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What changed in Kiniksa Pharmaceuticals International, plc's 10-K — 2024 vs 2025

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Paragraph-level year-over-year comparison of Kiniksa Pharmaceuticals International, plc'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.

+787 added−934 removedSource: 10-K (2026-02-24) vs 10-K (2025-02-25)

Top changes in Kiniksa Pharmaceuticals International, plc's 2025 10-K

787 paragraphs added · 934 removed · 596 edited across 7 sections

Item 1. Business

Business — how the company describes what it does

176 edited+78 added−81 removed172 unchanged
Biggest changeSee “ Risk Factors—Risks Related to Intellectual Property— If we are unable to adequately protect our proprietary technology or obtain and maintain patent protection for our technology and products, if the scope of the patent protection obtained is not sufficiently broad, or if the terms of our patents are insufficient to protect our product candidates for an adequate amount of time, our competitors could develop and commercialize technology and products similar or identical to ours, and our ability to successfully commercialize our technology and products may be materially impaired .” In the future, if and when our drug candidates receive approval by the FDA or comparable regulatory authorities in other jurisdictions (as applicable, “regulatory authorities”), provided the legal requirements are met, we expect to apply for patent term extensions on issued patents covering those drugs, depending upon the length of the clinical trials for each drug and other factors.
Biggest changeSee “ Risk Factors—Risks Related to Intellectual Property.” In the future, if and when our drug candidates receive approval by the FDA or comparable regulatory authorities in other jurisdictions (as applicable, “regulatory authorities”), provided the legal requirements are met, we expect to apply for patent term extensions on issued patents covering those drugs, depending upon the length of the clinical trials for each drug and other factors.
The European Commission granted Orphan Drug designation to ARCALYST for the treatment of idiopathic pericarditis in 2021; and ​ (3) Kiniksa has worldwide rights, excluding the Middle East and North Africa; Kiniksa granted Huadong exclusive rights in the Asia Pacific Region, excluding Japan.
The European Commission granted Orphan Drug designation to ARCALYST for the treatment of idiopathic pericarditis in 2021. (3) Kiniksa has worldwide rights, excluding the Middle East and North Africa; Kiniksa granted Huadong exclusive rights in the Asia Pacific Region, excluding Japan.
We believe disease awareness is essential to enable physicians to diagnose recurrent pericarditis earlier in its disease course and to treat the underlying disease, rather than to episodically manage individual flares.
We believe disease awareness is essential to enable physicians to diagnose recurrent pericarditis earlier in its disease course and to treat the underlying disease, rather than to manage individual flares episodically.
Royalties will be payable for ARCALYST on a country-by-country or region-by-region basis until the later of (i) 12 years after the first commercial sale of ARCALYST in such country or region in the Huadong Territory, (ii) the date of expiration of the last valid patent claim of our patent rights or any joint collaboration patent rights that covers ARCALYST in such country or region in the Huadong Territory, and (iii) the expiration of the last regulatory exclusivity for ARCALYST in such country or region in the Huadong Territory.
Royalties will be payable on a country-by-country or region-by-region basis until the later of (i) 12 years after the first commercial sale of ARCALYST in such country or region in the Huadong Territory, (ii) the date of expiration of the last valid patent claim of our patent rights or any joint collaboration patent rights that covers ARCALYST in such country or region in the Huadong Territory and (iii) the expiration of the last regulatory exclusivity for ARCALYST in such country or region in the Huadong Territory.
Furthermore, an IRB representing each institution at which the clinical trial will be conducted must review and approve the plan for any clinical trial, including, among other things, the protocol and informed consent information to be provided to clinical trial subjects or their legal representatives, to ensure that the 23 Table of Contents risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits.
Furthermore, an IRB representing each institution at which the clinical trial 23 Table of Contents will be conducted must review and approve the plan for any clinical trial, including, among other things, the protocol and informed consent information to be provided to clinical trial subjects or their legal representatives, to ensure that the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits.
The FDA also may inspect the sponsor and one or more clinical trial sites to assure compliance with GCP requirements and the integrity of the clinical data submitted to the FDA.
The FDA also may inspect the sponsor and one or more clinical trial sites to assure compliance with GCP requirements and integrity of the clinical data submitted to the FDA.
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; ● United States federal civil monetary penalties laws, which impose civil fines for, among other things, the offering or transfer of remuneration to a Medicare or state healthcare program beneficiary if the person knows or should know it is likely to influence the beneficiary’s selection of a particular provider, practitioner, or supplier of services reimbursable by Medicare or a state healthcare program; ● the United States federal physician payment transparency requirements, sometimes referred to as the “Sunshine Act”, which requires manufacturers of drugs, devices, biologics and medical supplies that are reimbursable under Medicare, Medicaid or the Children’s Health Insurance Program to report to the Department of Health and Human Services information related to certain financial interactions with physicians (defined to include medical doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (including physician assistants and nurse practitioners), and teaching hospitals, as well as the ownership and investment interests of physicians and their immediate family members; ● United States federal consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities that potentially harm consumers; ● United States federal, state and local laws, and similar foreign laws, regulations and standards governing the collection, use, access to, confidentiality and security of health-related and other personal information; ● analogous United States state laws and regulations, such as state anti-kickback and false claims laws that may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by nongovernmental third party payors, including private insurers; and state laws that require pharmaceutical companies to adopt certain compliance standards; restrict interactions with healthcare professionals; disclose financial interactions with healthcare professionals to the government and public; report pricing information or marketing expenditures; or register sales representatives; and ● similar healthcare laws and regulations in the EU, United Kingdom and other jurisdictions, including: Directive 2001/83/EC on the Community code relating to medicinal products for human use and its national implementing legislation; the UK Human Medicines Regulations 2012; Directive 2011/83/EU on consumer rights and its national implementing legislation; and reporting requirements detailing interactions with and payments to healthcare professionals, which may be applicable even if we are not commercializing a product in such jurisdictions. 37 Table of Contents Human Capital ​ We aim to cultivate a highly-skilled and passionate team determined to deliver transformative therapies to the patients who need them most.
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; ● United States federal civil monetary penalties laws, which impose civil fines for, among other things, the offering or transfer of remuneration to a Medicare or state healthcare program beneficiary if the person knows or should know it is likely to influence the beneficiary’s selection of a particular provider, practitioner or supplier of services reimbursable by Medicare or a state healthcare program; ● the United States federal physician payment transparency requirements, sometimes referred to as the “Sunshine Act”, which requires manufacturers of drugs, devices, biologics and medical supplies that are reimbursable under Medicare, Medicaid or the Children’s Health Insurance Program to report to the Department of Health and Human Services information related to certain financial interactions with physicians (defined to include medical doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (including physician assistants and nurse practitioners) and teaching hospitals, as well as the ownership and investment interests of physicians and their immediate family members; ● United States federal consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities that potentially harm consumers; ● United States federal, state and local laws, and similar foreign laws, regulations and standards governing the collection, use, access to, confidentiality and security of health-related and other personal information; ● analogous United States state laws and regulations, such as state anti-kickback and false claims laws that may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by nongovernmental third party payors, including private insurers; and state laws that require 39 Table of Contents pharmaceutical companies to adopt certain compliance standards; restrict interactions with healthcare professionals; disclose financial interactions with healthcare professionals to the government and public; report pricing information or marketing expenditures; or register sales representatives; and ● similar healthcare laws and regulations in the EU, United Kingdom and other jurisdictions, including: Directive 2001/83/EC on the Community code relating to medicinal products for human use and its national implementing legislation; the UK Human Medicines Regulations 2012; Directive 2011/83/EU on consumer rights and its national implementing legislation; and reporting requirements detailing interactions with and payments to healthcare professionals, which may be applicable even if we are not commercializing a product in such jurisdictions. 40 Table of Contents Human Capital ​ We aim to cultivate a highly-skilled and passionate team determined to deliver transformative therapies to the patients who need them most.
Our reliance on third parties to manufacture certain of our products and product candidates exposes us to risks, and any technology transfer of the manufacturing process for our products or product candidates may be subject to a number of risks and uncertainties, see “ Risk Factors – Risks Related to Manufacturing and Our Reliance on Third Parties. ” Commercial Operations Our commercial team combines dozens of years of pharmaceutical commercial leadership experience with a passion for helping patients with significant unmet medical need.
Our reliance on third parties to manufacture certain of our products and product candidates exposes us to risks, and any technology transfer of the manufacturing process for our products or product candidates may be subject to a number of risks and uncertainties, see “ Risk Factors – Risks Related to Manufacturing and Our Reliance on Third Parties. ” Commercial Operations Our commercial team combines years of pharmaceutical commercial leadership experience with a passion for helping patients with significant unmet medical need.
To the extent permitted in accordance with the Regeneron Agreement, the fully-burdened costs of each of us and Regeneron incurred in performing (or having performed) the technology transfer of the manufacturing process for ARCALYST drug substance will also be deducted from net sales of ARCALYST to determine profit.
To the extent permitted in accordance with the Regeneron Agreement, the fully-burdened costs incurred by each of us and Regeneron in performing (or having performed) the technology transfer of the manufacturing process for ARCALYST drug substance will also be deducted from net sales of ARCALYST to determine profit.
The CTR is directly applicable in all EU member states without the need for member states to further implement it into national law. The CTR notably harmonizes the assessment and supervision processes for clinical trials throughout the EU via a Clinical Trials Information System, which contains a centralized EU portal and database.
The CTR is directly applicable in all EU member states without the need for member states to further implement it into national law. The CTR notably harmonizes the assessment and supervision processes for clinical trials throughout the EU via a Clinical Trials Information System (“CTIS”), which contains a centralized EU portal and database.
Under Article 3 of Regulation (EC) 141/2000, a medicinal product may be designated as orphan if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) the product, without the benefits derived from orphan status, would not generate sufficient return in the EU to justify investment; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the product will be of significant benefit to those affected 29 Table of Contents by the condition.
Under Article 3 of Regulation (EC) 141/2000, a medicinal product may be designated as orphan if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) the product, without the benefits derived from orphan status, would not generate sufficient return in the EU to justify investment; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the product will be of significant benefit to those affected by the condition.
The process required by the FDA before a biologic may be marketed in the United States generally involves the following: ● Completion of extensive preclinical tests, animal studies, and toxicology, pharmacology and formulation studies in accordance with applicable regulations, including Good Laboratory Practice (“GLP”) regulations; ● Submission to FDA of an investigational new drug application (an “IND”) which must become effective before human clinical trials may begin; ● Approval by an independent institutional review board (an “IRB”) overseeing each clinical trial site, in each case before a trial may be initiated; ● Performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practices (“GCPs”) and other clinical trial related regulations to evaluate the safety and efficacy of the product candidate for each proposed indication; ● Submission to FDA of a BLA for marketing approval after completion of the required pivotal clinical trials; ● Satisfactory completion of any FDA pre-approval inspections of the manufacturing facility or facilities where the product will be produced to assess compliance with cGMPs; and ● FDA review and approval of the BLA.
The process required by the FDA before a biologic may be marketed in the United States generally involves the following: ● Completion of extensive preclinical tests; animal studies; and toxicology, pharmacology and formulation studies in accordance with applicable regulations, including the FDA’s good laboratory practice (“GLP”) regulations, or similar foreign standards ; ● Submission to FDA of an investigational new drug application (an “IND”) which must become effective before human clinical trials may begin; ● Approval by an independent institutional review board (an “IRB”) overseeing each clinical trial site, in each case before a trial may be initiated; ● Performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practices (“GCPs”) and other clinical trial related regulations to evaluate the safety and efficacy of the product candidate for each proposed indication; ● Submission to FDA of a BLA for marketing approval after completion of the required pivotal clinical trials; ● Satisfactory completion of any FDA pre-approval inspections of the manufacturing facility or facilities where the product will be produced to assess compliance with cGMPs; and ● FDA review and approval of the BLA.
Goflikicept, currently marketed solely in Russia, though with prior clinical studies conducted in the United States, is dosed subcutaneously every two weeks following an initial loading dose. We expect that additional therapies offering even more convenient dosing, including those listed in the sections above, may enter the market, including therapies that offer quarterly dosing.
Goflikicept, currently marketed solely in Russia, though with prior clinical studies conducted in the United States, is dosed subcutaneously every two weeks following an initial loading dose. We expect that additional therapies offering even more convenient dosing and administration, including those listed in the sections above, may enter the market, including therapies that offer quarterly dosing.
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 United States federal False Claims Act and civil monetary penalties laws, which, among other things, impose criminal and civil penalties, including through civil whistleblower or 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.
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; 38 Table of Contents ● the United States federal False Claims Act and civil monetary penalties laws, which, among other things, impose criminal and civil penalties, including through civil whistleblower or 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.
We have and may in the future seek collaborations, licenses and other strategic relationships to assist in advancing and expanding our current programs, as appropriate. In addition, strategic out-licensing transactions may be used as a source of non-dilutive capital to support our commercial and clinical activities. ● Work to Identify, Discover, Acquire and Develop New Therapies.
We have and may in the future seek collaborations, licenses and other strategic relationships to assist in advancing and expanding our current programs, as appropriate. In addition, strategic out-licensing transactions may be used as a source of non-dilutive capital to support our commercial and clinical activities. ● Working to Identify, Discover, Acquire and Develop New Therapies.
We currently perform most process development internally but are reliant on CDMOs for late-stage clinical manufacturing, process qualification and validation and commercial supply.
We currently perform most process development internally but are reliant on CDMOs for late-stage clinical product manufacturing, process qualification, validation and commercial supply.
During this ten-year orphan market exclusivity period, the competent authorities cannot accept another MAA, grant an MA, or accept an application to extend a MA for a similar product for the same indication. Orphan Drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process.
During this ten-year orphan market exclusivity period, the competent authorities cannot accept another MAA, grant an MA or accept an application to extend a MA for a similar product for the same indication. Orphan Drug designation does not confer any advantage in, or shorten the duration of, the regulatory review and approval process.
Bribery Act 2010 (the “Bribery Act”) and similar anti-bribery or anti-corruption laws, regulations or rules in other countries in which we operate, which prohibit companies and their representatives from paying, offering to pay, promising to pay 36 Table of Contents or authorizing the payment of anything of value to any foreign government official, government staff member, political party or political candidate for the purpose of obtaining or retaining business or to otherwise obtain favorable treatment or influence a person working in an official capacity abroad.
Bribery Act 2010 (the “Bribery Act”) and similar anti-bribery or anti-corruption laws, regulations or rules in other countries in which we operate, which prohibit companies and their representatives from paying, offering to pay, promising to pay or authorizing the payment of anything of value to any foreign government official, government staff member, political party or political candidate for the purpose of obtaining or retaining business or to otherwise obtain favorable treatment or influence a person working in an official capacity abroad.
Helping to ensure affordability and access to treatment by patients is one of our core principles. To this end, we offer a suite of programs to support affordability for eligible patients who are prescribed ARCALYST. Third, we have built a robust patient support program to optimize patient experiences with ARCALYST and Kiniksa.
Helping to ensure affordability and access to treatment by patients is one of our core principles. To this end, we offer a suite of programs to support affordability for eligible patients who are prescribed ARCALYST. Fifth, we have built a robust patient support program to optimize patient experiences with ARCALYST and Kiniksa.
Each employee of our company is required to confirm in writing that they understand and will comply with our policies, including but not limited to our Code of Business Conduct and Ethics, our insider trading and compliance policy, our policies against bribery and corruption and our policies regarding interactions with healthcare professionals.
Each employee of our company is required to confirm in writing that they understand and will comply with our policies, including but not limited to our Code of Business Conduct and Ethics, anti-harassment policy, our insider trading and compliance policy, our policies against bribery and corruption and our policies regarding interactions with healthcare professionals.
In the United States, the process for determining whether a third party payor will provide coverage and the related coverage criteria for a biological product typically is separate from, but related to, the process for setting the price of such product or for establishing the level of reimbursement that the payor will pay for the product once coverage is approved.
In the United States, the process for determining whether a third party payor will provide coverage and the related coverage criteria for a biological product typically is separate from the process for setting the price of such product or for establishing the level of reimbursement that the payor will pay for the product once coverage is approved.
Using these resources, our commercialization efforts are focused on four strategic imperatives to increase the uptake and adoption of ARCALYST as well as ensuring a positive patient experience. First, we are focused on increasing awareness of the disease and its impact on patients’ lives.
Using these resources, our commercialization efforts are focused on five strategic imperatives to increase the uptake and adoption of ARCALYST as well as ensuring a positive patient experience. First, we are focused on increasing awareness of the disease and its impact on patients’ lives.
The HTA permits EU member states to use common HTA tools, methodologies, and procedures across the EU, 35 Table of Contents working together in four main areas, including joint clinical assessment of the innovative health technologies with the most potential impact for patients, joint scientific consultations whereby developers can seek advice from HTA authorities, identification of emerging health technologies to identify promising technologies early, and continuing voluntary cooperation in other areas.
The HTA permits EU member states to use common HTA tools, methodologies and procedures across the EU, working together in four main areas, including joint clinical assessment of the innovative health technologies with the most potential impact for patients, joint scientific consultations whereby developers can seek advice from HTA authorities, identification of emerging health technologies to identify promising technologies early and continuing voluntary cooperation in other areas.
We require our CDMOs to conduct manufacturing activities in compliance with current good manufacturing practice or similar foreign requirements (“cGMP”). We have assembled a team of experienced employees and consultants to provide the necessary technical, quality and regulatory oversight of our CDMOs.
We require our CDMOs to conduct manufacturing activities in compliance with current good manufacturing practice or comparable foreign requirements (“cGMP”). We have assembled a team of experienced employees and consultants to provide the necessary technical, quality and regulatory oversight of our CDMOs.
For more information, see “ Business—Our Products—ARCALYST – Commercial Strategy for ARCALYST .” 14 Table of Contents Competition The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products.
For more information, see “ Business—Our Products—ARCALYST – Commercial Strategy for ARCALYST .” 16 Table of Contents Competition The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products.
Adverse events that may be caused by corticosteroids include glaucoma, fluid retention, hypertension, mood changes, memory changes, other psychological effects, weight gain and diabetes. Since our commercial launch of ARCALYST, we have seen a shift in the treatment paradigm, with healthcare professionals prescribing ARCALYST’s targeted immunomodulation before using corticosteroids.
Adverse events that may be caused by corticosteroids include glaucoma, fluid retention, hypertension, mood changes, memory changes, other psychological effects, weight gain and diabetes. Since our commercial launch of ARCALYST, we have seen a shift in the treatment paradigm, with an increasing number of healthcare professionals prescribing ARCALYST’s targeted immunomodulation before using corticosteroids.
Further, we have established an efficient marketing effort intended to educate and raise awareness of recurrent pericarditis among prescribers and patients and promote ARCALYST as the first and only treatment for this debilitating disease.
Further, we have established an efficient marketing effort intended to educate and raise awareness of recurrent pericarditis among prescribers and patients and promote ARCALYST as the first and only FDA-approved treatment for this debilitating disease.
There are disease states in which IL-1β inhibition alone does not appear to be sufficient for disease remission in the absence of IL-1α inhibition. Published studies suggest certain autoinflammatory diseases may, in fact, be pathologically driven primarily by IL-1α. 9 Table of Contents We believe that inhibiting both IL-1α and IL-1β signaling is important for treating recurrent pericarditis.
There are disease states in which IL-1β inhibition alone does not appear to be sufficient for disease remission in the absence of IL-1α inhibition. Published studies suggest certain autoinflammatory diseases may, in fact, be pathologically driven primarily by IL-1α. We believe that inhibiting both IL-1α and IL-1β signaling is important for treating recurrent pericarditis.
Some clinical trials also include oversight by an independent group of qualified experts organized by the clinical study sponsor, commonly known as a Data Safety Monitoring Board, which may recommend continuation of a trial as planned, changes in the trial or cessation of the trial at designated check points based on access to certain data from the trial.
Some clinical trials also include oversight by an independent group of qualified experts organized by the clinical study sponsor, commonly known as a Data Safety Monitoring Board (a “DSMB”) or Data Monitoring Committee (a “DMC”), which may recommend continuation of a trial as planned, changes in the trial or cessation of the trial at designated check points based on access to certain data from the trial.
While the Clinical Trials Directive required a separate clinical trial application (a “CTA”) to be submitted in each member state, to both the competent national health authority and an independent ethics committee, much like the FDA and IRB respectively, the CTR introduces a centralized process and only requires the submission of a single application to all member states concerned.
While the Clinical Trials Directive required a separate clinical trial application (a “CTA”) to be submitted in each member state, to both the competent national health authority and an independent ethics committee, much like the FDA and IRB respectively, the CTR introduces a centralized process and only requires the submission of a single application to all member states concerned to streamline the regulatory review.
Certain countries also mandate implementation of commercial compliance programs or require disclosure of marketing expenditures and pricing information. Coverage, Pricing and Reimbursement Significant uncertainty exists as to the coverage and reimbursement status of approved biological products. Governments around the world are exploring cost containment programs, including price controls, reimbursement restrictions, and requirements for biosimilar substitution.
Certain countries also mandate implementation of commercial compliance programs or require disclosure of marketing expenditures and pricing information. 34 Table of Contents Coverage, Pricing and Reimbursement Significant uncertainty exists as to the coverage and reimbursement status of approved biological products. Governments around the world are exploring cost containment programs, including price controls, reimbursement restrictions and requirements for biosimilar substitution.
In the United States and markets in other countries, patients rely on third party payors to reimburse healthcare costs. Third party payors include government authorities, managed care plans, private health insurers and other organizations.
In the United States and markets in other countries, patients rely on third party payors to reimburse healthcare costs. Third party payors include government authorities or health care programs, managed care plans, private health insurers and other organizations.
Failure to comply with EU and national laws that apply to the conduct of clinical trials, manufacturing approval, MA of medicinal products and marketing of such products, both before and after grant of the MA, manufacturing of medicinal products, statutory health insurance, bribery and anti-corruption or with other applicable regulatory requirements may result in administrative, civil or criminal penalties.
Failure to comply with EU and national laws that apply to the conduct of clinical trials, manufacturing approval, MA of medicinal products and marketing of such products, both before and after grant of the MA, manufacturing of medicinal products, bribery and anti-corruption or with other applicable regulatory requirements may result in administrative, civil or criminal penalties.
State Medicaid programs and Medicaid managed care plans can seek additional “supplemental” rebates from manufacturers. ● Medicare . Medicare is a federal program that is administered by the federal government that covers individuals age 65 and over, disabled individuals and individuals with certain conditions. Medicare Part B generally covers drugs that are usually administered by physicians or other clinicians.
