Inovio Pharmaceuticals (INO) 10-Q 13 May 24 2024 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2024	May 10, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-14888
Entity Registrant Name	INOVIO PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0969592
Entity Address, Address Line One	660 W. Germantown Pike
Entity Address, Address Line Two	Suite 110
Entity Address, City or Town	Plymouth Meeting
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19462
City Area Code	267
Local Phone Number	440-4200
Title of 12(b) Security	COMMON STOCK, $0.001 PAR VALUE
Trading Symbol	INO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		25,910,701
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001055726
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 19,601,829	$ 14,310,862
Short-term investments	86,013,044	130,982,913
Accounts receivable from affiliated entities	2,551,082	2,405,228
Prepaid expenses and other current assets	3,517,081	5,393,665
Prepaid expenses and other current assets from affiliated entities	0	20,432
Total current assets	111,683,036	153,113,100
Fixed assets, net	5,015,067	4,960,986
Investment in affiliated entity	2,654,269	2,780,287
Operating lease right-of-use assets	9,156,478	9,491,735
Other assets	605,315	605,315
Total assets	129,114,165	170,951,423
Current liabilities:
Accrued clinical trial expenses	3,022,486	2,365,382
Operating lease liability	2,155,540	2,406,522
Grant funding liability	0	87,489
Grant funding liability from affiliated entity	21,918	21,918
Convertible senior notes	0	16,770,654
Total current liabilities	23,400,945	42,570,228
Operating lease liability, net of current portion	11,271,257	11,032,066
Total liabilities	34,672,202	53,602,294
Stockholders’ equity:
Preferred stock	0	0
Common stock	23,370	22,792
Additional paid-in capital	1,748,529,814	1,740,954,074
Accumulated deficit	(1,653,435,007)	(1,622,965,136)
Accumulated other comprehensive loss	(676,214)	(662,601)
Total Inovio Pharmaceuticals, Inc. stockholders’ equity	94,441,963	117,349,129
Total liabilities and stockholders’ equity	129,114,165	170,951,423
Nonrelated Party
Current liabilities:
Accounts payable and accrued expenses	16,675,922	19,847,744
Related Party
Current liabilities:
Accounts payable and accrued expenses	$ 1,525,079	$ 1,070,519

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Revenues:
Revenue from collaborative arrangements and other contracts		$ 0	$ 114,943
Operating expenses:
Research and development		20,913,790	30,176,511
General and administrative		10,571,179	13,890,610
Total operating expenses		31,484,969	44,067,121
Loss from operations		(31,484,969)	(43,952,178)
Other income (expense):
Interest income		1,500,290	2,207,171
Interest expense		(177,833)	(313,488)
(Loss) gain on investment in affiliated entity		(126,018)	616,639
Net unrealized gain on available-for-sale equity securities		500,877	3,218,215
Other expense, net		(682,218)	(2,425,676)
Net loss		$ (30,469,871)	$ (40,649,317)
Net loss per share
Basic (in dollars per share)	[1]	$ (1.31)	$ (1.89)
Diluted (in dollars per share)	[1]	$ (1.31)	$ (1.89)
Weighted average number of common shares outstanding
Basic (in shares)	[1]	23,291,512	21,536,476
Diluted (in shares)	[1]	23,291,512	21,536,476
[1]Share and per share amounts have been restated to reflect the 1-for-12 reverse stock split effected in January 2024 on a retroactive basis for all periods presented.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Parenthetical)		1 Months Ended
	Jan. 24, 2024	Jan. 31, 2024
Income Statement [Abstract]
Stock split, conversion ratio	0.083333	0.083333

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net loss	$ (30,469,871)	$ (40,649,317)
Other comprehensive loss:
Foreign currency translation	32,403	(1,918)
Unrealized (loss) gain on short-term investments, net of tax	(46,016)	117,862
Comprehensive loss	$ (30,483,484)	$ (40,533,373)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity - USD ($)		Total	Preferred stock	Common stock		Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Beginning balance (in shares) at Dec. 31, 2022			9	21,090,938	[1]
Beginning balance at Dec. 31, 2022		$ 222,362,756	$ 0	$ 21,090	[1]	$ 1,710,888,191	$ (1,487,847,784)	$ (698,741)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (in shares)	[1]			760,083
Issuance of common stock for cash, net of financing costs		14,000,000		$ 760	[1]	13,999,240
Vesting of RSUs, net of tax payments (in shares)	[1]			43,901
Vesting of RSUs, net of tax payments		(424,704)		$ 44	[1]	(424,748)
Stock-based compensation		3,809,003				3,809,003
Net loss		(40,649,317)					(40,649,317)
Unrealized (loss) gain on short-term investments, net of tax		117,862						117,862
Foreign currency translation		(1,918)						(1,918)
Ending balance at Mar. 31, 2023		199,213,682	$ 0	$ 21,894	[1]	1,728,271,686	(1,528,497,101)	(582,797)
Ending balance (in shares) at Mar. 31, 2023			9	21,894,922	[1]
Beginning balance (in shares) at Dec. 31, 2023			9	22,793,075	[1]
Beginning balance at Dec. 31, 2023		117,349,129	$ 0	$ 22,792	[1]	1,740,954,074	(1,622,965,136)	(662,601)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (in shares)	[1]			543,620
Issuance of common stock for cash, net of financing costs		5,225,133		$ 544	[1]	5,224,589
Vesting of RSUs, net of tax payments (in shares)	[1]			34,558
Vesting of RSUs, net of tax payments		(174,248)		$ 34	[1]	(174,282)
Stock-based compensation		2,525,433				2,525,433
Net loss		(30,469,871)					(30,469,871)
Unrealized (loss) gain on short-term investments, net of tax		(46,016)						(46,016)
Foreign currency translation		32,403						32,403
Ending balance at Mar. 31, 2024		$ 94,441,963	$ 0	$ 23,370	[1]	$ 1,748,529,814	$ (1,653,435,007)	$ (676,214)
Ending balance (in shares) at Mar. 31, 2024			9	23,371,253	[1]
[1]All share amounts in this column, including appropriate reclassifications between common stock and additional paid-in capital, have been restated to reflect the 1-for-12 reverse stock split effected in January 2024 on a retroactive basis for all periods presented.

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical)		1 Months Ended
	Jan. 24, 2024	Jan. 31, 2024
Statement of Stockholders' Equity [Abstract]
Stock split, conversion ratio	0.083333	0.083333

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Cash flows from operating activities:
Net loss	$ (30,469,871)	$ (40,649,317)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	424,473	707,378
Amortization of intangible assets	0	82,083
Amortization of operating lease right-of-use assets	335,257	362,664
Non-cash stock-based compensation	2,525,433	3,809,003
Non-cash interest on senior convertible notes	(355,654)	(219,999)
Amortization of discounts on investments	(684,651)	(1,159,083)
Loss on sales of short-term investments	691,168	2,425,676
Loss on disposal of fixed assets	0	334,297
Loss (gain) on equity investment in affiliated entity	126,018	(616,639)
Net unrealized gain on available-for-sale equity securities	(500,877)	(3,218,215)
Changes in operating assets and liabilities:
Accounts receivable, including from affiliated entities	(145,854)	6,703,110
Prepaid expenses and other current assets, including from affiliated entities	1,897,016	39,324,542
Other assets	0	31,527
Accounts payable and accrued expenses, including due to affiliated entities	(3,160,238)	(40,737,879)
Accrued clinical trial expenses	657,104	(4,798,227)
Operating lease right-of-use assets and liabilities, net	(11,791)	(693,691)
Grant funding liability, including from affiliated entity	(87,489)	1,648,292
Net cash used in operating activities	(28,759,956)	(36,664,478)
Cash flows from investing activities:
Purchases of investments	(9,751,047)	(80,431,174)
Proceeds from sale or maturity of investments	55,169,260	93,657,050
Purchases of capital assets	(35,578)	(296,983)
Proceeds from sale of capital assets	0	6,071,000
Net cash provided by investing activities	45,382,635	18,999,893
Cash flows from financing activities:
Repayment of convertible senior notes	(16,415,000)	0
Proceeds from issuance of common stock, net of issuance costs	5,225,133	0	$ 5,500,000
Taxes paid related to net share settlement of equity awards	(174,248)	(424,704)
Net cash used in financing activities	(11,364,115)	(424,704)
Effect of exchange rate changes on cash and cash equivalents	32,403	(1,918)
Increase (Decrease) in cash and cash equivalents	5,290,967	(18,091,207)
Cash and cash equivalents, beginning of period	14,310,862	46,329,359	46,329,359
Cash and cash equivalents, end of period	19,601,829	28,238,152	$ 14,310,862
Supplemental disclosures:
Amounts accrued for purchases of fixed assets	442,976	0
Interest paid	533,487	533,187
Issuance of common stock as part of litigation settlement	$ 0	$ 14,000,000

Organization and Operations

Organization and Operations	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operations	Organization and Operations Inovio Pharmaceuticals, Inc. (the “Company” or “INOVIO”) is 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. INOVIO's 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. INOVIO uses proprietary technology to design DNA plasmids, which are small circular DNA molecules that work like software the body’s cells can download to produce specific proteins to target and fight disease. The Company's proprietary investigational CELLECTRA ® delivery devices help its DNA medicines enter the body’s cells for optimal effect. INOVIO's lead candidate is INO-3107 for the treatment of recurrent respiratory papillomatosis (RRP), a life-long, rare disease of the respiratory tract caused by HPV infection. In its completed Phase 1/2 clinical trial of INO-3107 for the treatment of HPV-6 and HPV-11-associated RRP, 81.3% of patients experienced a reduction in the number of surgical interventions in the year following administration of INO-3107, when compared with the year prior to treatment. In addition to its development efforts with INO-3107, INOVIO is actively developing or planning to develop DNA medicines for other indications, including HPV-related oropharyngeal squamous cell carcinoma (OPSCC) and anal dysplasia; glioblastoma multiforme (GBM), a deadly form of brain cancer; and a potential vaccine booster to protect against the Ebola virus. The Company was previously conducting clinical trials of a DNA medicine candidate for the treatment of HPV-related cervical high-grade squamous intraepithelial lesions (HSIL) but announced in August 2023 that it was ceasing development for this indication in the United States. However, its collaborator ApolloBio Corporation continues to conduct a Phase 3 clinical trial of this candidate in China and plans to seek regulatory approval for and potentially commercialize the candidate in that jurisdiction. The Company's 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. 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. INOVIO was incorporated in Delaware in June 2001 and has its principal executive offices in Plymouth Meeting, Pennsylvania.

