target patient population to try new therapies; • the willingness of hospital pharmacy directors to purchase the product for their formularies; • acceptance by physicians, patients, operators of hospitals and treatment facilities and parties responsible for coverage and reimbursement of the product; • the availability of coverage and adequate reimbursement by third-party payors and government authorities; • the effectiveness of our sales and marketing efforts; • the strength of marketing and distribution support; • limitations or warnings, including distribution or use restrictions, contained in the product’s approved labeling or an approved REMS; • whether the product is designated under physician treatment guidelines as a first-line therapy or as a second- or third-line therapy for particular infections; • the approval of other new products for the same indications; • the timing of market introduction of the approved product as well as competitive products; • adverse publicity about the product or favorable publicity about competitive products; • the emergence of bacterial resistance to the product; and • the rate at which resistance to other drugs in the target infections grows.
Among other things, these provisions: • establish a classified Board of Directors such that all members of the board are not elected at one time; • allow the authorized number of our directors to be changed only by resolution of our Board of Directors; • limit the manner in which stockholders can remove directors from our Board of Directors; • establish advance notice requirements for nominations for election to our Board of Directors or for proposing matters that can be acted on at stockholder meetings; • require that stockholder actions must be effected at a duly called stockholder meeting and prohibit actions by our stockholders by written consent; • limit who may call a special meeting of stockholders; 73 • authorize our Board of Directors to issue preferred stock without stockholder approval, which could be used to institute a “poison pill” that would work to dilute the stock ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our Board of Directors; and • require the approval of the holders of at least 75% of the votes that all of our stockholders would be entitled to cast to amend or repeal certain provisions of our Amended and Restated Certificate of Incorporation, as amended, or Amended and Restated Bylaws.
Among other things, these provisions: • establish a classified Board of Directors such that all members of the board are not elected at one time; • allow the authorized number of our directors to be changed only by resolution of our Board of Directors; • limit the manner in which stockholders can remove directors from our Board of Directors; • establish advance notice requirements for nominations for election to our Board of Directors or for proposing matters that can be acted on at stockholder meetings; • require that stockholder actions must be effected at a duly called stockholder meeting and prohibit actions by our stockholders by written consent; • limit who may call a special meeting of stockholders; • authorize our Board of Directors to issue preferred stock without stockholder approval, which could be used to institute a “poison pill” that would work to dilute the stock ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our Board of Directors; and • require the approval of the holders of at least 75% of the votes that all of our stockholders would be entitled to cast to amend or repeal certain provisions of our Amended and Restated Certificate of Incorporation, as amended, or Amended and Restated Bylaws.
In addition, if any product fails to comply with applicable regulatory requirements, a regulatory agency may: • issue warning letters, untitled letters or impose holds on clinical trials if any are still on-going; • mandate modifications to promotional materials or require provision of corrective information to healthcare practitioners; • impose restrictions on the product or its manufacturers or manufacturing processes; • impose restrictions on the labeling or marketing of the product; • impose restrictions on product distribution or use; • require post-marketing studies or clinical trials; • require withdrawal of the product from the market; • refuse to approve pending applications or supplements to approved applications that we submit; • require recall of the product; • require entry into a consent decree, which can include imposition of various fines (including restitution or disgorgement of profits or revenue), reimbursements for inspection costs, required due dates for specific actions and penalties for noncompliance; • suspend or withdraw marketing approvals; • refuse to permit the import or export of the product; • seize or detain supplies of the product; or • issue injunctions or impose civil or criminal penalties.
In addition, if any product fails to comply with applicable regulatory requirements, a regulatory agency may: • issue warning letters, untitled letters or impose holds on clinical trials if any are still on-going; • mandate modifications to promotional materials or require provision of corrective information to healthcare practitioners; • impose restrictions on the product or its manufacturers or manufacturing processes; • impose restrictions on the labeling or marketing of the product; • impose restrictions on product distribution or use; 60 • require post-marketing studies or clinical trials; • require withdrawal of the product from the market; • refuse to approve pending applications or supplements to approved applications that we submit; • require recall of the product; • require entry into a consent decree, which can include imposition of various fines (including restitution or disgorgement of profits or revenue), reimbursements for inspection costs, required due dates for specific actions and penalties for noncompliance; • suspend or withdraw marketing approvals; • refuse to permit the import or export of the product; • seize or detain supplies of the product; or • issue injunctions or impose civil or criminal penalties.
We may encounter unforeseen events prior to, during, or as a result of, clinical trials that could delay or prevent us from obtaining regulatory approval for any of our product candidates, including: • the FDA or other comparable foreign regulatory authorities may disagree as to the design or implementation of our clinical trials; • we may be delayed in or fail to reach agreement on acceptable terms with prospective CROs and clinical trial sites, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and trial sites; • clinical trials of our product candidates may produce unfavorable or inconclusive results; • we may decide, or regulators may cause us, to conduct additional clinical trials or abandon product development programs; • the number of patients required for clinical trials of our product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate, participants may drop out of these clinical trials at a higher rate than we anticipate or we may fail to recruit suitable patients to participate in clinical trials; • our third-party contractors, including those manufacturing our product candidates or conducting clinical trials on our behalf, may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all; • the FDA or institutional review boards may not authorize us or our investigators to commence a clinical trial or conduct a clinical trial at a prospective trial site; • regulators or institutional review boards may require that we or our investigators suspend or terminate clinical trials of our product candidates for various reasons, including noncompliance with regulatory requirements or a finding that the participants are being exposed to unacceptable health risks, undesirable side effects or other unexpected characteristics of the product candidate; 37 • the FDA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of third-party manufacturers with which we enter into agreements for clinical and commercial supplies; • the supply or quality of our product candidates or other materials necessary to conduct clinical trials of our product candidates may be insufficient or inadequate; and • the approval policies or regulations of the FDA or comparable foreign regulatory authorities may significantly change in a manner rendering our clinical data insufficient for approval.
We may encounter unforeseen events prior to, during, or as a result of, clinical trials that could delay or prevent us from obtaining regulatory approval for any product candidates, including: • the FDA or other comparable foreign regulatory authorities may disagree as to the design or implementation of our clinical trials; • we may be delayed in or fail to reach agreement on acceptable terms with prospective CROs and clinical trial sites, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and trial sites; • clinical trials of any product candidates may produce unfavorable or inconclusive results; • we may decide, or regulators may cause us, to conduct additional clinical trials or abandon product development programs; • the number of patients required for clinical trials of any product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate, participants may drop out of these clinical trials at a higher rate than we anticipate or we may fail to recruit suitable patients to participate in clinical trials; • our third-party contractors, including those manufacturing any product candidates or conducting clinical trials on our behalf, may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all; • the FDA or institutional review boards may not authorize us or our investigators to commence a clinical trial or conduct a clinical trial at a prospective trial site; • regulators or institutional review boards may require that we or our investigators suspend or terminate clinical trials of any product candidates for various reasons, including noncompliance with regulatory requirements or a finding that the participants are being exposed to unacceptable health risks, undesirable side effects or other unexpected characteristics of the product candidate; • the FDA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of third-party manufacturers with which we enter into agreements for clinical and commercial supplies; 34 • the supply or quality of any product candidates or other materials necessary to conduct clinical trials of any product candidates may be insufficient or inadequate; and • the approval policies or regulations of the FDA or comparable foreign regulatory authorities may significantly change in a manner rendering our clinical data insufficient for approval.
In addition, the government may assert that a claim that includes items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act; • the federal False Claims Act imposes criminal and civil penalties, which can be enforced by private citizens through civil whistleblower and qui tam actions, against individuals or entities for knowingly presenting, or causing to be presented, to the federal government, claims for payment that are false or fraudulent or making a false statement to avoid, decrease or conceal an obligation to pay money to the federal government; • HIPAA imposes criminal and civil liability for executing a scheme to defraud any healthcare benefit program or for making any false statements relating to healthcare matters; as in the case of the federal healthcare Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate the statute in order to have committed a violation; • HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, also imposes obligations on certain covered entities as well as their business associates that perform services involving the use or disclosure of protected health information, including mandatory contractual terms, with respect to safeguarding the privacy and security of protected health information, and requires notification to affected individuals and regulatory authorities of certain breaches of security of protected health information; • the federal false statements statute prohibits knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services; • the federal Physician Payments Sunshine Act requires manufacturers of drugs, devices, biologics and medical supplies covered by Medicare or Medicaid to report, on an annual basis, to the DHHS, information related to payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists, chiropractors and certain advanced non-physician health care practitioners), teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members; • state and federal consumer protection laws, including the Federal Trade Commission Act, govern the collection, use, disclosure and protection of health and other personal information and could apply to our operations and the operations of our collaborators; and • analogous state laws and regulations, such as state anti-kickback and false claims laws, may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors, including private insurers, and some state laws require pharmaceutical companies to implement compliance programs and to track and report gifts, compensation and other remuneration provided to physicians, in addition to requiring drug manufacturers to report information related to payments to physicians and other healthcare providers or marketing expenditures and pricing information.
In addition, the government may assert that a claim that includes items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act; • the federal False Claims Act imposes criminal and civil penalties, which can be enforced by private citizens through civil whistleblower and qui tam actions, against individuals or entities for knowingly presenting, or causing to be presented, to the federal government, claims for payment that are false or fraudulent or making a false statement to avoid, decrease or conceal an obligation to pay money to the federal government; • HIPAA imposes criminal and civil liability for executing a scheme to defraud any healthcare benefit program or for making any false statements relating to healthcare matters; as in the case of the federal healthcare Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate the statute in order to have committed a violation; • HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, also imposes obligations on certain covered entities as well as their business associates that perform services involving the use or disclosure of protected health information, including mandatory contractual terms, with respect to safeguarding the privacy and security of protected health information, and requires notification to affected individuals and regulatory authorities of certain breaches of security of protected health information; 61 • the federal False Statements statute prohibits knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services; • the federal Physician Payments Sunshine Act requires manufacturers of drugs, devices, biologics and medical supplies covered by Medicare or Medicaid to report, on an annual basis, to the HHS, information related to payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists, chiropractors and certain advanced non-physician health care practitioners), teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members; • state and federal consumer protection laws, including the Federal Trade Commission Act, govern the collection, use, disclosure and protection of health and other personal information and could apply to our operations and the operations of our collaborators; and • analogous state laws and regulations, such as state anti-kickback and false claims laws, may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors, including private insurers, and some state laws require pharmaceutical companies to implement compliance programs and to track and report gifts, compensation and other remuneration provided to physicians, in addition to requiring drug manufacturers to report information related to payments to physicians and other healthcare providers or marketing expenditures and pricing information.
Factors that may inhibit our efforts to commercialize our products on our own include: • our inability to recruit and retain adequate numbers of effective sales and marketing personnel; 41 • the inability of sales personnel to obtain access to or persuade adequate numbers of physicians to prescribe any future products; • the lack of complementary products to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive product lines; and • unforeseen costs and expenses associated with creating an independent sales and marketing organization.
Factors that may inhibit our efforts to commercialize our products on our own include: • our inability to recruit and retain adequate numbers of effective sales and marketing personnel; • the inability of sales personnel to obtain access to or persuade adequate numbers of physicians to prescribe any future products; • the lack of complementary products to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive product lines; and • unforeseen costs and expenses associated with creating an independent sales and marketing organization.
The market price for our common stock may be influenced by many factors, including: • the success of existing or new competitive products or technologies; • the timing of clinical trials of our product candidates; • results of clinical trials of any of our product candidates; • failure or discontinuation of any of our development programs; • results of clinical trials of product candidates of our competitors; • regulatory or legal developments in the United States and other countries; • the perception of the pharmaceutical and biotechnology industry by the public, legislatures, regulators and the investment community; • developments or disputes concerning patent applications, issued patents or other proprietary rights; • the recruitment or departure of key personnel; • the level of expenses related to any of our product candidates or clinical development programs; • the results of our efforts to develop, in-license or acquire additional product candidates or products; • actual or anticipated changes in estimates as to financial results or development timelines; • announcement or expectation of additional financing efforts; • sales of our common stock by us, our insiders or other stockholders; • variations in our financial results or those of companies that are perceived to be similar to us; • changes in estimates or recommendations by securities analysts, if any, that cover our stock; • changes in the structure of healthcare payment systems; • market conditions in the pharmaceutical and biotechnology sectors; • general economic, industry and market conditions; and • the other factors described in this “Risk Factors” section.
The market price for our common stock may be influenced by many factors, including: • the success of existing or new competitive products or technologies; • the timing of clinical trials of any of our product candidates; • results of clinical trials of any existing or future product candidates; • failure or discontinuation of any of our development programs; • results of clinical trials of product candidates of our competitors; • regulatory or legal developments in the United States and other countries; • the perception of the pharmaceutical and biotechnology industry by the public, legislatures, regulators and the investment community; • developments or disputes concerning patent applications, issued patents or other proprietary rights; • the recruitment or departure of key personnel; • the level of expenses related to any existing or future product candidates or clinical development programs; • the results of our efforts to develop, in-license or acquire additional product candidates or products; 69 • actual or anticipated changes in estimates as to financial results or development timelines; • announcement or expectation of additional financing efforts; • sales of our common stock by us, our insiders or other stockholders; • variations in our financial results or those of companies that are perceived to be similar to us; • changes in estimates or recommendations by securities analysts, if any, that cover our stock; • changes in the structure of healthcare payment systems; • market conditions in the pharmaceutical and biotechnology sectors; • general economic, industry and market conditions; and • the other factors described in this “Risk Factors” section.
Increasingly there are state laws and regulations that require prescription drug price reporting or impose other restrictions designed to control pharmaceutical product pricing, such as price or patient reimbursement constraints and discounts. 67 Our employees, independent contractors, principal investigators, contract research organizations, consultants or vendors may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements.