State Medicaid programs and Medicaid managed care plans can seek additional “supplemental” rebates from manufacturers. ● Medicare . Medicare is a federal program that is administered by the federal government that covers individuals age 65 and over, disabled individuals and certain other eligible individuals. Medicare Part B generally covers drugs that are usually administered by physicians or other clinicians.
Four patents covering methods of using ARCALYST in the treatment of recurrent pericarditis have issued in the United States and have a statutory term that expires in 2038, not including any patent term adjustment.
Five patents covering methods of using ARCALYST in the treatment of recurrent pericarditis have issued in the United States and have a statutory term that expires in 2038, not including any patent term adjustment.
In addition, references to “ordinary shares” prior to the Redomiciliation are to Kiniksa Pharmaceuticals, Ltd.’s common shares and from and after the Redomiciliation are to Kiniksa Pharmaceuticals International, plc’s ordinary shares. Where You Can Find More Information We are subject to the information requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).
In addition, references to “ordinary shares” prior to the Redomiciliation 41 Table of Contents are to Kiniksa Pharmaceuticals, Ltd.’s common shares and from and after the Redomiciliation are to Kiniksa Pharmaceuticals International, plc’s ordinary shares. Where You Can Find More Information We are subject to the information requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).
Third party payors are increasingly challenging the prices charged for medical products and services, examining the medical necessity and reviewing the cost-benefit of pharmaceutical products, in addition to questioning safety and efficacy.
Third party payors are increasingly challenging the prices charged for medical products and services, examining the medical necessity and reviewing the cost-benefit of biopharmaceutical products, in addition to questioning safety and efficacy.
The amount of the rebate for each product is set by law and depends in part on the prices at which our products are sold to certain other purchasers and may be subject to an additional discount if certain pricing increases more than inflation.
The amount of the rebate for each product is set by law and depends in part on the prices at which our products are sold to certain other purchasers and may be subject to an additional 35 Table of Contents discount if certain pricing increases more than inflation.
Under the Regeneron Agreement, we paid $32.5 million in connection with upfront fees and the achievement of regulatory milestones. We evenly split profits on sales of ARCALYST with Regeneron , where profits are determined 18 Table of Contents after deducting from net sales of ARCALYST certain costs related to the manufacturing and commercialization of ARCALYST.
Under the Regeneron Agreement, we paid $32.5 million in connection with upfront fees and the achievement of regulatory milestones. We evenly split profits on sales of ARCALYST with Regeneron , where profits are determined after deducting from net sales of ARCALYST certain costs related to the manufacturing and commercialization of ARCALYST.
Our website is located at www.kiniksa.com . The reference to our or the SEC’s website address does not constitute incorporation by reference of the information contained at or available through such websites, and you should not consider it to be a part of this Annual Report. ​
Our website is located at www.kiniksa.com . The reference to our or the SEC’s website address does not constitute incorporation by reference of the information contained at or available through such websites, and you should not consider it to be a part of this Annual Report. 42 Table of Contents ​
See “ Risk Factors—Risks Related to Competition, Executing our Strategy and Managing Growth—We face substantial competition, which may result in others discovering, developing or commercializing drugs before or more successfully than we do. ” We are aware of the following products currently marketed or in clinical development for the treatment of the diseases that we are targeting or may plan to target: ARCALYST Recurrent Pericarditis : We are not aware of any FDA-approved therapies for recurrent pericarditis, but we are aware of three competitors developing treatments for this indication.
For more information, see “ Risk Factors—Risks Related to Competition, Executing our Strategy and Managing Growth—We face substantial competition, which may result in others discovering, developing or commercializing drugs before or more successfully than we do. ” We are aware of the following drugs currently marketed or in clinical development for the treatment of the diseases that we are targeting or may plan to target: ARCALYST Recurrent Pericarditis : We are not aware of any other FDA-approved therapies for recurrent pericarditis, but we are aware of several competitors developing treatments for this indication.
The overall ten-year market exclusivity period can be extended to a maximum of eleven years if, during the first eight years of those ten years, the MA holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies.
The overall ten-year data and marketing exclusivity period can be extended to a maximum of eleven years if, during the first eight years of those ten years, the MA holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies.
Regulatory Framework in the United Kingdom Since the end of the Brexit transition period on January 1, 2021, Great Britain (England, Scotland and Wales) has not been directly subject to EU laws, however under the terms of the Ireland/Northern Ireland Protocol, EU laws generally apply to Northern Ireland.
Regulatory Framework in the United Kingdom Since the end of the Brexit transition period on January 1, 2021, Great Britain (England, Scotland and Wales) has not been directly subject to EU laws. However, under the terms of the Ireland/Northern Ireland Protocol, EU laws applied to Northern Ireland.
Additionally, coverage, coverage criteria, and reimbursement for products can differ significantly from payor to payor. One third party payor’s decision to cover a particular medical product does not ensure that other payors will also provide coverage for the medical product or will provide coverage at an adequate reimbursement rate.
Additionally, coverage, coverage criteria and reimbursement for products can differ significantly from payor to payor. One third party payor’s decision to cover a particular biologic does not ensure that other payors will also provide coverage for the biologic or will provide coverage at an adequate reimbursement rate.
Member states may approve a specific price or level of reimbursement for the 33 Table of Contents pharmaceutical product, or alternatively adopt a system of direct or indirect controls on the profitability of the company responsible for placing the pharmaceutical product on the market, including volume-based arrangements, caps and reference pricing mechanisms.
Member states may approve a specific price or level of reimbursement for the pharmaceutical product, or alternatively adopt a system of direct or indirect controls on the profitability of the company responsible for placing the pharmaceutical product on the market, including volume-based arrangements, caps and reference pricing mechanisms.
Before approving a BLA, the FDA will typically conduct a pre-approval inspection of the manufacturing facilities for the new product to determine whether the manufacturing processes and facilities comply with cGMPs and 24 Table of Contents are adequate to ensure consistent product production within required specifications.
Before approving a BLA, the FDA will typically conduct a pre-approval inspection of the manufacturing facilities for the new product to determine whether the manufacturing processes and facilities comply with cGMPs and are adequate to ensure consistent product production within required specifications.
The centralized procedure is optional for products containing a new active substance not yet authorized in the EU, or for products that represent a significant therapeutic, scientific or technical innovation, or whose authorization would be in the interest of public health in the EU.
The centralized procedure is optional for products containing a new active 28 Table of Contents substance not yet authorized in the EU, or for products that represent a significant therapeutic, scientific or technical innovation or whose authorization would be in the interest of public health in the EU.
We rely, and expect to continue to rely, on third party CDMOs for the production of clinical and commercial quantities of our products in accordance with cGMP regulations. We, and our CDMOs are required to 26 Table of Contents register our establishments with the FDA and certain state agencies.
We rely, and expect to continue to rely, on third party CDMOs for the production of clinical and commercial quantities of our products in accordance with cGMP regulations. We, and our CDMOs are required to register our establishments with the FDA and certain state agencies.
Additionally, the FDA may refer applications for novel biologic candidates, which present challenges in interpretation of the safety or efficacy data, to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation and a recommendation as to whether the application should be approved.
Additionally, the FDA may refer applications for novel biologic candidates, which present challenges in interpretation of the safety or efficacy data, to an Advisory Committee, typically a panel that includes clinicians and other experts appointed by the FDA Commissioner or a designee, for review, evaluation and a recommendation as to whether the application should be approved.
However, under the Retained EU Law (Revocation and Reform) Act 2023, which received royal assent on June 29, 2023, any retained EU law not expressly preserved and “assimilated” into domestic law or extended by ministerial regulations (to no later than June 23, 2026) was automatically expired and revoked by December 31, 2023.
However, under the Retained EU Law (Revocation and Reform) Act 2023, which 32 Table of Contents received royal assent on June 29, 2023, any retained EU law not expressly preserved and “assimilated” into domestic law or extended by ministerial regulations (to no later than June 23, 2026) was automatically expired and revoked by December 31, 2023.
Huadong will be responsible for all costs of development activities and commercialization in the Huadong Territory. We and Huadong participate in a joint steering committee, which coordinates and oversees the exploitation of ARCALYST in the Huadong Territory. We will supply certain materials to support development and commercialization activities for ARCALYST.
Huadong will be 19 Table of Contents responsible for all costs of development activities and commercialization in the Huadong Territory. We and Huadong participate in a joint steering committee, which coordinates and oversees the exploitation of ARCALYST in the Huadong Territory. We will supply certain materials to support development and commercialization activities for ARCALYST.
Either party may terminate the agreement in the event of a material breach by the other party that remains uncured for 90 days (or 30 days for payment-related breaches), or by either party due to the insolvency or bankruptcy of the other party.
Either party may terminate the agreement in the event of a material breach 20 Table of Contents by the other party that remains uncured for 90 days (or 30 days for payment-related breaches), or by either party due to the insolvency or bankruptcy of the other party.
Further, the obligation to provide pediatric clinical trial data can be waived by the PDCO when this data is not needed or appropriate because the product is likely to be ineffective or unsafe in children, the disease or condition for which the product is intended occurs only in adult populations, or when the product does not represent a significant therapeutic benefit over existing treatments for pediatric patients.
Further, the obligation to provide pediatric clinical trial data can be waived by the PDCO when such data are necessary or appropriate because the product is likely to be ineffective or unsafe in children, the disease or condition for which the product is intended occurs only in adult populations, or when the product does not represent a significant therapeutic benefit over existing treatments for pediatric patients.
Employees are required to participate in periodic and as-needed trainings in order to refresh their understanding of our policies and provide additional instruction for new issues as and when they arise. For the clinical and manufacturing activities that we perform and oversee, we adhere to operating within the accepted GLP, GCP, cGMP and other similar regulatory guidelines.
Employees are required to participate in periodic and as-needed trainings to refresh their understanding of our policies and to provide additional training for new issues as and when they arise. For the clinical and manufacturing activities that we perform and oversee, we adhere to operating within the accepted GLP, GCP, cGMP and other similar regulatory guidelines. Health and Safety.
Our sales and marketing teams work to educate patients and prescribers about the signs, symptoms, duration and treatment of the disease, and the impact that 11 Table of Contents recurrent pericarditis has on patients’ lives.
Our sales and marketing teams work to educate patients and prescribers about the signs, symptoms, duration and treatment of the disease, and the impact that recurrent pericarditis has on patients’ lives.
We provide our employees with competitive fixed salaries, cash bonus opportunities designed to incentivize achievement of our goals and individual objectives, equity awards and opportunities for equity ownership through our employee share purchase plan and a robust benefit package designed to promote well-being across different aspects of our employees’ lives, including comprehensive health insurance, dental and vision plans, life and other employment related insurance, retirement planning through a 401(k) plan with partial company match, and paid time off. ​ Diversity, Equity and Inclusion.
We provide our employees with competitive base salaries, cash bonus opportunities designed to incentivize achievement of our corporate goals, equity awards and opportunities for equity ownership through our employee share purchase plan and a robust benefit package designed to promote well-being across different aspects of our employees’ lives, including comprehensive health insurance, dental and vision plans, life and other employment related insurance, retirement planning through a 401(k) plan with partial company match and paid time off.
Canakinumab (ILARIS), marketed by Novartis Pharmaceuticals Corporation, is currently approved for use in CAPS, Tumor Necrosis Factor Receptor Associated Periodic Syndrome (TRAPS), Hyperimmunoglobulin D 15 Table of Contents Syndrome (HIDS), Mevalonate Kinase Deficiency (MKD), Familial Mediterranean Fever (FMF), Adult Onsent Still’s Disease (AOSD), Systemic Juvenile Idiopathic Arthritis (SJIA) and gout flares. Other Competitors .
Canakinumab (ILARIS), marketed by Novartis Pharmaceuticals Corporation, is currently approved for use in CAPS, Tumor Necrosis Factor Receptor Associated Periodic Syndrome (TRAPS), Hyperimmunoglobulin D Syndrome (HIDS), Mevalonate Kinase Deficiency (MKD), Familial Mediterranean Fever (FMF), Adult Onset Still’s Disease (AOSD), Systemic Juvenile Idiopathic Arthritis (SJIA) and gout flares. Other Competitors .
Other Healthcare Laws In the U.S., activities of pharmaceutical manufacturers are subject to numerous other federal, state, and local laws designed to, for example, prevent “fraud and abuse” in the delivery of and payment for healthcare; promote transparency in interactions with others in the healthcare industry; require reporting of drug prices and payment of rebates or offering of discounts to certain government programs and public and private payors; and regulate government payment for drugs.
Other Healthcare Laws In the United States, activities of pharmaceutical manufacturers are subject to numerous other federal, state and local laws designed to, for example, prevent “fraud and abuse” in the delivery of and payment for healthcare; promote transparency in interactions with others in the healthcare industry; require reporting of drug prices and payment of rebates or offering of discounts to certain government programs and public and private payors; protect consumers; and regulate government payment for drugs.
Our Strategy The core of our strategy is the identification, development and commercialization of therapeutic medicines for patients suffering from debilitating cardiovascular diseases with significant unmet medical need. We put patients first and live by our motto: Every Second Counts™. ​ Critical components of our business strategy include the following: ● Commercialize ARCALYST .
Our Strategy The core of our strategy is the identification, development and commercialization of therapeutic medicines for patients suffering from debilitating cardiovascular diseases with significant unmet medical need. We put patients first and live by our motto: Every Second Counts™. Critical components of our business strategy include the following: ● Continuing to Execute on ARCALYST Commercialization .
The product approval process ultimately varies between countries and jurisdictions and can involve additional product testing and additional administrative review periods. The time required to obtain approval in other countries and jurisdictions might differ from and be longer than that required to obtain FDA approval.
The product approval process ultimately varies between 27 Table of Contents countries and jurisdictions and can involve additional product testing and additional administrative review periods. The time required to obtain approval in other countries and jurisdictions might differ from and be longer than that required to obtain FDA approval.
However, if the conditions are not fulfilled within the timeframe set by the EMA and approved by the European Commission, the MA will cease to be renewed. Data and Marketing Exclusivity ​ The EU also provides opportunities for market exclusivity.
However, if the conditions are not fulfilled within the timeframe set by the EMA and approved by the European Commission, the MA will cease to be renewed or may be revoked. Data and Marketing Exclusivity The EU also provides opportunities for marketing exclusivity.
The CTR allows sponsors to make a single submission to both the competent authority and an ethics committee in each member state, leading to a single decision per member state. The CTA must include information concerning the trial protocol and the manufacture and quality of the medicinal product under investigation.
The CTR allows sponsors to make a single submission to both the competent authority and an ethics committee in each member state, leading to a single decision per member state. The CTA must include information concerning the trial protocol and the manufacture and quality of the medicinal product under investigation. The assessment procedure of the CTA has been harmonized.
Other literature published after the June 2022 completion of RHAPSODY corroborated these findings in larger populations of participants. Beyond recurrent pericarditis, we believe there is potential for ARCALYST to address additional indications driven by IL-1α or IL-1β.
Other literature published after the June 2022 completion of the phase 3 clinical trial of ARCALYST corroborated these findings in larger populations of participants. Beyond recurrent pericarditis, we believe there is potential for ARCALYST to address additional indications driven by IL-1α or IL-1β.
In addition, prices for drugs purchased by the Veterans Administration, Department of Defense (including drugs purchased by military personnel and dependents through the TRICARE retail pharmacy program), Coast Guard and PHS are subject to a cap on pricing (known as the “federal ceiling price”) and may be subject to an additional discount if pricing increases more than the rate of inflation. ● PHS 340B Drug Pricing Program .
By statute, prices for drugs purchased by the Veterans Administration, Department of Defense (including drugs purchased by military personnel and dependents through the TRICARE retail pharmacy program), Coast Guard and the Public Health Service (“PHS”) are subject to a cap on pricing (known as the “federal ceiling price”) and may be subject to an additional discount if pricing increases more than the rate of inflation. ● PHS 340B Drug Pricing Program .
If the product has not received a national MA in any member state at the time of application, it can be approved simultaneously in various member states through the decentralized procedure.
If the product has not received a national MA in any member state at the time of application, it can be approved simultaneously in two or more member states through the decentralized procedure.
For example, the Budget Control Act of 2011, as amended, resulted in the imposition of reductions in Medicare (but not Medicaid) payments to providers in 2013 and remains in effect through 2032 unless additional Congressional action is taken.
As another example, the Budget Control Act of 2011, as amended, resulted in the imposition of reductions in Medicare (but not Medicaid) payments to 37 Table of Contents providers in 2013 and remains in effect through 2032 unless additional Congressional action is taken.
Ventyx Biosciences is developing VTX2735, which is designed to inhibit the NLRP3 inflammasome, an intracellular sensor of a broad range of danger signals, that leads to the release of IL-1β and IL-18. In addition to their development program in CAPS, Ventyx Biosciences has announced their intention to initiate a Phase 2 trial of VTX2735 in recurrent pericarditis in January 2025.
Ventyx Biosciences is developing VTX2735, which is designed to inhibit the NLRP3 inflammasome, an intracellular sensor of a broad range of danger signals, that leads to the production and release of IL-1β and IL-18. In addition to their development program in CAPS, Ventyx Biosciences is conducting a Phase 2 trial of VTX2735 in recurrent pericarditis, which began in January 2025.
Huadong Collaboration Agreements In February 2022 we entered into two collaboration and license agreements (each, a “Huadong Collaboration Agreement” and together, the “Huadong Collaboration Agreements”) with Huadong, pursuant to which we granted Huadong exclusive rights to develop and commercialize ARCALYST and develop, manufacture and commercialize mavrilimumab (each, a “Huadong Licensed Product” and together, the “Huadong Licensed Products”) in the following countries: People’s Republic of China, Hong Kong SAR, Macao SAR, Taiwan Region, South Korea, Indonesia, Singapore, The Philippines, Thailand, Australia, Bangladesh, Bhutan, Brunei, Burma, Cambodia, India, Laos, Malaysia, Maldives, Mongolia, Nepal, New Zealand, Sri Lanka, and Vietnam (collectively, the “Huadong Territory”).
Huadong Collaboration Agreements In February 2022 we entered into two collaboration and license agreements (each, a “Huadong Collaboration Agreement” and together, the “Huadong Collaboration Agreements”) with Huadong, pursuant to which we granted Huadong exclusive rights to develop and commercialize ARCALYST and develop, manufacture and commercialize mavrilimumab in each case in a territory currently consisting of the following countries: People’s Republic of China, Hong Kong SAR, Macao SAR, Taiwan Region, Indonesia, The Philippines, Thailand, Bangladesh, Bhutan, Brunei, Burma, Cambodia, India, Laos, Malaysia, Maldives, Mongolia, Nepal, New Zealand, Sri Lanka and Vietnam (collectively, the “Huadong Territory”).
We believe that each of our product candidates holds the potential to offer differentiated therapy to patients, and we aim to unlock that potential through innovative research and development. 8 Table of Contents ● Explore Opportunities to Drive Value and Maximize the Potential of Our Existing Portfolio.
We believe that each of our product candidates holds the potential to offer differentiated therapy to patients, and we aim to unlock that potential through innovative research and development. ● Exploring Opportunities to Drive Value and Maximize the Potential of Our Existing Portfolio.
As another example, the Inflation Reduction Act (the “IRA”) of 2022 includes a number of changes intended to address rising prescription drug prices in Medicare Parts B and D, with varying implementation dates.
As another example, the IRA of 2022 includes a number of changes intended to address rising prescription drug prices in Medicare Parts B and D, with varying implementation dates.
We believe there are diseases of the cardiovascular system where tissue inflammation may be driven by IL-1α and/or IL-1β, and we intend to consider development of KPL-387 in these indications and in others where we believe IL-1α and/or IL-1β plays a key role in disease pathophysiology. Our Solution We are developing KPL-387 for the treatment of recurrent pericarditis.
We believe there are diseases of the cardiovascular system where tissue inflammation may be driven by IL-1α and/or IL-1β, and we intend to consider development of KPL-387 in these indications and in others where we believe IL-1α and/or IL-1β plays a key role in disease pathophysiology.
As of December 31, 2024, we had 315 full-time employees, of which 301 were located within the United States and 14 were located outside of the United States. ​ We believe that the success and growth of our business depends in large part on our continued ability to attract, retain and motivate qualified personnel at all levels of our company.
As of December 31, 2025, we had 366 full-time employees, of which 351 were located within the United States and 15 were located outside of the United States. We believe that the success and growth of our business depends in large part on our continued ability to attract, retain and motivate qualified personnel at all levels of our company.
Medicare Part D is administered by private prescription drug plans approved by the U.S. government and each drug plan establishes its own Medicare Part D formulary for prescription drug coverage and pricing, which the drug plan may modify from time-to-time. The prescription drug plans negotiate pricing with manufacturers and may condition formulary placement on the availability of manufacturer discounts.
Each drug plan establishes its own government-approved Medicare Part D formulary for prescription drug coverage and pricing, which the drug plan may modify from time-to-time. The prescription drug plans negotiate rebates with manufacturers and may condition formulary placement on the availability of manufacturer discounts.
We have seen that, as we expand awareness about the disease and our therapy, healthcare professionals look to prescribe ARCALYST earlier in the disease’s natural history. We expect that continuing to execute on this strategy will enable us to target this additional patient population more fully.
We have seen that, as we expand awareness about the disease and our therapy, healthcare professionals look to prescribe ARCALYST earlier in the disease’s natural history, including prescriptions to biologic-appropriate patients in their first recurrence. We expect that continuing to execute on this strategy will enable us to target this additional patient population more fully.
Under the Genentech License Agreement, we received an upfront payment of $80.0 million for the license. In total, we have recognized $50.0 million in additional payments from Genentech related to delivery of certain drug material to Genentech and Genentech’s achievement of development milestones under the Genentech License Agreement.
In total, we have recognized $50.0 million in additional payments from Genentech related to delivery of certain drug material to Genentech and Genentech’s achievement of development milestones under the Genentech License Agreement.
Additionally, a MA may be granted to a similar product for the same indication at any time if (i) the second applicant can establish that its product, although similar, is safer, more effective or otherwise clinically superior; (ii) the applicant consents to a second orphan medicinal product application; or (iii) the applicant cannot supply enough orphan medicinal product.
Additionally, a MA may be granted to a similar product for the same indication at any time if (i) the second applicant can establish that its product, although similar, is safer, more effective or otherwise clinically superior; (ii) the marketing authorization holder for the first approved product consents to a second orphan medicinal product application; or (iii) the marketing authorization holder cannot supply sufficient quantities of the approved orphan medicinal product.
There are two types of MAs: ● “Centralized MAs” are issued by the European Commission through the centralized procedure, based on the opinion of the Committee for Medicinal Products for Human Use (the “CHMP”) of the EMA, and are valid throughout the EU.
There are two types of MAs that can be granted by the relevant competent authorities: ● “Centralized MAs” are issued by the European Commission through the centralized procedure, based on the opinion of the Committee for Medicinal Products for Human Use (the “CHMP”) of the EMA, and are valid throughout the EU.
Such legislation could limit the price or payment for certain drugs, and a number of states may impose civil monetary penalties or pursue other enforcement mechanisms against manufacturers who fail to comply with drug price transparency requirements.
A number of states may impose civil monetary penalties or pursue other enforcement mechanisms against manufacturers who fail to comply with drug price transparency requirements. Certain other state legislation focuses on limiting the price or payment for certain drugs.
For example, in 2024 we announced our sponsorship of the American Heart Association’s Addressing Recurrent Pericarditis initiative. This initiative is designed to facilitate knowledge-sharing across a collaborative network of healthcare providers around the United States and streamline patient access to expert care. The participating healthcare sites offer patients dedicated, expert care and aim to shorten patients’ journeys to diagnoses.
For example, in 2024 we announced our sponsorship of the American Heart Association’s Addressing Recurrent Pericarditis initiative. This initiative is designed to facilitate knowledge-sharing across a network of healthcare providers around the United States and streamline patient access to expert care.
Our salesforce is complemented by our medical affairs, payor and patient services teams who work to secure broad patient access to ARCALYST, educate communities, collaborate with patient advocacy groups and drive scientific understanding of recurrent pericarditis.
Our specialty salesforce, which prioritizes calls on high-volume accounts and prescribers, is complemented by our medical affairs, payor and patient services teams who work to secure broad patient access to ARCALYST, educate communities, collaborate with patient advocacy groups and drive scientific understanding of recurrent pericarditis.