Basis of Presentation, Liquidit

Basis of Presentation, Liquidity and Risks and Uncertainties	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation, Liquidity and Risks and Uncertainties	Basis of Presentation, Liquidity and Risks and Uncertainties Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Inovio have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) as contained in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") for interim financial information and with instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, the condensed consolidated statements of stockholders' equity and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 are unaudited, but include all adjustments (consisting of normal recurring adjustments) that the Company considers necessary for a fair presentation of the financial position, results of operations, cash flows and changes in stockholders' equity for the periods presented. The results of operations for the three months ended March 31, 2024 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2024, or for any other period. These unaudited financial statements, and notes thereto, should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2023, included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 6, 2024. The balance sheet at December 31, 2023 has been derived from the audited financial statements at that date, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiary. As of March 31, 2024 and December 31, 2023, the Company consolidated its wholly-owned subsidiary Inovio Asia LLC. All intercompany accounts and transactions were eliminated upon consolidation. Liquidity The Company incurred a net loss attributable to common stockholders of $30.5 million for the three months ended March 31, 2024. The Company had working capital of $88.3 million and an accumulated deficit of $1.7 billion as of March 31, 2024. The Company has incurred losses in each year since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future in connection with the research and preclinical and clinical development of its product candidates. On April 18, 2024, the Company closed an underwritten registered direct offering (the “Offering”) relating to the issuance and sale of 2,536,258 shares (the “Shares”) of its common stock, par value $0.001 per share, at a price of $7.693 per share and pre-funded warrants to purchase up to 2,135,477 shares of common stock (the “Pre-Funded Warrants”) at a price of $7.692 per Pre-Funded Warrant, which represents the per share price for the Shares less the $0.001 per share exercise price for each Pre-Funded Warrant. The net proceeds from the Offering were approximately $33.2 million, after deducting the underwriting discounts and commissions and estimated offering expenses payable by the Company. The Company’s cash, cash equivalents and short-term investments of $105.6 million as of March 31, 2024, together with the net proceeds from the April 2024 Offering, are expected to be sufficient to support the Company's planned operations for a period of at least 12 months from the date of issuance of these financial statements. In order to continue to fund future research and development activit ies, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements, grant agreements and/or future public or private debt or equity financings including At-the-Market Equity Offering Sales Agreements (“Sales Agreements”). The Company has a history of conducting debt and equity financings, including the receipt of net proceeds of $5.2 million and $5.5 million under a Sales Agreement during the three months ended March 31, 2024 and year ended December 31, 2023, respectively . However, sufficient funding may not be available in the future, or if available, may be on terms that significantly dilute or otherwise adversely affect the rights of existing stockholders. If adequate funds are not available, the Company may need to delay, reduce the scope of or put on hold one or more of its clinical and/or preclinical programs. The Company’s ability to continue its operations is dependent upon its ability to obtain additional capital in the future and achieve profitable operations. The Company expects to continue to rely on outside sources of financing to meet its capital needs and the Company may never achieve positive cash flow. These condensed consolidated financial statements do not include any adjustments to the specific amounts and classifications of assets and liabilities, which might be necessary should Inovio be unable to continue as a going concern. The Company's condensed consolidated financial statements as of and for the three months ended March 31, 2024 have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has evaluated subsequent events after the balance sheet date through the date it issued these condensed consolidated financial statements. The Company is, and from time to time may in the future be, subject to various legal proceedings and claims arising in the ordinary course of business. The Company assesses contingencies to determine the degree of probability and range of possible loss for potential accrual in its consolidated financial statements. An estimated loss contingency is accrued in the consolidated financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Legal proceedings, including litigation, government investigations and enforcement actions, could result in material costs, occupy significant management resources and entail civil and criminal penalties, even if the Company ultimately prevails. Any of the foregoing consequences could result in serious harm to the Company’s business, results of operations and financial condition. Reverse Stock Split On January 24, 2024, the Company filed with the Secretary of State of the State of Delaware a certificate of amendment to its certificate of incorporation, as previously amended, to effect a 1-for-12 reverse stock split of its common stock (the “Reverse Stock Split”). As a result of the Reverse Stock Split, every 12 issued and outstanding shares of the Company's common stock were automatically combined into one issued and outstanding share of common stock. The reverse stock split was reflected on the Nasdaq Capital Market beginning with the opening of trading on January 25, 2024. Accordingly, an amount equal to the par value of the decreased shares resulting from the reverse stock split was reclassified from "Additional paid-in capital" to "Common stock" on the balance sheet and statement of changes in stockholders’ equity. Any fractional post-split shares as a result of the reverse stock split were eliminated by the payment of cash for the value of such fractional share. As a result of the Reverse Stock Split, proportionate adjustments were made to the number of shares underlying, and the exercise or conversion prices of, the Company's outstanding stock options and outstanding shares of Series C Cumulative Convertible Preferred Stock and to the number of shares of common stock issuable under the Company's equity incentive plans. The reverse stock split did not change the par value of the Company's common stock or the authorized number of shares of the Company's common stock. All share amounts and per share amounts disclosed in this Quarterly Report on Form 10-Q have been restated to reflect the reverse stock split on a retroactive basis for all periods presented.

Critical Accounting Policies

Critical Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Critical Accounting Policies	Critical Accounting Policies Collaboration Agreements and Revenue Recognition The Company assesses whether its collaboration agreements are subject to Accounting Standards Codification ("ASC") Topic 808: Collaborative Arrangements (“Topic 808”) based on whether they involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of Topic 808 and the Company concludes that its collaboration partner is not a customer, the Company presents such payments as a reduction of research and development expense. If payments from the collaboration partner to the Company represent consideration from a customer, then the Company accounts for those payments within the scope of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“Topic 606”). Research and Development Expenses - Clinical Trial Accruals The Company's activities have largely consisted of research and development efforts related to developing its proprietary device technology and DNA medicine candidates. For clinical trial expenses, judgements used in estimating accruals rely on estimates of total costs incurred based on participant enrollment, completion of studies and other events. Accrued clinical trial costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to the Company's results of operations.