Increasingly there are state laws and regulations that require prescription drug price reporting or impose other restrictions designed to control pharmaceutical product pricing, such as price or patient reimbursement constraints and discounts. Our employees, independent contractors, principal investigators, contract research organizations, consultants or vendors may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements.
During the previous congressional session, numerous bipartisan PBM reforms were considered in both the Senate and the House of Representatives; they include diverse 66 legislative proposals such as eliminating rebates; divorcing service fees from the price of a drug, discount, or rebate; prohibiting spread pricing; limiting administrative fees; requiring PBMs to report formulary placement rationale; promoting transparency.
During the previous congressional session, numerous bipartisan PBM reforms were considered in both the Senate and the House of Representatives; they include diverse legislative proposals such as eliminating rebates; divorcing service fees from the price of a drug, discount, or rebate; prohibiting spread pricing; limiting administrative fees; requiring PBMs to report formulary placement rationale; promoting transparency.
Even if we eventually receive approval of an NDA or foreign marketing application for our product candidates, the FDA or the applicable foreign regulatory agency may grant approval contingent on the performance of costly additional clinical trials, often referred to as Phase 4 clinical trials, and the FDA may require the implementation of a REMS which may be required to ensure safe use of the drug after approval.
Even if we eventually receive approval of an NDA or foreign marketing application for any of our product candidates, the FDA or the applicable foreign regulatory agency may grant approval contingent on the performance of costly additional clinical trials, often referred to as Phase 4 clinical trials, and the FDA may require the implementation of a REMS which may be required to ensure safe use of the drug after approval.
Failure to comply with data protection laws and regulations, where 45 applicable, could result in government enforcement actions, which could include civil or criminal penalties, private litigation and/or adverse publicity and could negatively affect our operating results and business. For example, California has enacted the California Consumer Privacy Act (“CCPA”), which went into effect in January of 2020.
Failure to comply with data protection laws and regulations, where applicable, could result in government enforcement actions, which could include civil or criminal penalties, private litigation and/or adverse publicity and could negatively affect our operating results and business. For example, California has enacted the California Consumer Privacy Act (“CCPA”), which went into effect in January of 2020.
The Federal Trade Commission in mid-2022 also launched sweeping investigations into the practices of the PBM industry, and published interim reports with its finding in mid-2024 and January 2025, that could lead to additional federal and state legislative or regulatory proposals targeting such entities’ operations, pharmacy networks, or financial arrangements, including in the current 2025-2026 congressional session.
The Federal Trade Commission (“FTC”) in mid-2022 also launched sweeping investigations into the practices of the PBM industry, and published interim reports with its finding in mid-2024 and January 2025, that could lead to additional federal and state legislative or regulatory proposals targeting such entities’ operations, pharmacy networks, or financial arrangements, including in the current 2025-2026 congressional session.
If we are unable to obtain or maintain sufficient insurance coverage at an acceptable cost or to otherwise protect against potential product liability claims, it could prevent or inhibit the development and commercial production and sale of our product candidates, which could adversely affect our business, financial condition, results of operations and prospects.
If we are unable to obtain or maintain sufficient insurance coverage at an acceptable cost or to otherwise protect against potential product liability claims, it could prevent or inhibit the development and commercial production and sale of any product candidates, which could adversely affect our business, financial condition, results of operations and prospects.
The CCPA gives California residents expanded rights to access and require deletion of their personal information, opt out of certain personal information sharing, and receive detailed information about how their personal information is used. The CCPA provides for civil penalties for violations, as well as a private right of action for data breaches that may increase data breach litigation.
The CCPA gives California residents expanded rights to access and require deletion of their personal information, opt out of certain personal information sharing, and receive detailed information about how their personal information is used. The CCPA provides for civil penalties for violations, as well as a private 43 right of action for data breaches that may increase data breach litigation.
Litigation is usually expensive and diverts management’s attention and resources, which could adversely affect our business and cash resources and our ability to execute on our partnership with GSK to eventually commercialize tebipenem HBr, or the ultimate value our stockholders receive in such partnership or other opportunity. Item 1B. Unresolve d Staff Comments. None.
Litigation is usually expensive and diverts management’s attention and resources, which could adversely affect our business and cash resources and our ability to execute on our partnership with GSK to eventually commercialize tebipenem HBr, or the ultimate value our stockholders receive in such partnership or other opportunity. 73 Item 1B. Unresolve d Staff Comments. None.
Patient enrollment is a significant factor in the timing of clinical trials, and is affected by many factors, including: • the size and nature of the target patient population; • the severity of the disease under investigation; • the proximity of patients to clinical sites; • the patient eligibility criteria for participation in the clinical trial; • the design of the clinical trial; • the availability of clinically evaluable patients; • our ability to recruit clinical trial investigators with appropriate competencies and experience; 38 • competing clinical trials and clinicians’ and patients’ perceptions as to the potential advantages and risks of the product candidate being studied in relation to other available therapies, including any new drugs that may be approved for the indications that we are investigating; • our ability to obtain and maintain patient consents; and • the risk that participants enrolled in clinical trials will drop out of the trials before completion.
Patient enrollment is a significant factor in the timing of clinical trials, and is affected by many factors, including: • the size and nature of the target patient population; • the severity of the disease under investigation; • the proximity of patients to clinical sites; • the patient eligibility criteria for participation in the clinical trial; • the design of the clinical trial; • the availability of clinically evaluable patients; • our ability to recruit clinical trial investigators with appropriate competencies and experience; 35 • competing clinical trials and clinicians’ and patients’ perceptions as to the potential advantages and risks of the product candidate being studied in relation to other available therapies, including any new drugs that may be approved for the indications that we are investigating; • our ability to obtain and maintain patient consents; and • the risk that participants enrolled in clinical trials will drop out of the trials before completion.
The FDA may also require a REMS as a condition of approval of our product candidates, which could include requirements for a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools.
The FDA may also require a REMS as a condition of approval of any of our product candidates, which could include requirements for a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools.
As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, which may negatively affect the revenues that we are able to generate from the sale of the product in that 42 country.
As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, which may negatively affect the revenues that we are able to generate from the sale of the product in that country.
There can be no assurance that the FDA will grant orphan designation for any indication for which we apply. 62 In the United States, orphan designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers.
There can be no assurance that the FDA will grant orphan designation for any indication for which we apply. In the United States, orphan designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers.
In addition, if any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent such third party, or those to whom they communicate 59 such technology or information, from using that technology or information to compete with us.
In addition, if any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent such third party, or those to whom they communicate such technology or information, from using that technology or information to compete with us.
If we are unable to achieve and sustain profitability, the market value of our common stock will likely decline. Because of the numerous risks and uncertainties associated with developing biopharmaceutical products, we are unable to predict the extent of any future losses or when, if ever, we will become profitable.
If we are unable to achieve and sustain profitability, the market value of our common stock will likely decline. 45 Because of the numerous risks and uncertainties associated with developing biopharmaceutical products, we are unable to predict the extent of any future losses or when, if ever, we will become profitable.
If we are required to conduct additional clinical trials or other testing of any of our product candidates beyond the trials and testing that we contemplate, if we are unable to successfully complete clinical trials or other testing of our product candidates, if the results of these trials or tests are unfavorable or are only modestly favorable or if there are safety concerns associated with any of our product candidates, we may: • incur additional unplanned costs; • be delayed in obtaining marketing approval for our product candidates; • not obtain marketing approval at all; • obtain approval for indications or patient populations that are not as broad as intended or desired; • obtain approval with labeling that includes significant use or distribution restrictions or significant safety warnings, including boxed warnings; • be subject to additional post-marketing testing or other requirements; or • be required to remove the product from the market after obtaining marketing approval.
If we are required to conduct additional clinical trials or other testing of any existing or future product candidates beyond the trials and testing that we contemplate, if we are unable to successfully complete clinical trials or other testing of our existing or future product candidates, if the results of these trials or tests are unfavorable or are only modestly favorable or if there are safety concerns associated with any existing or future product candidates, we may: • incur additional unplanned costs; • be delayed in obtaining marketing approval for any product candidates; • not obtain marketing approval at all; • obtain approval for indications or patient populations that are not as broad as intended or desired; • obtain approval with labeling that includes significant use or distribution restrictions or significant safety warnings, including boxed warnings; • be subject to additional post-marketing testing or other requirements; or • be required to remove the product from the market after obtaining marketing approval.
Laws in a number of other U.S. states took effect, or are set to take effect, in 2025, in 2026, and beyond, and additional U.S. states have proposals under consideration, all of which are likely to increase our regulatory compliance costs and risks, exposure to regulatory enforcement action and other liabilities.
Laws in a number of other U.S. states took effect, or are set to take effect, in 2026, and beyond, and additional U.S. states have proposals under consideration, all of which are likely to increase our regulatory compliance costs and risks, exposure to regulatory enforcement action and other liabilities.
Any delay in obtaining, or inability to obtain, applicable regulatory approval would delay or prevent commercialization of that product candidate and would materially adversely impact our business and prospects. A fast track designation may not actually lead to a faster development or regulatory review or approval process.
Any delay in obtaining, or inability to obtain, applicable regulatory approval would delay or prevent commercialization of that product candidate and would materially adversely impact our business and prospects. 56 A fast track designation may not actually lead to a faster development or regulatory review or approval process.
In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of any of our product candidates. If we experience delays or difficulties in the enrollment of patients in clinical trials, clinical development activities could be delayed or otherwise adversely affected.
In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of any product candidates. If we experience delays or difficulties in the enrollment of patients in clinical trials, clinical development activities could be delayed or otherwise adversely affected.
In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities, including: • the timing and terms of the potential FDA approval of tebipenem HBr; • the timing, costs and results of our ongoing, planned and potential clinical trials for our product candidates; • the amount of funding that we receive under our government awards; • the number and characteristics of product candidates that we pursue; • the outcome, timing and costs of seeking regulatory approvals; • the costs of commercialization activities for our product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities; • the terms and timing of any future collaborations, licensing or other arrangements that we may establish; • the amount and timing of any payments we may be required to make, or that we may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights, including milestone and royalty payments and patent prosecution fees that we are obligated to pay pursuant to our license agreements; • the costs of preparing, filing and prosecuting patent applications, maintaining and protecting our intellectual property rights and defending against any intellectual property related claims; 48 • the costs of our continued operation as a public company; and • the extent to which we in-license or acquire other products and technologies.
In that event, we may have to delay, scale back, or eliminate some or all of our planned development activities, including: • the timing and terms of the potential FDA approval of tebipenem HBr; • the timing, costs and results potential clinical trials for any of our existing and future product candidates; • the amount of funding that we receive under our government awards; • the number and characteristics of product candidates that we pursue; • the outcome, timing and costs of seeking regulatory approvals; • the costs of commercialization activities for our existing and future product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities; • the terms and timing of any future collaborations, licensing or other arrangements that we may establish; • the amount and timing of any payments we may be required to make, or that we may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights, including milestone and royalty payments and patent prosecution fees that we are obligated to pay pursuant to our license agreements; • the costs of preparing, filing and prosecuting patent applications, maintaining and protecting our intellectual property rights and defending against any intellectual property related claims; • the costs of our continued operation as a public company; and • the extent to which we in-license or acquire other products and technologies.
Future product candidates may also receive marketing exclusivity under the FDCA after approval that may similarly be subject to challenge or uncertainty. If we or our partners are unable to obtain marketing approval in international jurisdictions, we will not be able to market our product candidates abroad.
Future product candidates may also receive marketing exclusivity under the FDCA after approval that may similarly be subject to challenge or uncertainty. If we or our partners are unable to obtain marketing approval in international jurisdictions, we will not be able to market our existing or future product candidates abroad.
We also do not have any current contractual relationships for the manufacture of commercial supplies of any of our product candidates. If any of our existing manufacturers should become unavailable to us for any reason, we may incur delays in identifying or qualifying replacements.
We also do not have any current contractual relationships for the manufacture of commercial supplies of any existing or future product candidates. If any of our existing manufacturers should become unavailable to us for any reason, we may incur delays in identifying or qualifying replacements.
Unless and until we can generate a substantial amount of revenue from our product candidates, we expect to finance our future cash needs through public or private equity offerings, debt financings, collaborations, licensing arrangements and government funding arrangements.
Unless and until we can generate a substantial amount of revenue from our existing and future product candidates, we expect to finance our future cash needs through public or private equity offerings, debt financings, collaborations, licensing arrangements and government funding arrangements.
The time required to obtain approval, if any, by the FDA and comparable foreign authorities is unpredictable but typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities.
The time required to obtain approval, if any, by the FDA and comparable foreign authorities is unpredictable but typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of 55 the regulatory authorities.
In 71 addition, if one or more of these analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.
In addition, if one or more of these analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.
The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our product candidates.
The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of any of our product candidates.
In the case of a Change of Control of Spero, GSK similarly may, in lieu of terminating the GSK License Agreement, assume responsibility and expense of development of tebipenem HBr in the United States and no development milestones would be payable to Spero, as described above.
In the case of a Change of Control (as defined in the GSK License Agreement) of Spero, GSK similarly may, in lieu of terminating the GSK License Agreement, assume responsibility and expense of development of tebipenem HBr in the United States and no development milestones would be payable to Spero, as described above.
Adverse differences between preliminary or interim data and final data could affect our planned clinical path for any of our product candidates we advance into clinical trials, including potentially increasing cost and/or causing delay in such development.
Adverse differences between preliminary or interim data and final data could affect our planned clinical path for any product candidates we advance into clinical trials, including potentially increasing cost and/or causing delay in such development.
If we fail to comply with our obligations in the agreements under which we in-license or out-license acquire development or commercialization rights to products, technology or data from or to third parties, we could lose such rights that are important to our business.