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Item 1A. Risk Factors

Risk Factors — what could go wrong, per management

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Biggest changeEvents that have and may in the future delay or prevent commencement or successful completion of clinical development of our product candidates as planned and on schedule, if at all, include but are not limited to: ● inability to generate sufficient preclinical, toxicology or other in vivo or in vitro data to support the initiation of human clinical trials; ● delays or failure in reaching a consensus with regulatory agencies on trial design or implementation, including the appropriate dosage levels, frequency of dosing, or treatment period in clinical trials; ● delays or failure in reaching 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 clinical trial sites; ● difficulties in obtaining required IRB, ethics committee approval or positive opinion at each clinical trial site; ● delays or failure in obtaining regulatory approval to commence a trial, or imposition of a clinical hold by regulatory authorities; ● difficulty in identifying and enrolling suitable participants in a particular trial, including due to competition from other companies’ clinical trials for a particular indication, which may reduce the power of a clinical trial to detect statistically significant results; ● amendments to clinical trial protocols impacting study criteria, endpoints or design, including amendments that either we initiate or are requested by regulatory authorities; 50 Table of Contents ● difficulty collaborating with patient groups and investigators; ● failure by our CROs, medical institutions, or other third parties we contract with in connection with our clinical trials to adhere to clinical trial requirements or to perform their obligations in a timely manner or in compliance with all applicable laws and regulations, including the FCPA; ● failure to perform in accordance with GCPs or applicable comparable regulatory guidelines in other countries; ● participants not completing a clinical trial or not returning for post-treatment follow-up, including as a result of trial demands on participants; ● clinical trial sites withdrawing from or being unable to conduct activities, or participants withdrawing from clinical trials, including as a result of a pandemic or other outbreak of disease and global conflict; ● participants experiencing serious adverse events or undesirable side effects or being exposed to unacceptable health risks; ● participants failing to experience confirmed pre-specified events during the clinical trial within an expected timeframe, if at all; ● safety issues, including occurrence of adverse events associated with a product candidate, that are viewed to outweigh its potential benefits; ● changes in regulatory requirements, policies and guidance that require amending or submitting new clinical protocols; ● the cost of clinical trials being greater than we anticipate; ● strategic decisions regarding clinical study priority for capital preservation purposes; ● failure by us, our CROs, or other third parties with whom we contract to properly collect, analyze, and/or assess clinical data, including the performance of assays, analyses and other activities; ● clinical trials of our product candidates producing negative, inconclusive or uncompetitive results, which may result in us deciding, or regulatory authorities requiring us, to conduct additional clinical trials or modify or cease development programs for our product candidates; ● failure to replicate safety, efficacy or other data from earlier preclinical studies and clinical trials conducted by us or third parties, including the companies from whom we have licensed or acquired or may in the future license or acquire our product candidates, in our later clinical trials; ● the occurrence of adverse or other events not observed in earlier studies ; ● suspensions or terminations of our clinical trials by us or the IRBs of the institutions in which our clinical trials are being conducted, the Data Safety Monitoring Board for such trials or the FDA or comparable regulatory authorities; ● failure of manufacturers, or us, to produce sufficient quantities of or phase-appropriate supplies of our product candidates for use in our clinical trials in accordance with applicable cGMP requirements and regulations or applicable comparable regulatory guidelines in other countries; 51 Table of Contents ● delays in manufacturing, testing, releasing, validating or importing/exporting sufficient stable quantities of our product candidates for use in clinical trials or the inability to do any of the foregoing either as a result of quality assurance or due to our reliance on third party manufacturers; and ● disruptions to our business operations, including our manufacturing operations, and the business operations of our third party manufacturers, CROs upon whom we rely to conduct our clinical trials, or other third parties with whom we conduct business or otherwise engage, as well as disruptions in supply chain distribution in the countries in which we conduct our clinical trials, our manufacturers produce our product candidates or we otherwise conduct business or engage with other third parties, now or in the future.
Biggest changeFactors that have and may in the future delay or prevent commencement or successful completion of clinical development of our product candidates as planned and on schedule, if at all, include but are not limited to: ● insufficient preclinical, toxicology or other data to support initiation of human trials; ● disagreements with regulatory agencies regarding trial design or implementation, including the appropriate dose levels, frequency of dosing, treatment period or endpoints in clinical trials; ● delays or failure in reaching agreement on acceptable terms with prospective CROs and clinical trial sites; ● difficulties obtaining IRB or ethics committee approval at each clinical trial site; ● delays or failure in obtaining regulatory approval to commence a clinical trial or the imposition of a clinical hold by regulators; ● difficulties in enrolling suitable participants due to competition from other clinical trials in the particular indication; ● clinical trial protocol amendments impacting study criteria, endpoints or design, including amendments that either we initiate or are requested by regulatory authorities; ● difficulty collaborating with patient groups and/or investigators; ● CROs, clinical trial sites or applicable third parties failing to adhere to clinical trial requirements or comply with applicable law; ● CROs, clinical trial sites or applicable third parties failing to conform to GCPs; 52 Table of Contents ● participants not completing a clinical trial or not returning for post-treatment follow-up; ● clinical trial sites withdrawing from a trial or being unable to conduct activities or participants withdrawing from clinical trials; ● participants experiencing serious adverse events, undesirable side effects or unacceptable health risks; ● participants failing to experience confirmed pre-specified events during the clinical trial within the expected timeframe, if at all; ● safety concerns outweighing potential benefits; ● regulatory changes requiring protocol amendments or new submissions; ● failure by us, our CROs or other third parties with whom we contract to timely and properly collect, analyze and/or assess clinical data; ● higher than expected clinical trial or clinical product manufacturing costs; ● strategic clinical trial reprioritization; ● errors in collecting, analyzing and assessing clinical data; ● clinical trials producing negative, inconclusive or uncompetitive results; ● failures to replicate safety, efficacy or other data from earlier preclinical studies and clinical trials conducted by us or third parties, including the trials of companies from whom we have licensed or acquired assets; ● the occurrence of unforeseen adverse events; ● trial suspensions or terminations by us, IRBs, DSMBs, DMCs, or regulators; ● insufficient production of product candidates meeting cGMP standards; ● manufacturing or supply chain delays; and ● operational disruptions affecting us, our CROs or our CDMOs and other third parties we rely on to conduct our clinical trials.
Our business operations are subject to extensive healthcare regulation and enforcement by various government entities, and our failure to strictly adhere to these regulatory requirements could have a detrimental impact on our business.
Our business and operations are subject to extensive healthcare regulation and enforcement by various government entities, and our failure to strictly adhere to these regulatory requirements could have a detrimental impact on our business.
In such an event, we may be held liable for any resulting damages and such liability could exceed our resources, and state or federal or other applicable authorities may curtail our use of certain materials or interrupt our business operations. Furthermore, environmental laws and regulations are complex, change frequently and have tended to become more stringent.
In such an event, we may be held liable for any resulting damages and such liability could exceed our resources, and state, federal or other applicable authorities may curtail our use of certain materials or interrupt our business operations. Furthermore, environmental laws and regulations are complex, change frequently and have tended to become more stringent.
Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all.
Publications of discoveries in scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all.
The issuance of a patent is not conclusive as to its inventorship, scope, validity, enforceability or term, and our owned and licensed patents may be challenged in the courts or patent offices in the United States and abroad.
Issuance of a patent is not conclusive as to its inventorship, scope, validity, enforceability or term, and our owned and licensed patents may be challenged in courts or patent offices, in the United States and abroad.
We believe the key competitive factors affecting the success of ARCALYST and any product candidates that we successfully develop and commercialize, are their efficacy, safety, convenience, price, the effectiveness of companion diagnostics in guiding the use of related products, market acceptance by prescribers and patients, the level of biosimilar competition and the availability of reimbursement from government and other third party payors.
We believe the key competitive factors affecting the success of ARCALYST and any product candidates that we successfully develop and commercialize, are their efficacy, safety, convenience, price, the effectiveness of companion diagnostics (if any) in guiding the use of related products, market acceptance by prescribers and patients, the level of biosimilar competition and the availability of reimbursement from government and other third party payors.
The impacts of climate change on the global economy and our industry are rapidly evolving. Physical impacts of climate change (including but not limited to floods, droughts, more frequent and/or intense storms and wildfires), could negatively impact our business and operations, as well as the business and operations of our third party CDMOs and CROs upon whom we rely.
The impacts of climate change on the global economy and our industry are rapidly evolving. Physical impacts of climate change (including but not limited to floods, hurricanes, droughts, more frequent and/or intense storms and wildfires), could negatively impact our business and operations, as well as the business and operations of our third party CDMOs and CROs upon whom we rely.
Companies that must comply with the GDPR face increased compliance obligations and risk, including more robust regulatory enforcement of data protection requirements and potential fines for noncompliance of up to €20 million or 4% of the annual global revenues of the noncompliant company, whichever is greater.
Companies that must comply with the GDPR face increased compliance obligations and risk, including more robust regulatory enforcement of data protection requirements and potential fines. GDPR noncompliance of up to €20 million or 4% of the annual global revenues of the noncompliant company, whichever is greater.
Orphan Drug designation neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process. We may seek Breakthrough Therapy designation or Fast Track designation by the FDA, for one or more of our product candidates, which we may not receive.
Orphan Drug designation also neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process. We may seek Breakthrough Therapy designation or Fast Track designation by the FDA, for one or more of our product candidates, which we may not receive.
In addition, many of the factors that cause, or lead to, difficulties and delays in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates or us deciding to modify or cease development of our product candidates.
In addition, many of the factors that cause, or lead to, difficulties and delays in the commencement or completion of clinical trials may also lead to the denial of regulatory approval of our product candidates or us deciding to modify or cease development of our product candidates.
In certain countries, the term of a patent that covers a drug product may also be eligible for patent term extension when regulatory approval is granted, provided that the legal requirements are met.
In certain countries, the term of a patent that covers a drug product may be eligible for patent term extension when regulatory approval is granted, provided that the legal requirements are met.
Further, pursuant to the Investors Rights Agreement (a) the holders affiliated with certain of our directors are entitled to certain registration rights under the Securities Act with respect to registrable securities they may own now or in the future and (b) our executive officers are also entitled to certain registration rights under the Securities Act with respect to registrable securities they may own now or in the future, including, on an as-converted to Class A ordinary shares basis, approximately 1.7 million Class A ordinary shares held by certain of our executive officers as of December 31, 2024.
Further, pursuant to the Investors Rights Agreement (a) the holders affiliated with certain of our directors are entitled to certain registration rights under the Securities Act with respect to registrable securities they may own now or in the future and (b) our executive officers are also entitled to certain registration rights under the Securities Act with respect to registrable securities they may own now or in the future, including, on an as-converted to Class A ordinary shares basis, approximately 1.7 million Class A ordinary shares held by certain of our executive officers as of December 31, 2025.
Further, even if we obtain significant market share for our product candidates, because the potential target populations are small for many of our approved and targeted indications, we may never achieve significant and sustained profitability. 43 Table of Contents Evolving health policy and associated legislative changes related to coverage and reimbursement aimed at lowering healthcare expenditures could impact the commercialization of our product candidates.
Further, even if we obtain significant market share for our product candidates, because the potential target populations are small for many of our approved and targeted indications, we may never achieve significant and sustained profitability. 46 Table of Contents Evolving health policy and associated legislative changes related to coverage and reimbursement aimed at lowering healthcare expenditures could impact the commercialization of our product candidates.
Unfavorable global economic or operational conditions could adversely affect our business, financial condition or results of operations. Our results of operations could be adversely affected by general conditions in the global economy and in the global financial markets.
Unfavorable global economic or operational conditions could adversely affect our business, financial condition or results of operations. Our results of operations could be adversely affected by general conditions in the global economy and disruptions in global financial markets.
Such trial sites may also incur risks associated with further delays and expenses as a result of increased shipment costs (including as a result of local quality release or in-country testing of a product candidate supply produced in a different jurisdiction for our clinical trials) and political and economic risks relevant to such countries outside the United States, the EU and the United Kingdom.
Such trial sites may also incur risks associated with further delays and expenses as a result of increased shipment costs (including as a result of local quality release or in-country testing of a product candidate supply produced in a different jurisdiction for our clinical trials) and political and economic risks relevant to such countries outside the United States, the EU and the UK.
As of December 31, 2024, on an as-converted to Class A ordinary shares basis, we have registered approximately 31.8 million Class A ordinary shares held by certain holders affiliated with certain of our directors as well as certain other shareholders pursuant to our investor rights agreement, which are freely tradable without restriction under the Securities Act, to the extent permitted by Rule 144.
As of December 31, 2025, on an as-converted to Class A ordinary shares basis, we have registered approximately 31.8 million Class A ordinary shares held by certain holders affiliated with certain of our directors as well as certain other shareholders pursuant to our investor rights agreement, which are freely tradable without restriction under the Securities Act, to the extent permitted by Rule 144.
Other parties may have developed or may develop technologies that may be related or competitive to our own, and such parties may have filed or may file patent applications, or may have received or may receive patents, claiming inventions that may overlap or conflict with those claimed in our patent applications or issued patents, with respect to either the same methods or formulations or the same subject matter, in either case, that we may rely upon to dominate our patent position in the market.
Other parties may have developed or may develop technologies that may be related or competitive to our own, and such parties may have filed or may file patent applications, or may have received or may receive patents, claiming inventions that may overlap or conflict with those claimed in our patent applications or issued patents, with respect to either the same methods or formulations or the same subject matter, in either case, that we may rely upon to protect our patent position in the market.
These provisions provide for: ● a classified board of directors with staggered three-year terms; ● directors only to be removed for a limited number of reasons; ● limitations on the acquisition of more than 30% or more of our voting rights, except through certain defined permitted acquisitions; ● our multiclass ordinary share structure, which provides our holders of Class B ordinary shares with the ability to significantly influence the outcome of matters requiring shareholder approval, even if they own less than a majority of our outstanding Class A ordinary shares; and ● restrictions on the time period in which directors may be nominated.
These provisions provide for: ● a classified board of directors with staggered three-year terms; ● directors only to be removed for a limited number of reasons; 89 Table of Contents ● limitations on the acquisition of more than 30% or more of our voting rights, except through certain defined permitted acquisitions; ● our multiclass ordinary share structure, which provides our holders of Class B ordinary shares with the ability to significantly influence the outcome of matters requiring shareholder approval, even if they own less than a majority of our outstanding Class A ordinary shares; and ● restrictions on the time period in which directors may be nominated.
Attacks upon information technology systems are increasing in their frequency, levels of persistence, sophistication and intensity, and are being conducted by sophisticated and organized groups and individuals with a wide range of motives and expertise. Technologies such as artificial intelligence and machine learning are additionally being used to create more sophisticated attacks on targets, including targeted social engineering attempts.
Attacks upon information technology systems are increasing in frequency, persistence, sophistication and intensity, and are being conducted by sophisticated and organized groups and individuals with a wide range of motives and expertise. Technologies such as artificial intelligence and machine learning are additionally being used to create more sophisticated attacks on targets, including targeted social engineering attempts.
If we fail to comply with reporting and payment obligations under the MDRP or other governmental pricing programs, we could be subject to additional reimbursement requirements, penalties, sanctions and fines, which could have a material adverse effect on our business, financial condition, results of operations and growth prospects.
If we fail to comply with reporting and payment obligations under the MDRP or other governmental pricing and price reporting programs, we could be subject to additional reimbursement requirements and penalties or sanctions, which could have a material adverse effect on our business, financial condition, results of operations and growth prospects.
Under English law, in most cases, only Kiniksa Pharmaceuticals International, plc may be the proper plaintiff for the purposes of maintaining proceedings in respect of wrongful acts committed against it and, generally, neither an individual shareholder, nor any group of shareholders, has any right of action in such circumstances.
Under English law, in most cases, only Kiniksa International may be the proper plaintiff for the purposes of maintaining proceedings in respect of wrongful acts committed against it and, generally, neither an individual shareholder, nor any group of shareholders, has any right of action in such circumstances.
If the market opportunities for our products and product candidates are smaller than we estimate, or if any approval that we obtain is based on a narrower definition of our targeted patient population, our revenue and ability to achieve profitability may be materially adversely affected.
If the market opportunities for our products and product candidates are smaller than we estimate, or if any approval that we obtain is based on a narrower definition of our targeted patient population, our revenue and ability to sustain profitability may be materially adversely affected.
We also may be unable to expand our operations or otherwise capitalize on our business opportunities or may be 84 Table of Contents required to relinquish rights to our product candidates or products. Any of these occurrences could materially affect our business, financial condition and results of operations. Financing our activities also carries risk.
We also may be unable to expand our operations or otherwise capitalize on our business opportunities or may be required to relinquish rights to our product candidates or products. Any of these occurrences could materially affect our business, financial condition and results of operations. 79 Table of Contents Financing our operations and activities also carries risk.
We completed an analysis of the Company’s and its subsidiaries sources of income and character of their assets for United States federal income tax purposes and determined that neither the Company nor any of its subsidiaries would be classified as a PFIC for the taxable year ending December 31, 2023.
We completed an analysis of the Company’s and its subsidiaries sources of income and character of their assets for United States federal income tax purposes and determined that neither the Company nor any of its subsidiaries would be classified as a PFIC for the taxable year ending December 31, 2025.
Outside parties may: ● have staffing difficulties; ● have disruptions to their business and operations, including as a result of the impact from a pandemic or other outbreak of disease or as the result of war, conflict or terrorism; ● fail to comply with contractual obligations; ● have difficulty controlling the performance of their subcontractors; ● experience regulatory compliance issues; ● undergo changes in priorities or become financially distressed; or ● form relationships with other entities, some of which may be our competitors.
CROs may: ● have staffing difficulties; ● have disruptions to their business and operations, including as a result of the impact from a pandemic or other outbreak of disease or as the result of war, conflict or terrorism; ● fail to comply with contractual obligations; ● have difficulty controlling the performance of their subcontractors; ● experience regulatory compliance issues; ● undergo changes in priorities or become financially distressed; or ● form relationships with other entities, some of which may be our competitors.
In addition, English law may be subject change in the future in ways that are disadvantageous to United States-based shareholders, which could adversely affect the rights of our investors. Rights afforded to shareholders under English law differ in certain respects from the rights of shareholders in companies incorporated in the United States or Bermuda.
In addition, English law may be subject to change in the future in ways that are disadvantageous to United States-based shareholders, which could adversely affect the rights of our investors. Rights afforded to shareholders under English law differ in certain respects from the rights of shareholders in companies incorporated in the United States.
We are unable to predict what tax reform may be proposed or enacted in the future by the United States, United Kingdom, Switzerland or the OECD or what effect such changes would have on our business and results of operations.
We are unable to predict what tax reform may be proposed or enacted in the future by the United States, UK, Switzerland or the OECD or what effect such changes would have on our business and results of operations.
The consummation or performance of any acquisition, business combination, collaboration or other strategic transaction we may undertake in furtherance of our growth strategy or any refined or otherwise altered strategy, may involve additional risks, such as difficulties in assimilating different workplace cultures; retaining personnel and integrating operations, which may be geographically dispersed; increased costs; exposure to liabilities; incurrence of indebtedness; use of a substantial portion of our available cash for all or a portion of the consideration; or causing dilution to our existing shareholders if we issue equity securities for all or a portion of the consideration.
The consummation or performance of any acquisition, business combination, collaboration or other strategic transaction in furtherance of our growth strategy may involve additional risks, such as difficulties in assimilating different workplace cultures; retaining personnel and integrating operations, which may be geographically dispersed; increased costs; exposure to liabilities; incurrence of indebtedness; use of a substantial portion of our available cash for all or a portion of the consideration; or causing dilution to our existing shareholders if we issue equity securities for all or a portion of the consideration.
We may seek Breakthrough Therapy or Fast Track designation for one or more of our product candidates, which, if granted, offers the potential for a rolling review of a BLA if a number of conditions are met, which would allow data to be submitted and reviewed as they become available rather than waiting for the full data package to 59 Table of Contents become available to be submitted.
We may seek Breakthrough Therapy or Fast Track designation for one or more of our product candidates, which, if granted, offers the potential for a rolling review of a BLA if a number of conditions are met, which would allow data to be submitted and reviewed as they become available rather than waiting for the full data package to become available to be submitted.
If a United States Holder is treated as owning (directly, indirectly or constructively) at least 10% of the value or voting power of our shares, such United States Holder may be treated as a “United States shareholder” (as such term is defined in the Code) with respect to us (if we are classified as a controlled foreign corporation) and each controlled foreign corporation in our group (if any).
If a United States Holder is treated as owning (directly, indirectly or constructively) at least 10% of the value or voting power of our shares, such United States Holder may be treated as a 92 Table of Contents “United States shareholder” (as such term is defined in the Code) with respect to us (if we are classified as a controlled foreign corporation) and each controlled foreign corporation in our group (if any).
We continue to evaluate the opportunities for the development and commercialization of our product candidates in certain markets outside of the United States, including through our Managed Access Program and collaborations with third parties, including Huadong.
We continue to evaluate the opportunities for the development and commercialization of our product candidates in certain markets outside of the United States, including through our Named Patient Program, Managed Access Program and collaborations with third parties, including Huadong.
With respect to ARCALYST, we do not currently have arrangements in place for a redundant or second-source manufacturer of drug substance or drug product, or a redundant or second-source packager and labeler, in the event any of our current vendors cease or have a substantial delay in their operations or stop offering us sufficient quantities of these materials for any reason, as applicable.
We do not currently have arrangements in place for a redundant or second-source manufacturer of ARCALYST drug substance or drug product, or a redundant or second-source packager and labeler, in the event any of our current vendors cease or have a substantial delay in their operations or stop offering us sufficient quantities of these materials for any reason, as applicable.
If we are not able to continue to attract and retain, on acceptable terms, the qualified personnel necessary for the continued development of our business, we may not be able to sustain our operations or growth. 89 Table of Contents Effective succession planning is also important to our long-term success and ability to operate as a generational company.
If we are not able to continue to attract and retain, on acceptable terms, the qualified personnel necessary for the continued development of our business, we may not be able to sustain our operations or growth. Effective succession planning is also important to our long-term success and ability to operate as a generational company.
If we are found to infringe a third party’s intellectual property rights, we could be required to obtain a license from such third party to continue developing and marketing our product candidates and technology. Under any such license, we would most likely be required to pay various types of fees, milestones, royalties or other amounts.
If we are found to infringe a third party’s intellectual property rights, we could be required to obtain a license from such third party to continue developing and marketing our product candidates and technology. Under any such 74 Table of Contents license, we would most likely be required to pay various types of fees, milestones, royalties or other amounts.
Failure or perceived failure to comply with the GDPR, the United Kingdom GDPR, the DPA and other countries’ privacy or data security-related laws, rules or regulations could result in significant regulatory penalties and fines, affect our compliance with contracts entered into with our partners and collaborators, and could have an adverse effect on our reputation, business and financial condition.
Failure or perceived failure to comply with the GDPR, the UK GDPR, the DPA and other countries’ privacy or data security-related laws, rules or regulations could result in significant regulatory penalties and fines, affect our compliance with contracts entered into with our partners and collaborators, and could have an adverse effect on our reputation, business and financial condition.
Obtaining funds through licensing, collaboration or other strategic transactions or arrangements with third parties may require us to relinquish rights to some of our technologies, product candidates or future revenue streams, or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects.
Obtaining funds through licensing, collaboration or other strategic transactions or arrangements may require us to relinquish rights to some of our technologies, product candidates or future revenue streams, or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects.
For example, we are currently incorporated under the laws of England and Wales and have subsidiaries in the United States, the United Kingdom, Bermuda, Germany, Switzerland and France. If we succeed in growing our business, we expect to conduct increased operations through our subsidiaries in various tax jurisdictions subject to transfer pricing arrangements between us and such subsidiaries.
For example, we are currently incorporated under the laws of England and Wales and have subsidiaries in the United States, the UK, Switzerland, Germany and France. If we succeed in growing our business, we expect to conduct increased operations through our subsidiaries in various tax jurisdictions subject to transfer pricing arrangements between us and such subsidiaries.
Further, announcement of preliminary, interim or top-line data by us or differences between that data and the final data could result in volatility in the price of our Class A ordinary shares. 55 Table of Contents Risks Related to Marketing Approval and Regulatory Matters Regulatory approval processes are lengthy, time consuming and inherently unpredictable.
Further, announcement of preliminary, interim or top-line data by us or differences between that data and the final data could result in volatility in the price of our Class A ordinary shares. Risks Related to Marketing Approval and Regulatory Matters Regulatory approval processes are lengthy, time consuming and inherently unpredictable.
In addition, clinical trials that are conducted in countries outside the United States, the EU and the United Kingdom may subject us to risks associated with the engagement of non-United States, non-EU and non-United Kingdom CROs who are unknown to the FDA, the EMA or the EU national component authorities or the MHRA and may have different standards of diagnosis, screening and medical care.
In addition, clinical trials that are conducted in countries outside the United States, the EU and the UK may subject us to risks associated with the engagement of CROs who are unknown to the FDA, the EMA or the EU national component authorities or the MHRA and may have different standards of diagnosis, screening and medical care.
These disruptions could adversely affect our ability to manufacture, market and sell our commercialized products, including ARCALYST, and satisfy the required supply for any of our product candidates or successfully complete preclinical and clinical development of our product candidates, which could require us to incur additional costs, and impair our ability to obtain regulatory approval of our product candidates and generate revenue.