Short-term Investments and Fair

Short-term Investments and Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Short-term Investments and Fair Value Measurements	Short-term Investments and Fair Value Measurements The following is a summary of available-for-sale securities as of March 31, 2024 and December 31, 2023: As of March 31, 2024 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 45,541,438 $ — $ (3,022,011) $ 42,519,427 U.S. treasury securities Less than 1 39,596,119 — (8,719) 39,587,400 Certificates of deposit Less than 1 2,979,254 11,222 (295) 2,990,181 U.S. agency mortgage-backed securities * 1,331,885 — (415,849) 916,036 $ 89,448,696 $ 11,222 $ (3,446,874) $ 86,013,044 As of December 31, 2023 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 55,389,289 $ — $ (3,522,888) $ 51,866,401 U.S. treasury securities Less than 1 75,164,782 24,938 — 75,189,720 Certificates of deposit Less than 1 2,978,917 11,709 (300) 2,990,326 U.S. agency mortgage-backed securities * 1,340,439 — (403,973) 936,466 $ 134,873,427 $ 36,647 $ (3,927,161) $ 130,982,913 *No single maturity date. During the three months ended March 31, 2024 and 2023, the Company recorded gross realized gains on investments of $200 and $300, respectively, and gross realized losses on investments of $691,000 and $2.4 million, respectively. During the three months ended March 31, 2024 and 2023, the Company recorded net unrealized gain on available-for-sale equity securities of $501,000 and $3.2 million, respectively. No material balances were reclassified out of accumulated other comprehensive loss for the three months ended March 31, 2024 and 2023. Interest and dividends on investments classified as available-for-sale are included in interest income in the condensed consolidated statements of operations. As of March 31, 2024, the Company had 25 available-for-sale securities with an aggregate total unrealized loss of $3.4 million. Of these securities, 19 had been in a loss position for longer than 12 months as of March 31, 2024. The Company periodically reviews its portfolio of available-for-sale debt securities to determine if any investment is impaired due to credit loss or other potential valuation concerns. For the debt securities where the fair value of the investment is less than the amortized cost basis, the Company has assessed at the individual security level for various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of impairment. Unrealized losses on available-for-sale debt securities as of March 31, 2024 were primarily due to changes in interest rates , and not due to increased credit risks associated with specific securities. Based on the credit quality of the available-for-sale debt securities that are in an unrealized loss position, and the Company’s estimates of future cash flows to be collected from those securities, the Company believes the unrealized losses are not credit losses. Accordingly, at March 31, 2024, the Company has not recorded an allowance for credit losses related to its available-for-sale debt securities. The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of March 31, 2024: Fair Value Measurements at March 31, 2024 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 42,519,427 $ 42,519,427 $ — $ — U.S. treasury securities 39,587,400 39,587,400 — — Certificates of deposit 2,990,181 — 2,990,181 — U.S. agency mortgage-backed securities 916,036 — 916,036 — Total short-term investments 86,013,044 82,106,827 3,906,217 — Investment in affiliated entity 2,654,269 2,654,269 — — Total assets measured at fair value $ 88,667,313 $ 84,761,096 $ 3,906,217 $ — The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of December 31, 2023: Fair Value Measurements at December 31, 2023 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 51,866,401 $ 51,866,401 $ — $ — U.S. treasury securities 75,189,720 75,189,720 — — Certificates of deposit 2,990,326 — 2,990,326 — U.S. agency mortgage-backed securities 936,466 — 936,466 — Total short-term investments 130,982,913 127,056,121 3,926,792 — Investment in affiliated entity 2,780,287 2,780,287 — — Total assets measured at fair value $ 133,763,200 $ 129,836,408 $ 3,926,792 $ — Level 1 assets at March 31, 2024 consisted of mutual funds and U.S. treasury securities held by the Company that are valued at quoted market prices, as well as the Company’s investment in its affiliated entity, PLS. The Company accounts for its investment in 597,808 common shares of PLS based on the closing price of the shares on the Korea New Exchange Market on the applicable balance sheet date. Unrealized gains and losses on the Company's equity securities are reported in the consolidated statement of ope rations as unrealized gain or loss on available-for-sale equity securities or as a gain or loss on investment in affiliated entity. Level 2 assets at March 31, 2024 consisted of certificates of deposit and U.S. agency mortgage-backed securities held by the Company that are initially valued at the transaction price and subsequently valued, at the end of each reporting period, typically utilizing market observable data. The Company obtains the fair value of its Level 2 assets from a professional pricing service, which may use quoted market prices for identical or comparable instruments, or inputs other than quoted prices that are observable either directly or indirectly. The professional pricing service gathers quoted market prices and observable inputs from a variety of industry data providers. The valuation techniques used to measure the fair value of the Company's Level 2 financial instruments were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models such as discounted cash flow techniques. The Company validates the quoted market prices provided by the primary pricing service by comparing the service's assessment of the fair values of the Company's investment portfolio balance against the fair values of the Company's investment portfolio balance obtained from an independent source. There were no Level 3 assets held as of March 31, 2024 or December 31, 2023.
Short-term Investments and Fair Value Measurements	Short-term Investments and Fair Value Measurements The following is a summary of available-for-sale securities as of March 31, 2024 and December 31, 2023: As of March 31, 2024 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 45,541,438 $ — $ (3,022,011) $ 42,519,427 U.S. treasury securities Less than 1 39,596,119 — (8,719) 39,587,400 Certificates of deposit Less than 1 2,979,254 11,222 (295) 2,990,181 U.S. agency mortgage-backed securities * 1,331,885 — (415,849) 916,036 $ 89,448,696 $ 11,222 $ (3,446,874) $ 86,013,044 As of December 31, 2023 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 55,389,289 $ — $ (3,522,888) $ 51,866,401 U.S. treasury securities Less than 1 75,164,782 24,938 — 75,189,720 Certificates of deposit Less than 1 2,978,917 11,709 (300) 2,990,326 U.S. agency mortgage-backed securities * 1,340,439 — (403,973) 936,466 $ 134,873,427 $ 36,647 $ (3,927,161) $ 130,982,913 *No single maturity date. During the three months ended March 31, 2024 and 2023, the Company recorded gross realized gains on investments of $200 and $300, respectively, and gross realized losses on investments of $691,000 and $2.4 million, respectively. During the three months ended March 31, 2024 and 2023, the Company recorded net unrealized gain on available-for-sale equity securities of $501,000 and $3.2 million, respectively. No material balances were reclassified out of accumulated other comprehensive loss for the three months ended March 31, 2024 and 2023. Interest and dividends on investments classified as available-for-sale are included in interest income in the condensed consolidated statements of operations. As of March 31, 2024, the Company had 25 available-for-sale securities with an aggregate total unrealized loss of $3.4 million. Of these securities, 19 had been in a loss position for longer than 12 months as of March 31, 2024. The Company periodically reviews its portfolio of available-for-sale debt securities to determine if any investment is impaired due to credit loss or other potential valuation concerns. For the debt securities where the fair value of the investment is less than the amortized cost basis, the Company has assessed at the individual security level for various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of impairment. Unrealized losses on available-for-sale debt securities as of March 31, 2024 were primarily due to changes in interest rates , and not due to increased credit risks associated with specific securities. Based on the credit quality of the available-for-sale debt securities that are in an unrealized loss position, and the Company’s estimates of future cash flows to be collected from those securities, the Company believes the unrealized losses are not credit losses. Accordingly, at March 31, 2024, the Company has not recorded an allowance for credit losses related to its available-for-sale debt securities. The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of March 31, 2024: Fair Value Measurements at March 31, 2024 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 42,519,427 $ 42,519,427 $ — $ — U.S. treasury securities 39,587,400 39,587,400 — — Certificates of deposit 2,990,181 — 2,990,181 — U.S. agency mortgage-backed securities 916,036 — 916,036 — Total short-term investments 86,013,044 82,106,827 3,906,217 — Investment in affiliated entity 2,654,269 2,654,269 — — Total assets measured at fair value $ 88,667,313 $ 84,761,096 $ 3,906,217 $ — The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of December 31, 2023: Fair Value Measurements at December 31, 2023 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 51,866,401 $ 51,866,401 $ — $ — U.S. treasury securities 75,189,720 75,189,720 — — Certificates of deposit 2,990,326 — 2,990,326 — U.S. agency mortgage-backed securities 936,466 — 936,466 — Total short-term investments 130,982,913 127,056,121 3,926,792 — Investment in affiliated entity 2,780,287 2,780,287 — — Total assets measured at fair value $ 133,763,200 $ 129,836,408 $ 3,926,792 $ — Level 1 assets at March 31, 2024 consisted of mutual funds and U.S. treasury securities held by the Company that are valued at quoted market prices, as well as the Company’s investment in its affiliated entity, PLS. The Company accounts for its investment in 597,808 common shares of PLS based on the closing price of the shares on the Korea New Exchange Market on the applicable balance sheet date. Unrealized gains and losses on the Company's equity securities are reported in the consolidated statement of ope rations as unrealized gain or loss on available-for-sale equity securities or as a gain or loss on investment in affiliated entity. Level 2 assets at March 31, 2024 consisted of certificates of deposit and U.S. agency mortgage-backed securities held by the Company that are initially valued at the transaction price and subsequently valued, at the end of each reporting period, typically utilizing market observable data. The Company obtains the fair value of its Level 2 assets from a professional pricing service, which may use quoted market prices for identical or comparable instruments, or inputs other than quoted prices that are observable either directly or indirectly. The professional pricing service gathers quoted market prices and observable inputs from a variety of industry data providers. The valuation techniques used to measure the fair value of the Company's Level 2 financial instruments were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models such as discounted cash flow techniques. The Company validates the quoted market prices provided by the primary pricing service by comparing the service's assessment of the fair values of the Company's investment portfolio balance against the fair values of the Company's investment portfolio balance obtained from an independent source. There were no Level 3 assets held as of March 31, 2024 or December 31, 2023.

Certain Balance Sheet Items

Certain Balance Sheet Items	3 Months Ended
	Mar. 31, 2024
Certain Balance Sheet Items [Abstract]
Certain Balance Sheet Items	Certain Balance Sheet Items Prepaid and other current assets consisted of the following: March 31, 2024 December 31, 2023 Prepaid manufacturing expenses 228,378 1,486,638 Other prepaid expenses 3,288,703 3,907,027 $ 3,517,081 $ 5,393,665 Accounts payable and accrued expenses consisted of the following: March 31, 2024 December 31, 2023 Trade accounts payable $ 6,772,184 $ 3,577,826 Accrued compensation 5,685,560 9,837,104 Other accrued expenses (a) 4,218,178 6,432,814 $ 16,675,922 $ 19,847,744 (a) As of March 31, 2024 and December 31, 2023, balance includes $2.3 million and $4.3 million, respectively, of liability for unused grant funding.

Convertible Debt

Convertible Debt	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Convertible Debt	Convertible Debt Convertible Senior Notes On February 19, 2019 and March 1, 2019, the Company completed a private placement of $78.5 million aggregate principal amount of its 6.50% convertible senior notes due 2024 (the “Notes”). The Notes were sold in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. Net proceeds from the offering were $75.7 million. The Notes were senior unsecured obligations of the Company and accrued interest payable in cash semi-annually in arrears on March 1 and September 1 of each year at a rate of 6.50% per annum. The Notes matured on March 1, 2024 and the Company paid the then remaining $16.9 million obligation in full, including accrued interest. For the three months ended March 31, 2024 and 2023, the Company recognized $178,000 and $313,000, respectively, of interest expense related to the Notes, of which $178,000 and $267,000, respectively, related to the contractual interes

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity The following is a summary of the Company's authorized and issued common and preferred stock as of March 31, 2024 and December 31, 2023: Outstanding as of Authorized Issued March 31, 2024 December 31, 2023 Common Stock, par value $0.001 per share 600,000,000 23,371,253 23,371,253 22,793,075 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 9 9 Issuances of Common Stock On November 9, 2021, the Company entered into an ATM Equity Offering SM Sales Agreement (the “2021 Sales Agreement”) with outside sales agents (collectively, the “Sales Agents”) for the offer and sale of its common stock for an aggregate offering price of up to $300.0 million. The 2021 Sales Agreement provides that the Sales Agents were entitled to compensation in an amount equal to up to 3.0% of the gross sales proceeds of any common stock sold through the Sales Agents under the 2021 Sales Agreement. During the three months ended March 31, 2024, the Company sold 543,620 shares of its common stock under the 2021 Sales Agreement at a weighted average price of $9.76 per share, resulting in aggregate net proceeds of $5.2 million. During the year ended December 31, 2023, the Company sold 875,305 shares of its common stock under the 2021 Sales Agreement at a weighted average price of $6.33 per share, resulting in aggregate net proceeds of $5.5 million. As of March 31, 2024, the registration statement relating to the shares of common stock issuable under the 2021 Sales Agreement has expired, and therefore as of the date of these financial statements the Company may not sell any additional shares under the 2021 Sales Agreement. During the three months ended March 31, 2023, the Company issued 760,083 shares of common stock pursuant to the securities class action settlement, as described in Note 11. Stock Options and Restricted Stock Units The Board of Directors adopted the 2023 Omnibus Incentive Plan (the “2023 Plan”) on March 24, 2023, pursuant to which the Company may grant stock options, restricted stock awards, restricted stock units ("RSUs") and other stock-based awards or short-term cash incentive awards to employees, directors and consultants. The 2023 Plan was approved by stockholders on May 16, 2023. The aggregate number of shares of the Company’s common stock that may be issued under the 2023 Plan will not exceed the sum of 1,166,666 shares plus any shares that may return from time to time from the 2016 Omnibus Incentive Plan (as amended, the “2016 Plan”) as a result of expirations, terminations or forfeitures of awards outstanding under the 2016 Plan as of May 16, 2023. At March 31, 2024, the Company had 917,945 shares of common stock available for future grant under the 2023 Plan, 171,750 shares underlying outstanding RSUs and 260,109 shares underlying options outstanding to purchase common stock under the 2023 Plan. The awards granted and available for future grant under the 2023 Plan generally vest over three years and have a maximum contractual term of ten years. The 2023 Plan terminates by its terms on March 24, 2033. At March 31, 2024, the Company had 207,594 shares underlying outstanding but unvested RSUs and options outstanding to purchase 950,763 shares of common stock under the 2016 Plan. The outstanding awards granted under the 2016 Plan generally vest over three years and have a maximum contractual term of ten years. Following adoption of the 2023 Plan, no further awards may be made under the 2016 Plan, but outstanding awards continue to be governed by their existing terms. On June 24, 2022, the Company's board of directors adopted a stock-based incentive plan (the "2022 Inducement Plan"), which provides for the discretionary grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, RSU awards, performance awards, and other awards to individuals as a material inducement to entering into employment with the Company. The aggregate number of shares of the Company’s common stock that may be issued under the 2022 Inducement Plan will not exceed 166,666 shares. At March 31, 2024, the Company had 116,515 shares of common stock available for future grant under the 2022 Inducement Plan, 12,776 shares underlying outstanding but unvested RSUs and options outstanding to purchase 33,071 shares of common stock under the 2022 Inducement Plan. The 2022 Inducement Plan can be terminated by the Company's board of directors at any time. The Amended and Restated 2007 Omnibus Incentive Plan (the "2007 Incentive Plan") was adopted on M

