Biggest changeResults of Operations The consolidated financial data for the years ended December 31, 2022, 2021 and 2020 is presented in the following table and the results of these periods are used in the discussion thereafter. 57 Year Ended December 31, Increase/(Decrease) 2022 vs. 2021 Increase/(Decrease) 2021 vs. 2020 2022 2021 2020 $ % $ % Revenue from collaborative arrangements and other contracts, including affiliated entity $ 10,262,268 $ 1,774,758 $ 7,411,220 $ 8,487,510 478 % $ (5,636,462) (76) % Operating expenses: Research and development 187,650,503 249,240,324 94,245,436 (61,589,821) (25) 154,994,888 164 General and administrative 90,185,285 53,752,353 37,247,828 36,432,932 68 16,504,525 44 Total operating expenses 277,835,788 302,992,677 131,493,264 (25,156,889) (8) 171,499,413 130 Loss from operations (267,573,520) (301,217,919) (124,082,044) 33,644,399 11 (177,135,875) (143) Interest income 4,782,030 3,363,080 3,311,846 1,418,950 42 51,234 2 Interest expense (1,253,952) (1,936,447) (8,702,450) 682,495 (35) 6,766,003 (78) Change in fair value of derivative liability — — (75,670,977) — * 75,670,977 * (Loss) gain on investment in affiliated entity (1,899,654) (553,570) 36,556,658 (1,346,084) * (37,110,228) * Net unrealized (loss) gain on available-for-sale equity securities (7,846,172) (3,222,838) 1,695,497 (4,623,334) * (4,918,335) * Other (expense) income, net (3,861,584) 343,371 (704,896) (4,204,955) * 1,048,267 * Gain on deconsolidation of Geneos — — 4,121,075 — * (4,121,075) * Loss on extinguishment of convertible bonds — — (8,177,043) — * 8,177,043 * Gain on extinguishment of convertible senior notes — — 8,762,030 — * (8,762,030) * Net loss before share in net loss of Geneos (277,652,852) (303,224,323) (162,890,304) 25,571,471 8 (140,334,019) (86) Share in net loss of Geneos (2,165,213) (434,387) (4,584,610) (1,730,826) * 4,150,223 * Net loss (279,818,065) (303,658,710) (167,474,914) 23,840,645 (8) (136,183,796) 81 Net loss attributable to non-controlling interest — — 1,063,757 — * (1,063,757) (100) Net loss attributed to Inovio Pharmaceuticals, Inc. $ (279,818,065) $ (303,658,710) $ (166,411,157) $ 23,840,645 8 % $ (137,247,553) (82) % *Not meaningful Comparison of Years Ended December 31, 2022 and 2021 Revenue Revenue was primarily derived under collaborative arrangements and contracts, including arrangements with affiliated entities, for the years ended December 31, 2022 and 2021 .
Biggest changeYear Ended December 31, Increase/(Decrease) 2023 vs. 2022 Increase/(Decrease) 2022 vs. 2021 2023 2022 2021 $ % $ % Revenue from collaborative arrangements and other contracts, including affiliated entity $ 832,010 $ 10,262,268 $ 1,774,758 $ (9,430,258) (92) % $ 8,487,510 478 % Operating expenses: Research and development 86,676,563 187,650,503 249,240,324 (100,973,940) (54) (61,589,821) (25) General and administrative 47,582,104 90,185,285 53,752,353 (42,603,181) (47) 36,432,932 68 Impairment of Goodwill 10,513,371 — — 10,513,371 100 — — Total operating expenses 144,772,038 277,835,788 302,992,677 (133,063,750) (48) (25,156,889) (8) Loss from operations (143,940,028) (267,573,520) (301,217,919) 123,633,492 46 33,644,399 11 Interest income 8,133,290 4,782,030 3,363,080 3,351,260 70 1,418,950 42 Interest expense (1,222,789) (1,253,952) (1,936,447) 31,163 (2) 682,495 (35) Gain (loss) on investment in affiliated entity 773,145 (1,899,654) (553,570) 2,672,799 * (1,346,084) * Net unrealized gain (loss) on available-for-sale equity securities 5,850,626 (7,846,172) (3,222,838) 13,696,798 * (4,623,334) * Other (expense) income, net (4,711,596) (3,861,584) 343,371 (850,012) * (4,204,955) * Net loss before share in net loss of Geneos (135,117,352) (277,652,852) (303,224,323) 142,535,500 51 25,571,471 8 Share in net loss of Geneos — (2,165,213) (434,387) 2,165,213 * (1,730,826) * Net loss $ (135,117,352) $ (279,818,065) $ (303,658,710) $ 144,700,713 (52) % $ 23,840,645 (8) % *Not meaningful Comparison of Years Ended December 31, 2023 and 2022 Revenue Revenue was primarily derived under collaborative arrangements and other contracts, including arrangements with affiliated entities, for the years ended December 31, 2023 and 2022 .