These disruptions could adversely affect our ability to manufacture, market and sell ARCALYST, and satisfy the required supply for any of our product candidates or successfully complete preclinical and clinical development of our product candidates, which could require us to incur additional costs, and impair our ability to obtain regulatory approval of our product candidates and generate revenue.
Our ability to continue to commercialize ARCALYST in its approved indications or any of our future products, if any, particularly in orphan or rare disease indications, will depend in part on the availability of favorable coverage, the adequacy of reimbursement (including affordability of patient cost-sharing obligations) for ARCALYST or the future product and alternative treatments from third party payors (e.g., governmental authorities, private health insurers and other organizations).
Our ability to continue to commercialize ARCALYST in its approved indications or our future products, if any, particularly in orphan or rare disease indications, will depend in part on the availability of favorable coverage and adequate reimbursement (including affordability of patient cost-sharing obligations) for ARCALYST or the future product and associated treatments from third party payors (e.g., governmental authorities, private health insurers and other organizations).
If work permits are denied, revoked, or not renewed, we may face disruptions in its operations, increased costs for hiring and training replacements, and potential delays in project execution.
If work permits are denied, revoked or not renewed, we may face disruptions in our operations, increased costs for hiring and training replacements, and potential delays in project execution.
For example, as of December 31, 2024, entities affiliated with certain members of our directors could convert their Class A1 ordinary shares and Class B1 ordinary shares upon 61-days’ prior written notice into Class A ordinary shares and Class B ordinary shares, respectively, which in the aggregate would result in such entities holding approximately 76% of our aggregate voting power and having the ability to control the outcome of certain matters submitted to our shareholders for approval .
For example, as of December 31, 2025, entities affiliated with certain members of our directors could convert their Class A1 ordinary shares and Class B1 ordinary shares upon 61-days’ prior written notice into Class A ordinary shares and Class B ordinary shares, respectively, which in the aggregate would result in such entities holding approximately 74% of our aggregate voting power and having the ability to control the outcome of certain matters submitted to our shareholders for approval .
If the CROs, their subcontractors or the clinical trial sites do not perform clinical trials in a satisfactory manner, breach their obligations to us or fail to comply with regulatory requirements, the development, regulatory approval and commercialization of our product candidates may be delayed or unsuccessful.
If the CROs, their subcontractors or the clinical trial sites do not perform clinical trials in a satisfactory manner, do not devote sufficient resources to a trial, breach their obligations to us or fail to comply with regulatory requirements, the development, regulatory approval and commercialization of our product candidates may be delayed or unsuccessful.
In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our Class A ordinary shares.
In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our 75 Table of Contents Class A ordinary shares.
If tax authorities in any of these countries were to successfully challenge our transfer prices as not reflecting arms’ length transactions, they could require us to adjust our transfer prices and thereby reallocate our income to reflect these revised transfer prices, which could result in a higher tax liability to us.
If tax authorities in any of these countries were to successfully challenge our transfer prices as not reflecting arms’ length transactions, they could require us to adjust our transfer prices and thereby reallocate our income to reflect 91 Table of Contents these revised transfer prices, which could result in a higher tax liability to us.
As of December 31, 2024, approximately 2.0 million Class A ordinary shares directly held by our executive officers and directors, inclusive of Class A ordinary shares issuable upon conversion of our Class B, Class A1, and Class B1 ordinary shares, were eligible for resale in the public market to the extent permitted by the provisions of Rule 144 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), and such rule, Rule 144.
As of December 31, 2025, approximately 2.1 million Class A ordinary shares directly held by our executive officers and directors, inclusive of Class A ordinary shares issuable upon conversion of our Class B, Class A1 and Class B1 ordinary shares, were eligible for resale in the public market to the extent permitted by the provisions of Rule 144 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), and such rule, Rule 144.
The United States Patent and Trademark Office (the “USPTO”) international patent offices or judicial bodies may deny or significantly narrow claims made under our patent applications and our issued patents may be successfully challenged, may be designed around or may otherwise be of insufficient scope to provide protection for our commercial products.
The United States Patent and Trademark Office (the “USPTO”), international patent offices or judicial bodies may deny or significantly narrow claims made under our patent applications and our issued patents may be successfully challenged or may be of insufficient scope to provide protection for our commercial products.
In such cases, regulatory exclusivity, such as data exclusivity or orphan exclusivity as applicable, is expected to be relied upon for our or our licensees’ product candidates. The expiration date of regulatory exclusivity is determined on a country-by country-basis if the applicable product is approved in such country and if any applicable regulatory exclusivity applies and is granted.
In such cases, regulatory exclusivity, such as data exclusivity or orphan exclusivity (if available) as applicable, is expected to be relied upon for our or our licensees’ products. The expiration date of regulatory exclusivity is determined on a country-by country-basis if the applicable product is approved in such country and if any applicable regulatory exclusivity applies and is granted.
The rights of holders of our ordinary shares are governed by English law and our articles of association, and these may not provide the same rights as shares offered by American or Bermudan companies.
The rights of holders of our ordinary shares are governed by English law and our articles of association, and these may not provide the same rights as shares offered by American companies.
We believe we will likely be classified as a “controlled foreign corporation” (as such term is defined in the Code) for the taxable year ended December 31, 2024.
We believe we will likely be classified as a “controlled foreign corporation” (as such term is defined in the Code) for the taxable year ended December 31, 2025.
Furthermore, the type, scope and duration of such exclusivities will 73 Table of Contents vary on a country-by-country basis depending on the jurisdiction in which a product candidate is approved and the particular regulatory exclusivity for which the product is eligible as of the time of approval in such jurisdiction.
Furthermore, the type, scope and duration of any regulatory exclusivities will vary on a country-by-country basis depending on the jurisdiction in which a product candidate is approved and the particular regulatory exclusivity for which the product is eligible as of the time of approval in such 70 Table of Contents jurisdiction.
If a defendant were to prevail on a legal assertion of invalidity or unenforceability of our patents covering our product or one of our product candidates, we or our licensees 79 Table of Contents would lose at least part, and perhaps all, of the patent protection covering such product candidate.
If a defendant were to prevail on a legal assertion of invalidity or unenforceability of our patents covering our product or one of our product candidates, we or our licensees would lose at least part, and perhaps all, of the patent protection covering such product candidate.
If any of these shareholders sell, convert or transfer, or indicate an intention to sell, convert or 94 Table of Contents transfer, a substantial amount of their ordinary shares (after certain restrictions on conversion or resale lapse), the market price of our Class A ordinary shares could decline.
If any of these shareholders sell, convert or transfer or indicate an intention to sell, convert or transfer, a substantial amount of their ordinary shares (after certain restrictions on conversion or resale lapse), the market price of our Class A ordinary shares could decline.
A United States patent covering methods of using ARCALYST in the treatment of recurrent pericarditis was issued in June 2021 and has a statutory term that expires in 2038, not including any patent term adjustment. We are unable to obtain composition of matter patents covering amino acid sequences, or corresponding nucleic acid sequences, of KPL-387.
A United States patent covering methods of using ARCALYST in the treatment of recurrent pericarditis was issued in June 2021 and has a statutory term that expires in 2038, not including any patent term adjustment. We are unable to obtain composition of matter patents for KPL-387’s amino acid or nucleic acid sequences.
In addition, laws and regulations may restrict our ability to attract, motivate and retain the required level of qualified personnel. For example, our business operations may rely on foreign personnel who require work permits. Any changes in immigration policies, work permit regulations, or visa requirements could adversely affect our ability to retain skilled employees.
In addition, laws and regulations may restrict our ability to attract, motivate and retain the required level of qualified personnel. For example, our business operations may rely on foreign personnel who require work permits. Any changes in immigration policies, work permit regulations or visa requirements (including the cost to obtain visas) could adversely affect our ability to retain skilled employees.
Regardless of merit or eventual outcome, liability claims may result in: ● decreased demand for any products we commercialize; ● injury to our reputation and significant negative media attention; ● regulatory investigations that could require costly recalls or product modifications; ● difficulty in enrolling participants in clinical trials or withdrawal of clinical trial participants; ● significant costs to defend the related litigation; ● substantial monetary awards to trial participants; 44 Table of Contents ● loss of potential revenue; ● the diversion of management’s attention away from managing our business; and ● the inability to commercialize any product candidates that we may develop, if approved.
Regardless of merit or eventual outcome, liability claims may result in: ● decreased demand for any approved products; ● injury to our reputation and significant negative media attention; ● regulatory investigations that could require costly recalls or product modifications (or withdrawal of the product from the market); ● difficulty in enrolling participants in clinical trials or withdrawal of clinical trial participants; ● significant costs to defend the related litigation; ● loss of potential revenue; 47 Table of Contents ● the diversion of management’s attention away from managing our business; and ● the inability to commercialize any product candidates that we may develop, if approved.
If coverage and reimbursement are not available, or available only at limited levels, or if such coverage will require patient out-of-pocket costs that are unacceptably high, our ability to successfully commercialize ARCALYST or any of the product candidates 41 Table of Contents for which we obtain marketing approval may be adversely affected.
If coverage and reimbursement are not available, or available at limited levels, or if such coverage will require patient out-of-pocket costs that are unacceptably high, our ability to successfully commercialize ARCALYST or any of the product candidates for which we obtain marketing approval may be adversely affected.
Further, disputes may arise between us and any of these counterparties regarding such obligations under, or the intellectual property subject to, such agreements, including: ● our diligence obligations to develop and commercialize the licensed technology, and what activities satisfy those diligence obligations; ● the scope of rights granted under the agreement and other interpretation-related issues; ● whether our use of the licensed technology is within the scope of the rights granted to us or otherwise consistent with the agreement; 76 Table of Contents ● our obligations to make milestone, royalty or other payments under those agreements; ● other parties’ performance being maintained under these agreements; ● whether and the extent to which our technology and processes infringe on intellectual property of the licensor that is not subject to the agreement; ● our right to sublicense patents and other rights to third parties; ● the ownership of inventions, know-how and other intellectual property, including intellectual property rights resulting from the joint creation or use of intellectual property by us and our licensors, licensees, partners or collaborators; ● our right to transfer or assign the license; and ● the effects of termination.
Disputes may arise between us and any of these counterparties regarding obligations under, or the intellectual property subject to, such agreements, including: ● our diligence obligations to develop and commercialize the licensed technology, and what activities satisfy those diligence obligations; ● the scope of rights granted under the agreement and other interpretation-related issues; ● whether our use of the licensed technology is within the scope of the rights granted to us or otherwise consistent with the agreement; ● milestone, royalty or other payment obligations; ● other parties’ performance being maintained under these agreements; ● whether and the extent to which our technology and processes infringe on intellectual property of the licensor not subject to the agreement; ● our right to sublicense patents and other rights to third parties; ● the ownership of inventions, know-how and other intellectual property, including intellectual property rights resulting from the joint creation or use of intellectual property by us and our licensors, licensees, partners or collaborators; ● our right to transfer or assign the license; and ● the effects of termination.
Moreover, our ability to progress our preclinical and clinical programs or successfully commercialize our products could be materially and adversely impacted if any of the third party suppliers upon which we rely for raw materials and preclinical and clinical stage product candidate and commercial stage product supply were to experience a significant business challenge, disruption or failure due to issues such as financial difficulties or bankruptcy, issues relating to other customers such as regulatory or quality compliance issues, or other financial, legal, regulatory or reputational issues.
In addition, the development of commercial Moreover, our ability to progress our preclinical and clinical programs or successfully commercialize our products could be materially and adversely impacted if any of the third party suppliers upon which we rely for raw 64 Table of Contents materials and preclinical and clinical stage product candidate and commercial stage product supply were to experience a significant business challenge, disruption or failure due to issues such as financial difficulties or bankruptcy, issues relating to other customers such as regulatory or quality compliance issues, or other financial, legal, regulatory or reputational issues.
Therefore, we cannot know with certainty whether we or our licensors were the first to make the inventions claimed in our owned or licensed patents or pending patent applications, or that we 74 Table of Contents or our licensors were the first to file for patent protection of such inventions.
Therefore, we cannot know with certainty whether we or our licensors were the first to make the inventions claimed in our owned or licensed patents or pending patent applications, or that we or our licensors were the first to file for patent protection of such inventions.
A majority of our ordinary shares are held by our executive officers and other members of our senior management team, together with entities affiliated with certain of our directors. As of December 31, 2024, on an as-converted to Class A ordinary shares basis, these shareholders collectively held approximately 33.8 million of our Class A ordinary shares.
A majority of our ordinary shares are held by our executive officers and other members of our senior management team, together with entities affiliated with certain of our directors. As of December 31, 2025, on an as-converted to Class A ordinary shares basis, these shareholders collectively held approximately 33.9 million of our Class A ordinary shares.
Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation.
Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure.
Our executive officers and certain other members of our senior management hold Class A ordinary shares and Class B ordinary shares representing approximately 26% of our aggregate voting power as of December 31, 2024 and may have the ability to influence the outcome of certain matters submitted to our shareholders for approval.
Our executive officers and certain other members of our senior management hold Class A ordinary shares and Class B ordinary shares representing approximately 25% of our aggregate voting power as of December 31, 2025 and may have the ability to influence the outcome of certain matters submitted to our shareholders for approval.
The clinical success of our current and future product candidates depends upon several factors, including, but not limited to, the following: ● submission to and authorization to proceed with clinical trials by the FDA under INDs and CTAs to applicable authorities outside of the United States for our product candidates to commence planned clinical trials or future clinical trials; ● successful completion of nonclinical studies, including toxicology studies, pharmacological, and biodistribution studies, as conducted, where applicable, under GLP; ● successful site activation for, enrollment in, and completion of clinical trials, including the ability of our CROs to successfully conduct such trials within our planned budget and timing parameters without adversely impacting our trials, and our ability to successfully oversee CRO activities; ● positive data from our clinical programs, including post-marketing trials and those intended to satisfy regulatory commitments or for label expansion, with sufficient quality to support an acceptable risk-benefit profile of our products and product candidates for the targeted indications in the intended populations to the satisfaction of the applicable regulatory authorities; ● timely receipt, if at all, of approvals from applicable regulatory authorities and maintenance of any such approvals; 48 Table of Contents ● as applicable, acceptance of pediatric study plans by regulatory authorities, and the follow through of any pediatric study commitments, such as development of pediatric formulations, if required; ● establishment and maintenance of arrangements with third party manufacturers, as applicable, for continued clinical supply and commercial manufacturing; ● successful development of our manufacturing processes and transfer to third party CDMO facilities to support our development and commercialization activities in a manner compliant with all regulatory requirements; ● successful manufacture of sufficient supply of our product candidates within approved specifications for purity, efficacy and cGMP requirements from our facility and from our CDMOs or other sole-source manufacturers in order to meet clinical or commercial demand, as applicable, for ourselves and for our partners; ● continued compliance with any post-marketing requirements imposed by regulatory authorities, including any required post-marketing clinical trial commitments or REMS or similar risk management measures; and ● maintenance of a continued acceptable safety profile of our product candidates before and following approval.
The clinical success of our current and future product candidates depends upon several factors, including, but not limited to, the following: ● submission to and authorization to proceed with clinical trials by the FDA under INDs and CTAs to applicable authorities outside of the United States; ● successful completion of required nonclinical studies, including toxicology studies, pharmacological and biodistribution studies, as conducted, where applicable, under GLP; ● successful site activation for, enrollment in and completion of clinical trials, including the ability of our CROs to successfully conduct such trials within our planned budget and timing parameters without adversely impacting our trials, and our ability to successfully oversee CRO activities; ● positive data from our clinical programs, including post-marketing trials and those intended to satisfy regulatory commitments or for label expansion, with sufficient quality to support an acceptable risk-benefit profile of our products and product candidates for the targeted indications in the intended populations to the satisfaction of the applicable regulatory authorities; ● timely receipt, if at all, of approvals from applicable regulatory authorities and maintenance of any such approvals; ● as applicable, acceptance of pediatric study plans by regulatory authorities, and the follow through of any pediatric study commitments, such as development of pediatric formulations, if required; ● successful manufacture of sufficient supply of our product candidates within approved specifications for purity, efficacy and cGMP requirements from our facility and from our CDMOs or other sole-source manufacturers in order to meet clinical or commercial demand, as applicable, for ourselves and for our partners; ● continued compliance with any post-marketing requirements imposed by regulatory authorities, including any required post-marketing clinical trial commitments or REMS or similar risk management measures; and ● maintenance of a continued acceptable safety profile of our product candidates before and following approval.
General Risk Factors We have a history of operating losses and may require substantial additional financing in the future. Biopharmaceutical product development is a highly speculative undertaking and involves a substantial degree of risk.
General Risk Factors We have a history of operating losses and may require substantial additional financing in the future. Biopharmaceutical product development is highly speculative and involves significant risk.
Despite the implementation of security measures, our information technology systems and those of our third party CDMOs, CROs, specialty pharmacies, third party logistics providers and other contractors, consultants and service providers are vulnerable to attack, damage or interruption from viruses and malware (e.g., ransomware), malicious code, theft, natural disasters, terrorism, war, telecommunication and electrical failures, hacking, cyberattacks, phishing attacks and other social engineering schemes, employee misuse, human error, fraud, denial or degradation of service attacks, sophisticated nation-state and nation-state-supported actors or unauthorized access or use by persons inside our organization, or persons with access to systems inside our organization.
Despite the implementation of security measures, our information technology systems and those of our third-party CDMOs, CROs, specialty pharmacies, logistics providers and other contractors, consultants and service providers remain vulnerable to attack, damage or interruption from malware (e.g., ransomware), viruses, theft, natural disasters, terrorism, war, telecommunication and power failures, hacking, cyberattacks, phishing attacks and other social engineering schemes, employee misuse, human error, fraud, denial or degradation of service attacks, nation-state and nation-state-supported actors or unauthorized access or use by persons within our organization, or persons with access to systems inside our organization.
The actual protection afforded by a patent varies on a product-by-product basis, from country to country and depends upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions, the availability of legal remedies in a particular country and the validity and enforceability of the patent.
The actual protection afforded by a patent varies on a product-by-product basis, from country to country and depends upon many factors, including the type of patent, the scope of its coverage, the availability of patent term extensions and adjustments, the availability of legal remedies in a particular country and the validity and enforceability of the patent.
There may be significant delays in obtaining reimbursement for newly approved products or product indications, coverage may be limited to a subset of the patient population for which the treatment is approved by the FDA or similar regulatory authorities outside the United States including health technology assessment bodies in the EU and United Kingdom, and reimbursement rates may vary according to the use of the product and the clinical setting in which it is used.
There may be significant delays in obtaining reimbursement for newly approved products or product indications; coverage may be limited to a subset of the patient population for which the treatment is approved by the FDA or by similar regulatory authorities outside the United States including health technology assessment bodies in the European Union (the “EU”) and the UK; and reimbursement rates may vary according to the use of the product and the clinical setting in which it is used.
It is also possible that taxing authorities in any such jurisdictions could assert that we are subject to greater taxation than we currently anticipate. Any such tax liability, if greater than our overall effective tax rate, could materially adversely affect our results of operations.
It is also possible that taxing authorities in any such jurisdictions could assert that we are subject to greater taxation than we currently anticipate. Any such tax liability could materially adversely affect our results of operations.
Further, conducting global clinical trials , as we do for certain of our product candidates, may require that we coordinate among the legal requirements and guidelines of regulatory authorities across a number of jurisdictions, including the United States, the EU, the United Kingdom and countries outside of those jurisdictions, which could require that we amend clinical trial protocols or determine not to conduct a trial in one or more jurisdictions or to run separate trials in various jurisdictions due to the inability, cost or delay in harmonizing divergent requests from such regulatory authorities, all of which could increase costs.
Further, conducting global clinical trials , as we do for certain of our product candidates, requires that we coordinate among the legal requirements and guidelines of regulatory authorities across a number of jurisdictions, including the United States, the EU, the UK and countries outside of those jurisdictions, which could require that we amend clinical trial protocols, terminate a trial in one or more jurisdictions or run separate trials in various jurisdictions due to the inability, cost or delay in harmonizing divergent requests from such regulatory authorities, all of which could increase costs.
The strength of patents in the biotechnology and pharmaceutical field involves complex legal and scientific questions and can be uncertain. The patent applications that we own or license may fail to result in issued patents in the United States or in other countries.
The strength of patents in the biotechnology and pharmaceutical field involves complex legal and scientific questions and can be uncertain. Patent applications we own or license may not result in issued patents in the United States or in other countries.
Doing business internationally involves a number of other risks, including but not limited to: ● multiple, conflicting and changing laws and regulations such as privacy regulations, tax laws, employment laws, regulatory requirements, permits and export and import restrictions; ● failure by us to obtain and maintain regulatory approvals for the use of our products in various countries; ● additional potentially relevant third party patent rights; 90 Table of Contents ● complexities and difficulties in obtaining protection and enforcing our intellectual property; ● difficulties in staffing and managing operations outside of the United States; ● complexities associated with managing multiple payor reimbursement regimes, government payors or patient self-pay systems; ● limits in our ability to penetrate international markets; ● financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the impact of local and regional financial crises on demand and payment for our products and exposure to foreign currency exchange rate fluctuations; ● natural disasters, political and economic instability such as war, terrorism, political unrest, outbreak of disease, labor disputes and boycotts; ● curtailment of trade, and other business restrictions; ● certain expenses including, among others, expenses for travel, translation and insurance; and ● regulatory and compliance risks that relate to maintaining accurate information and control over clinical activities, sales and other functions that may fall within the purview of the United States Foreign Corrupt Practices Act, its books and records provisions or its antibribery provisions.
Doing business internationally involves a number of other risks, including but not limited to: ● multiple, conflicting and changing laws and regulations such as privacy regulations, tax laws, employment laws, regulatory requirements, permits and export and import restrictions; 86 Table of Contents ● failure by us to obtain and maintain regulatory approvals for the use of our products in various countries; ● additional potentially relevant third-party patent rights; ● difficulties in staffing and managing operations outside of the United States; ● complexities associated with managing multiple payor reimbursement regimes, government payors or patient self-pay systems; ● limits in our ability to penetrate international markets; ● financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the impact of local and regional financial crises on demand and payment for our products and exposure to foreign currency exchange rate fluctuations; ● natural disasters, political and economic instability such as war, terrorism, political unrest, outbreak of disease, labor disputes and boycotts; ● imposition of tariffs, curtailment of trade and other business restrictions; ● certain expenses including, among others, expenses for travel, translation and insurance; and ● regulatory and compliance risks that relate to maintaining accurate information and control over clinical activities, sales and other functions that may fall within the purview of the FCPA, its books and records provisions or its antibribery provisions and the application of anti-corruption and anti-bribery laws in applicable jurisdictions.
The number of addressable patients in the United States and other major markets outside of the United States may turn out to be lower than expected, patients may not be otherwise amenable to treatment with our products or new patients may become increasingly difficult to identify or gain access to, all of which would adversely affect our results of operations and our business.
The number of addressable patients in the United States, the country where substantially all ARCALYST sales occur, and other major markets outside of the United States may turn out to be lower than expected, patients may not be otherwise amenable to treatment with our products or new patients may become increasingly difficult to identify or gain access to, all of which would adversely affect our results of operations and our business.
Similar proceedings are available in other jurisdictions, and in some jurisdictions third parties can raise questions of validity with a patent office even before a patent has granted.
Similar proceedings exist in other jurisdictions, and in some jurisdictions, third parties can raise questions of validity with a patent office even before a patent has granted.
Even if price increases lie below contractual price protection clauses, payors may request price concessions in exchange for covering our products or may opt to change coverage or reimbursement policies with respect to such products.
Even if price increases lie below contractual price protection clauses, payors may request 45 Table of Contents price concessions in exchange for covering our products or may opt to change coverage or reimbursement policies with respect to such products.
As we encounter employee turnover, including turnover of key personnel, we may be unable to timely train or locate replacement personnel in a way that delays our strategic planning and clinical and commercial execution.
As we encounter employee turnover, including turnover of key personnel, we may be unable to timely train or locate replacement personnel in a way that does not delay our strategic planning and clinical and commercial execution.
Accordingly, U.S. shareholders may be forced to bring legal proceedings against us under English law and in the English courts in order to enforce any claims that they may have against us or our directors and officers.
Accordingly, United States shareholders may be forced to bring legal proceedings against us under English law and in the English courts in order to enforce any claims that they may have against us or our directors and officers.
Governmental authorities, private health insurers and other third party payors have attempted to control costs through a number of efforts, including by delaying the time to reimbursement, by restricting the breadth of coverage, implementing utilization management controls such as requiring prior authorization, limiting the amount of reimbursement for particular products and increasing the proportion of the cost for which the patient is responsible.
Governmental authorities, private health insurers and other third party payors have attempted to control costs through a number of efforts, including by delaying the time to reimbursement; restricting the breadth of coverage; implementing utilization management controls such as requiring prior authorization; limiting the amount of reimbursement for a particular product; restricting the prices that manufacturers may charge for their products and increasing the proportion of the cost for which the patient is responsible.
A failure by our CDMOs to supply sufficient quantities of drug supply may cause us to breach our contractual obligations, triggering potential penalties under our agreements, including termination of such agreements, if we fail to adequately cure such breach.
A failure by our CDMOs to supply sufficient quantities of drug supply may cause us to breach our contractual obligations, triggering potential penalties, including termination of the agreement, if we fail to adequately cure such breach.