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss for the period by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is calculated in accordance with the treasury stock method for the outstanding stock options and RSUs and refle cts the potential dilution that would occur if securities or other con tracts to issue common stock were exercised or converted to common stock. The dilutive impact of the Notes previously issued by the Company (discussed in Note 6) was considered using the "if-converted" method. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the options or other securities and the presumed exercise of such securities are dilutive to net loss per share for the period, an adjustment to the net loss used in the calculation is required to remove the change in fair value of such securities from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any. For the three months ended March 31, 2024 and 2023, basic and diluted net loss per share were the same, as the assumed exercise or settlement of stock options and RSUs and the potentially dilutive shares issuable upon conversion of the Notes would have been anti-dilutive. The following table summarizes potential shares of common stock that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect: Three Months Ended March 31, 2024 2023 Options to purchase common stock 1,355,178 1,271,620 Service-based restricted stock units 392,120 179,149 Convertible preferred stock 275 275 Convertible notes — 254,165 Total 1,747,573 1,705,209

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company incurs stock-based compensation expense related to RSUs and stock options. The fair value of restricted stock is determined by the closing price of the Company's common stock reported on the Nasdaq Capital Market on the date of grant. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of subjective assumptions, including the expected stock price volatility and expected option life. The Company amortizes the fair value of the awards on a straight-line basis over the requisite vesting period of the awards. Expected volatility is based on historical volatility. The expected life of options granted is based on historical expected life. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. The Company recognizes forfeitures as they occur. The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Three Months Ended March 31, 2024 2023 Risk-free interest rate 4.21% 4.09% Expected volatility 105% 99% Expected life in years 5.5 5.5 Dividend yield — — Total employee and director stock-based compensation expense recognized in the condensed consolidated statements of operations for the three months ended March 31, 2024 and 2023 was $2.4 million and $3.6 million, respectively, of which $1.0 million and $1.5 million, respectively, was included in research and development expenses, and $1.4 million and $2.1 million, respectively, was included in general and administrative expenses. At March 31, 2024, there was $4.3 million of total unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average period of 1.7 years. The weighted average grant date fair value per share, calculated using the Black-Scholes option pricing model, was $6.77 and $11.64 for employee and director stock options granted during the three months ended March 31, 2024 and 2023, respectively. At March 31, 2024, there was $4.1 million of total unrecognized compensation expense related to unvested service-based RSUs, which is expected to be recognized over a weighted-average period of 1.9 years. The weighted average grant date fair value per share was $8.39 and $14.40 for service-based RSUs granted during the three months ended March 31, 2024 and 2023, respectively.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Plumbline Life Sciences, Inc. The Company owned 597,808 shares of common stock in PLS as of March 31, 2024, representing an ownership interest of 17.8%, and one of the Company's directors, Dr. David B. Weiner, acts as a consultant to PLS. The Wistar Institute Dr. Weiner is a director of the Vaccine Center of The Wistar Institute ("Wistar") and an Executive Vice President of Wistar. In March 2016, the Company entered into collaborative research agreements with Wistar for preventive and therapeutic DNA-based immunotherapy applications and products developed by Dr. Weiner and Wistar for the treatment of cancers and infectious diseases. Under the terms of the agreement, the Company reimbursed Wistar for all direct and indirect costs incurred in the conduct of the collaborative research, not to exceed $3.1 million during the five-year term of the agreements. In March 2021, upon expiration of the March 2016 agreements, the Company entered into new collaborative research agreements with Wistar with the same terms. The Company has the exclusive right to in-license new intellectual property developed under this agreement. In 2020, the Company received a $10.7 million sub-grant through Wistar, which was amended in 2021 to $13.6 million, for the preclinical development and translational studies of DMAbs as countermeasures for COVID-19, with funding extended through August 2024 . The sub-grant also includes an option for an additional $1.6 million in funding through September 2025. In December 2022, the Company received a $1.2 million sub-grant through Wistar with funding through November 2023, with an option for an additional $5.4 million in funding that extends the sub-grant through November 2027. The Company will support the Wistar lead consortium in the research and development of synthetic DNA-launched nanoparticles (dLNPs) for vaccination against HIV infection. Deferred grant funding recognized from Wistar and recorded as contra-research and development expense is related to work performed by the Company on the research sub-contract agreements. For the three months ended March 31, 2024 and 2023, the Company recorded $140,000 and $211,000, respectively, as contra-research and development expense from Wistar. Research and development expenses recorded from Wistar relate primarily to the collaborative research agreements. Research and development expenses recorded from Wistar for the three months ended March 31, 2024 and 2023 were $475,000 and $422,000, respectively. At March 31, 2024 and December 31, 2023, the Company had an accounts receivable balance of $2.5 million and $2.4 million, respectively, and an accounts payable and accrued liability balance of $1.5 million and $1.1 million, respectively, related to Wistar. At each of March 31, 2024 and December 31, 2023, the Company recorded $22,000 as deferred grant funding on its condensed consolidated balance sheet related to Wistar.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company leases approximately 56,600 square feet of office, laboratory, and manufacturing space in San Diego, California and approximately 57,400 square feet of office space in Plymouth Meeting, Pennsylvania under various non-cancellable operating lease agreements with remaining lease terms as of March 31, 2024 of 3.2 to 5.8 ye ars, which represent the non-cancellable periods of the leases. The Company has excluded the extension options from its lease terms in the calculation of future lease payments as they are not reasonably certain to be exercised. The Company's lease payments consist primarily of fixed rental payments for the right to use the underlying leased assets over the lease terms as well as payments for common area maintenance and administrative services. The Company has received customary incentives from its landlords, such as reimbursements for tenant improvements and rent abatement periods, which effectively reduce the total lease payments owed for these leases. In November 2023, the Company entered into a lease agreement for research and development laboratory space in San Diego, California. The total space under the lease is approximately 5,600 square feet. The term of the lease commenced on February 10, 2024 and the initial term is 4.3 years. The base rent adjusts periodically throughout the term of the lease. Rent payments under the lease will include base rent with an annual increase of approximately three percent, and additional monthly fees to cover the Company's share of certain facility expenses, including utilities, property taxes, insurance and maintenance. The Company performed an evaluation of its contracts with customers and suppliers in accordance with ASC Topic 842 and determined that, except for the real estate leases described above and various copier leases, none of its other contracts contain a right-of-use asset. Operating lease right-of-use assets and liabilities on the condensed consolidated balance sheet represents the present value of the remaining lease payments over the remaining lease terms. Payments for additional monthly fees to cover the Company's share of certain facility expenses are not included in operating lease right-of-use assets and liabilities. The Company uses its incremental borrowing rate to calculate the present value of its lease payments, as the implicit rates in the leases are not readily determinable. As of March 31, 2024, the maturities of the Company's operating lease liabilities were as follows: Remainder of 2024 $ 2,457,000 2025 3,467,000 2026 3,555,000 2027 2,955,000 2028 2,310,000 Thereafter 2,132,000 Total remaining lease payments 16,876,000 Less: present value adjustment (3,449,000) Total operating lease liabilities 13,427,000 Less: current portion (2,156,000) Long-term operating lease liabilities $ 11,271,000 Weighted-average remaining lease term 5.0 years Weighted-average discount rate 9.0% Lease costs included in operating expenses in the condensed consolidated statements of operations for the three months ended March 31, 2024 and 2023 were $837,000 and $840,000, respectively. Operating lease costs consisting of the fixed lease payments included in operating lease liabilities are recorded on a straight-line basis over the lease terms. Variable lease costs are recorded as incurred. In the third and fourth quarters of 2023, the Company entered into agreements to sublease a total of approximately 4,400 and 7,000 square feet, respectively, in its Plymouth Meeting headquarters, in each case with sublease terms through December 31, 2026. In the fourth quarter of 2019, the Company entered into two agreements to sublease a total of approximately 13,500 square feet in its Plymouth Meeting headquarters, with one sublease term through March 31, 2025 and the other month-to-month. In the normal course of business, the Company is a party to a variety of agreements pursuant to which it may be obligated to indemnify the other party. It is not possible to predict the maximum potential amount of future payments under these types of agreements due to the conditional nature of the Company's obligations and the unique facts and circumstances involved in each particular agreement. Historically, payments made by the Company under these types of agreements have not had a material effect on its business, consolidated results of operations or financial condition. Legal Proceedings Securities Litigation In March 2020, a purported shareholder class action complaint, McDermid v. Inovio Pharmaceuticals, Inc. and J. Joseph Kim, was filed in the United States District Court for the Eastern District of Pennsylvania, naming the Company and its former President and Chief Executive Officer as defendants. The lawsuit alleged that the Company made materially false and misleading statements in violation of certain federal securities laws. The plaintiffs sought unspecified monetary damages on behalf of the putative class and an award of costs and expenses, including reasonable attorneys’ fees. The plaintiffs’ complaint was later amended to include certain of the Company’s other officers as defendants. After additional motions were filed in the case, in June 2022 the parties negotiated an agreement in principle to settle the shareholder class action complaint, which was approved by the court in January 2023. Under the settlement, the Company agreed to pay $30.0 million in cash and $14.0 million in shares of its common stock to settle all outstanding claims. The Company's insurance carriers paid the $30.0 million cash component of the settlement. During the three months ended March 31, 2023, the Company issued 760,083 shares of common stock pursuant to the securities class action settlement. Shareholder Derivative Litigation In April 2020, a purported shareholder derivative complaint, Behesti v. Kim, et al., was filed in the United States District Court for the Eastern District of Pennsylvania, naming eight current and former directors of the Company as defendants. The lawsuit asserted state and federal claims and was based on the same alleged misstatements as the shareholder class action complaint described above. The lawsuit accused the Company’s board of directors of failing to exercise reasonable and prudent supervision over the Company’s management, policies, practices, and internal controls. The plaintiff sought unspecified monetary damages on behalf of the Company as well as governance reforms. Between June 2020 and August 2020, additional shareholder derivative complaints were filed and later consolidated by the court. In March 2022, an additional shareholder derivative complaint was filed in the Delaware Court of Chancery, asserting substantially similar claims as those in the consolidated derivative action. In May 2022, the Delaware Court of Chancery entered a stay of the litigation. In March 2023, the parties submitted a joint status report to the Court of Chancery reporting that the parties agreed to a settlement in principle, which also provided for the resolution of the consolidated derivative action and certain stockholder demands. In April 2023, the plaintiffs in the consolidated derivative action filed a motion for preliminary approval of settlement with the United States District Court for the Eastern District of Pennsylvania. The proposed settlement provided for resolution of the consolidated derivative action, the derivative action pending in the Delaware Court of Chancery, and certain stockholder demands. In June 2023, the court entered an order preliminarily approving the proposed settlement of the derivative claims, in accordance with a Stipulation of Settlement. The Stipulation of Settlement contemplated that, following the settlement hearing and the final approval of the settlement by the court, the Company would implement certain corporate governance reforms described in the Stipulation of Settlement. The preliminary order also approved the form and manner of the notice of the Settlement. As part of the Settlement, in July 2023 the Company paid $1.2 million to plaintiffs’ counsel for their fees and expenses. In October 2023, the court entered an order and final judgment approving the Settlement, which became effective in November 2023. The Company has implemented the corporate governance reforms in response to the provisions of the Stipulation of Settlement. VGXI Litigation In June 2020, the Company filed a complaint in the Court of Common Pleas of Montgomery County, Pennsylvania against VGXI, Inc. and GeneOne Life Science, Inc., or GeneOne, and together with VGXI, Inc. collectively referred to as VGXI, alleging that VGXI had materially breached the Company’s supply agreement with them. The complaint seeks declaratory judgments, specific performance of the agreement, injunctive relief, an accounting, damages, attorneys’ fees, interest, costs and other relief from VGXI. In June 2020, the Company filed a petition for preliminary injunction, which was denied. Following an appeal by the Company, in July 2020, VGXI filed counterclaims against the Company, alleging that the Company had breached the supply agreement, as well as misappropriation of trade secrets and unjust enrichment. The counterclaims seek injunctive relief, damages, attorneys’ fees, interest, costs and other relief from the Company. VGXI also filed a third-party complaint against Ology Bioservices, Inc., a contract manufacturing organization that the Company had engaged to provide services similar to those that were being provided by VGXI. The Company filed an answer to VGXI’s counterclaims, disputing the allegations and the claims raised in VGXI’s filing. In October 2020, the Company filed a notice of discontinuance of appeal with the Pennsylvania Superior Court. A trial date for the litigation has not been set. The Company intends to aggressively prosecute the claims set forth in its complaint against VGXI and to vigorously defend itself against VGXI’s counterclaims. GeneOne Litigation In December 2020, GeneOne filed a complaint in the Court of Common Pleas of Montgomery County, Pennsylvania against the Company, alleging that the Company had breached the CELLECTRA Device License Agreement, or the Agreement, between the Company and GeneOne. The Company terminated the Agreement in October 2020. The complaint asserts claims for breach of contract, declaratory judgment, unfair competition, and unjust enrichment. The complaint seeks injunctive relief, an accounting, damages, disgorgement of profits, attorneys’ fees, interest, and other relief from the Company. The Company filed preliminary objections to the complaint, which were overruled by the court. In September 2021, the Company filed an answer to the complaint, new matter, and counterclaims. The Company’s counterclaims allege that GeneOne breached the Agreement and assert claims for breach of contract and declaratory judgment. The counterclaims seek damages, interest, expenses, attorney’s fees, and costs. In October 2021, GeneOne filed its answer to the Company’s counterclaims and new matter. On February 29, 2024, the Company filed a motion for summary judgment. On April 1, 2024, GeneOne filed an opposition to the Company’s motion for summary judgment. The Court has set the motion for summary judgment for a hearing on June 28, 2024. A trial date for this litigation has not been set. The Company intends to aggressively prosecute the claims set forth in its counterclaims against GeneOne and to vigorously defend itself against the claims in GeneOne’s complaint. Other Matters From time to time, the Company may be involved in disputes, including litigation, relating to claims arising out of operations in the normal course of its business. Any of these claims could subject the Company to costly legal expenses and, while the Company generally believes that it has adequate insurance to cover many different types of liabilities, its insurance carriers may deny coverage or its policy limits may be inadequate to fully satisfy any damage awards or settlements. If this were to happen, the payment of any such awards could have a material adverse effect on the Company's consolidated results of operations and financial position. Additionally, any such claims, whether or not successful, could damage the Company's reputation and business. Except as described above, the Company is not a party to any legal proceedings, the adverse outcome of which, in management’s opinion, individually or in the aggregate, would be reasonably expected to have a material adverse effect on the Company’s consolidated results of operations or financial position.