Readers are also urged to carefully review and consider the various disclosures made by us which attempt to advise interested parties of the factors which affect our business, including without limitation the disclosures made in Item 1A of Part I of this Annual Report under the caption “Risk Factors.” Risk factors that could cause actual results to differ from those contained in the forward-looking statements include but are not limited to: our history of losses; our lack of products that have received regulatory approval; uncertainties inherent in clinical trials and product development programs, including but not limited to the fact that pre-clinical and clinical results may not be indicative of results achievable in other trials or for other indications, that the studies or trials may not be successful or achieve desired results, that preclinical studies and clinical trials may not commence, have sufficient enrollment or be completed in the time periods anticipated, that results from one study may not necessarily be reflected or supported by the results of other similar studies, that results from an animal study may not be indicative of results achievable in human studies, that clinical testing is expensive and can take many years to complete, that the outcome of any clinical trial is uncertain and failure can occur at any time during the clinical trial process, and that our proprietary smart device technology and DNA medicine candidates may fail to show the desired safety and efficacy traits in clinical trials; the availability of funding; the ability to manufacture our DNA medicine candidates; the availability or potential availability of alternative therapies or treatments for the conditions targeted by us or our collaborators, including alternatives that may be more efficacious or cost-effective than any therapy or treatment that we and our collaborators hope to develop; our ability to receive development, regulatory and commercialization event-based payments under our collaborative agreements; whether our proprietary rights are enforceable or defensible or infringe or allegedly infringe on rights of others or can withstand claims of invalidity; and the impact of government healthcare laws and proposals.
Readers are also urged to carefully review and consider the various disclosures made by us which attempt to advise interested parties of the factors which affect our business, including without limitation the disclosures made in Item 1A of Part I of this Annual Report under the caption “Risk Factors.” Risk factors that could cause actual results to differ from those contained in the forward-looking statements include but are not limited to: our history of losses; our lack of products that have received regulatory approval; uncertainties inherent in clinical trials and product development programs, including but not limited to the fact that pre-clinical and clinical results may not be indicative of results achievable in other trials or for other indications, that the studies or trials may not be successful or achieve desired results, that preclinical studies and clinical trials may not commence, have sufficient enrollment or be completed in the time periods anticipated, that results from one study may not necessarily be reflected or supported by the results of other similar studies, that results from an animal study may not be indicative of results achievable in human studies, that clinical testing is expensive and can take many years to complete, that the outcome of any clinical trial is uncertain and failure can occur at any time during the clinical trial process, and that our proprietary device technology and DNA medicine candidates may fail to show the desired safety and efficacy traits in clinical trials; the availability of funding; the ability to manufacture our DNA medicine candidates; the availability or potential availability of alternative therapies or treatments for the conditions targeted by us or our collaborators, including alternatives that may be more efficacious or cost-effective than any therapy or treatment that we and our collaborators hope to develop; our ability to receive development, regulatory and commercialization event-based payments under our collaborative agreements; whether our proprietary rights are enforceable or defensible or infringe or allegedly infringe on rights of others or can withstand claims of invalidity; and the impact of government healthcare laws and proposals.
We utilize a labor reporting system to record employee compensation on a project-by-project basis. Unallocated research and development expenses include engineering and device-related expenses that are not allocable to a specific project, as well as stock-based compensation, other employee-related expenses that are not related to a specific project, and facilities and depreciation expenses.
We utilize a labor reporting system to record employee 59 compensation on a project-by-project basis. Unallocated research and development expenses include engineering and device-related expenses that are not allocable to a specific project, as well as stock-based compensation, other employee-related expenses that are not related to a specific project, and facilities and depreciation expenses.
Research and Development Expenses - Clinical Trial Accruals Our activities have largely consisted of research and development efforts related to developing proprietary smart device technologies, DNA medicine candidates and dMABs. For clinical trial expenses, judgments used in estimating accruals rely on estimates of total costs incurred based on participant enrollment, completion of studies and other events.