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Item 1C. Cybersecurity

Cybersecurity — threats and controls disclosure

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Biggest changeOur business depends on the availability, reliability and security of our and our third party contractors’ information systems, networks and data. Various risks arising out of a cyberattack, security breach or a failure on our or our third party contractors’ part to maintain an adequate cybersecurity program could adversely affect our business, financial condition, and results of operations.
Biggest changeVarious risks arising out of a cyberattack, security breach or a failure on our or our third party contractors’ part to 93 Table of Contents maintain an adequate cybersecurity program could adversely affect our business, financial condition and results of operations.
See “ Risk Factors – General Risk Factors – Our information technology systems, or those of our third party CDMOs, CROs, specialty pharmacies, third party logistics providers and other contractors, consultants and service 99 Table of Contents providers, may fail or suffer cyberattacks or security breaches, which could result in a material disruption of our or such third party’s business or operations, impede our development programs for our product candidates or materially impact our ability to commercialize our products.” ​
See “ Risk Factors – General Risk Factors – Our information technology systems, or those of our third party CDMOs, CROs, specialty pharmacies, third party logistics providers and other contractors, consultants and service providers, may fail or suffer cyberattacks or security breaches, which could result in a material disruption of our or such third party’s business or operations, impede our development programs for our product candidates or materially impact our ability to commercialize our products.”
Added
Our business depends on the availability, reliability and security of our and our third party contractors’ information systems, networks and data.