Collaborative Agreements

Collaborative Agreements	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Agreements	Collaborative Agreements Advaccine Biopharmaceuticals Suzhou Co., Ltd. On December 31, 2020, the Company entered into a Collaboration and License Agreement with Advaccine Biopharmaceuticals Suzhou Co., Ltd. (“Advaccine”), which was amended and restated on June 7, 2021 (as amended and restated, the “Advaccine Agreement”). Under the terms of the Advaccine Agreement, the Company granted to Advaccine the exclusive right to develop, manufacture and commercialize the Company’s vaccine candidate INO-4800 within the territories of China, Taiwan, Hong Kong and Macau (referred to collectively as “Greater China”) and 33 additional countries in Asia. The June 2021 amendment related to a collaboration between the Company and Advaccine to jointly conduct a global Phase 3 segment of the Company’s clinical trial of INO-4800 that was planned. The parties were jointly participating in the trial and were to equally share the global development costs for the trial, including the Company’s manufacturing costs to supply INO-4800. Advaccine agreed to be fully responsible for conducting the trial in Greater China, including its costs and expenses incurred. In the fourth quarter of 2022, the Company discontinued its internally funded efforts to develop INO-4800 as a COVID-19 heterologous booster vaccine. Advaccine continues to develop INO-4800 with its own resources under the terms of the Advaccine Agreement. In connection with the June 2021 amendment, the Company determined that the global Phase 3 trial component of the agreement was a collaboration and not a contract with a customer and therefore accounted for the June 2021 amendment under ASC Topic 808. Reimbursements from Advaccine were recognized as contra-research development expense on the condensed consolidated statement of operations once earned and collectibility was assured. For the three months ended March 31, 2023, the Company received funding of $1.2 million from Advaccine that was recorded as contra-research and development expense. No funding was received during the three months ended March 31, 2024. ApolloBio Corporation On December 29, 2017, the Company entered into an Amended and Restated License and Collaboration Agreement (the "ApolloBio Agreement"), with ApolloBio Corporation ("ApolloBio"), which was amended on June 14, 2023. Under the terms of the ApolloBio Agreement, the Company granted to ApolloBio the exclusive right to develop and commercialize VGX-3100, its DNA immunotherapy product candidate designed to treat pre-cancers caused by HPV, within the agreed upon territories. The Company is entitled to receive up to an aggregate of $20.0 million, less required income, withholding or other taxes, upon the achievement of specified milestones related to the regulatory approval of VGX-3100 in accordance with the ApolloBio Agreement. In the event that VGX-3100 is approved for marketing, the Company will be entitled to receive royalty payments based on a tiered percentage of annual net sales, with such percentage being in the low- to mid-teens, subject to reduction in the event of generic competition in a particular territory. ApolloBio’s obligation to pay royalties will continue for 10 years after the first commercial sale in a particular territory or, if later, until the expiration of the last-to-expire patent covering the licensed products in the specified territory. There were no significant reimbursable program costs under the ApolloBio Agreement during the three months ended March 31, 2024 and 2023. Coalition for Epidemic Preparedness Innovations The Company previously entered into agreements with CEPI, pursuant to which the Company intended to develop vaccine candidates against Lassa fever and MERS. As part of the arrangement between the parties, CEPI agreed to fund up to an aggregate of $56 million of costs over a five-year period for preclinical studies, as well as planned Phase 1 and Phase 2 clinical trials, to be conducted by the Company and collaborators, with funding from CEPI based on the achievement of identified milestones. In November 2022, the Company announced that it and CEPI would discontinue the development of these product candidates targeting Lassa fever and MERS, following the initial analysis of data from the studies conducted by the Company and funded by CEPI. During the three months ended March 31, 2024 and 2023, the Company received funding of $0 and $1.6 million, respectively, related to these grants and recorded those payments as contra-research and development expense. As of each of March 31, 2024 and December 31, 2023, the Company had $2.2 million recorded as an accrued liability on the condensed consolidated balance sheet related to these CEPI grants. In January 2020, CEPI awarded the Company a grant of up to $9.0 million to support preclinical and clinical development of INO-4800 through Phase 1 human testing in the United States. In April 2020, CEPI awarded the Company a grant of $6.9 million to work with the International Vaccine Institute ("IVI") and the Korea National Institute of Health ("KNIH") to conduct clinical trials of INO-4800 in South Korea, a grant of $5.0 million to accelerate development of the Company's next-generation intradermal electroporation device, known as CELLECTRA 3PSP, for the intradermal delivery of INO-4800, and a grant of $1.3 million to support large-scale manufacturing of INO-4800. During the three months ended March 31, 2024 and 2023, the Company received funding of $0 and $53,000, respectively, from CEPI related to these grants for INO-4800 and recorded such amounts as contra-research and development expense. Bill & Melinda Gates Foundation In October 2018, Gates awarded and funded the Company a grant of $2.2 million to advance the development of DMAbs to address issues in infectious disease prevention and therapy. This technology has high relevance for the control of influenza and HIV. This next-generation approach to the delivery of monoclonal antibodies would make the technology accessible to low and middle-income countries. In August 2019, Gates funded an additional $1.1 million for the project. During the three months ended March 31, 2024 and 2023, the Company recorded $39,000 and $59,000, respectively, as contra-research and development expense related to the Gates DMAb grant. As of March 31, 2024, the Company had $49,000 recorded as an accrued liability on the condensed consolidated balance sheet related to the grant.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company uses an estimated annual effective tax rate, which is based on expected annual income, statutory tax rates and tax planning opportunities available in the various jurisdictions in which the Company operates, to determine its quarterly provision for income taxes. Certain significant or unusual items are separately recognized in the quarter in which they occur and can be a source of variability in the effective tax rates from quarter to quarter. Due to the adoption of ASU 2019-12 which removes the exception under ASC 740-20-45-7 to consider all sources of income in order to determine the tax benefit resulting from a loss from continuing operations, ASC 740-20-45-7 no longer applies.