Research and Development Expenses - Clinical Trial Accruals 58 Our activities have largely consisted of research and development efforts related to developing proprietary device technologies, DNA medicine candidates and dMABs. For clinical trial expenses, judgments used in estimating accruals rely on estimates of total costs incurred based on participant enrollment, completion of studies and other events.
Comparison of Years Ended December 31, 2021 and 2020 For a comparison of the years ended December 31, 2021 and 2020, you may refer to Part II, Item 7 of our Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on March 1, 2022.
Comparison of Years Ended December 31, 2022 and 2021 For a comparison of the years ended December 31, 2022 and 2021, you may refer to Part II, Item 7 of our Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on March 1, 2023.
Our partners and collaborators include Advaccine Biopharmaceuticals Suzhou Co, ApolloBio Corporation, AstraZeneca, The Bill & Melinda Gates Foundation (Gates), Coalition for Epidemic Preparedness Innovations (CEPI), Defense Advanced Research Projects Agency (DARPA), The U.S.
Our partners and collaborators include Advaccine Biopharmaceuticals Suzhou Co, ApolloBio Corporation, AstraZeneca, The Bill & Melinda Gates Foundation (Gates), Coalition for Epidemic Preparedness Innovations (CEPI), Coherus Biosciences, Defense Advanced Research Projects Agency (DARPA), The U.S.
During the year ended December 31, 2022, stock options to purchase 118,694 shares of common stock were exercised for aggregate net proceeds of $283,000, which proceeds were offset by tax payments made related to net share settlement of RSU awards of $1.4 million.
During the year ended December 31, 2022, stock options to purchase 9,891 shares of common stock were exercised for aggregate net proceeds of $283,000, which proceeds were offset by tax payments made related to net share settlement of RSU awards of $1.4 million.
Issuances of Common Stock On November 9, 2021, we entered into an ATM Equity Offering SM Sales Agreement (the “Sales Agreement”) with outside sales agents (collectively, the “Sales Agents”) under which we may offer and sell, from time to time at our sole discretion, shares of our common stock with aggregate gross proceeds of up to $300.0 million, through the Sales Agents.
Issuances of Common Stock On November 9, 2021, we entered into an ATM Equity Offering SM Sales Agreement, or the Sales Agreement, with outside sale s agents, or collectively, the Sales Agents, under which we may offer and sell, from time to time at our sole discretion, shares of our common stock with aggregate gross proceeds of up to $300.0 million, through the Sales Agents.
Liquidity and Capital Resources Historically, our primary uses of cash have been to finance research and development activities including clinical trial activities for the advancement of DNA medicine candidates. Since inception, we have satisfied our cash requirements principally from proceeds from the sale of equity securities, indebtedness and grants and government contracts.
Liquidity and Capital Resources Our primary uses of cash are to finance research and development activities, including clinical trial activities for the advancement of our DNA medicine candidates. We have satisfied our cash requirements principally from proceeds from the sale of equity securities, indebtedness and grants and government contracts.
We may not be successful in our research and development efforts, and we may never generate sufficient product revenue to be profitable. As of December 31, 2022, we had an accumulated deficit of $1.5 billion.
We may not be successful in our research and development efforts, and we may never generate sufficient product revenue to be profitable. As of December 31, 2023, we had an accumulated deficit of $1.6 billion.
During the year ended December 31, 2021, stock options to purchase 1,310,263 shares of common stock were exercised for aggregate net proceeds of $6.7 million, which proceeds were offset by tax payments made related to net share settlement of RSU awards of $4.6 million.
During the year ended December 31, 2021, stock options to purchase 109,188 shares of common stock were exercised for aggregate net proceeds of $6.7 million, which proceeds were offset by tax payments made related to net share settlement of RSU awards of $4.6 million.
Our current cash resources, including amounts that we may be able to obtain through sales of common stock under our “at the market” equity facility, will not be sufficient to complete the clinical development of any of our product candidates, and we anticipate that additional financing will be required in order to commercialize and generate revenues from the sale of any product candidates that receive regulatory approval.
Our current cash resources, including amounts that we may be able to obtain through sales of common stock under the S ales Agreement, will not be sufficient to complete the clinical development of any of our product candidates, and we anticipate that additional financing will be required in order to complete the development of and to commercialize and generate revenues from the sale of any product candidates that receive regulatory approval.