If we fail to comply with our obligations in the agreements under which we in-license or acquire development or commercialization rights to products, technology or data from or to third parties, we could lose such rights that are important to our business.
Moreover, holders of a substantial number of shares of our common stock have rights, subject to conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders.
Moreover, holders of a substantial number of shares of our common stock have 71 rights, subject to conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders.
If such an event occurs during development, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of, or could deny approval of our product candidates.
If such an event occurs during development, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of, or could deny approval of any product candidates.
If we or our collaborators are unable to establish sales, marketing and distribution capabilities or enter into sales, marketing and distribution agreements with third parties, we may not be successful in commercializing any of our product candidates if such product candidates are approved.
If we or our collaborators are unable to establish sales, marketing and distribution capabilities or enter into sales, marketing and distribution agreements with third parties, we may not be successful in commercializing any product candidates if such product candidates are approved.
We expect to continue to incur significant expenses and operating losses for the foreseeable future as we continue to advance our product candidates through preclinical and clinical development and marketing approval for such candidates whose clinical trials are successful.
We expect to continue to incur significant expenses and operating losses for the foreseeable future as we continue to advance our existing and future product candidates through preclinical and clinical development and marketing approval for such candidates whose clinical trials are successful.
For example, these rules and regulations have made it more difficult and more expensive for us to obtain director and officer liability insurance, which could make it more 72 difficult for us to attract and retain qualified members of our Board of Directors.
For example, these rules and regulations have made it more difficult and more expensive for us to obtain director and officer liability insurance, which could make it more difficult for us to attract and retain qualified members of our Board of Directors.
Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development for many reasons, including the following: • the research methodology used may not be successful in identifying potential product candidates; 43 • we may be unable to successfully modify candidate compounds to be active in Gram-negative bacteria or defeat bacterial resistance mechanisms or identify viable product candidates in our screening campaigns; • competitors may develop alternatives that render our product candidates obsolete; • product candidates that we develop may nevertheless be covered by third parties’ patents or other exclusive rights; • a product candidate may, on further study, be shown to have harmful side effects or other characteristics that indicate it is unlikely to be effective or otherwise does not meet applicable regulatory criteria; • a product candidate may not be capable of being produced in commercial quantities at an acceptable cost, or at all; • a product candidate may not be accepted as safe and effective by patients, the medical community or third-party payors; and • the development of bacterial resistance to potential product candidates may render them ineffective against target infections.
Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development for many reasons, including the following: • the research methodology used may not be successful in identifying potential product candidates; • we may be unable to successfully modify candidate compounds to be active in Gram-negative bacteria or defeat bacterial resistance mechanisms or identify viable product candidates in our screening campaigns; • competitors may develop alternatives that render our existing or future product candidates obsolete; 41 • product candidates that we develop may nevertheless be covered by third parties’ patents or other exclusive rights; • a product candidate may, on further study, be shown to have harmful side effects or other characteristics that indicate it is unlikely to be effective or otherwise does not meet applicable regulatory criteria; • a product candidate may not be capable of being produced in commercial quantities at an acceptable cost, or at all; • a product candidate may not be accepted as safe and effective by patients, the medical community or third-party payors; and • the development of bacterial resistance to potential product candidates may render them ineffective against target infections.
The third parties with whom we contract for execution of our GLP studies and our clinical trials play a significant role in the conduct of these studies and trials and the subsequent collection and analysis of data.
The third parties 49 with whom we contract for execution of our GLP studies and our clinical trials play a significant role in the conduct of these studies and trials and the subsequent collection and analysis of data.
Even if such approval is obtained, the timeline of, and any requirements imposed as part of, such approval may impact the attractiveness of eventual commercialization of tebipenem HBr through our partnership with GSK.
Even if such approval is obtained, the timeline of, and any requirements imposed as part of, such approval may impact the attractiveness of commercialization of tebipenem HBr through our partnership with GSK.
We will need to increase our insurance coverage if and when we receive marketing approval for and begin selling any of our product candidates. In addition, insurance coverage is becoming increasingly expensive.
We will need to increase our insurance coverage if and when we receive marketing approval for and begin selling any product candidates. In addition, insurance coverage is becoming increasingly expensive.
Under the Orphan Drug Act of 1983, the FDA may designate a product as an orphan product if it is intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals in the United States, or a patient population of greater than 200,000 individuals in the United States, but for which there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States.
Under the Orphan Drug Act of 1983 (the “Orphan Drug Act”), the FDA may designate a product as an orphan product if it is intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals in the United States, or a patient population of greater than 200,000 individuals in the United States, but for which there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States.
Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law (the “DGCL”), which prohibits a person who owns in excess of 15% of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.
Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law (the “DGCL”), which prohibits a person who owns 15% or more of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired 15% or more of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.
Hospitals bill third-party payors for all or a portion of the fees associated with the patient’s hospitalization and bill patients for any deductibles or co-payments. Because there is typically no separate reimbursement for drugs administered in a hospital inpatient setting, some of our target customers may be unwilling to adopt our product candidates in light of the additional associated cost.
Hospitals bill third-party payors for all or a portion of the fees associated with the patient’s hospitalization and bill patients for any deductibles or co-payments. Because there is typically no separate reimbursement for drugs administered in a hospital inpatient setting, some of our target customers may be unwilling to adopt our product candidate in light of the additional associated cost.
Serious adverse events or undesirable side effects caused by, or other unexpected properties of, our product candidates could cause us, an IRB, or regulatory authorities to interrupt, delay or halt our clinical trials and could result in a more restrictive label, the imposition of distribution or use restrictions or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities.
Serious adverse events or undesirable side effects caused by, or other unexpected properties of, our existing or future product candidates could cause us, an IRB, or regulatory authorities to interrupt, delay or halt our clinical trials and could result in a more restrictive label, the imposition of distribution or use restrictions or the delay or denial of regulatory approval by the FDA or comparable foreign regulatory authorities.
If we are not successful in discovering, developing and commercializing additional product candidates, our ability to expand our business and achieve our strategic objectives would be impaired.
If we are not successful in developing and commercializing additional product candidates, our ability to expand our business and achieve our strategic objectives would be impaired.
The FDA’s policies may change and additional government regulations may be enacted that could prevent, limit or delay marketing approval of our product candidates.
The FDA’s policies may change and additional government regulations may be enacted that could prevent, limit or delay marketing approval of any of our product candidates.
We will be required to demonstrate through well-controlled clinical trials that our product candidates are safe and effective for use in a diverse population before we can seek marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful.
We will be required to demonstrate through well-controlled clinical trials that our existing or future product candidates are safe and effective for use in a diverse population before we can seek marketing approvals for their commercial sale. Success in preclinical studies and early-stage clinical trials does not mean that future larger registration clinical trials will be successful.
If any of our other product candidates are associated with serious or unexpected adverse events or undesirable side effects, the FDA, the IRBs responsible for overseeing our studies, or a DSMB, could suspend or terminate our clinical trials or the FDA or comparable foreign regulatory authorities could order us to cease clinical trials or deny approval of our product candidates for any or all targeted indications.
If any of our other product candidates are associated with serious or unexpected adverse events or undesirable side effects, the FDA, the IRBs responsible for overseeing our studies, or a DSMB, could suspend or terminate our clinical trials or the FDA or comparable foreign regulatory authorities could order us to cease clinical trials or deny approval of our existing or future product candidates for any or all targeted indications.
The BCA requires sequestration for most federal programs, excluding Medicaid, Social Security, and certain other programs. The BCA caps the cuts to Medicare payments for items and services and payments to Part D plans at 2%. As long as these cuts remain in effect, they could adversely affect payment for our product candidates, if approved for commercial marketing.
The BCA requires sequestration for most federal programs, excluding Medicaid, Social Security, and certain other programs. The BCA caps the cuts to Medicare payments for items and services and payments to Part D plans at 2%. As long as these cuts remain in effect, they could adversely affect payment for any of our product candidates, if approved for commercial marketing.
Even if we obtain FDA or other regulatory approvals and are able to launch any of our product candidates commercially, the approved product candidate may nonetheless fail to gain sufficient market acceptance among physicians, patients, hospitals (including pharmacy directors) and third-party payors and, ultimately, may not be commercially successful.
Even if we obtain FDA or other regulatory approvals and are able to launch any product candidates commercially, the approved product candidate may nonetheless fail to gain sufficient market acceptance among physicians, patients, hospitals (including pharmacy directors) and third-party payors and, ultimately, may not be commercially successful.
Risks Related to Our Intellectual Property If we are unable to obtain and maintain sufficient patent protection for our technology or our product candidates, or if the scope of the patent protection is not sufficiently broad, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully commercialize our technology and product candidates may be adversely affected.
Risks Related to Our Intellectual Property If we are unable to obtain and maintain sufficient patent protection for our technology or our existing or future product candidates, or if the scope of the patent protection is not sufficiently broad, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully commercialize our technology and product candidates may be adversely affected.
A finding of infringement could prevent us from commercializing our product candidates or force us to cease some of our business operations, which could materially harm our business. Claims that we or our third-party collaborators have misappropriated the intellectual property, confidential information or trade secrets of third parties could have a similar negative effect on our business.
A finding of infringement could prevent us from commercializing our existing or future product candidates or force us to cease some of our business operations, which could materially harm our business. Claims that we or our third-party collaborators have misappropriated the intellectual property, confidential information or trade secrets of third parties could have a similar negative effect on our business.
A disruption resulting from any one of these events could cause significant delays in shipments of our products and the loss of revenue and customers, which could have a material adverse effect on our financial position, results of operations, and cash flows. Our facilities in Japan and Taiwan are located in seismically-active areas.
A disruption resulting from any one of these events could cause significant delays in shipments of our products and the loss of revenue and customers, which could have a material adverse effect on our financial position, results of operations, and cash flows. Our manufacturer's facilities in Japan are located in seismically-active areas.
If we or our third-party contractors fail to comply with applicable GCP standards, the clinical data generated in our clinical trials may be deemed unreliable and the FDA may require us to perform additional clinical trials before approving our product candidates, which would delay the regulatory approval process.
If we or our third-party contractors fail to comply with applicable GCP standards, the clinical data generated in our clinical trials may be deemed unreliable and the FDA may require us to perform additional clinical trials before approving any of our product candidates, which would delay the regulatory approval process.
If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we may not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates.
If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we may not be able to obtain, or may be delayed in obtaining, marketing approvals for any of our product candidates.
Failure by any of our 53 manufacturers to comply with applicable cGMPs or other regulatory requirements could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspensions or withdrawals of approvals, operating restrictions, interruptions in supply and criminal prosecutions, any of which could significantly and adversely affect supplies of our product candidates and have a material adverse effect on our business, financial condition and results of operations.
Failure by any of our manufacturers to comply with applicable cGMPs or other regulatory requirements could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspensions or withdrawals of approvals, operating restrictions, interruptions in supply and criminal prosecutions, any of which could significantly and adversely affect supplies of our existing or future product candidates and have a material adverse effect on our business, financial condition and results of operations.
If that occurs, we may not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates. In such an event, our financial results and the commercial prospects for our product candidates could be harmed, our costs could increase and our ability to generate revenue could be delayed, impaired or foreclosed.
If that occurs, we may not be able to, or may be delayed in our efforts to, successfully commercialize any of our product candidates. In such an event, our financial results and the commercial prospects for any of our product candidates could be harmed, our costs could increase and our ability to generate revenue could be delayed, impaired or foreclosed.
These global economic and political factors could also strain certain of our suppliers and manufacturers, possibly resulting in supply disruptions or increased raw material or manufacturing costs, or adversely impacting their ability to manufacture clinical trial materials for our product candidates.
These global economic and political factors could also strain 70 certain of our suppliers and manufacturers, possibly resulting in supply disruptions or increased raw material or manufacturing costs, or adversely impacting their ability to manufacture clinical trial materials for any of our product candidates.
A number of companies in the pharmaceutical industry, including biotechnology companies, have suffered significant setbacks in clinical trials, even after promising results in earlier nonclinical studies or clinical trials. The results of preclinical and other nonclinical studies and/or early clinical trials of our product candidates may not be predictive of the results of later-stage clinical trials.
A number of companies in the pharmaceutical industry, including biotechnology companies, have suffered significant setbacks in clinical trials, even after promising results in earlier nonclinical studies or clinical trials. The results of preclinical and other nonclinical studies and/or early clinical trials of any product candidates may not be predictive of the results of later-stage clinical trials.
If coverage is not available, or reimbursement is limited, we may not be able to successfully commercialize our product candidates. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a sufficient return on our investments.
If coverage is not available, or reimbursement is limited, we may not be able to successfully commercialize our existing or future product candidates. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a sufficient return on our investments.
For example, notwithstanding the obligations of a contract research organization for a trial of one of our product candidates, we remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial and applicable regulatory requirements.
For example, notwithstanding the obligations of a contract research organization for a trial of any product candidates, we remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial and applicable regulatory requirements.
Our current and anticipated future dependence upon others for the manufacture of our product candidates and potential product candidates may adversely affect our future profit margins and our ability to commercialize any products for which we receive marketing approval on a timely and competitive basis.
Our current and anticipated future dependence upon others for the manufacture of our existing or future product candidates and potential product candidates may adversely affect our future profit margins and our ability to commercialize any products for which we receive marketing approval on a timely and competitive basis.
When we file trademark applications for our product candidates, those applications may not be allowed for registration, and registered trademarks may not be obtained, maintained, or enforced. During trademark registration proceedings in the United States and foreign jurisdictions, we may receive rejections.
When we file trademark applications for our existing or future product candidates, those applications may not be allowed for registration, and registered trademarks may not be obtained, maintained, or enforced. During trademark registration proceedings in the United States and foreign jurisdictions, we may receive rejections.