Geneos Therapeutics, Inc.

Geneos Therapeutics, Inc.	3 Months Ended
	Mar. 31, 2024
Noncontrolling Interest [Abstract]
Geneos Therapeutics, Inc.	Geneos Therapeutics, Inc. In 2016, the Company formed Geneos Therapeutics to develop and commercialize neoantigen-based personalized cancer therapies. Geneos was considered a variable interest entity (VIE) for which the Company was the primary beneficiary. The Company's Chief Scientific Officer Dr. Laurent Humeau is on the Board of Directors of Geneos. The Company's director Dr. David B. Weiner is the Chairman of the Scientific Advisory Board of Geneos. Following a series of financing transactions through June 2020, the Company held less than a majority of the outstanding equity of Geneos on an as-converted to common stock basis, which triggered a VIE reconsideration, as the Company no longer held a controlling financial interest. Based on the Company’s assessment, Geneos continued to be a VIE as it did not have sufficient equity at risk to finance its activities without additional subordinated financial support. However, the Company was not the primary beneficiary of Geneos, as it did not have the power to direct the activities that most significantly impact Geneos’ economic performance. Accordingly, the Company deconsolidated its investment in Geneos in 2020. Following the deconsolidation, the Company accounts for its common stock investment in Geneos, in which the Company lacks control but does have the ability to exercise significant influence over operating and financial policies, using the equity method. Generally, the ability to exercise significant influence is presumed when the investor possesses more than 20% of the voting interests of the investee. This presumption may be overcome based on specific facts and circumstances that demonstrate that the ability to exercise significant influence is restricted. The Company's equity method investments are reviewed for indicators of impairment at each reporting period and are written down to fair value if there is evidence of a loss in value that is other-than-temporary. Any difference between the carrying amount of the Company’s investment and the amount of underlying equity in Geneos’ net assets is amortized into income or expense accordingly. There were no basis differences identified as of the deconsolidation date that would need to be amortized. Upon deconsolidation, the Company recorded its investment at fair value. The Company determined that its investment in Geneos did not have a readily determinable fair value and therefore elected the measurement alternative in ASC 321 to subsequently record the investment at cost, less any impairments, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer. When fair value becomes determinable, from observable price changes in orderly transactions, the Company’s investment is marked to fair value. There have been no observable price changes or impairments identified since the deconsolidation date. The Company’s share of net losses of Geneos for the three months ended March 31, 2021 was $1.5 million; however, only $434,000 was recorded, reducing the Company's total investment in Geneos to $0. Of the total amount, $819,000 was allocated to the equity method investment, reducing the balance to $0 as of March 31, 2021. The remaining $4.2 million loss was allocated to the Company’s Series A and Series A-1 preferred stock investment in Geneos, on a ratable basis, reducing the balance to $0 as of March 31, 2021. In February 2021, Geneos completed a second closing of its Series A-1 preferred stock financing, in which the Company did not participate. Following this transaction, the Company held approximately 35% of the outstanding equity, on an as-converted to common stock basis. In March 2022, Geneos completed the closing of a Series A-2 preferred stock financing. The Company invested $2.0 million in the Series A-2 preferred stock financing, which was led by outside investors. The closing date of this transaction was determined to be a VIE reconsideration event; based on the Company’s assessment, Geneos continued to be a VIE as it did not have sufficient equity at risk to finance its activities without additional subordinated financial support. The Company continued to not be the primary beneficiary of Geneos, as it did not have the power to direct the activities that most significantly impact Geneos’s economic performance and should not consolidate Geneos. Following this transaction, the Company held approximately 28% of the outstanding equity, on an as-converted to common stock basis. Accordingly, the Company continued to account for its common stock investment in Geneos as an equity method investment under ASC 323 and its preferred stock investments as equity securities under ASC 321. The fair value of Geneos’s Series A-2 preferred stock was based on the per share price paid by third-party investors. The Company concluded that its Series A-2 preferred stock investment was a similar financial instrument as its Series A-1 preferred stock, and therefore remeasured the carrying value of the Series A-1 preferred stock investment at the Series A-2 preferred stock price, resulting in a gain on remeasurement of $165,000. The Company recorded its current and accumulated share of net losses of Geneos of $2.2 million, which was allocated to the Series A-1 and Series A-2 preferred stock investment in Geneos, thereby reducing the balance to $0 as of March 31, 2022. The Company has not made any further investment in Geneos subsequent to March 31, 2022. The Company will not reduce its investment below $0 and will not record its share of further net losses of Geneos as the Company has no obligation to fund Geneos. In 2023, Geneos completed the closing of its Series A-3 preferred stock financing, in which the Company did not participate. Following this transaction, the Company held approximately 23% of the outstanding equity of Geneos on an as-converted to common stock basis. The Company continues to exclusively license its SynCon ® immunotherapy and CELLECTRA ®

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On April 18, 2024, the Company closed an underwritten registered direct offering (the “Offering”) relating to the issuance and sale by the Company of 2,536,258 shares (the “Shares”) of the Company’s common stock, par value $0.001 per share (the “Common Stock”), at a price of $7.693 per share and pre-funded warrants to purchase up to 2,135,477 shares of Common Stock (the “Pre-Funded Warrants”) at a price of $7.692 per Pre-Funded Warrant, which represents the per share price for the Shares less the $0.001 per share exercise price for each Pre-Funded Warrant. The net proceeds to the Company from the Offering were approximately $33.2 million, after deducting the underwriting discounts and commissions and estimated offering expenses payable by the Company. All of the Shares and the Pre-Funded Warrants were sold by the Company. Each Pre-Funded Warrant has an initial exercise price per share of $0.001, subject to certain adjustments. The Pre-Funded Warrants may be exercised at any time until exercised in full. A holder (together with its affiliates and other attribution parties) may not exercise any portion of a Pre-Funded Warrant to the extent that immediately prior to or after giving effect to such exercise the holder would own more than 9.99% of the Company’s outstanding Common Stock immediately after exercise, which percentage may be changed at the holder’s election to a lower or higher percentage not in excess of 19.99% (if exceeding such percentage would result in a change of control under Nasdaq Listing Rule 5635(b) or any successor rule) upon 61 days’ notice to the Company subject to the terms of the Pre-Funded Warrants.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net loss	$ (30,469,871)	$ (40,649,317)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Basis of Presentation, Liquid_2

Basis of Presentation, Liquidity and Risks and Uncertainties (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation and Liquidity	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Inovio have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) as contained in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") for interim financial information and with instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, the condensed consolidated statements of stockholders' equity and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 are unaudited, but include all adjustments (consisting of normal recurring adjustments) that the Company considers necessary for a fair presentation of the financial position, results of operations, cash flows and changes in stockholders' equity for the periods presented. The results of operations for the three months ended March 31, 2024 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2024, or for any other period. These unaudited financial statements, and notes thereto, should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2023, included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 6, 2024. The balance sheet at December 31, 2023 has been derived from the audited financial statements at that date, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiary. As of March 31, 2024 and December 31, 2023, the Company consolidated its wholly-owned subsidiary Inovio Asia LLC. All intercompany accounts and transactions were eliminated upon consolidation. Liquidity The Company incurred a net loss attributable to common stockholders of $30.5 million for the three months ended March 31, 2024. The Company had working capital of $88.3 million and an accumulated deficit of $1.7 billion as of March 31, 2024. The Company has incurred losses in each year since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future in connection with the research and preclinical and clinical development of its product candidates. On April 18, 2024, the Company closed an underwritten registered direct offering (the “Offering”) relating to the issuance and sale of 2,536,258 shares (the “Shares”) of its common stock, par value $0.001 per share, at a price of $7.693 per share and pre-funded warrants to purchase up to 2,135,477 shares of common stock (the “Pre-Funded Warrants”) at a price of $7.692 per Pre-Funded Warrant, which represents the per share price for the Shares less the $0.001 per share exercise price for each Pre-Funded Warrant. The net proceeds from the Offering were approximately $33.2 million, after deducting the underwriting discounts and commissions and estimated offering expenses payable by the Company. The Company’s cash, cash equivalents and short-term investments of $105.6 million as of March 31, 2024, together with the net proceeds from the April 2024 Offering, are expected to be sufficient to support the Company's planned operations for a period of at least 12 months from the date of issuance of these financial statements. In order to continue to fund future research and development activit ies, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements, grant agreements and/or future public or private debt or equity financings including At-the-Market Equity Offering Sales Agreements (“Sales Agreements”). The Company has a history of conducting debt and equity financings, including the receipt of net proceeds of $5.2 million and $5.5 million under a Sales Agreement during the three months ended March 31, 2024 and year ended December 31, 2023, respectively . However, sufficient funding may not be available in the future, or if available, may be on terms that significantly dilute or otherwise adversely affect the rights of existing stockholders. If adequate funds are not available, the Company may need to delay, reduce the scope of or put on hold one or more of its clinical and/or preclinical programs. The Company’s ability to continue its operations is dependent upon its ability to obtain additional capital in the future and achieve profitable operations. The Company expects to continue to rely on outside sources of financing to meet its capital needs and the Company may never achieve positive cash flow. These condensed consolidated financial statements do not include any adjustments to the specific amounts and classifications of assets and liabilities, which might be necessary should Inovio be unable to continue as a going concern. The Company's condensed consolidated financial statements as of and for the three months ended March 31, 2024 have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has evaluated subsequent events after the balance sheet date through the date it issued these condensed consolidated financial statements.
Collaboration Agreements and Revenue Recognition	Collaboration Agreements and Revenue Recognition
Research and Development Expenses - Clinical Trial Accruals	Research and Development Expenses - Clinical Trial Accruals The Company's activities have largely consisted of research and development efforts related to developing its proprietary device technology and DNA medicine candidates. For clinical trial expenses, judgements used in estimating accruals rely on estimates of total costs incurred based on participant enrollment, completion of studies and other events. Accrued clinical trial costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to the Company's results of operations.
Net Loss Per Share	Basic net loss per share is computed by dividing the net loss for the period by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is calculated in accordance with the treasury stock method for the outstanding stock options and RSUs and refle cts the potential dilution that would occur if securities or other con tracts to issue common stock were exercised or converted to common stock. The dilutive impact of the Notes previously issued by the Company (discussed in Note 6) was considered using the "if-converted" method. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the options or other securities and the presumed exercise of such securities are dilutive to net loss per share for the period, an adjustment to the net loss used in the calculation is required to remove the change in fair value of such securities from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any. For the three months ended March 31, 2024 and 2023, basic and diluted net loss per share were the same, as the assumed exercise or settlement of stock options and RSUs and the potentially dilutive shares issuable upon conversion of the Notes would have been anti-dilutive.
Stock-Based Compensation	The Company incurs stock-based compensation expense related to RSUs and stock options. The fair value of restricted stock is determined by the closing price of the Company's common stock reported on the Nasdaq Capital Market on the date of grant. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of subjective assumptions, including the expected stock price volatility and expected option life. The Company amortizes the fair value of the awards on a straight-line basis over the requisite vesting period of the awards. Expected volatility is based on historical volatility. The expected life of options granted is based on historical expected life. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. The Company recognizes forfeitures as they occur.