Cash Flows Operating Activities Net cash used in operating activities was $216.2 million and $215.7 million for the years ended December 31, 2022 and 2021, respectively. The variance was primarily due to the timing and changes in working capital balances, offset by decreased operating expenses.
Cash Flows Operating Activities Net cash used in operating activities was $124.4 million and $216.2 million for the years ended December 31, 2023 and 2022, respectively. The variance was primarily due to the timing and changes in working capital balances, offset by decreased operating expenses.
As of December 31, 2022, we expect to receive aggregate future minimum lease payments totaling $434,000 (non-discounted) over the duration of the sublease agreements, which expected payments are not included in the table above. (3) Remaining purchase obligations from supply agreements with contract manufacturers.
As of December 31, 2023, we expect to receive aggregate future minimum lease payments totaling $1.3 million (non-discounted) over the duration of the sublease agreements, which expected payments are not included in the table above. (3) Purchase obligations from supply agreements with contract manufacturers.
Investing Activities 60 Net cash provided by (used in) investing activities was $109.6 million and $(175.3) million for the years ended December 31, 2022 and 2021, respectively. The variance was primarily the result of timing differences in short-term investment purchases, sales and maturities.
Investing Activities Net cash provided by investing activities was $87.4 million and $109.6 million for the years ended December 31, 2023 and 2022, respectively. The variance was primarily the result of timing differences in short-term investment purchases, sales and maturities.
Contractual Obligations 61 As of December 31, 2022, future minimum payments due under our contractual obligations are set forth in the table below. We expect to be able to satisfy these obligations, both in the short-term and in the longer-term, with cash on hand and proceeds from sales of our common stock under the Sales Agreement.
Contractual Obligations As of December 31, 2023, future minimum payments due under our contractual obligations are set forth in the table below. We expect to be able to satisfy these obligations, both in the short-term and in the longer-term, with cash on hand.
Loss on Investment in Affiliated Entity The loss on investment in affiliated entity resulted from the declines in the fair market value of our investment in PLS of $1.9 million and $554,000 for the years ended December 31, 2022 and 2021, respectively.
Gain (Loss) on Investment in Affiliated Entity The gain (loss) on investment in affiliated entity resulted from the change in the fair market value of our investment in PLS of $773,000 and $(1.9) million for the years ended December 31, 2023 and 2022, respectively.
Our DNA medicine candidates will require significant additional research and development efforts, including extensive preclinical and clinical testing. All DNA medicine candidates that we advance to clinical testing will require regulatory approval prior to commercial use, and will require significant costs for commercialization.
We earn revenue from license fees and milestone revenue and collaborative research and development agreements and contracts. Our DNA medicine candidates will require significant additional research and development efforts, including extensive preclinical and clinical testing. All DNA medicine candidates that we advance to clinical testing will require regulatory approval prior to commercial use, and will require significant costs for commercialization.
We also had U.S. federal and state research and development tax credits of $40.5 million and $4.7 million, respectively, net of the federal research and development credits that will expire due to IRC Section 383 limitations. The net operating losses and credits began to expire during 2022.
We also had U.S. federal and state research and development tax credits of $41.6 million and $6.1 million, respectively, net of the federal research and development credits that will expire due to IRC Section 383 limitations. The net operating losses and credits began to expire during 2023.
As of December 31, 2022, we had net operating loss carry forwards for U.S. federal, California and Pennsylvania income tax purposes of $920.6 million, $210.3 million and $89.6 million, respectively, net of the net operating losses that will expire due to IRC Section 382 limitations.
As of December 31, 2023, we had net operating loss carry forwards for U.S. federal, California and Pennsylvania income tax purposes of $1,013.3 million, $251.4 million and $102.6 million, respectively, net of the net operating losses that will expire due to IRC Section 382 61 limitations.
Net Unrealized Loss on Available-for-Sale Equity Securities The net unrealized loss on available-for-sale equity securities for the years ended December 31, 2022 and 2021 was $7.8 million and $3.2 million, respectively, which resulted from a change in the fair market value of the investments.
Net Unrealized Gain (Loss) on Available-for-Sale Equity Securities The net unrealized gain (loss) on available-for-sale equity securities for the years ended December 31, 2023 and 2022 was $5.9 million and $(7.8) million, respectively, which resulted from a change in the fair market value of the investments. Other (Expense) Income , net.