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Item 1C. Cybersecurity

Cybersecurity — threats and controls disclosure

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Biggest changeOur Board of Directors receives prompt and timely information regarding any cybersecurity incident that meets established reporting thresholds, as well as ongoing updates regarding any such incident until it has been addressed. 75 Our Head of IT , who leads our cybersecurity risk management and strategy processes , has over ten years of information technology and cybersecurity work experience.
Biggest changeOur Board of Directors receives prompt and timely information regarding any cybersecurity incident that meets established reporting thresholds, as well as ongoing updates regarding any such incident until it has been addressed. Our Head of IT , who leads our cybersecurity risk management and strategy processes , has over ten years of information technology and cybersecurity work experience.

Item 2. Properties

Properties — owned and leased real estate

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Biggest changeItem 2. Properties. Our headquarters are located in Cambridge, Massachusetts, where we lease approximately 23,400 square feet of office space. Our lease extends through July 2027. We believe that our existing facilities will be sufficient to meet our current needs.
Biggest changeItem 2. Properties. Our headquarters are located in Cambridge, Massachusetts, where we lease approximately 23,400 square feet of office space. Our lease extends through July 2027. In September 2025, we entered into sublease agreements for a portion of our lease through the remainder of its lease term.
Added
We believe that our existing facilities will be sufficient to meet our current needs. 74