Item 2. Properties

Properties — owned and leased real estate

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Biggest changeWe have also leased office space in London, UK, Zug, Switzerland and San Diego, these spaces include commercial and logistical operations, as well as office space to support our research and development operations. ​ ITEM 3. LEGAL PROCEEDINGS. We are not party to any material legal proceedings. ​ ​ ITEM 4. MINE SAFETY DISCLOSURES.
Biggest changeThese spaces include commercial and logistical operations, as well as office space to support our research and development operations. ​ ITEM 3. LEGAL PROCEEDINGS. We are not party to any material legal proceedings. ​ ​ ITEM 4. MINE SAFETY DISCLOSURES. Not applicable. 94 Table of Contents ​ ​ ​ PART II
ITEM 2. PROPERTIES. Our United States headquarters are located in Lexington, Massachusetts, where we have leased office and laboratory space, under a lease that expires in August 2028.
ITEM 2. PROPERTIES. Our executive headquarters are located in Lexington, Massachusetts, where we have leased office and laboratory space, under a lease that expires in August 2028. We have also leased office space in London, UK, Zug, Switzerland and San Diego, California.
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Not applicable. 100 Table of Contents ​ ​ ​ PART II

Item 4. Mine Safety Disclosures

Mine Safety Disclosures — required of mining issuers

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Biggest changeItem 4. Mine Safety Disclosures ​ 100 ​ ​ ​ ​ ​ ​ PART II ​ ​ ​ ​ ​ Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities ​ 101 ​ ​ ​
Biggest changeItem 4. Mine Safety Disclosures ​ 94 ​ ​ ​ ​ ​ ​ PART II ​ ​ ​ ​ ​ Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities ​ 95 ​ ​ ​

Item 5. Market for Registrant's Common Equity

Market for Common Equity — stock, dividends, buybacks

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Biggest changeUnder our articles of association, each of our ordinary shares is entitled to dividends if, as and when dividends are declared by our board of directors, subject to any preferred dividend right of the holders of any preferred shares. 101 Table of Contents Performance Graph The following graph shows a comparison of the total cumulative total shareholder returns (assuming reinvestment of dividends, if any) of an investment of $100 in cash on the last trading day of 2019 to the close of the last trading day of 2024 in each of (i) our Class A ordinary shares, (ii) the Nasdaq Composite Index and (iii) the Nasdaq Biotechnology Index.
Biggest changeUnder our articles of association, each of our ordinary shares is entitled to dividends if, as and when dividends are declared by our board of directors, subject to any preferred dividend right of the holders of any preferred shares. 95 Table of Contents Performance Graph The following graph shows a comparison of the total cumulative total shareholder returns (assuming reinvestment of dividends, if any) of an investment of $100 in cash on the last trading day of 2020 to the close of the last trading day of 2025 in each of (i) our Class A ordinary shares, (ii) the Nasdaq Composite Index and (iii) the Nasdaq Biotechnology Index.
The comparisons in the graph are required by the SEC and are not intended to forecast or be indicative of the possible future performance of our ordinary shares. ​ ​ ​ ITEM 6. RESERVED. ​ ​ ​ 102 Table of Contents
The comparisons in the graph are required by the SEC and are not intended to forecast or be indicative of the possible future performance of our ordinary shares. ​ ​ ​ ITEM 6. RESERVED. ​ ​ ​ 96 Table of Contents
Principal Market Our Class A ordinary shares are listed on The Nasdaq Global Select Market under the symbol “KNSA.” Holders As of February 21, 2025, there were four holders of record of our Class A ordinary shares, one holder of record of our Class B ordinary shares, one holder of record of our Class A1 ordinary shares and one holder of record of our Class B1 ordinary shares.
Principal Market Our Class A ordinary shares are listed on The Nasdaq Global Select Market under the symbol “KNSA.” Holders As of February 20, 2026, there were two holders of record of our Class A ordinary shares, one holder of record of our Class B ordinary shares, one holder of record of our Class A1 ordinary shares and one holder of record of our Class B1 ordinary shares.