Total employee stock-based compensation cost for the 59 years ended December 31, 2022 and 2021 was $22.2 million and $25.0 million, of which $8.8 million and $13.4 million was included in research and development expenses and $13.4 million and $11.6 million was included in general and administrative expenses, respectively.
Total employee stock-based compensation cost for the years ended December 31, 2023 and 2022 was $10.4 million and $22.2 million, of which $4.5 million and $8.8 million was included in research and development expenses and $5.9 million and $13.4 million was included in general and administrative expenses, respectively.
Working Capital and Liquidity As of December 31, 2022, we had cash and short-term investments of $253.0 million and working capital of $218.4 million, as compared to $401.3 million and $382.7 million as of December 31, 2021, respectively.
Working Capital and Liquidity As of December 31, 2023, we had cash and short-term investments of $145.3 million and working capital of $110.5 million, as compared to $253.0 million and $218.4 million as of December 31, 2022, respectively.
We expect to continue to incur substantial operating losses in the future due to our commitment to our research and development programs, the funding of preclinical studies, clinical trials and regulatory activities and the costs of general and administrative activities. VGX-3100 Update REVEAL2 is our second Phase 3 trial with VGX-3100.
We expect to continue to incur substantial operating losses in the future due to our commitment to our research and development programs, the funding of preclinical studies, clinical trials and regulatory activities and the costs of general and administrative activities.
Funding Requirements As of December 31, 2022, we had an accumulated deficit of $1.5 billion and we expect to continue to operate at a loss for some time. The amount of the accumulated deficit will continue to increase, as it will be expensive to continue research and development efforts.
Funding Requirements 62 As of December 31, 2023, we had an accumulated deficit of $1.6 billion and we expect to continue to operate at a loss in the near term. The amount of our accumulated deficit will continue to increase, as it will be expensive to continue research and development efforts.
Utilization of net operating losses and tax credits are subject to a substantial annual limitation due to ownership change limitations provided by the Internal Revenue Code of 1986, as amended, or IRC.
Income Taxes Since inception, we have incurred operating losses and accordingly have not recorded a provision for U.S. income taxes for any of the periods presented. Utilization of net operating losses and tax credits are subject to a substantial annual limitation due to ownership change limitations provided by the Internal Revenue Code of 1986, as amended, or IRC.
Employee stock-based compensation cost is measured at the grant date, based on the fair value of the award, and is recognized as expense over the employee’s requisite service period.
For more information, see Note 8 – Goodwill and Intangible Assets to the consolidated financial statements included in this report. Stock-based compensation Employee stock-based compensation cost is measured at the grant date, based on the fair value of the award, and is recognized as expense over the employee’s requisite service period.
(2) We have entered into operating leases for our facilities, which expire from 2023 to 2029, and operating leases for office equipment, which expire in 2024.
See Note 9, Convertible Debt, to the consolidated financial statements in this report for additional information. (2) We have entered into operating leases for our facilities, which expire from 2024 to 2029, and operating leases for office equipment, which expire in 2024.
In the fourth quarter of 2019, we entered into two subleases for a portion of our Plymouth Meeting corporate headquarters facility with one period through March 31, 2025 and the other month-to-month after December 31, 2022.
We have four active subleases for portions of our Plymouth Meeting corporate headquarters facility with periods through March 31, 2025, two through December 31, 2026 and the other month-to-month.
Department of Defense (DoD), HIV Vaccines Trial Network, International Vaccine Institute (IVI), Kaneka Eurogentec, National Cancer Institute (NCI), National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID), the Parker Institute for Cancer Immunotherapy, Plumbline Life Sciences, Regeneron Pharmaceuticals, Richter-Helm BioLogics, Thermo Fisher Scientific, the University of Pennsylvania, the Walter Reed Army Institute of Research, and The Wistar Institute. 54 We or our collaborators are currently evaluating the feasibility of, or conducting or planning clinical studies of, our DNA medicines for Ebola HPV-related precancers, including cervical, vulvar, and anal dysplasia; HPV-related cancers, including head & neck, cervical, anal, penile, vulvar, and vaginal; other HPV-related disorders, such as RRP; and GBM.