Item 3. Legal Proceedings

Legal Proceedings — active lawsuits and investigations

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Biggest changeIf additional similar complaints are filed, absent new or different allegations that are material, the Company will not necessarily announce such additional filings. 76 SEC Investigation and Wells Notice On January 9, 2025, the Company responded to a “Wells Notice” from the staff of the Boston Regional Office (“Staff”) of the SEC regarding its preliminary determination to recommend a civil enforcement action or administrative proceeding against the Company, its former Chief Executive Officer and Chairman of the Board of Directors, Ankit Mahadevia, M.D.
Biggest changeSEC Investigation and Wells Notice On January 9, 2025, the Company responded to a “Wells Notice” from the Staff of the SEC regarding its preliminary determination to recommend a civil enforcement action or administrative proceeding against the Company, its former Chief Executive Officer and a former member of its Board of Directors, Ankit Mahadevia, M.D. (“Dr.
Shukla”), relating to certain public disclosures by the Company from March 31, 2022 leading up to the Company’s announcement on May 3, 2022 that it had determined to cease commercialization of tebipenem HBr based on feedback from the FDA, and whether the Company’s disclosures may have violated the federal securities laws (the “Investigation”).
Shukla”), relating to certain public disclosures by the Company from March 31, 2022 leading up to the Company’s announcement on May 3, 2022 that it had determined to cease commercialization of tebipenem HBr based on feedback from the FDA, and whether the Company’s disclosures may have violated the federal securities laws.
The parties moved to consolidate the two complaints on July 22, 2022, which were ordered consolidated on August 5, 2022 (“Consolidated Putative Class Action”). The parties filed an Amended Complaint on December 5, 2022, purported to be brought on behalf of stockholders who purchased the Company's common stock from September 8, 2020 through May 2, 2022.
The parties moved to consolidate the two complaints on July 22, 2022, which were ordered consolidated on August 5, 2022 (“Consolidated Putative Class Action”). The parties filed an Amended Complaint on December 5, 2022, purported to be brought on behalf of stockholders who purchased our common stock from September 8, 2020 through May 2, 2022.
(“Dr. Mahadevia”), and its former Chief Financial Officer and President and Chief Executive Officer, Satyavrat “Sath” Shukla (“Mr.
Mahadevia”), and its former Chief Financial Officer and President and Chief Executive Officer, Satyavrat “Sath” Shukla (“Mr.
If the SEC were to authorize an action against the Company and/or any of the identified individuals, it may seek an injunction or cease-and-desist order against future violations of provisions of the federal securities laws, the imposition of civil monetary penalties, disgorgement or other equitable relief within the SEC’s authority, or any combination of the foregoing.
If the SEC were to authorize an action against the Company and/or any of the identified individuals, it may seek an injunction or cease-and-desist order against future violations of provisions of the federal securities laws, the imposition of civil monetary penalties, disgorgement or other equitable relief.
The Amended Complaint generally alleges that the Company and certain of its current and former officers violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the New Drug Application (“NDA”) for tebipenem HBr in an effort to lead investors to believe that the drug would receive approval from the FDA.
The Amended Complaint generally alleges that the Company and certain of its current and former officers violated Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the NDA for tebipenem HBr in an effort to lead investors to believe that the drug would receive approval from the FDA.
By Order entered on September 30, 2024, the motion to stay the First Derivative Complaint was denied as moot due to the dismissal of the Consolidated Putative Class Action. On March 20, 2025, the Second Derivative Complaint was voluntarily dismissed by the plaintiff. The Company denies any allegations of wrongdoing and intends to vigorously defend against these lawsuits.
By Order entered on September 30, 2024, the motion to stay the First Derivative Complaint was denied as moot due to the dismissal of the Consolidated Putative Class Action. On March 20, 2025, the Second Derivative Complaint was voluntarily dismissed by the plaintiff. On March 31, 2025, the First Derivative Complaint was voluntarily dismissed by the plaintiff.
Additional lawsuits against the Company and certain of its officers or directors may be filed in the future.
Additional lawsuits against the Company and certain of its officers or directors may be filed in the future. If additional similar complaints are filed, absent new or different allegations that are material, the Company will not necessarily announce such additional filings.
Removed
However, there is no assurance that the Company will be successful in its defense or that insurance will be available or adequate to fund any settlement or judgment or the litigation costs of these actions. Moreover, the Company is unable to predict the outcomes or reasonably estimate a range of possible loss at this time.
Added
On January 16, 2026, acting pursuant to an offer of settlement submitted by each of Dr. Mahadevia and Mr. Shukla, the SEC issued an order instituting cease-and-desist proceedings, making findings, and imposing a cease-and-desist order pursuant to Section 8A of the 1933 Act, directing Dr. Mahadevia and Mr.
Removed
Specifically, the contemplated civil enforcement action, if approved by the Commissioners, could include allegations that the Company violated Section 17(a) of the Securities Act and Sections 10(b) and 13(a) of the Exchange Act and Rules 10b-5, 12b-20, and 13a-1 thereunder; and could allege against Dr. Mahadevia and Mr.
Added
Shukla to cease and desist from committing or causing any violations of Section 17(a)(2) of the 1933 Act, 15 U.S.C. § 77q(a)(2) (the “SEC Order”). In the SEC Order, the SEC made findings that, from March 31, 2022 to May 3, 2022, Dr. Mahadevia and Mr.
Removed
Shukla violations of Section 17(a) of the Securities Act and Section 10(b) of the Exchange Act and Rules 10b-5 and 13a-14 thereunder. The Company, Dr. Mahadevia and Mr. Shukla continue to cooperate with the SEC, they have engaged in further dialogue with the Staff and maintain that the Company’s disclosures were appropriate.
Added
Shukla, violated Section 17(a)(2) of 1933 Act, which provides that it is unlawful for any person, in the offer or sale of a security, to “obtain money or property by means of any untrue statement of material fact” or a material 75 omission necessary to make statements made not misleading.
Removed
The SEC could also seek an order barring each identified individual from serving as an officer or director of a public company for a specified period of time.
Added
A violation of this provision does not require scienter and may rest on a finding of negligence. Dr. Mahadevia and Mr. Shukla consented to entry of the SEC Order without admitting or denying the findings contained therein, except as to jurisdiction.
Removed
The results of the Investigation and the Wells Notice process and any corresponding enforcement action against the Company and/or any of the identified individuals, and the costs, timing and other potential consequences of responding and complying therewith are unknown at this time. Item 4. Mine Saf ety Disclosures. Not applicable. 77 PART II
Added
On January 20, 2026, the Company received a letter (the “Letter”) from the SEC advising the Company that the SEC has concluded its investigation into the Company and that, based on the information as of the date of the Letter, the SEC does not intend to recommend an enforcement action against the Company at this time.
Added
The Letter was provided under the guidelines set out in the final paragraph of Securities Act Release No. 5310. The Company and Mr. Shukla mutually decided to separate, and Mr. Shukla resigned from the Board of Directors, in each case effective as of May 2, 2025. On January 30, 2026, Dr.
Added
Mahadevia resigned from the Board of Directors, including from his service on the Development Committee of the Board and from all officer and director positions he then held with any and all subsidiaries of the Company, effective as of January 30, 2026. Item 4. Mine Saf ety Disclosures. Not applicable. 76 PART II

Item 5. Market for Registrant's Common Equity

Market for Common Equity — stock, dividends, buybacks

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Biggest changeAdditionally, our ability to pay dividends on our capital stock could be limited by terms and covenants of any future indebtedness. Purchases of Equity Securities by the Issuer None. Item 6. [ Reserved] 78
Biggest changeAdditionally, our ability to pay dividends on our capital stock could be limited by terms and covenants of any future indebtedness. Recent Sales of Unregistered Securities None. Purchases of Equity Securities by the Issuer None. Item 6. [ Reserved] 77
Item 5. Market for Registrant’s Common Equity, Related Stock holder Matters and Issuer Purchases of Equity Securities. Market Information Our common stock is publicly traded on the Nasdaq Global Select Market under the symbol “SPRO”. Holders of Record As of March 21, 2025, we had approximately eight stockholders of record of our common stock.
Item 5. Market for Registrant’s Common Equity, Related Stock holder Matters and Issuer Purchases of Equity Securities. Market Information Our common stock is publicly traded on the Nasdaq Global Select Market under the symbol “SPRO”. Holders of Record As of March 20, 2026, we had approximately eight stockholders of record of our common stock.