Item 7. Management's Discussion & Analysis

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

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Biggest changeIn connection with the termination of Kiniksa UK rights and the contribution, we revalued the assets at fair market value and did not incur any material tax liabilities. ​ Results of Operations Comparison of the Years Ended December 31, 2024, 2023 and 2022 The following table summarizes our results of operations for the years ended December 31, 2024, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024/2023 ​ 2023/2022 ​ ​ Years Ended ​ Comparison ​ Comparison ​ ​ December 31, ​ Increase/(Decrease) ​ Increase/(Decrease) ​ 2024 2023 2022 $ % $ % ​ ​ (in thousands) ​ (in thousands, except percentages) Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Product revenue, net ​ $ 417,029 ​ $ 233,176 ​ $ 122,524 ​ $ 183,853 ​ 79% ​ $ 110,652 ​ 90% License and collaboration revenue ​ ​ 6,210 ​ ​ 37,083 ​ ​ 97,656 ​ ​ (30,873) ​ (83)% ​ ​ (60,573) ​ (62)% Total revenue ​ ​ 423,239 ​ ​ 270,259 ​ ​ 220,180 ​ ​ 152,980 ​ 57% ​ ​ 50,079 ​ 23% Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost of goods sold ​ ​ 60,910 ​ ​ 33,407 ​ ​ 22,895 ​ ​ 27,503 ​ 82% ​ ​ 10,512 ​ 46% Collaboration expenses ​ ​ 128,311 ​ ​ 56,524 ​ ​ 24,071 ​ ​ 71,787 ​ 127% ​ ​ 32,453 ​ 135% Research and development ​ ​ 111,623 ​ ​ 76,097 ​ ​ 65,490 ​ ​ 35,526 ​ 47% ​ ​ 10,607 ​ 16% Selling, general and administrative ​ 168,011 ​ 129,427 ​ 97,951 ​ 38,584 ​ 30% ​ 31,476 ​ 32% Total operating expenses ​ 468,855 ​ 295,455 ​ 210,407 ​ 173,400 ​ 59% ​ 85,048 ​ 40% Income (loss) from operations ​ (45,616) ​ (25,196) ​ 9,773 ​ (20,420) ​ 81% ​ (34,969) ​ (358)% Other income ​ 9,464 ​ 8,544 ​ 1,253 ​ 920 ​ 11% ​ 7,291 ​ 582% Income (loss) before income taxes ​ (36,152) ​ (16,652) ​ 11,026 ​ (19,500) ​ 117% ​ (27,678) ​ (251)% Benefit (provision) for income taxes ​ (7,041) ​ 30,736 ​ 172,337 ​ (37,777) ​ (123)% ​ (141,601) ​ (82)% Net income (loss) ​ $ (43,193) ​ $ 14,084 ​ $ 183,363 ​ $ (57,277) ​ (407)% ​ $ (169,279) ​ (92)% ​ Product Revenue, Net We recognized net revenue from the sale of ARCALYST of $417.0 million, $233.2 million and $122.5 million for the years ended December 31, 2024, 2023 and 2022, respectively.
Biggest changeIn connection with the termination of Kiniksa UK rights and the contribution, we revalued the assets at fair market value and did not incur any material tax liabilities. ​ ​ 101 Table of Contents Results of Operations Comparison of the Years Ended December 31, 2025, 2024 and 2023 The following table summarizes our results of operations for the years ended December 31, 2025, 2024 and 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2025/2024 ​ 2024/2023 ​ ​ Years Ended ​ Comparison ​ Comparison ​ ​ December 31, ​ Increase/(Decrease) ​ Increase/(Decrease) ​ ​ ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 ​ ​ ​ $ % ​ ​ ​ $ % ​ ​ (in thousands) ​ (in thousands, except percentages) Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Product revenue, net ​ $ 677,564 ​ $ 417,029 ​ $ 233,176 ​ $ 260,535 ​ 62% ​ $ 183,853 ​ 79% License and collaboration revenue ​ ​ — ​ ​ 6,210 ​ ​ 37,083 ​ ​ (6,210) ​ (100)% ​ ​ (30,873) ​ (83)% Total revenue ​ ​ 677,564 ​ ​ 423,239 ​ ​ 270,259 ​ ​ 254,325 ​ 60% ​ ​ 152,980 ​ 57% Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost of goods sold ​ ​ 77,673 ​ ​ 60,910 ​ ​ 33,407 ​ ​ 16,763 ​ 28% ​ ​ 27,503 ​ 82% Collaboration expenses ​ ​ 229,545 ​ ​ 128,311 ​ ​ 56,524 ​ ​ 101,234 ​ 79% ​ ​ 71,787 ​ 127% Research and development ​ ​ 96,853 ​ ​ 111,623 ​ ​ 76,097 ​ ​ (14,770) ​ (13)% ​ ​ 35,526 ​ 47% Selling, general and administrative ​ 196,272 ​ 168,011 ​ 129,427 ​ 28,261 ​ 17% ​ 38,584 ​ 30% Total operating expenses ​ 600,343 ​ 468,855 ​ 295,455 ​ 131,488 ​ 28% ​ 173,400 ​ 59% Income (loss) from operations ​ 77,221 ​ (45,616) ​ (25,196) ​ 122,837 ​ (269)% ​ (20,420) ​ 81% Other income ​ 11,647 ​ 9,464 ​ 8,544 ​ 2,183 ​ 23% ​ 920 ​ 11% Income (loss) before income taxes ​ 88,868 ​ (36,152) ​ (16,652) ​ 125,020 ​ (346)% ​ (19,500) ​ 117% Benefit (provision) for income taxes ​ (29,863) ​ (7,041) ​ 30,736 ​ (22,822) ​ 324% ​ (37,777) ​ (123)% Net income (loss) ​ $ 59,005 ​ $ (43,193) ​ $ 14,084 ​ $ 102,198 ​ (237)% ​ $ (57,277) ​ (407)% ​ Product Revenue, Net We recognized net revenue from the sale of ARCALYST of $677.6 million, $417.0 million and $233.2 million for the years ended December 31, 2025, 2024 and 2023, respectively.
This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs.
This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs.
Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products. ​ As of December 31, 2024, a 10% change in our product revenue allowance and reserve would not result in a material change in our net revenue. ​ Accrued Research and Development Expenses As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued research and development expenses.
Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products. ​ As of December 31, 2025, a 10% change in our product revenue allowance and reserve would not result in a material change in our net revenue. ​ Accrued Research and Development Expenses As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued research and development expenses.
These expenses may include: ● expenses incurred to conduct the necessary preclinical studies and clinical trials required to obtain regulatory approval; ● expenses incurred under agreements with CROs that are primarily engaged in the oversight and conduct of our clinical trials and CDMOs that are primarily engaged to provide preclinical and clinical drug substance and product for our research and development programs for our product candidates; ● other costs related to acquiring and manufacturing preclinical and clinical trial materials, including manufacturing validation batches, as well as investigative sites and consultants that conduct our clinical trials, preclinical studies and other scientific development services; ● payments made in cash or equity securities under third party licensing, acquisition and other similar agreements; ● employee-related expenses, including salaries and benefits, travel and share-based compensation expense for employees engaged in research and development functions; ● costs related to compliance with regulatory requirements; and ● allocated facilities-related costs, which include rent and utilities, depreciation and other expenses.
These expenses may include: ● expenses incurred to conduct the necessary preclinical studies and clinical trials required to obtain regulatory approval; 99 Table of Contents ● expenses incurred under agreements with CROs that are primarily engaged in the oversight and conduct of our clinical trials and CDMOs that are primarily engaged to provide preclinical and clinical drug substance and product for our research and development programs for our product candidates; ● other costs related to acquiring and manufacturing preclinical and clinical trial materials, including manufacturing validation batches, as well as investigative sites and consultants that conduct our clinical trials, preclinical studies and other scientific development services; ● payments made in cash or equity securities under third party licensing, acquisition and other similar agreements; ● employee-related expenses, including salaries and benefits, travel and share-based compensation expense for employees engaged in research and development functions; ● costs related to compliance with regulatory requirements; and ● allocated facilities-related costs, which include rent and utilities, depreciation and other expenses.
We have recognized $0.2 million of revenue of the $32.0 million transaction price under the ARCALYST license agreement as of December 31, 2024, and will recognize the remaining revenue as materials are shipped. In August 2022, we entered into the Genentech License Agreement, pursuant to which we granted Genentech exclusive worldwide rights to develop and commercialize the Genentech Licensed Products.
We have recognized $0.2 million of revenue of the $32.0 million transaction price under the ARCALYST license agreement as of December 31, 2025, and will recognize the remaining revenue as materials are shipped. In August 2022, we entered into the Genentech License Agreement, pursuant to which we granted Genentech exclusive worldwide rights to develop and commercialize the Genentech Licensed Products.
Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products. ​ License and collaboration revenue ​ License and collaboration revenue includes amounts recognized related to upfront payments, royalty revenue, milestone payments and products sold under collaboration agreements. ​ In February 2022, we entered into the Huadong Collaboration Agreements, pursuant to which we granted Huadong exclusive rights to develop and commercialize the Huadong Licensed Products in the Huadong Territory.
Adjustments for variable consideration are determined based on the contractual terms with customers, historical trends, communications with customers and the levels of inventory remaining in the distribution channel, as well as expectations about the market for the product and anticipated introduction of competitive products. ​ License and collaboration revenue ​ License and collaboration revenue includes amounts recognized related to upfront payments, royalty revenue, milestone payments and products sold under collaboration agreements. ​ In February 2022, we entered into the Huadong Collaboration Agreements with Huadong, pursuant to which we granted Huadong exclusive rights to develop and commercialize ARCALYST and mavrilimumab, in the Huadong Territory.
As a result, we have not recorded any income tax benefits from our losses incurred in Bermuda during each reporting periods in which it was incorporated there, and no net operating loss carryforwards are currently available to us for those losses.
As a result, we have not recorded any income tax benefits from our losses incurred in Bermuda during each of the reporting periods in which it was incorporated there, and no net operating loss carryforwards are currently available to us for those losses.
Other Income Other income consists of interest income recognized from investments in money market funds, United States Treasury notes and other miscellaneous income offset by expenses related to investments. Income Taxes Prior to the Redomiciliation, our principal holding company was incorporated and principally subject to taxation in Bermuda.
Other Income Other income consists of interest income recognized from investments in money market funds, United States Treasury securities and other miscellaneous income offset by expenses related to investments. Income Taxes Prior to the Redomiciliation, our principal holding company was incorporated and principally subject to taxation in Bermuda.
Following the Redomiciliation, our principal holding company is incorporated and principally subject to taxation in the United Kingdom. Under the current laws of Bermuda, there is no corporate income tax levied on an exempted company’s income, resulting in an effective zero percent tax rate.
Following the Redomiciliation, our principal holding company is incorporated and principally subject to taxation in the United Kingdom. Under the previous laws of Bermuda, there is no corporate income tax levied on an exempted company’s income, resulting in an effective zero percent tax rate.
During the year ended December 31, 2024 expenses incurred primarily related to a $18.5 million write-off of prepayments for future manufacturing we no longer expect to utilize, manufacturing of clinical material, continuation of cohort four and study wind-down activities of our Phase 2 clinical trial in RA and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease.
During the year ended December 31, 2024 expenses incurred primarily related to a $18.5 million write-off of prepayments for future manufacturing we no 103 Table of Contents longer expect to utilize, manufacturing of clinical material, continuation of cohort four and study wind-down activities of our Phase 2 clinical trial in RA and start-up costs of our Phase 2b clinical trial in Sjögren’s Disease.
We will be eligible to receive up to a total of approximately $600.0 million in contingent payments, including specified development, regulatory and sales-based milestones, of which approximately $570.0 million remains as of December 31, 2024.
We will be eligible to receive up to a total of approximately $600.0 million in contingent payments, including specified development, regulatory and sales-based milestones, of which approximately $570.0 million remains as of December 31, 2025.
Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period.
Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services 108 Table of Contents performed may vary and may result in reporting amounts that are too high or too low in any particular period.
With respect to the technology transfer of ARCALYST drug substance manufacturing initiated by Regeneron in March 2023, to the extent permitted by the Regeneron Agreement, the fully-burdened costs of each of us and Regeneron incurred in performing such technology 105 Table of Contents transfer shall also be deducted from net sales of ARCALYST to determine profit.
With respect to the technology transfer of ARCALYST drug substance manufacturing initiated by Regeneron in March 2023, to the extent permitted by the Regeneron Agreement, the fully-burdened costs of each of us and Regeneron incurred in performing such technology transfer shall also be deducted from net sales of ARCALYST to determine profit.
In addition, if we obtain regulatory approval for any of our current or future product candidates, pursue additional indications or additional territories for our products or any of our current or future 113 Table of Contents product candidates, we expect to incur significant expenses related to product development and manufacturing, sales, marketing and distribution, depending on where we choose to commercialize.
In addition, if we obtain regulatory approval for any of our current or future product candidates, pursue additional indications or additional territories for our products or any of our current or future product candidates, we expect to incur significant expenses related to product development and manufacturing, sales, marketing and distribution, depending on where we choose to commercialize.
Cost of goods sold also includes labor and overhead costs associated with the production of ARCALYST associated with supply chain, quality, and regulatory activities, and the technology transfer of the manufacturing process for the ARCALYST drug substance.
Cost of goods sold also includes labor and overhead costs associated with the production of ARCALYST associated with supply chain, quality, and regulatory activities, and the technology transfer of the manufacturing process for ARCALYST.
Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of United States interest rates. Such interest rates have and in the future may be subject to significant volatility.
Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of United 109 Table of Contents States interest rates. Such interest rates have and in the future may be subject to significant volatility.
Huadong will also be obligated to pay us tiered percentage royalties on ARCALYST ranging from the low-to-mid teens on annual net sales in the Huadong 104 Table of Contents Territory, subject to certain reductions tied to ARCALYST manufacturing costs and certain other customary reductions, with an aggregate minimum floor.
Huadong will also be obligated to pay us tiered percentage royalties on ARCALYST ranging from the low-to-mid teens on annual net sales in the Huadong Territory, subject to certain reductions tied to ARCALYST manufacturing costs and certain other customary reductions, with an aggregate minimum floor.
We believe our estimates for the valuation allowances against certain deferred tax assets recognized in our financial statements are appropriate based upon our assessment of the factors mentioned above.
We believe our estimates for our uncertain tax positions and the valuation allowances against certain deferred tax assets recognized in our financial statements are appropriate based upon our assessment of the factors mentioned above.
As a result, we expect that our research and development 106 Table of Contents expenses will be substantial over the next several years as we conduct our ongoing and/or planned clinical trials for our product candidates, as well as conduct other preclinical and clinical development, and make regulatory filings for our product candidates.
As a result, we expect that our research and development expenses will be substantial over the next several years as we conduct our ongoing and/or planned clinical trials for our product candidates, as well as conduct other preclinical and clinical development, and make regulatory filings for our product candidates.
For more information, see “ Business –License and Acquisition Agreements—Out-Licensing Agreements—Genentech License Agreement ”. Under the Genentech License Agreement, we received an upfront payment of $80.0 million for the license.
For more information, see “ Business –License and Acquisition Agreements—Out-Licensing Agreements—Genentech License Agreement ”. 98 Table of Contents Under the Genentech License Agreement, we received an upfront payment of $80.0 million for the license.
Interest Rate Risk We are exposed to market risk related to changes in interest rates. As of December 31, 2024, our cash, cash equivalents and short-term investments consisted of money market funds and United States Treasury notes.
Interest Rate Risk We are exposed to market risk related to changes in interest rates. As of December 31, 2025, our cash, cash equivalents and short-term investments consisted of money market funds and United States Treasury securities.
Financing Activities During the years ended December 31, 2024, 2023 and 2022, net cash provided by financing activities was $12.3 million, $1.5 million and $2.5 million, respectively, consisting of proceeds from the exercise of employee share options and our 2018 Employee Share Purchase Plan (the “2018 ESPP”).
Financing Activities During the years ended December 31, 2025, 2024 and 2023, net cash provided by financing activities was $33.0 million, $12.3 million and $1.5 million, respectively, consisting of proceeds from the exercise of employee share options and our 2018 Employee Share Purchase Plan (the “2018 ESPP”).
The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales, offset by a decrease in cash received from licensing agreements of $20.0 million. ​ Net cash provided by operations was $13.3 million for the year ended December 31, 2023, compared to $5.8 million for the year ended December 31, 2022.
The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales, offset by a decrease in cash received from licensing agreements of $5.0 million. ​ Net cash provided by operations was $25.7 million for the year ended December 31, 2024, compared to $13.3 million for the year ended December 31, 2023.
To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses. As of December 31, 2024, we have accrued $11 million of estimated research and development expenses.
To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses. As of December 31, 2025, we have accrued $6.6 million of estimated research and development expenses.
Our net income (losses) were ($43.2) million, $14.1 million and $183.4 million for the years ended December 31, 2024, 2023 and 2022, respectively. We expect our cash balance and our expected cash inflows from operations to allow us to meet our current operating plan.
Our net income (losses) were $59.0 million, ($43.2) million and $14.1 million for the years ended December 31, 2025, 2024 and 2023, respectively. We expect our cash balance and our expected cash inflows from operations to allow us to meet our current operating plan.
Personnel-related costs for the years ended December 31, 2024, 2023 and 2022 included share-based compensation of $6.1 million, $5.5 million and $6.8 million, respectively. ​ Selling, General and Administrative Expenses Selling, general and administrative expenses were $168.0 million, $129.4 million and $98.0 million for the years ended December 31, 2024, 2023 and 2022, respectively.
Personnel-related costs for the years ended December 31, 2025, 2024 and 2023 included share-based compensation of $6.6 million, $6.1 million and $5.5 million, respectively. ​ Selling, General and Administrative Expenses Selling, general and administrative expenses were $196.3 million, $168.0 million and $129.4 million for the years ended December 31, 2025, 2024 and 2023, respectively.
We have additionally entered into agreements with several CDMOs to provide us with preclinical and clinical trial materials for our non-ARCALYST assets, which obligate us to minimum payments of $40.8 million, $39.0 million of which are due within one year.
We have additionally entered into agreements with several CDMOs to provide us with preclinical and clinical trial materials for our non-ARCALYST assets, which obligate us to minimum payments of $3.4 million, all of which are due within one year.
Direct costs for our vixarelimab program were $1.5 million, $7.7 million and $12.8 million for the year ended December 31, 2024, 2023 and 2022, respectively. During the year ended December 31, 2024, expenses incurred were primarily related to the wind-down activities of our Phase 2b clinical trial in prurigo nodularis.
Direct costs for our vixarelimab program were less than $0.1 million, $1.5 million and $7.7 million for the years ended December 31, 2025, 2024 and 2023, respectively. During the year ended December 31, 2024, expenses incurred were primarily related to the wind-down activities of our Phase 2b clinical trial in prurigo nodularis.
As of December 31, 2024, we have recognized the $130.0 million received from Genentech under the Genentech License Agreement as revenue. ​ Operating Expenses Cost of Goods Sold Cost of goods sold includes production and distribution costs of ARCALYST, amortization of the $20.0 million payment we made to Regeneron in the first quarter of 2021 upon achievement of a regulatory milestone and other miscellaneous product costs associated with ARCALYST.
In 2024, we completed our remaining obligations under the Genentech License Agreement and we have recognized as revenue all of the consideration received. ​ Operating Expenses Cost of Goods Sold Cost of goods sold includes production and distribution costs of ARCALYST, amortization of the $20.0 million payment we made to Regeneron in the first quarter of 2021 upon achievement of a regulatory milestone and other miscellaneous product costs associated with ARCALYST.
The increase of $10.5 million in 2023 from 2022 related primarily to the increase in sales of ARCALYST and $3.3 million related to the initiation of the technology transfer of the manufacturing process offset by a decrease in average cost per unit resulting from favorable production variances. ​ Collaboration Expenses We recognized collaboration expenses of $128.3 million, $56.5 million and $24.1 million for the years ended December 31, 2024, 2023 and 2022, respectively.
The increase of $27.5 million in 2024 from 2023 related primarily to the increase in sales of ARCALYST and a $12.6 million increase related to the technology transfer of the manufacturing process offset by a decrease in average cost per unit resulting from favorable production variances . ​ Collaboration Expenses We recognized collaboration expenses of $229.5 million, $128.3 million and $56.5 million for the years ended December 31, 2025, 2024 and 2023, respectively.
We have committed to minimum payments to Regeneron of $40.7 million, all of which are due within one year. We have entered into lease agreements for office and laboratory space, and vehicles, with total future lease payments of $11.3 million, $2.7 million of which are due within one year.
We have committed to minimum payments to Regeneron of $24.6 million, all of which are due within one year. We have entered into lease agreements for office and laboratory space, and vehicles, with total future lease payments of $10.5 million, $3.5 million of which are due within one year.
Net cash used in investing activities was $29.6 million for the year ended December 31, 2023, compared to $8.1 million for the year ended December 31, 2022 as part of managing our cash and short-term investment portfolio mix.
Net cash provided by investing activities was $37.7 million for the year ended December 31, 2024, compared to net cash used in investing activities of $29.6 million for the year ended December 31, 2023 as part of managing our cash and short-term investment portfolio mix.
Benefit (Provision) for Income Taxes For the year ended December 31, 2024, we recorded an income tax provision of $7.0 million relating primarily to income earned in Switzerland and the U.S., net of Foreign-Derived Intangible Income (“FDII”) deduction and U.S. federal and state R&D Credits utilized. ​ For the year ended December 31, 2023, we recorded an income tax benefit of $30.7 million relating to a non-cash deferred tax benefit of $33.8 million primarily associated with Kiniksa UK’s allocation of its ARCALYST assets to its Swiss branch office and the release of the valuation allowance on U.S. deferred tax assets offset by the establishment of a partial valuation allowance on our UK deferred tax assets.
Benefit (Provision) for Income Taxes For the year ended December 31, 2025, we recorded an income tax provision of $29.9 million relating primarily to income earned in Switzerland, the United States, and the UK; valuation allowance on Swiss losses and revaluation of Swiss deferred tax assets for enacted rate changes; offset by benefits related to share-based compensation, and United States federal and state R&D Credits. ​ For the year ended December 31, 2024, we recorded an income tax provision of $7.0 million relating primarily to income earned in Switzerland and the United States, offset by Foreign-Derived Intangible Income (“FDII”) deduction and United States federal and state R&D Credits utilized. ​ For the year ended December 31, 2023, we recorded an income tax benefit of $30.7 million relating to a non-cash deferred tax benefit of $33.8 million primarily associated with Kiniksa UK’s allocation of its ARCALYST assets to its Swiss branch office and the release of the valuation allowance on United States deferred tax assets offset by the establishment of a partial valuation allowance on our UK deferred tax assets.
Income Taxes We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in our tax returns.
We recognize both accrued interest and penalties related to unrecognized tax benefits in income tax expense. We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in our tax returns.
The increases in 2024 and 2023 were primarily driven by an increase in patient enrollment. ​ License and Collaboration Revenue ​ We reported $6.2 million of license and collaboration revenue for the year ended December 31, 2024 , primarily driven by the achievement of a $5.0 million development milestone related to a third indication under the Genentech License Agreement, $0.7 million of products sold under the ARCALYST Huadong Collaboration Agreements, and $0.2 million of deferred revenue recognized related to the delivery of such materials.
We reported $6.2 million of license and collaboration revenue for the year ended December 31, 2024 , primarily driven by the achievement of a $5.0 million development milestone related to a third indication under the Genentech License Agreement and $0.7 million of products sold under the ARCALYST Huadong Collaboration Agreements.
The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales, offset by a decrease in cash received from licensing agreements of $67.0 million. ​ Investing Activities Net cash provided by investing activities was $37.7 million for the year ended December 31, 2024, compared to net cash used in investing activities of $29.6 million for the year ended December 31, 2023 as part of managing our cash and short-term investment portfolio mix.
The increase in cash provided by operating activities is primarily due to an increase in net contribution from higher ARCALYST sales, offset by a decrease in cash received from licensing agreements of $20.0 million. ​ Investing Activities Net cash used in investing activities was $189.0 million for the year ended December 31, 2025, compared to net cash provided by investing activities of $37.7 million for the year ended December 31, 2024 as part of managing our cash and short-term investment portfolio mix as we deployed higher levels of investable cash into treasury securities with longer-terms.
We reported $37.1 million of license 108 Table of Contents and collaboration revenue for the year ended December 31, 2023, related to the Genentech License Agreement primarily driven by the achievement of $25.0 million in development milestones related to two new indications, materials delivered and our ongoing recognition of the transaction price related to the in-progress Phase 2b clinical trial of vixarelimab in prurigo nodularis.
We reported $37.1 million of license and collaboration revenue for the year ended December 31, 2023, related to the Genentech License Agreement primarily driven by the achievement of $25.0 million in development milestones related to two new indications, materials delivered and our ongoing recognition of the transaction price related to the in-progress Phase 2b clinical trial of vixarelimab in prurigo nodularis. ​ Cost of Goods Sold We recognized cost of goods sold of $77.7 million, $60.9 million, and $33.4 million for the years ended December 31, 2025, 2024 and 2023, respectively.
The future viability of our company is dependent on our ability to fund our operations through sales of ARCALYST and/or raise additional capital, such as through debt or equity offerings, as needed. We anticipate that we may require additional capital if we choose to pursue in-licenses or acquisitions of other product candidates and technologies or their related businesses.