Department of Defense (DoD), HIV Vaccines Trial Network, International Vaccine Institute (IVI), Kaneka Eurogentec, National Cancer Institute (NCI), National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID), Plumbline Life Sciences, Regeneron Pharmaceuticals, Richter-Helm BioLogics, Thermo Fisher Scientific, the University of Pennsylvania, the Walter Reed Army Institute of Research, and The Wistar Institute.
These decreases were offset by an increase of $5.3 million, earned primarily under the sub-grant through Wistar for DARPA COVID-19 dMAb. General and Administrative Expenses General and administrative expenses, which include business development expenses, the amortization of intangible assets and patent expenses, were $90.2 million for the year ended December 31, 2022 as compared to $53.8 million in 2021.
General and Administrative Expenses General and administrative expenses, which include business development expenses, the amortization of intangible assets and patent expenses, were $47.6 million for the year ended December 31, 2023 as compared to $90.2 million in 2022.
The decrease year over year was primarily due to decreases of $21.0 million, $5.8 million, $3.3 million and $3.2 million earned under the DoD 3PSP device development grant, CEPI grants related to INO-4800 and device development activities, reimbursements from Advaccine and the CEPI Lassa and MERS grant, respectively.
The decrease year over year was primarily due to decreases of $7.7 million earned under the sub-grant through Wistar primarily for DARPA COVID-19 dMAb, $6.1 million from the DoD 3PSP device development grant and $5.0 million earned under the CEPI Lassa and MERS grants. These decreases were offset by an increase of $2.4 million in reimbursements from Advaccine.
During the year ended December 31, 2022, we sold 34,445,743 shares of common stock under the Sales Agreement for aggregate net proceeds of $83.0 million. During the year ended December 31, 2021, we sold 6,955,341 shares of common stock under the Sales Agreement for aggregate net proceeds of $47.7 million.
During the year ended December 31, 2022, we sold 2,870,478 shares of common stock under the Sales Agreement for aggregate net proceeds of $83.0 million. From January 1, 2024 through the date of this report, we sold an additional 543,620 shares of common stock under the Sales Agreement for net proceeds of $5.2 million.
The $36.4 overall increase year over year was primarily the result of: • $44.0 million related to the class action securities litigation settlement, which was reduced by $30.0 million of insurance recoveries, resulting in a net $14.0 million expense, which is the value of our common stock to be issued in connection with the settlement; • $14.3 million in higher legal expenses, primarily related to litigation matters; • $6.9 million in severance expenses related to the separation of our former President and Chief Executive Officer in May 2022, including $4.2 million of stock-based compensation expense related to equity award modifications (see Note 10 to our consolidated financial statements included in this report for additional information); and • $1.6 million in overall higher employee compensation.
The $42.6 overall decrease year over year was primarily the result of: 60 • $14.0 million in net expense related to the class action securities litigation settlement, which was accrued in 2022 but paid in 2023; • $11.3 million in lower legal expenses, primarily the result of the conclusion of litigation in 2023; • $6.9 million in one-time severance expenses related to the separation of our former President and Chief Executive Officer in 2022, including $4.2 million of stock-based compensation expense related to equity award modifications, that did not recur in 2023; • $5.9 million in lower employee compensation, including employee and consultant stock-based compensation, as a result of headcount reductions in 2023; • $1.9 million in lower insurance expenses; and • $1.4 million in lower other outside services related to our discontinued INO-4800 and VGX-3100 programs.
Overview We are a biotechnology company focused on developing and commercializing DNA medicines to help treat and protect people from diseases associated with HPV, cancer, and infectious diseases. Our goal is to advance our diverse pipeline of product candidates and deliver on the promise of DNA medicines technology in treating and preventing a wide array of diseases.
Overview We are a clinical-stage biotechnology company focused on developing and commercializing DNA medicines to help treat and protect people from diseases associated with human papillomavirus (HPV), cancer, and infectious diseases. Our platform harnesses the power of in vivo protein production, featuring optimized design and delivery of DNA medicines that teach the body to manufacture its own disease-fighting tools.
During the year ended December 31, 2020, stock options to purchase 2,178,252 shares of common stock were exercised for aggregate net proceeds of $12.3 million, which proceeds were offset by tax payments made related to net share settlement of RSU awards of $4.0 million.
During the year ended December 31, 2023, no stock options were exercised and tax payments of $467,000 were made related to the net sh are settlement of RSU awards.
During the year ended December 31, 2020, we sold 66,064,887 shares of common stock for aggregate net proceeds of $454.5 million under previous ATM sales agreements. On January 25, 2021, we closed an underwritten public offering of 20,355,000 shares of our common stock at a public offering price of $8.50 per share.