Short-term Investments and Fa_2

Short-term Investments and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Summary of Investments	The following is a summary of available-for-sale securities as of March 31, 2024 and December 31, 2023: As of March 31, 2024 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 45,541,438 $ — $ (3,022,011) $ 42,519,427 U.S. treasury securities Less than 1 39,596,119 — (8,719) 39,587,400 Certificates of deposit Less than 1 2,979,254 11,222 (295) 2,990,181 U.S. agency mortgage-backed securities * 1,331,885 — (415,849) 916,036 $ 89,448,696 $ 11,222 $ (3,446,874) $ 86,013,044 As of December 31, 2023 Contractual Cost Gross Unrealized Gross Unrealized Fair Market Value Mutual funds --- $ 55,389,289 $ — $ (3,522,888) $ 51,866,401 U.S. treasury securities Less than 1 75,164,782 24,938 — 75,189,720 Certificates of deposit Less than 1 2,978,917 11,709 (300) 2,990,326 U.S. agency mortgage-backed securities * 1,340,439 — (403,973) 936,466 $ 134,873,427 $ 36,647 $ (3,927,161) $ 130,982,913 *No single maturity date.
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of March 31, 2024: Fair Value Measurements at March 31, 2024 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 42,519,427 $ 42,519,427 $ — $ — U.S. treasury securities 39,587,400 39,587,400 — — Certificates of deposit 2,990,181 — 2,990,181 — U.S. agency mortgage-backed securities 916,036 — 916,036 — Total short-term investments 86,013,044 82,106,827 3,906,217 — Investment in affiliated entity 2,654,269 2,654,269 — — Total assets measured at fair value $ 88,667,313 $ 84,761,096 $ 3,906,217 $ — The following table presents the Company’s assets that were measured at fair value on a recurring basis, determined using the following inputs as of December 31, 2023: Fair Value Measurements at December 31, 2023 Total Quoted Prices Significant Significant Short-term investments Mutual funds $ 51,866,401 $ 51,866,401 $ — $ — U.S. treasury securities 75,189,720 75,189,720 — — Certificates of deposit 2,990,326 — 2,990,326 — U.S. agency mortgage-backed securities 936,466 — 936,466 — Total short-term investments 130,982,913 127,056,121 3,926,792 — Investment in affiliated entity 2,780,287 2,780,287 — — Total assets measured at fair value $ 133,763,200 $ 129,836,408 $ 3,926,792 $ —

Certain Balance Sheet Items (Ta

Certain Balance Sheet Items (Tables)	3 Months Ended
	Mar. 31, 2024
Certain Balance Sheet Items [Abstract]
Schedule Of Prepaid Expenses And Other Current Assets	Prepaid and other current assets consisted of the following: March 31, 2024 December 31, 2023 Prepaid manufacturing expenses 228,378 1,486,638 Other prepaid expenses 3,288,703 3,907,027 $ 3,517,081 $ 5,393,665
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued expenses consisted of the following: March 31, 2024 December 31, 2023 Trade accounts payable $ 6,772,184 $ 3,577,826 Accrued compensation 5,685,560 9,837,104 Other accrued expenses (a) 4,218,178 6,432,814 $ 16,675,922 $ 19,847,744 (a) As of March 31, 2024 and December 31, 2023, balance includes $2.3 million and $4.3 million, respectively, of liability for unused grant funding.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Schedule of Summary of Common and Preferred Stock Authorized, Issued and Outstanding	The following is a summary of the Company's authorized and issued common and preferred stock as of March 31, 2024 and December 31, 2023: Outstanding as of Authorized Issued March 31, 2024 December 31, 2023 Common Stock, par value $0.001 per share 600,000,000 23,371,253 23,371,253 22,793,075 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 9 9

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes potential shares of common stock that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect: Three Months Ended March 31, 2024 2023 Options to purchase common stock 1,355,178 1,271,620 Service-based restricted stock units 392,120 179,149 Convertible preferred stock 275 275 Convertible notes — 254,165 Total 1,747,573 1,705,209

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Weighted Average Assumptions	The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Three Months Ended March 31, 2024 2023 Risk-free interest rate 4.21% 4.09% Expected volatility 105% 99% Expected life in years 5.5 5.5 Dividend yield — —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	As of March 31, 2024, the maturities of the Company's operating lease liabilities were as follows: Remainder of 2024 $ 2,457,000 2025 3,467,000 2026 3,555,000 2027 2,955,000 2028 2,310,000 Thereafter 2,132,000 Total remaining lease payments 16,876,000 Less: present value adjustment (3,449,000) Total operating lease liabilities 13,427,000 Less: current portion (2,156,000) Long-term operating lease liabilities $ 11,271,000 Weighted-average remaining lease term 5.0 years Weighted-average discount rate 9.0%

Basis of Presentation, Liquid_3

Basis of Presentation, Liquidity and Risks and Uncertainties (Details)			1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 18, 2024 USD ($) $ / shares shares	Jan. 24, 2024	Jan. 31, 2024	Mar. 31, 2024 USD ($) $ / shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) $ / shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss				$ 30,469,871	$ 40,649,317
Working capital				88,300,000
Accumulated deficit				$ 1,653,435,007		$ 1,622,965,136
Common stock, par value (in dollars per share) | $ / shares				$ 0.001		$ 0.001
Cash, cash equivalents, and short-term investments				$ 105,600,000
Proceeds from issuance of stock				$ 5,225,133	$ 0	$ 5,500,000
Stock split, conversion ratio		0.083333	0.083333
Underwritten Registered Direct Offering | Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from sale of stock	$ 33,200,000
Underwritten Registered Direct Offering | Common stock | Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of shares issued in transaction (in shares) | shares	2,536,258
Common stock, par value (in dollars per share) | $ / shares	$ 0.001
Sale of stock, price per share (in dollars per share) | $ / shares	$ 7.693
Underwritten Registered Direct Offering | Warrant | Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of shares issued in transaction (in shares) | shares	2,135,477
Sale of stock, price per share (in dollars per share) | $ / shares	$ 7.692
Warrant exercise price (in dollars per share) | $ / shares	$ 0.001

Short-term Investments and Fa_3

Short-term Investments and Fair Value Measurements - Summary of Available-for-sale Securities (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Abstract]
Cost	$ 89,448,696	$ 134,873,427
Gross Unrealized Gains	11,222	36,647
Gross Unrealized Losses	(3,446,874)	(3,927,161)
Fair Market Value	86,013,044	130,982,913
Mutual funds
Debt Securities, Available-for-sale [Abstract]
Cost	45,541,438	55,389,289
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3,022,011)	(3,522,888)
Fair Market Value	$ 42,519,427	$ 51,866,401
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Contractual Maturity (in years)	1 year	1 year
Debt Securities, Available-for-sale [Abstract]
Cost	$ 39,596,119	$ 75,164,782
Gross Unrealized Gains	0	24,938
Gross Unrealized Losses	(8,719)	0
Fair Market Value	$ 39,587,400	$ 75,189,720
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Contractual Maturity (in years)	1 year	1 year
Debt Securities, Available-for-sale [Abstract]
Cost	$ 2,979,254	$ 2,978,917
Gross Unrealized Gains	11,222	11,709
Gross Unrealized Losses	(295)	(300)
Fair Market Value	2,990,181	2,990,326
U.S. agency mortgage-backed securities
Debt Securities, Available-for-sale [Abstract]
Cost	1,331,885	1,340,439
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(415,849)	(403,973)
Fair Market Value	$ 916,036	$ 936,466

Short-term Investments and Fa_4

Short-term Investments and Fair Value Measurements - Narrative (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) position shares	Mar. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Realized gain on investments	$ 200	$ 300
Realized loss on investments	691,000	2,400,000
Net unrealized (gain) loss on available-for-sale equity securities	$ 500,877	$ 3,218,215
Number of securities in a gross unrealized loss position | position	25
Unrealized loss	$ 3,400,000
Number of securities in a gross unrealized loss position for more than twelve months | position	19
Level 1
Debt Securities, Available-for-sale [Line Items]
Investment owned (in shares) | shares	597,808