Item 7. Management's Discussion & Analysis

Management's Discussion & Analysis (MD&A) — revenue / margin commentary

66 edited+23 added−28 removed48 unchanged
Biggest changeThese factors raise substantial doubt about our ability to continue as a going concern. 84 Comparison of the Years Ended December 31, 2024 and 2023 The following table summarizes our results of operations for the years ended December 31, 2024 and 2023: Year Ended December 31, 2024 2023 $ Change Revenues: Grant revenue $ 20,581 $ 7,046 $ 13,535 Collaboration revenue - related party 27,025 95,802 (68,777 ) Collaboration revenue 371 933 (562 ) Total revenues 47,977 103,781 (55,804 ) Operating expenses: Research and development 96,757 51,440 45,317 General and administrative 23,704 25,554 (1,850 ) Restructuring 877 — 877 Impairment of long-term asset — 5,306 (5,306 ) Total operating expenses 121,338 82,300 39,038 Income (loss) from operations (73,361 ) 21,481 (94,842 ) Other income (expense): Interest income 4,735 3,937 798 Other income (expense), net 60 (14 ) 74 Total other income, net 4,795 3,923 872 Net income (loss) before income taxes (68,566 ) 25,404 (93,970 ) Income tax expense - (2,598 ) 2,598 Net income (loss) $ (68,566 ) $ 22,806 $ (91,372 ) Grant Revenue Year Ended December 31, 2024 2023 $ Change BARDA Contract (Tebipenem HBr) $ 20,200 $ 4,361 $ 15,839 NIAID Contract (SPR206) 381 2,685 (2,304 ) Total revenue $ 20,581 $ 7,046 $ 13,535 Grant revenue recognized during 2024 and 2023 consisted of the reimbursement of qualifying expenses incurred in connection with our various government awards.
Biggest changeResults of Operations Comparison of the Years Ended December 31, 2025 and 2024 The following table summarizes our results of operations for the years ended December 31, 2025 and 2024 (in thousands): Year Ended December 31, 2025 2024 $ Change Revenues: Grant revenue $ 7,183 $ 20,581 $ (13,398 ) Collaboration revenue - related party 47,033 27,025 20,008 Collaboration revenue 12,586 371 12,215 Total revenues 66,802 47,977 18,825 Operating expenses: Research and development 38,467 96,757 (58,290 ) General and administrative 21,176 23,704 (2,528 ) Restructuring 258 877 (619 ) Impairment of long-term asset 587 — 587 Total operating expenses 60,488 121,338 (60,850 ) Income (loss) from operations 6,314 (73,361 ) 79,675 Other income: Interest income 2,512 4,735 (2,223 ) Other income (expense), net 7 60 (53 ) Total other income, net 2,519 4,795 (2,276 ) Net income (loss) before income taxes 8,833 (68,566 ) 77,399 Income tax expense (261 ) — (261 ) Net income (loss) $ 8,572 $ (68,566 ) $ 77,138 84 Grant Revenue (in thousands): Year Ended December 31, 2025 2024 $ Change BARDA Contract (Tebipenem HBr) $ 7,154 $ 20,200 $ (13,046 ) NIAID Contract (SPR206) 29 381 (352 ) Total revenue $ 7,183 $ 20,581 $ (13,398 ) Grant revenue recognized during the years ended December 31, 2025 and 2024 consisted of the reimbursement of qualifying expenses incurred in connection with our various government awards.
This is due to the numerous risks and uncertainties, including the following: • successful completion of clinical trials with safety, tolerability and efficacy profiles that are satisfactory to the FDA or any comparable foreign regulatory authority, including on account of the disruptive impacts of any global health, economic or political crises; • receipt of marketing approvals from applicable regulatory authorities; • establishment of arrangements with third-party manufacturers to obtain manufacturing supply; • obtainment and maintenance of patent, trade secret protection and regulatory exclusivity, both in the United States and internationally, including our ability to maintain our license agreement with Meiji with respect to tebipenem HBr; • protection of our rights in our intellectual property portfolio; • launch of commercial sales of our product candidates, if approved, whether alone or in collaboration with others; • acceptance of our product candidates, if approved, by patients, the medical community and third-party payors; • competition with other therapies; and • a continued acceptable safety profile of our product candidates, if approved.
This is due to the numerous risks and uncertainties, including the following: • successful completion of clinical trials with safety, tolerability and efficacy profiles that are satisfactory to the FDA or any comparable foreign regulatory authority, including on account of the disruptive impacts of any global health, economic or political crises; • receipt of marketing approvals from applicable regulatory authorities; • establishment of arrangements with third-party manufacturers to obtain manufacturing supply; • obtainment and maintenance of patent, trade secret protection and regulatory exclusivity, both in the United States and internationally, including our ability to maintain our license agreement with Meiji with respect to tebipenem HBr; • protection of our rights in our intellectual property portfolio; • launch of commercial sales of any of our product candidates, if approved, whether alone or in collaboration with others; • acceptance of any of our product candidates, if approved, by patients, the medical community and third-party payors; • competition with other therapies; and • a continued acceptable safety profile of any of our product candidates, if approved.
Collaboration Revenue During the year ended December 31, 2024 we recognized $0.4 million in collaboration revenue related to our agreement with Pfizer.
During the year ended December 31, 2024 we recognized $0.4 million in collaboration revenue related to our agreement with Pfizer.
In addition, we have agreed to pay to PBB royalties, on a product-by-product and country-by-country basis, of a low single-digit percentage based on net sales of products licensed under the agreement.
In addition, we have agreed to pay PBB royalties, on a product-by-product and country-by-country basis, of a low single-digit percentage based on net sales of products licensed under the agreement.
If we obtain regulatory approval for any of our product candidates and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our internal commercialization capability to support product sales, marketing and distribution. Further, we expect to incur additional costs associated with our continued operation as a public company.
If we obtain regulatory approval for any of our future product candidates and do not enter into a commercialization partnership, we expect to incur significant expenses related to developing our internal commercialization capability to support product sales, marketing and distribution. Further, we expect to incur additional costs associated with our continued operation as a public company.
Revenue from government grants is recognized as the qualifying expenses related to the contracts are incurred, provided that 82 there is reasonable assurance of recoverability. Revenue recognized upon incurring qualifying expenses in advance of receipt of funding is recorded as unbilled receivables, a component of prepaid expenses and other current assets, in the consolidated balance sheet.
Revenue from government grants is recognized as the qualifying expenses related to the contracts are incurred, provided that there is reasonable assurance of recoverability. Revenue recognized upon incurring qualifying expenses in advance of receipt of funding is recorded as unbilled receivables, a component of prepaid expenses and other current assets, in the consolidated balance sheet.
Operating Expenses Research and Development Expenses Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts, and the development of our product candidates, which include: • employee-related expenses, including salaries, related benefits, travel and share-based compensation expense for employees engaged in research and development functions; 80 • expenses incurred in connection with the preclinical and clinical development of our product candidates, including under agreements with contract research organizations (“CROs”); • costs incurred in connection with our government awards; • the cost of consultants and contract manufacturing organizations (“CMOs”) that manufacture drug products for use in our preclinical studies and clinical trials; • facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and supplies; and • payments made under third-party licensing agreements.
Operating Expenses Research and Development Expenses Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts, and the development of any of our product candidates, which include: • employee-related expenses, including salaries, related benefits, travel and share-based compensation expense for employees engaged in research and development functions; • expenses incurred in connection with the preclinical and clinical development of any of our product candidates, including under agreements with contract research organizations (“CROs”); • costs incurred in connection with our government awards; • the cost of consultants and contract manufacturing organizations (“CMOs”) that manufacture drug products for use in our preclinical studies and clinical trials; • facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, insurance and supplies; and • payments made under third-party licensing agreements.
If the payments to and from the collaborative partner are not within the scope of other authoritative accounting guidance, we base the statement of operations classification for the payments received on a reasonable, rational analogy to authoritative accounting guidance, applied in a consistent manner.
If the payments to and 82 from the collaborative partner are not within the scope of other authoritative accounting guidance, we base the statement of operations classification for the payments received on a reasonable, rational analogy to authoritative accounting guidance, applied in a consistent manner.
To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses. Share-Based Compensation We issue stock-based awards to employees and directors in the form of stock options and restricted stock units.
To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses. 83 Share-Based Compensation We issue stock-based awards to employees and directors in the form of stock options and restricted stock units.
The actions necessary to reduce spending under this plan at a level that mitigates the factors described above is not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.
The actions necessary to reduce spending under this plan at a level that mitigates the factors described above are not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.
The actions necessary to reduce spending under this plan at a level that mitigates the factors described above is not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.
The actions necessary to reduce spending under this plan at a level that mitigates the factors described above are not considered probable, as defined in the accounting standards and therefore, the full extent to which management may extend our funds through these actions may not be considered in management’s assessment of our ability to continue as a going concern.
Funding Requirements Our future use of operating cash and capital requirements, and the timing and amount thereof, will depend largely on: • the timing and costs of our ongoing and planned clinical trials; • the initiation, progress, timing, costs and results of preclinical studies and clinical trials of our product candidates and potential new product candidates; • the amount of funding that we receive under government contracts that we have applied for or may apply for in the future; • the number and characteristics of product candidates that we pursue; • the outcome, timing and costs of seeking regulatory approvals; • the costs of commercialization activities for our product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities; • the terms and timing of any future collaborations, licensing or other arrangements that we may establish; • the amount and timing of any payments we may be required to make, or that we may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights, including milestone and royalty payments and patent prosecution fees that we are obligated to pay pursuant to our license agreements; • the costs of preparing, filing and prosecuting patent applications, maintaining and protecting our intellectual property rights and defending against any intellectual property related claims; • the costs of operating as a public company; • the extent to which we in-license or acquire other products and technologies; and • costs associated with litigation and any government investigation.
Funding Requirements Our future use of operating cash and capital requirements, and the timing and amount thereof, will depend largely on: • the initiation, progress, timing, costs and results of any preclinical studies and clinical trials of any of our product candidates and potential new product candidates; • the amount of funding that we receive under government contracts that we may apply for in the future; • the number and characteristics of product candidates that we may pursue; • the outcome, timing and costs of seeking regulatory approvals; • the costs of commercialization activities for our future product candidates if we receive marketing approval, including the costs and timing of establishing product sales, marketing, distribution and manufacturing capabilities; • the terms and timing of any future collaborations, licensing or other arrangements that we may establish; • the amount and timing of any payments we may be required to make, or that we may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights, including milestone and royalty payments and patent prosecution fees that we are obligated to pay pursuant to our license agreements; 87 • the costs of preparing, filing and prosecuting patent applications, maintaining and protecting our intellectual property rights and defending against any intellectual property related claims; • the costs of operating as a public company; • the extent to which we in-license or acquire other products and technologies; and • costs associated with litigation and any government investigation.
Government Contracts We generate revenue from government contracts that reimburse us for certain allowable costs for funded projects. For contracts with government agencies, when we have concluded that we are the principal in conducting the research and development expenses and where the funding arrangement is considered central to our ongoing operations, we classify the recognized funding received as revenue.
Government Contracts We have generated revenue from government contracts that reimburse us for certain allowable costs for funded projects. For contracts with government agencies, when we have concluded that we are the principal in conducting the research and development expenses and where the funding arrangement is considered central to our ongoing operations, we classify the recognized funding received as revenue.
Net cash provided by changes in our operating assets and liabilities was $36.3 million and consisted primarily of a $46.4 million decrease in our related party collaboration receivable, primarily due to the receipt of the first and second installments of the development milestone payments from GSK (see Note 13 - License, Collaboration and Service Agreements), a $26.6 million net decrease in deferred revenue, offset by an increase of $17.1 million in accrued expenses and accounts payable.
Net cash provided by changes in our operating assets and liabilities was $36.3 million and consisted primarily of a $46.4 million decrease in our related party collaboration receivable, primarily due to the receipt of the first and second installments of the development milestone payments from GSK (see Note 13 to the consolidated financial statements), a $26.6 million net decrease in deferred revenue, offset by an increase of $17.1 million in accrued expenses and accounts payable.
Personnel-related costs for the years ended December 31, 2024 and 2023 included share-based compensation expenses of $2.6 million and $2.7 million, respectively. Facility-related and other costs primarily reflect costs related to supporting our research and development staff.
Personnel-related costs for the years ended December 31, 2025 and 2024 included share-based compensation expenses of $1.7 million and $2.6 million, respectively. 85 Facility-related and other costs primarily reflect costs related to supporting our research and development staff.
Changes in collaboration receivable - related party related to the GSK License Agreement. Investing Activities We did not undertake any investing activities during either of the years ended December 31, 2024 or 2023. 87 Financing Activities We did not undertake any financing activities during the year ended December 31, 2024.
Changes in collaboration receivable - related party related to the GSK License Agreement. Investing Activities We did not undertake any investing activities during either of the years ended December 31, 2025 or 2024. Financing Activities We did not undertake any financing activities during either of the years ended December 31, 2025 or 2024.
These contracts are cancelable by us upon prior notice. Payments due upon cancellation consist only of payments for services provided or expenses incurred, including non-cancellable obligations of our service providers, up to the date of cancellation. These payments are not included in the table of contractual obligations and commitments above.
Payments due upon cancellation consist only of payments for services provided or expenses incurred, including non-cancellable obligations of our service providers, up to the date of cancellation. These payments are not included in the table of contractual obligations and commitments above.
To date, we have funded our operations with payments received under license and collaboration agreements and funding from government contracts, and from the proceeds of multiple common stock offerings. As of December 31, 2024, we had cash and cash equivalents of $52.9 million.
To date, we have funded our operations with payments received under license and collaboration agreements and government contracts and from the proceeds of multiple common stock offerings. As of December 31, 2025, we had cash and cash equivalents of $40.3 million.
Personnel-related costs for the years ended December 31, 2024 and 2023 included share-based compensation expense of $5.2 million and $5.3 million, respectively. The increase in professional and consultant fees was primarily due to increased legal and consulting expenses incurred during the year ended December 31, 2024.
Personnel-related costs for the years ended December 31, 2025 and 2024 included share-based compensation expense of $2.6 million and $5.2 million, respectively. The decrease in professional and consultant fees was primarily due to decreased legal and consulting expenses incurred during the year ended December 31, 2025.
Total other income for the year ended December 31, 2024 included $4.7 million of interest income, of which $1.5 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency.
Total other income for the year ended December 31, 2025 included $2.5 million of interest income, of which $0.9 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency.
Collaboration Agreements For collaboration agreements with a third party, to determine the appropriate statement of operations classification of the recognized funding, we first assess whether the collaboration arrangement is within the scope of the accounting guidance for collaboration arrangements.
We do not anticipate receiving any additional funding under the BARDA contract. Collaboration Agreements For collaboration agreements with a third party, to determine the appropriate statement of operations classification of the recognized funding, we first assess whether the collaboration arrangement is within the scope of the accounting guidance for collaboration arrangements.
Contractual Obligations and Commitments The following table summarizes our contractual obligations as of December 31, 2024 and the effects that such obligations are expected to have on our liquidity and cash flows in future periods: Payments Due by Period Total Less Than 1 Year 1 to 3 Years 4 to 5 Years More than 5 Years (in thousands) Operating lease commitments (1) 4,858 1,746 3,112 — — Total $ 4,858 $ 1,746 $ 3,112 $ — $ — (1) Reflects payments due for our lease of office space under an operating lease agreement that expires in 2027.
Contractual Obligations and Commitments The following table summarizes our contractual obligations as of December 31, 2025 and the effects that such obligations are expected to have on our liquidity and cash flows in future periods (in thousands): Payments Due by Period Total Less Than 1 Year 1 to 3 Years 4 to 5 Years More than 5 Years (in thousands) Operating lease commitments (1) $ 3,112 $ 1,956 $ 1,156 $ — $ — Total $ 3,112 $ 1,956 $ 1,156 $ — $ — (1) Reflects payments due for our lease of office space under an operating lease agreement that expires in 2027. 88 In the third quarter of 2025, we entered into agreements to sublease a portion of our office space through the remainder of our lease agreement that expires in 2027.
Facility-related and other costs primarily reflect costs related to supporting our general and administrative staff. Restructuring During the year ended December 31, 2024, we incurred restructuring expenses of $0.9 million related to our strategic restructuring that we announced in October 2024. Restructuring expenses for the period were primarily comprised of severance and other employee costs.
Facility-related and other costs primarily reflect costs related to supporting our general and administrative staff. Restructuring During the years ended December 31, 2025 and 2024, we incurred restructuring expenses of $0.3 million and $0.9 million, respectively, related to our strategic restructuring that we announced in October 2024.
Income Taxes Except for year ended December 31, 2022, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our earned research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized.
Other Income (Expense), Net Other income (expense), net, consists of insignificant amounts of miscellaneous income, as well as realized and unrealized gains and losses from foreign currency-denominated cash balances and vendor payables. 81 Income Taxes Except for year ended December 31, 2022, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our earned research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss carryforwards and tax credits will not be realized.
Under an agreement we entered into with PBB, we are obligated to make milestone payments of up to $5.8 million upon the achievement of specified clinical milestones and a payment of £5.0 million ($6.3 million as of December 31, 2024) upon the achievement of a specified commercial milestone for SPR206.
Under an agreement we entered into with PBB, Cantab Anti-Infectives Ltd. and New Pharma License Holdings Limited, we are obligated to make milestone payments of up to $5.8 million upon the achievement of specified clinical milestones and a payment of £5.0 million ($6.7 million as of December 31, 2025) upon the achievement of a specified commercial milestone for SPR206.
We cannot predict if, when, or to what extent we will generate revenue from the commercialization and sale of our product candidates. We may never succeed in obtaining regulatory approval for any of our product candidates.
If our development efforts for any of our product candidates are successful and result in regulatory approval, we may generate revenue in the future from product sales. We cannot predict if, when, or to what extent we will generate revenue from the commercialization and sale of any of our product candidates.
Until such time, if ever, as we can generate substantial product revenue, we expect to finance our operations through a combination of equity offerings, debt financings, government funding, collaborations, strategic alliances and marketing, distribution or licensing arrangements.
Our future funding requirements will depend on and could increase significantly as a result of many factors, including those listed above. Until such time, if ever, as we can generate substantial product revenue, we expect to finance our operations through a combination of equity offerings, debt financings, government funding, collaborations, strategic alliances and marketing, distribution or licensing arrangements.
Direct costs related to our tebipenem HBr program during the year ended December 31, 2024 reflect a $3.6 million reduction to expense related to a purchase of drug substance material by GSK.
In December 2025, GSK resubmitted the NDA for tebipenem HBr to the FDA. Direct costs related to our tebipenem HBr program during the years ended December 31, 2025 and 2024, reflect a $0.5 million and $3.6 million reduction to expense related to a purchase of drug substance material by GSK, respectively.
Collaboration Revenue - Related Party During the years ended December 31, 2024 and 2023, collaboration revenue - related party related to revenue recognized under the GSK License Agreement. During the year ended December 31, 2024, we recognized $27.0 million in collaboration revenue - related party under the GSK License Agreement.
Collaboration Revenue - Related Party During the years ended December 31, 2025 and 2024, collaboration revenue - related party related to revenue recognized under the GSK License Agreement.
As a result, we will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, government funding arrangements, collaborations, strategic alliances and marketing, distribution or licensing arrangements.
Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of equity offerings, debt financings, government funding arrangements, collaborations, strategic alliances and marketing, distribution or licensing arrangements. If we are not able to secure adequate additional funding, we will have to make further reductions in spending.