The future viability of our company is dependent on our ability to fund our operations through sales of ARCALYST and/or raise additional capital, such as through debt or equity offerings, as needed. We anticipate that we may require additional capital if we choose to pursue collaboration, licensing or other strategic transactions.
We may also incur expenses in connection with the in-licensing or acquisition of additional product candidates. As a result, we expect to incur additional expenses related to milestone, royalty and other payments payable 112 Table of Contents to third parties with whom we have entered into license, acquisition and other similar agreements to acquire the rights to our product candidates.
We may also incur expenses in connection with collaboration, licensing or other strategic transactions. Further, we may incur expenses related to milestone, royalty and other payments payable to third parties with whom we have entered into license, acquisition and other similar agreements to acquire the rights to our product candidates.
We expect that our selling, general and administrative expenses will continue to increase in the future as we continue to expand our infrastructure related to the commercialization of ARCALYST and our other product candidates, if approved.
Selling, general and administrative expenses also include external commercialization, marketing, and professional fees for legal, patent, and accounting services. We expect that our selling, general and administrative expenses will continue to increase in the future as we continue to expand our infrastructure related to the commercialization of ARCALYST and our other product candidates, if approved.
We did not incur any expenses related to KPL-1161 for the years ended December 31, 2023 and 2022. For the year ended December 31, 2024 expenses incurred primarily related to pre-clinical development. Direct costs for our abiprubart program were $59.5 million, $28.4 million and $11.6 million for the years ended December 31, 2024, 2023 and 2022, respectively.
For the years ended December 31, 2025 and 2024 expenses incurred primarily related to pre-clinical development. Direct costs for our abiprubart program were $6.1 million, $59.5 million and $28.4 million for the years ended December 31, 2025, 2024 and 2023, respectively.
Product Revenue, Net Net revenue from product sales is recognized at the transaction price when the specialty pharmacy or specialty distributors obtains control of our products, which occurs at a point in time, typically upon shipment of the product from the third party logistics provider. ​ Our net revenues represent total revenues adjusted for discounts and allowances, including estimated cash discounts, chargebacks, rebates, returns, copay assistance, and specialty pharmacy and distributor fees.
ARCALYST is currently only approved for sale in the United States, and, therefore, we expect to derive substantially all of our product revenue from the United States for the foreseeable future. ​ Net revenue from product sales is recognized at the transaction price when the customer obtains control of our product, which occurs at a point in time, typically upon shipment of the product from the third party logistics provider. ​ Our net revenues represent total revenues adjusted for discounts and allowances, including estimated cash discounts, chargebacks, rebates, returns, copay assistance, and specialty pharmacy and distributor fees.
Research and development expenses were $76.1 million for the year ended December 31, 2023 compared to $65.5 million for the year ended December 31, 2022, or an increase of $10.6 million. 109 Table of Contents Direct costs for our KPL-387 program were $11.2 million, $2.5 million and less than $0.1 million for the years ended December 31, 2024, 2023 and 2022, respectively.
Research and development expenses were $111.6 million for the year ended December 31, 2024 compared to $76.1 million for the year ended December 31, 2023, or an increase of $35.5 million. Direct costs for our KPL-387 program were $47.3 million, $11.2 million and $2.5 million for the years ended December 31, 2025, 2024 and 2023, respectively.
Selling, General and Administrative Expenses Selling, general and administrative expenses consist primarily of salaries and benefits, including share based compensation expense for personnel in selling, marketing, medical, executive, business development, finance, human resources, legal and support personnel functions. Selling, general and administrative expenses also include external commercialization, marketing, and professional fees for legal, patent, and accounting services.
Selling, General and Administrative Expenses Selling, general and administrative expenses consist primarily of salaries and benefits, including share based compensation expense for personnel in selling, marketing, medical, executive, business development, finance, human 100 Table of Contents resources, legal and support personnel functions.
In the fourth quarter of 2024, Kiniksa UK contributed all of its rights, title and interest in, among other things, certain contracts, intellectual property rights, product filings and approvals and other information, plans and materials owned or controlled by Kiniksa UK insofar as they related exclusively or primarily to vixarelimab to Kiniksa Switzerland.
In connection with each of the foregoing transfers and /or allocations, we recognized a step-up in basis and did not incur any material tax liabilities. ​ In the fourth quarter of 2024, Kiniksa UK contributed all of its rights, title and interest in, among other things, certain contracts, intellectual property rights, product filings and approvals and other information, plans and materials owned or controlled by Kiniksa UK insofar as they related exclusively or primarily to vixarelimab to Kiniksa Switzerland.
Generally, our performance obligations are transferred to customers at a point in time, typically upon receipt of the product by the customer. 114 Table of Contents ASC 606 requires entities to record a contract asset when a performance obligation has been satisfied or partially satisfied, but the amount of consideration has not yet been received because the receipt of the consideration is conditioned on something other than the passage of time.
ASC 606 requires entities to record a contract asset when a performance obligation has been satisfied or partially satisfied, but the amount of consideration has not yet been received because the receipt of the consideration is conditioned on something other than the passage of time.
In the first quarter of 2024, Kiniksa Bermuda transferred to Kiniksa Switzerland all rights, title and interest in, among other things, certain contracts, intellectual property rights, product filings and approvals and other information, plans and materials owned insofar as they related exclusively or primarily to abiprubart, mavrilimumab, KPL-387, KPL-1161 and other preclinical assets, with such exceptions as necessary to allow the completion of Cohort 4 of our Phase 2 clinical trial of abiprubart in rheumatoid arthritis (“RA”).
In the first quarter of 2024, Kiniksa Bermuda transferred to Kiniksa Pharmaceuticals, GmbH (“Kiniksa Switzerland”) all rights, title and interest in, among other things, certain contracts, intellectual property rights, product filings and approvals and other information, plans and materials owned insofar as they related exclusively or primarily to abiprubart, mavrilimumab, KPL-387, KPL-1161 and other preclinical assets.
Cash Flows The following table summarizes our cash flows for each of the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, ​ 2024 2023 2022 ​ ​ (in thousands) Net cash provided by operating activities ​ $ 25,689 ​ $ 13,301 ​ $ 5,807 Net cash provided by (used in) investing activities ​ 37,672 ​ (29,557) ​ (8,078) Net cash provided by financing activities ​ 12,266 ​ 1,495 ​ 2,516 Net increase (decrease) in cash and cash equivalents ​ $ 75,627 ​ $ (14,761) ​ $ 245 Operating Activities Net cash provided by operations was $25.7 million for the year ended December 31, 2024, compared to $13.3 million for the year ended December 31, 2023.
As of December 31, 2025, we had cash, cash equivalents and short-term investments of $414.1 million. ​ 105 Table of Contents Cash Flows The following table summarizes our cash flows for each of the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, ​ ​ ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 ​ ​ (in thousands) Net cash provided by operating activities ​ $ 137,985 ​ $ 25,689 ​ $ 13,301 Net cash provided by (used in) investing activities ​ (188,993) ​ 37,672 ​ (29,557) Net cash provided by financing activities ​ 33,023 ​ 12,266 ​ 1,495 Net increase (decrease) in cash and cash equivalents ​ $ (17,985) ​ $ 75,627 ​ $ (14,761) Operating Activities Net cash provided by operations was $138.0 million for the year ended December 31, 2025, compared to $25.7 million for the year ended December 31, 2024.
Personnel-related costs for the years ended December 31, 2024, 2023 and 2022 included share-based compensation of $22.9 million, $19.8 million and $17.7 million, respectively. ​ 110 Table of Contents Other Income Other income was $9.5 million for the year ended December 31, 2024, compared to $8.5 million for the year ended December 31, 2023.
Personnel-related costs for the years ended December 31, 2025, 2024 and 2023 included share-based compensation of $28.2 million, $22.9 million and $19.8 million, respectively. ​ Other Income Other income was $11.6 million, $9.5 million and $8.5 million for the years ended December 31, 2025, 2024 and 2023.
In the fourth quarter of 111 Table of Contents 2024, following Huadong’s achievement of a regulatory milestone under the ARCALYST Huadong Collaboration Agreement, Huadong became obligated to pay a $20.0 million milestone, which was received in the first quarter of 2025. ​ These agreements impact our short-term and long-term liquidity and capital needs.
In 2025, we received a $20.0 million milestone payment related to Huadong’s achievement of a regulatory milestone under the ARCALYST Huadong Collaboration Agreement, $10.0 million of which was paid to Regeneron in 2025 as part of the Regeneron Agreement. ​ These agreements impact our short-term and long-term liquidity and capital needs.
During the year ended December 31, 2024, expenses primarily related to our Phase 1 study in normal healthy volunteers and manufacturing of clinical supply. During the year ended December 31, 2023, expenses primarily related to manufacturing of clinical supply. Direct costs for our KPL-1161 program were $0.6 million for the year ended December 31, 2024.
During the year ended December 31, 2023, expenses primarily related to manufacturing of clinical supply. Direct costs for our KPL-1161 program were $4.2 million and $0.6 million for the years ended December 31, 2025 and 2024, respectively. We did not incur any expenses related to KPL-1161 for the year ended December 31, 2023.
In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or the amount of prepaid expenses accordingly.
If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or the amount of prepaid expenses accordingly.
The increase of $32.5 million in 2023 from 2022 relates primarily to an increase in revenue from the sales of ARCALYST and improved profitability under the Regeneron agreement. ​ Research and Development Expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024/2023 ​ 2023/2022 ​ ​ Years Ended ​ Comparison ​ Comparison ​ December 31, ​ Increase/(Decrease) ​ Increase/(Decrease) ​ ​ 2024 2023 2022 $ % $ % ​ ​ (in thousands) ​ (in thousands, except percentages) Direct research and development expenses by program: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ARCALYST ​ $ 1,080 ​ $ 2,628 ​ $ 853 ​ $ (1,548) ​ (59)% ​ $ 1,775 ​ 208% KPL-387 ​ ​ 11,221 ​ ​ 2,537 ​ ​ 2 ​ ​ 8,684 ​ 342% ​ ​ 2,535 ​ 126750% KPL-1161 ​ ​ 581 ​ ​ — ​ ​ — ​ ​ 581 ​ 100% ​ ​ — ​ 0% Abiprubart ​ 59,459 ​ ​ 28,388 ​ ​ 11,563 ​ ​ 31,071 ​ 109% ​ ​ 16,825 ​ 146% Vixarelimab ​ 1,530 ​ ​ 7,717 ​ ​ 12,809 ​ ​ (6,187) ​ (80)% ​ ​ (5,092) ​ (40)% Mavrilimumab ​ 647 ​ ​ 768 ​ ​ 6,379 ​ ​ (121) ​ (16)% ​ ​ (5,611) ​ (88)% Unallocated research and development expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personnel related (including share-based compensation) ​ 24,302 ​ ​ 22,462 ​ ​ 22,548 ​ ​ 1,840 ​ 8% ​ ​ (86) ​ 0% Other ​ 12,803 ​ ​ 11,597 ​ ​ 11,336 ​ ​ 1,206 ​ 10% ​ ​ 261 ​ 2% Total research and development expenses ​ $ 111,623 ​ $ 76,097 ​ $ 65,490 ​ $ 35,526 ​ 47% ​ $ 10,607 ​ 16% ​ Research and development expenses were $111.6 million for the year ended December 31, 2024, compared to $76.1 million for the year ended December 31, 2023, or an increase of $35.5 million.
The increase of $71.8 million in 2024 from 2023 relates primarily to an increase in revenue from the sales of ARCALYST driving higher profits under the Regeneron agreement and to a $10.0 million payment due to Regeneron related to a regulatory milestone achieved under the ARCALYST Huadong Collaboration Agreement. ​ Research and Development Expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2025/2024 ​ 2024/2023 ​ ​ Years Ended ​ Comparison ​ Comparison ​ ​ ​ ​ December 31, ​ Increase/(Decrease) ​ Increase/(Decrease) ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 ​ ​ ​ $ % ​ ​ ​ $ % ​ ​ (in thousands) ​ (in thousands, except percentages) Direct research and development expenses by program: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ARCALYST ​ $ 1,040 ​ $ 1,080 ​ $ 2,628 ​ $ (40) ​ (4)% ​ $ (1,548) ​ (59)% KPL-387 ​ ​ 47,265 ​ ​ 11,221 ​ ​ 2,537 ​ ​ 36,044 ​ 321% ​ ​ 8,684 ​ 342% KPL-1161 ​ ​ 4,198 ​ ​ 581 ​ ​ — ​ ​ 3,617 ​ 623% ​ ​ 581 ​ 0% Abiprubart ​ 6,122 ​ ​ 59,459 ​ ​ 28,388 ​ ​ (53,337) ​ (90)% ​ ​ 31,071 ​ 109% Vixarelimab ​ 44 ​ ​ 1,530 ​ ​ 7,717 ​ ​ (1,486) ​ (97)% ​ ​ (6,187) ​ (80)% Unallocated research and development expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Personnel related (including share-based compensation) ​ 23,943 ​ ​ 24,302 ​ ​ 22,462 ​ ​ (359) ​ (1)% ​ ​ 1,840 ​ 8% Other ​ 14,241 ​ ​ 13,450 ​ ​ 12,365 ​ ​ 791 ​ 6% ​ ​ 1,085 ​ 9% Total research and development expenses ​ $ 96,853 ​ $ 111,623 ​ $ 76,097 ​ $ (14,770) ​ (13)% ​ $ 35,526 ​ 47% ​ Research and development expenses were $96.9 million for the year ended December 31, 2025, compared to $111.6 million for the year ended December 31, 2024, or a decrease of $14.8 million.
Unallocated research and development expenses were $37.7 million, $34.1 million and $33.9 million for the years ended December 31, 2024, 2023 and 2022, respectively. The increase of $3.6 million in unallocated research and development expenses in 2024 from 2023 was primarily due to an increase in personnel to support our clinical trials.
The increase of $0.8 million in unallocated research and development expenses in 2025 from 2024 was primarily due to an increase in pre-clinical development. The increase of $3.0 million in unallocated research and development expenses in 2024 from 2023 was primarily due to an increase in personnel to support our clinical trials.
Following the Redomiciliation, our income is subject to the enacted United Kingdom statutory corporate tax rate and net operating losses incurred have an indefinite carryforward. Our wholly owned United States subsidiaries, Kiniksa US, and Primatope Therapeutics, Inc. are subject to federal and state income taxes in the United States.
Following the Redomiciliation, our income is subject to the enacted United Kingdom statutory corporate tax rate and net operating losses incurred have an indefinite carryforward. Our wholly owned subsidiaries (including any foreign branch offices thereof) are subject to taxation in their respective countries. ​ In the third quarter of 2022, Kiniksa Pharmaceuticals, Ltd.
We recognize as revenues the amount of the transaction price that is allocated to each respective performance obligation when the performance obligation is satisfied or as it is satisfied.
We recognize as revenues the amount of the transaction price that is allocated to each respective performance obligation when the performance obligation is satisfied or as it is satisfied. Generally, our performance obligations are transferred to customers at a point in time, typically upon receipt of the product by the customer.
During the year ended December 31, 2024 we received $10.0 million, following Genentech’s achievement of a development milestone in the fourth quarter of 2023 related to a second indication under the Genentech License Agreement and $5.0 million following Genentech’s achievement of a development milestone related to a third indication under the Genentech License Agreement.
In 2024, we received $15.0 million in development milestone payments from Genentech related to a second and third indication under the Genentech License Agreement.
ARCALYST is sold through a third party logistics provider that distributes primarily through a select network of specialty pharmacies (collectively, “customers”), which deliver the medication to patients by mail. ​ Net revenue from product sales is recognized at the transaction price when the customer obtains control of our product, which occurs at a point in time, typically upon shipment of the product from the third party logistics provider. ​ Our net revenues represent total revenues adjusted for discounts and allowances, including estimated cash discounts, chargebacks, rebates, returns, copay assistance, and specialty pharmacy and distributor fees.
ASC 606 also requires an entity to present a revenue contract as a contract liability in instances when a customer pays consideration, or an entity has a right to an amount of consideration that is unconditional (e.g. receivable), before the entity transfers a good or service to the customer. 107 Table of Contents Product Revenue, Net Net revenue from product sales is recognized at the transaction price when the specialty pharmacy or specialty distributors obtains control of our products, which occurs at a point in time, typically upon shipment of the product from the third party logistics provider. ​ Our net revenues represent total revenues adjusted for discounts and allowances, including estimated cash discounts, chargebacks, rebates, returns, copay assistance, and specialty pharmacy and distributor fees.
The increase of $31.5 million in 2023 from 2022 was primarily due to an increase of $18.9 million in personnel-related costs and an increase in sales and marketing of $6.0 million largely attributable to the expansion of our salesforce.
The increase of $28.3 million in 2025 from 2024 was primarily due to an increase of $23.1 million in personnel-related costs largely attributable to an increase in headcount and an increase in sales and marketing expenses of $5.5 million .
During the years ended December 31, 2023 and 2022, expenses incurred related primarily to our ongoing Phase 2b clinical trial of vixarelimab in prurigo nodularis. The decrease of $5.1 million in 2023 from 2022 was primarily related to a decrease in active participants in our ongoing Phase 2b clinical trial of vixarelimab in prurigo nodularis.
During the year ended December 31, 2023 expenses incurred primarily related to our ongoing Phase 2b clinical trial of vixarelimab in prurigo nodularis. Unallocated research and development expenses were $38.2 million, $37.8 million and $34.8 million for the years ended December 31, 2025, 2024 and 2023, respectively.
We believe that our existing cash, cash equivalents and short-term investments will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months.
For more information on our near and long-term funding requirements, see “ Risk Factors – General Risk Factors – We have a history of operating losses and may require substantial additional financing in the future. ” 106 Table of Contents We believe that our existing cash, cash equivalents and short-term investments will enable us to fund our operating expenses and capital expenditure requirements for at least the next 12 months.
Non-refundable prepayments determined to be used within one year for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses. 115 Table of Contents Non-refundable prepayments or minimum balance requirements associated to clinical trials determined to not be used within one year are classified as other long-term assets.
Payments under some of these contracts depend on factors such as the successful enrollment of participants and the completion of clinical trial milestones. Non-refundable prepayments determined to be used within one year for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses.
In the third quarter of 2022, Kiniksa Bermuda transferred exclusive worldwide rights to develop and commercialize vixarelimab to Kiniksa UK.
(“Kiniksa Bermuda”) transferred exclusive worldwide rights to develop and commercialize vixarelimab to Kiniksa Pharmaceuticals (UK), Ltd. (“Kiniksa UK”).
In February 2025, we announced our plan to initiate a Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis in mid-2025. We expect data from the Phase 2 portion of the trial in the second half of 2026. KPL-1161 is an independently developed, pre-clinical, Fc-modified immunoglobulin G2 monoclonal antibody that binds IL-1R1, inhibiting IL-1α- and IL-1β-mediated signaling.
KPL-1161 is an independently developed, pre-clinical, Fc-modified immunoglobulin G2 monoclonal antibody that binds IL-1R1, inhibiting IL-1α- and IL-1β-mediated signaling. KPL-1161 is a modified version of KPL-387 designed to have an increased drug half-life that we believe could support quarterly subcutaneous dosing.
The net benefit in the net deferred tax asset was offset by current income tax expense of $3.1 million primarily associated with income earned in the UK and the United States. ​ For the year ended December 31, 2022, we recorded an income tax benefit of $172.3 million relating to a non-cash deferred tax benefit of $185.5 million primarily associated with the release of the valuation allowance on our UK deferred tax assets.
The net benefit in the net deferred tax asset was offset by current income tax expense of $3.1 million primarily associated with income earned in the UK and the United States. ​ 104 Table of Contents Liquidity and Capital Resources As of December 31, 2025, our principal source of liquidity was cash, cash equivalents and short-term investments, which totaled $414.1 million.
During the years ended December 31, 2024 and 2023, expenses related primarily to intellectual property maintenance. During the year ended December 31, 2022, expenses related primarily to the wind-down activities of the Phase 3 portion of our clinical trial of mavrilimumab in COVID-19 related ARDS.
During the year ended December 31, 2025, expenses primarily related to the start-up of our Phase 2/3 clinical trial in recurrent pericarditis and manufacturing of clinical supply. During the year ended December 31, 2024, expenses primarily related to our Phase 1 study in normal healthy volunteers and manufacturing of clinical supply.
In 2023, Regeneron initiated a technology transfer of the manufacturing process for ARCALYST drug substance, and we are working to qualify Samsung as our replacement CDMO. KPL-387 is an investigational, fully human immunoglobulin G2 monoclonal antibody that binds IL1-R1, inhibiting IL-1α and IL-1β mediated signaling.
In 2023, Regeneron initiated a technology transfer of the manufacturing process for ARCALYST drug substance, and we are working to qualify Samsung as our replacement CDMO. In December 2024, we initiated a collaborative study agreement with The Mayo Clinic (together with Johns Hopkins University) to investigate the effects of ARCALYST in the treatment of cardiac sarcoidosis.
Such commitment, which includes the purchase of raw materials and related service fees, obligates us to minimum payments of $151.0 million, $15.2 million of which are due within one year.
In connection with our ongoing technology transfer of ARCALYST drug substance manufacturing, we have entered into a Master Services Agreement and a Product Specific Agreement with Samsung. Our commitments under such agreements, which includes the purchase of raw materials and related service fees, obligates us to minimum payments of $147.7 million, $18.9 million of which are due within one year.
As of the date of this report, we expect to pay between $14.0 million and $17.0 million in termination cost. ​ Under various agreements with third parties, we are entitled to receive upfront payments, milestone payments, and royalties, each based upon specified milestones.
We have long-term incentive plans for our employees that may result in cash award payments of $23.1 million, based upon the achievement of certain regulatory milestones, none of which are expected to be achieved in the next year. ​ Under various agreements with third parties, we are entitled to receive upfront payments, milestone payments, and royalties, each based upon specified milestones.
See “Management’s Discussion and Analysis of Financial Condition and Results Of Operations — Liquidity and Capital Resources .” Components of Our Results of Operations Product revenue, net We have been generating product revenue from sales of ARCALYST since April 2021.
In February 2025, we announced our plans to discontinue development of abiprubart in the indication and to explore strategic alternatives for the asset. 97 Table of Contents Components of Our Results of Operations Product revenue, net We have been generating product revenue from sales of ARCALYST since April 2021.
KPL-387 is an independently developed asset that we believe has the potential to further advance recurrent pericarditis treatment options for patients by providing the added convenience of monthly subcutaneous dosing with a liquid formulation. In June 2024, we initiated a Phase 1 clinical trial of KPL-387 in normal healthy volunteers.
KPL-387 is an investigational, fully human immunoglobulin G2 monoclonal antibody that binds IL1-R1, inhibiting IL-1α and IL-1β mediated signaling. KPL-387 is an independently developed asset that we believe may expand the recurrent pericarditis market and provide an additional treatment option for patients, with the potential to add the convenience of monthly subcutaneous self-administration with a liquid formulation.
We previously announced a Phase 2b clinical trial of abiprubart in Sjögren’s Disease. In February 2025, we announced our plans to discontinue development of abiprubart in the indication and explore strategic alternatives for the asset. Mavrilimumab is an investigational monoclonal antibody inhibitor targeting GM-CSFRα. In 2017, we licensed exclusive worldwide rights in all indications to mavrilimumab from MedImmune.
We hold an exclusive worldwide license to abiprubart from BIDMC. We previously announced a Phase 2b clinical trial of abiprubart in Sjögren’s Disease.
The increase of $71.8 million in 2024 from 2023 relates primarily to increased revenue from sales of ARCALYST driving higher profits under the Regeneron agreement and to a $10.0 million payment due to Regeneron related to a regulatory milestone achieved under the ARCALYST Huadong Collaboration Agreement.
The increase of $101.2 million in 2025 from 2024 relates primarily to increased revenue from sales of ARCALYST.
KPL-1161 is a modified version of KPL-387 designed to have an increased drug half-life that we believe could support quarterly subcutaneous dosing. Abiprubart is an investigational monoclonal antibody inhibitor of CD40-CD154 costimulatory interaction, which we believe to be an attractive approach to address multiple autoimmune disease pathologies. We hold an exclusive worldwide license to abiprubart from BIDMC.
We are currently conducting preclinical activities with respect to this asset, with an expectation to initiate a Phase 1 first-in-human clinical trial by the end of 2026. Abiprubart is an investigational monoclonal antibody inhibitor of CD40-CD154 costimulatory interaction, which we believe to be an attractive approach to address multiple autoimmune disease pathologies.
Removed
In February 2025, we announced our termination of our license agreement from MedImmune for convenience, effective in May 2025.
Added
In July 2025, we announced that the Phase 2 dose-focusing portion of the Phase 2/3 clinical trial of KPL-387 in recurrent pericarditis had begun recruiting. We expect data from the Phase 2 portion of the trial in the second half of 2026 and plan to use the totality of the data to determine further development strategy.
Removed
In addition, in February 2025, we provided written notice to Huadong that Huadong has not conducted material development activity with respect to mavrilimumab in the People’s Republic of China for a continuous period in excess of six months as required under the mavrilimumab Huadong Collaboration Agreement.
Added
In September 2025, we announced plans to conduct a supplemental Phase 2 transition to KPL-387 monotherapy dosing and administration study to evaluate the efficacy and safety of dosing regimens used to transition patients from standard therapies to KPL-387 monotherapy. In October 2025, the FDA granted Orphan Drug Designation to KPL-387 for the treatment of pericarditis.
Removed
Unless Huadong conducts material development activity within 60 days of the notice, the mavrilimumab Huadong Collaboration Agreement will terminate in April 2025. 103 Table of Contents Our ability to generate product revenue sufficient to sustain our organization will depend heavily on a number of factors, including the continued commercialization of ARCALYST, the development and eventual commercialization of one or more of our current or future product candidates, if approved, and the management of our costs consistent with our current operating plan.
Added
ARCALYST is sold through a third party logistics provider that distributes primarily through a select network of specialty pharmacies (collectively, “customers”), which deliver the medication to patients by mail.

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Other KNSA 10-K year-over-year comparisons