During the year ended December 31, 2023 , we sold 875,305 shares of our common stock under the Sales Agreement at a weighted average price of $6.33 per share, resulting in aggregate net proceeds of $5.5 million.
Payments Due by Period Total Less than 1 year 1 – 3 years 3 – 5 years More than 5 years Convertible senior notes (1) $ 18,015,000 $ 1,067,000 $ 16,948,000 $ — $ — Operating lease obligations (2) $ 20,090,000 $ 4,089,000 $ 6,113,000 $ 5,665,000 $ 4,223,000 Manufacturing commitments (3) $ 11,515,000 $ 11,515,000 $ — $ — $ — (1) Amounts represent remaining contractual amounts due under our Notes, including interest based on the fixed rate of 6.5% per year.
Payments Due by Period Total Less than 1 year 1 – 3 years 3 – 5 years More than 5 years Convertible senior notes (1) $ 16,948,000 $ 16,948,000 $ — $ — $ — Operating lease obligations (2) $ 17,665,000 $ 3,247,000 $ 7,021,000 $ 5,265,000 $ 2,132,000 Manufacturing commitments (3) $ 4,489,000 $ 4,489,000 $ — $ — $ — (1) On March 1, 2024 these Convertible Senior Notes matured and we satisfied the obligation in full from existing cash.
Also, in October 2022, we announced that we have discontinued our internally funded efforts to develop INO-4800 as a COVID-19 heterologous booster vaccine. We expect these actions to reduce our operating expenses incrementally and extend our cash runway into the first quarter of 2025, without giving effect to any further capital raising activities, whether under the Sales Agreement or otherwise.
Taking into account these actions, as well as the changes to our clinical development plan for INO-3107 as a result of FDA feedback, we expect our cash runway to extend into the second quarter of 2025, without giving effect to any further capital raising activities.
The capitalized amounts are expensed as the related goods are delivered or the services are performed. 58 The following tables summarize our research and development expense by product candidate for the years ended December 31, 2022 and 2021 : Years Ended December 31, Increase (Decrease) (dollars in thousands) 2022 2021 $ % INO-4800 and other Covid-19 $ 93,464 $ 109,587 $ (16,123) (15) % VGX-3100 15,989 30,873 (14,884) (48) INO-3107 8,133 9,109 (976) (11) INO-5401 and other Immuno-oncology 2,775 2,404 371 15 Other research and development programs 6,227 4,442 1,785 40 Engineering and device-related 25,187 47,889 (22,702) (47) Stock-based compensation 9,059 13,378 (4,319) (32) Other unallocated expenses 26,817 31,558 (4,741) (15) Research and development expense $ 187,651 $ 249,240 $ (61,589) (25) % The $61.6 million overall decrease in research and development expenses year over year was primarily the result of: • $45.9 million in lower drug manufacturing and outside services related to INO-4800; • $21.9 million of costs related to the acquisition and installation of manufacturing equipment for INO-4800 during 2021 that did not recur in 2022; • $15.6 million in lower engineering services and expensed equipment related to our CELLECTRA 3PSP device and array automation project; • $11.8 million in lower clinical study, outside services and immunology expenses related to VGX-3100; • $4.9 million in lower expensed inventory related to the CELLECTRA 2000 device; and • $4.6 million in lower employee stock-based compensation primarily from lower weighted average grant date fair values for the awards granted during 2022.
The following tables summarize our research and development expense by product candidate for the years ended December 31, 2023 and 2022 : Years Ended December 31, Increase (Decrease) (dollars in thousands) 2023 2022 $ % INO-4800 and other Covid-19 $ 8,869 $ 93,464 $ (84,595) (91) % VGX-3100 4,748 15,989 (11,241) (70) INO-3107 17,841 8,133 9,708 119 INO-5401 and other Immuno-oncology 8,372 2,775 5,597 202 Other research and development programs (a) 8,472 6,227 2,245 36 Engineering and device-related 8,863 25,187 (16,324) (65) Stock-based compensation 4,606 9,059 (4,453) (49) Other unallocated expenses (b) 24,906 26,817 (1,911) (7) Research and development expense $ 86,677 $ 187,651 $ (100,974) (54) % (a) Net of contributions received from grant agreements and recorded as contra-research and development expense.