Grant Revenue We expect a portion of our revenue will continue to be derived from payments under our active government awards and any awards that we may receive in the future. Collaboration Revenue Current collaboration revenue relates to our agreements with Pfizer and GSK.
We may never succeed in obtaining regulatory approval for any existing or future product candidates. Grant Revenue A portion of our revenue may be derived from payments under any government awards that we may receive in the future. Collaboration Revenue Collaboration revenue relates to our agreements with Pfizer and GSK.
For further information, refer to Note 9 – Restructuring to the consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K.
Restructuring expenses for both periods were primarily comprised of severance and other employee costs. For further information, refer to Note 9 to the consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K.
Net cash used in operating activities for the year ended December 31, 2023 was $33.0 million, primarily resulting from our net income of $22.8 million, adjusted for net non-cash items of $14.6 million (primarily due to stock-based compensation and asset impairment).
Net cash used in operating activities for the year ended December 31, 2024 was $23.4 million, primarily resulting from our net loss of $68.6 million, adjusted for net non-cash items of $8.8 million (primarily due to share-based compensation).
Total other income for the year ended December 31, 2023 included $3.9 million of interest income, offset by fluctuations in unrealized foreign currency. Liquidity and Capital Resources Since our inception, we have incurred significant operating losses.
Total other income for the year ended December 31, 2024 included $4.7 million of interest income, of which $1.5 million related to the significant financing component recognized under the GSK License Agreement, offset by immaterial fluctuations in unrealized foreign currency. Liquidity and Capital Resources Since our inception, we have incurred significant operating losses.
Examples of estimated accrued research and development expenses include fees paid to: • vendors in connection with the preclinical development activities; • CMOs in connection with the production of preclinical and clinical trial materials; • CROs in connection with preclinical and clinical studies; and • investigative sites in connection with clinical trials. 83 We base our expenses related to preclinical studies and clinical trials on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple research institutions and CROs that conduct and manage preclinical studies and clinical trials on our behalf.
We base our expenses related to preclinical studies and clinical trials on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple research institutions and CROs that conduct and manage preclinical studies and clinical trials on our behalf.
In that event, we may have to delay, scale back, or eliminate some or all of our planned clinical trials, and research stage.
If we are not able to secure adequate additional funding, we plan to make reductions in spending. In that event, we may have to delay, scale back, or eliminate some or all of our planned clinical trials, and research stage programs.
As of December 31, 2024, we had cash and cash equivalents of $52.9 million.
As of December 31, 2025, we had cash and cash equivalents of $40.3 million.
General and Administrative Expenses Year Ended December 31, 2024 2023 $ Change Personnel related (including share-based compensation) $ 13,188 $ 15,324 $ (2,136 ) Professional and consultant fees 8,198 8,151 47 Facility related and other 2,318 2,079 239 Total general and administrative expenses $ 23,704 $ 25,554 $ (1,850 ) The decrease in personnel-related costs of $2.1 million was primarily a result of decreased headcount costs in our general and administrative functions during the period.
General and Administrative Expenses (in thousands): Year Ended December 31, 2025 2024 $ Change Personnel related (including share-based compensation) $ 11,792 $ 13,188 $ (1,396 ) Professional and consultant fees 7,435 8,198 (763 ) Facility related and other 1,949 2,318 (369 ) Total general and administrative expenses $ 21,176 $ 23,704 $ (2,528 ) The decrease in personnel-related costs of $1.4 million was primarily a result of decreased headcount costs in our general and administrative functions between the periods.
Direct costs related to our SPR206 program decreased by $2.7 million during the year ended December 31, 2024, primarily due to decreased preclinical activity.
Direct costs related to our SPR206 program decreased by $0.5 million during the year ended December 31, 2025, primarily due to decreased preclinical activity and the cessation of development of the program announced in March 2025.
This timeline is subject to uncertainty as to the timing of future expenditures. We have developed plans to mitigate this risk, which primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations and/or reducing cash expenditures. If we are not able to secure adequate additional funding, we plan to make reductions in spending.
This timeline is uncertain and subject to change as we explore opportunities to grow our pipeline. We have developed plans to mitigate this risk, which primarily consist of raising additional capital through some combination of equity or debt financings, potential new collaborations and/or reducing cash expenditures.
The increase in revenue during 2024 was primarily due to an increase of $15.8 million in funding under our BARDA contract related to our pivotal Phase 3 clinical trial of tebipenem HBr, partially offset by a decrease of $2.3 million in qualified expenses incurred under our NIAID award relating to SPR206.
The decrease in grant revenue during 2025 was primarily due to a decrease of $13.0 million in funding under our BARDA contract related to the conclusion of the Phase 3 clinical trial of tebipenem HBr, and a decrease of $0.4 million in qualified expenses incurred under our NIAID award relating to SPR206 as we ceased development of SPR206 and the NIAID award was terminated in April 2025.
Direct costs related to our SPR720 program increased by $3.6 million during the year ended December 31, 2024, compared to the year ended December 31, 2023, due to clinical activity during the period related to our Phase 2a clinical trial of SPR720, which completed enrollment in the second quarter of 2024.
Direct costs related to our SPR720 program decreased by $15.6 million during the year ended December 31, 2025, compared to the year ended December 31, 2024, due to decreased clinical activity during the period and the cessation of development on the program announced in November 2025.
If we fail to raise capital or enter into such agreements as, and when needed, we may have to significantly delay, scale back or discontinue the development and commercialization of one or more of our product candidates. 79 Because of the numerous risks and uncertainties associated with pharmaceutical product development, we are unable to accurately predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability.
Because of the numerous risks and uncertainties associated with pharmaceutical product development, we are unable to accurately predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability. Even if we are able to generate product sales, we may not become profitable.
As of December 31, 2024, we also had federal and state research and development tax credit carryforwards of $6.2 million and $2.1 million, respectively, which begin to expire in 2036 and 2033, respectively. We have recorded a full valuation allowance against our net deferred tax assets at each balance sheet date.
The federal and state research and development tax credits begin to expire in 2035 and the federal orphan drug credits begin to expire in 2044. We have recorded a full valuation allowance against our net deferred tax assets at each balance sheet date.
As a result, management has concluded that substantial doubt exists about our ability to continue as a going concern. We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates.
We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for any of our product candidates.
As of December 31, 2024, we had federal and state net operating loss carryforwards ("NOLs") of $165.2 million and $120.6 million, respectively which may be available to offset future income tax liabilities. $152.0 million of the federal NOLs can be carried forward indefinitely and $13.2 million of the federal NOLs begin to expire in 2034.
As of December 31, 2025, we had United States federal, state and foreign net operating loss carryforwards ("NOLs") of $226.1 million, $184.8 million and $4.7 million, respectively. $212.8 million of the federal NOLs can be carried forward indefinitely and $13.2 million of NOLs begin to expire in 2034.
Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials.
Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. 80 At this time, we cannot reasonably estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any existing or future product candidates.
The related costs incurred by us are included in research and development expense in our consolidated statements of operations and comprehensive loss.
The related costs incurred by us are included in research and development expense in our consolidated statements of operations and comprehensive loss. In March 2025, we announced that we ceased development of SPR206 and in April 2025, NIAID communicated to us that it had terminated the contract for convenience effective immediately.
During the year ended December 31, 2023, we recognized $95.8 million in collaboration revenue - related party, of which $21.2 million was recognized upon achievement of the $30.0 million milestone under the GSK License Agreement and $64.7 million upon achievement of the $95.0 million milestone under the GSK License Agreement.
During the year ended December 31, 2024, we recognized $27.0 million in collaboration revenue - related party under the GSK License Agreement. Collaboration Revenue During the year ended December 31, 2025 we recognized $12.6 million in collaboration revenue related to our agreement with Pfizer, all of which was recognized upon termination of our agreement with Pfizer in December 2025.
Impairment of Long-Term Asset 86 In 2023, we concluded that we have no future use for the Savior facility (further described in Note 13 – License, Collaboration and Service Agreements to our consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K).
Impairment Charges In September 2025 as a result of our review of our space needs and our existing lease agreements, we concluded that we had an impairment of our right of use asset (further described in Note 5 to the consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K).
Based on our cash and cash equivalents as of December 31, 2024, together with earned and non-contingent development milestone payments from GSK, as well as other non-dilutive funding commitments, we believe that our cash runway will be sufficient to fund our operating expenses and required capital expenditures into the second quarter of 2026.
Based on our current operating plan, we believe that our cash and cash equivalents as of December 31, 2025 will be sufficient to fund our operating expenses and required capital expenditures into 2028.
Cash Flows The following table summarizes our sources and uses of cash for the years ended December 31, 2024 and 2023: Year Ended December 31, 2024 2023 Cash used in operating activities $ (23,444 ) $ (32,995 ) Cash provided by financing activities — 221 Net decrease in cash and cash equivalents $ (23,444 ) $ (32,774 ) Operating Activities Net cash used in operating activities for the year ended December 31, 2024 was $23.4 million, primarily resulting from our net loss of $68.6 million, adjusted for net non-cash items of $8.8 million (primarily due to stock-based compensation).
In February 2026, we received a $25.0 million milestone payment under the GSK agreement, which we were entitled to receive upon GSK’s filing of an NDA for tebipenem HBr with the FDA. 86 Cash Flows The following table summarizes our sources and uses of cash for the years ended December 31, 2025 and 2024 (in thousands): Year Ended December 31, 2025 2024 Cash used in operating activities $ (12,624 ) $ (23,444 ) Net decrease in cash and cash equivalents $ (12,624 ) $ (23,444 ) Operating Activities Net cash used in operating activities for the year ended December 31, 2025 was $12.6 million, primarily resulting from our net income of $8.6 million, adjusted for net non-cash items of $6.0 million (primarily due to share-based compensation).
We anticipate that we will continue to incur accounting, audit, legal, regulatory, compliance, infrastructure and director and officer insurance costs, as well as investor and public relations expenses associated with our continued operation as a public company. 81 Restructuring In light of our decision to suspend planned development activities for our oral SPR720 program and our strategic restructuring, we expect that our future expenses relating to development activities with respect to SPR720 will be substantially reduced as we evaluate potential paths forward for SPR720 and implement our restructuring.
We anticipate that we will continue to incur accounting, audit, legal, regulatory, compliance, infrastructure and director and officer insurance costs, as well as investor and public relations expenses associated with our continued operation as a public company. Impairment Charges In the third quarter of 2025, we evaluated our real estate leases in light of our new sublease agreements.
During the year ended December 31, 2023 we recognized $0.9 million in collaboration revenue related to our agreement with Pfizer. 85 Research and Development Expenses Year Ended December 31, 2024 2023 $ Change Direct research and development expenses by program: Tebipenem HBr $ 60,502 $ 16,695 $ 43,807 SPR720 16,626 13,031 3,595 SPR206 570 3,240 (2,670 ) Unallocated expenses: Personnel related (including share-based compensation) 14,111 13,788 323 Facility related and other 4,948 4,686 262 Total research and development expenses $ 96,757 $ 51,440 $ 45,317 Direct costs related to our tebipenem HBr program increased by $43.8 million during the year ended December 31, 2024, compared to the year ended December 31, 2023, due to increased clinical activities related to our Phase 3 clinical trial of tebipenem HBr, which we initiated in the fourth quarter of 2023.
Research and Development Expenses (in thousands): Year Ended December 31, 2025 2024 $ Change Direct research and development expenses by program: Tebipenem HBr $ 22,562 $ 60,502 $ (37,940 ) SPR720 985 16,626 (15,641 ) SPR206 49 570 (521 ) Unallocated expenses: Personnel related (including share-based compensation) 9,631 14,111 (4,480 ) Facility related and other 5,240 4,948 292 Total research and development expenses $ 38,467 $ 96,757 $ (58,290 ) Direct costs related to our tebipenem HBr program decreased by $37.9 million during the year ended December 31, 2025, compared to the year ended December 31, 2024, due to decreased clinical activities related to our Phase 3 clinical trial of tebipenem HBr, which met its primary endpoint and was stopped early for efficacy during the first half of 2025.
Because of the numerous risks and uncertainties associated with research, development and commercialization of pharmaceutical product candidates, we are unable to estimate the exact amount of our working capital requirements. Our future funding requirements will depend on and could increase significantly as a result of many factors, including those listed above.
We have based these estimates on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we expect. Because of the numerous risks and uncertainties associated with research, development and commercialization of pharmaceutical product candidates, we are unable to estimate the exact amount of our working capital requirements.
Our most advanced clinical stage product candidate, tebipenem HBr, is in Phase 3 development, with the potential to be the first broad-spectrum oral carbapenem to treat adult patients with cUTIs, including pyelonephritis, caused by certain microorganisms. The other programs in our pipeline are SPR206 and SPR720.
Overview We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases with high unmet need. Our clinical-stage product candidate, tebipenem HBr, has completed a second Phase 3 trial, and we believe has the potential to be the first oral carbapenem to treat adult patients with cUTIs, including pyelonephritis, caused by certain microorganisms.
Income Tax Expense During the year ended December 31, 2023, we recorded $2.6 million of income tax expense primarily related to a change in estimate with respect to the tax treatment of the GSK License Agreement. Other Income, Net Other income, net was $4.8 million during 2024, compared to $3.9 million during 2023.
Other Income, Net Other income, net was $2.5 million during the year ended December 31, 2025, compared to $4.8 million during the year ended December 31, 2024.
Components of Our Results of Operations Sales Revenue To date, we have not generated any revenue from product sales. If our development efforts for our product candidates are successful and result in regulatory approval, we may generate revenue in the future from product sales.
SPR720 In November 2025, we announced that we ceased development of SPR720 and Vertex subsequently exercised its right to terminate the Vertex Assignment and License Agreement. 79 Components of Our Results of Operations Sales Revenue To date, we have not generated any revenue from product sales.
Net cash used by our operating assets and liabilities was $70.4 million and consisted primarily of a $95.7 million increase in our related party collaboration receivable, $29.0 million net increase in deferred revenue and a decrease of $1.7 million in accrued expenses and accounts payable.
Net cash provided by changes in our operating assets and liabilities was $27.2 million and consisted primarily of a $24.0 million decrease in our related party collaboration receivable, primarily due to the receipt of the third and fourth installments of the development milestone payments from GSK, offset by the addition of the milestone for submission of an NDA for tebipenem HBr (see Note 13 to the consolidated financial statements), a $34.7 million net decrease in deferred revenue, and a net decrease of $18.8 million in accrued expenses and accounts payable.
Even if we are able to generate product sales, we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and be forced to reduce or terminate our operations.
If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and be forced to reduce or terminate our operations. 78 Recent Developments Tebipenem HBr In May 2025, we and GSK announced that the pivotal Phase 3 PIVOT-PO trial evaluating tebipenem HBr, an investigational oral treatment for cUTIs, including pyelonephritis, caused by certain microorganisms, met its primary endpoint and the trial was stopped early for efficacy.
The state NOLs begin to expire in 2034 and will expire at various dates through 2044. In addition, as of December 31, 2024, we had foreign net operating loss carryforwards of $4.6 million, which may be available to offset future income tax liabilities and do not expire.
As of December 31, 2025, we also had federal and state research and development tax credit carryforwards of $6.7 million and $1.7 million, respectively, and federal orphan drug tax credit carryforwards of $3.1 million, which may be available to offset future income tax liabilities.
Under our agreement with Vertex, we are obligated to make future milestone payments of up to $80.2 million upon the achievement of specified clinical, regulatory and commercial milestones related to SPR720 and to pay to Vertex tiered royalties, on a product-by-product and country-by-country basis, of a mid-single-digit to low double-digit percentage based on net sales of products licensed under the agreement. 89 We enter into contracts in the normal course of business with CROs, CMOs and other third parties for clinical trials, preclinical research studies and testing, manufacturing and other services.
We enter into contracts in the normal course of business with CROs, CMOs and other third parties for clinical trials, preclinical research studies and testing, manufacturing and other services. These contracts are cancelable by us upon prior notice.
At this time, we cannot reasonably estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any of our product candidates. The successful development and commercialization of our product candidates is highly uncertain.
The successful development and commercialization of any of our product candidates is highly uncertain.
Based on our cash and cash equivalents as of December 31, 2024, together with earned and non-contingent development milestone payments from GSK, as well as other non-dilutive funding commitments, we believe that our cash runway will be sufficient to fund our operating expenses and capital expenditure requirements into the second quarter of 2026.
Based on our current operating plan, we believe that our cash and cash equivalents as of December 31, 2025 will enable us to fund our operating expenses and required capital expenditure requirements for at least 12 months from the issuance of the financial statements included in this report and into 2028.
Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our product candidates. As of December 31, 2024, we had an accumulated deficit of $459.6 million, and cash and cash equivalents of $52.9 million.
We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and commercialization of tebipenem HBr, or any product candidate we may develop in the future.
We expect to continue to incur significant expenses and operating losses for at least the next year.
As of December 31, 2025, we had an accumulated deficit of $451.1 million, and cash and cash equivalents of $40.3 million. We expect to continue to incur significant expenses and operating losses for the foreseeable future.
Removed
Overview We are a clinical-stage biopharmaceutical company focused on identifying and developing novel treatments for rare diseases and diseases caused by MDR bacterial infections with high unmet need.
Added
In September 2022, we entered into an exclusive license agreement with GSK for the development, manufacture and commercialization of tebipenem HBr, which includes the transfer of the IND and the NDA ownership to GSK.
Removed
Since our inception in 2013, we have focused our efforts and financial resources on acquiring and developing product and technology rights, building our intellectual property portfolio and conducting research and development activities for our product candidates. We do not have any products approved for sale and have not generated any revenue from product sales.
Added
In May 2025, we and GSK announced that the pivotal Phase 3 PIVOT-PO trial evaluating tebipenem HBr met its primary endpoint and was stopped early for efficacy. GSK has submitted the data from the trial as part of an NDA Class 2 resubmission for tebipenem HBr to the FDA in December 2025, which has been accepted by the FDA.
Removed
We believe that our novel product candidates, if successfully developed and approved, could provide meaningful benefits to patients suffering from serious rare diseases and life-threatening bacterial infections, in both the community and hospital settings. Our pipeline consists of mid-to late-stage clinical assets.
Added
GSK reported that the PDUFA date has been set as June 18, 2026. Following the termination of our earlier stage programs (SPR206 and SPR720), we remain focused on supporting GSK in the FDA approval process pursuant to our obligations under the GSK License Agreement and advancing other corporate activities, including exploring opportunities to grow our portfolio of clinical-stage product candidates.
Removed
SPR206 is an IV-administered next generation polymyzin product candidate for the treatment of HABP/VABP caused by MDR Gram-negative bacterial infections. In March 2025, following a reprioritization of our programs, we announced that we are no longer pursuing a planned Phase 2 clinical trial for SPR206. SPR720 is a product candidate for first-line treatment of NTM pulmonary disease.
Added
During this period, we remain focused on supporting GSK in the FDA approval process pursuant to our obligations under our GSK License Agreement and advancing other corporate activities, including exploring opportunities to grow our portfolio of clinical-stage product candidates.
Removed
In October 2024, we announced that results from a planned interim analysis of our Phase 2a clinical trial for SPR720 demonstrated the oral agent did not meet its primary endpoint and we elected to suspend development of SPR720 in its oral formulation.
Added
Beyond this point, or in the event we change our current operating plan, we will need additional funding to support our continuing operations.
Removed
We are currently completing analysis of remaining data from all 25 patients dosed in the trial ahead of determining next steps. We have experienced mostly net losses and significant cash outflows from cash used in operating activities since our inception.
Added
The decision followed a recommendation from an IDMC that completed a pre-specified interim analysis of data from 1,690 patients enrolled in the trial.
Removed
During this period, we plan to prioritize advancing the Phase 3 clinical trial activities for tebipenem HBr under our GSK License Agreement and completing our analysis of the full dataset from the 25 treated patients in the Phase 2a proof-of-concept trial of SPR720.
Added
Following the review of the interim analysis data by the IDMC, it was determined that the Phase 3 PIVOT-PO trial met the primary endpoint of non-inferiority of tebipenem HBr compared to intravenous imipenem-cilastatin in hospitalized adult patients with cUTI, including pyelonephritis, on overall response (composite of clinical cure plus microbiological eradication) at the test-of-cure visit.

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Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Market Risk — interest-rate, FX, commodity exposure

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Biggest changeItem 7A. Quantitative and Qualitati ve Disclosures About Market Risk. As of December 31, 2024, we had cash and cash equivalents of $52.9 million, consisting of cash and money market accounts. The primary objectives of our investment activities are to preserve principal, provide liquidity and maximize income without significantly increasing risk.
Biggest changeItem 7A. Quantitative and Qualitati ve Disclosures About Market Risk. As of December 31, 2025, we had cash and cash equivalents of $40.3 million, consisting of cash and money market accounts. The primary objectives of our investment activities are to preserve principal, provide liquidity and maximize income without significantly increasing risk.
As we incur research expenses in foreign countries, we face exposure to movements in foreign currency exchange rates, primarily the Euro, British Pound and Australian dollar against the U.S. dollar. Historically, foreign currency fluctuations have not had a material impact on our consolidated financial statements. 90
As we incur research expenses in foreign countries, we face exposure to movements in foreign currency exchange rates, primarily the Euro, British Pound and Australian dollar against the U.S. dollar. Historically, foreign currency fluctuations have not had a material impact on our consolidated financial statements. 89
Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. Treasury interest rates. We did not have any assets classified as marketable securities as of December 31, 2024.
Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of U.S. Treasury interest rates. We did not have any assets classified as marketable securities as of December 31, 2025.

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