Short-term Investments and Fa_5

Short-term Investments and Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	$ 86,013,044	$ 130,982,913
Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	42,519,427	51,866,401
Certificates of deposit
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	2,990,181	2,990,326
U.S. agency mortgage-backed securities
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	916,036	936,466
Fair Value, Measurements, Recurring
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	86,013,044	130,982,913
Investment in affiliated entity	2,654,269	2,780,287
Total assets measured at fair value	88,667,313	133,763,200
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	82,106,827	127,056,121
Investment in affiliated entity	2,654,269	2,780,287
Total assets measured at fair value	84,761,096	129,836,408
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	3,906,217	3,926,792
Investment in affiliated entity	0	0
Total assets measured at fair value	3,906,217	3,926,792
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Investment in affiliated entity	0	0
Total assets measured at fair value	0	0
Fair Value, Measurements, Recurring | Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	42,519,427	51,866,401
Fair Value, Measurements, Recurring | Mutual funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	42,519,427	51,866,401
Fair Value, Measurements, Recurring | Mutual funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | Mutual funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | U.S. treasury securities
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	39,587,400	75,189,720
Fair Value, Measurements, Recurring | U.S. treasury securities | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	39,587,400	75,189,720
Fair Value, Measurements, Recurring | U.S. treasury securities | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | U.S. treasury securities | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | Certificates of deposit
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	2,990,181	2,990,326
Fair Value, Measurements, Recurring | Certificates of deposit | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | Certificates of deposit | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	2,990,181	2,990,326
Fair Value, Measurements, Recurring | Certificates of deposit | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | U.S. agency mortgage-backed securities
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	916,036	936,466
Fair Value, Measurements, Recurring | U.S. agency mortgage-backed securities | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	0	0
Fair Value, Measurements, Recurring | U.S. agency mortgage-backed securities | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	916,036	936,466
Fair Value, Measurements, Recurring | U.S. agency mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Short-term investments	$ 0	$ 0

Certain Balance Sheet Items - P

Certain Balance Sheet Items - Prepaid and Other Current Assets (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Certain Balance Sheet Items [Abstract]
Prepaid manufacturing expenses	$ 228,378	$ 1,486,638
Other prepaid expenses	3,288,703	3,907,027
Prepaid expense and other assets, current	$ 3,517,081	$ 5,393,665

Certain Balance Sheet Items - A

Certain Balance Sheet Items - Accounts Payable and Accrued Expenses (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounts Payable and Accrued Expenses [Line Items]
Grant liability	$ 2,300,000	$ 4,300,000
Nonrelated Party
Accounts Payable and Accrued Expenses [Line Items]
Trade accounts payable	6,772,184	3,577,826
Accrued compensation	5,685,560	9,837,104
Other accrued expenses	4,218,178	6,432,814
Total	$ 16,675,922	$ 19,847,744

Convertible Debt - Narrative (D

Convertible Debt - Narrative (Details) - USD ($)			3 Months Ended
	Mar. 01, 2024	Mar. 01, 2019	Mar. 31, 2024	Mar. 31, 2023	Feb. 19, 2019
Debt Instrument [Line Items]
Repayment of convertible senior notes			$ 16,415,000	$ 0
Non-cash interest expense			177,833	313,488
Convertible senior notes | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, face amount		$ 78,500,000			$ 78,500,000
Debt interest based on the fixed rate (in percent)		6.50%			6.50%
Proceeds from issuance of debt		$ 75,700,000
Repayment of convertible senior notes	$ 16,900,000
Non-cash interest expense			178,000	313,000
Interest expense, contractual interest			$ 178,000	$ 267,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Authorized and Issued Common and Preferred Stock (Details) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Summary of common and preferred stock authorized, issued and outstanding
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares, authorized (in shares)	600,000,000
Common stock, shares, issued (in shares)	23,371,253
Common stock, shares, outstanding (in shares)	23,371,253	22,793,075
Series C Preferred Stock
Summary of common and preferred stock authorized, issued and outstanding
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,091
Preferred stock, shares issued (in shares)	1,091
Preferred stock, shares outstanding (in shares)	9	9

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
	Nov. 09, 2021	Mar. 31, 2024	Dec. 31, 2023	May 16, 2023	Mar. 31, 2023	Jun. 24, 2022
2023 Incentive Plan
Class of Stock [Line Items]
Number of shares authorized (in shares)				1,166,666
Number of shares available for grant (in shares)		917,945
Number of shares of unvested restricted stock units and options outstanding (in shares)		171,750
Common stock, other shares, outstanding (in shares)		260,109
Award vesting period (in years)		3 years
Maximum contractual term (in years)		10 years
2016 Incentive Plan
Class of Stock [Line Items]
Number of shares of unvested restricted stock units and options outstanding (in shares)		207,594
Common stock, other shares, outstanding (in shares)		950,763
Award vesting period (in years)		3 years
Maximum contractual term (in years)		10 years
2022 Inducement Plan
Class of Stock [Line Items]
Number of shares authorized (in shares)						166,666
Number of shares available for grant (in shares)		116,515
Number of shares of unvested restricted stock units and options outstanding (in shares)		12,776
Common stock, other shares, outstanding (in shares)		33,071
2007 Incentive Plan
Class of Stock [Line Items]
Common stock, other shares, outstanding (in shares)		111,235
Maximum contractual term (in years)		10 years
McDermid v. Inovio Pharmaceuticals, Inc. and J. Joseph Kim
Class of Stock [Line Items]
Shares issued in settlement (in shares)					760,083
Common stock | 2021 Sales Agreement
Class of Stock [Line Items]
Maximum authorized amount	$ 300
Sale of stock, sales proceeds of any common stock, percentage (in percent)	3%
Aggregate number of shares issued (in shares)		543,620	875,305
Stock sale agreement weighted average price (in dollars per share)		$ 9.76	$ 6.33
Aggregate proceeds		$ 5.2	$ 5.5

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	1,747,573	1,705,209
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	1,355,178	1,271,620
Service-based restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	392,120	179,149
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	275	275
Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	0	254,165

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions (Details) - Stock Options - Employees and Directors	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	4.21%	4.09%
Expected volatility	105%	99%
Expected life in years	5 years 6 months	5 years 6 months
Dividend yield	0%	0%

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation	$ 2,525,433	$ 3,809,003
Total unrecognized compensation cost related to unvested stock options	$ 4,300,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized (in years)	1 year 8 months 12 days
Weighted average grant date fair value (in dollars per share)	$ 6.77	$ 11.64
Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested stock options	$ 4,100,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized (in years)	1 year 10 months 24 days
Weighted average grant date fair value, restricted stock units (in dollars per share)	$ 8.39	$ 14.40
Employees and Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation	$ 2,400,000	$ 3,600,000
Employees and Directors | Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	1,000,000	1,500,000
Employees and Directors | General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	1,400,000	2,100,000
Non Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation	$ 103,000	$ 220,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended		3 Months Ended		12 Months Ended
	Dec. 31, 2022	Mar. 31, 2016	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2023
Related Party Transaction [Line Items]
Research and development expenses			$ 20,913,790	$ 30,176,511
Accounts receivable			2,551,082				$ 2,405,228
The Wistar Institute
Related Party Transaction [Line Items]
Collaborative agreement, amended amount					$ 13,600,000
Affiliated Entity
Related Party Transaction [Line Items]
Expenses to reimburse		$ 3,100,000
Collaborative arrangement, term (in years)		5 years
Contra-research and development expense			140,000	211,000
Affiliated Entity | The Wistar Institute
Related Party Transaction [Line Items]
Awarded amount	$ 1,200,000					$ 10,700,000
Awarded option amount	$ 5,400,000				$ 1,600,000
Research and development expenses			475,000	$ 422,000
Accounts receivable			2,500,000				2,400,000
Accounts payable and accrued liabilities, current			1,500,000				1,100,000
Deferred grant funding, from affiliate			$ 22,000				$ 22,000
Plumbline Life Sciences
Related Party Transaction [Line Items]
Investment owned (in shares)			597,808
Non-controlling interest (in percent)			17.80%

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	1 Months Ended			3 Months Ended
	Nov. 30, 2023 ft²	Jul. 31, 2023 USD ($)	Apr. 30, 2020 director	Mar. 31, 2024 USD ($) ft²	Dec. 31, 2023 ft²	Sep. 30, 2023 ft²	Mar. 31, 2023 USD ($) shares	Dec. 31, 2019 ft² agreement	Jan. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Lease cost				$ 837			$ 840
Number of agreements | agreement								2
McDermid v. Inovio Pharmaceuticals, Inc. and J. Joseph Kim
Lessee, Lease, Description [Line Items]
Estimate of cash settlement									$ 30,000
Estimate of shares settlement									$ 14,000
Shares issued in settlement (in shares) | shares							760,083
Behesti v. Kim, et al.
Lessee, Lease, Description [Line Items]
Number of defendants | director			8
Damages paid		$ 1,200
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease term (in years)				3 years 2 months 12 days
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease term (in years)				5 years 9 months 18 days
San Diego, California
Lessee, Lease, Description [Line Items]
Area leased (in square feet) | ft²				56,600
Plymouth Meeting, Pennsylvania
Lessee, Lease, Description [Line Items]
Area leased (in square feet) | ft²				57,400	7,000	4,400		13,500
San Diego, California
Lessee, Lease, Description [Line Items]
Area leased (in square feet) | ft²	5,600
Lessee, operating lease, term of contract (in years)	4 years 3 months 18 days
Lessee, operating lease, base rate percentage (in percent)	3%

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2024	$ 2,457,000
2025	3,467,000
2026	3,555,000
2027	2,955,000
2028	2,310,000
Thereafter	2,132,000
Total remaining lease payments	16,876,000
Less: present value adjustment	(3,449,000)
Total operating lease liabilities	13,427,000
Less: current portion	(2,155,540)	$ (2,406,522)
Long-term operating lease liabilities	$ 11,271,257	$ 11,032,066
Weighted-average remaining lease term	5 years
Weighted-average discount rate	9%

Collaborative Agreements (Detai

Collaborative Agreements (Details) - USD ($)	1 Months Ended					3 Months Ended
	Apr. 30, 2020	Jan. 31, 2020	Aug. 30, 2019	Oct. 31, 2018	Apr. 30, 2018	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from related parties						$ 0	$ 114,943
Advaccine | Collaborative Arrangement, Product
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received						0	1,200,000
ApolloBio | Collaborative Arrangement, Product
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional revenue to be achieved						$ 20,000,000
Royalty period (in years)						10 years
Revenue from related parties						$ 0	0
Coalition for Epidemic Preparedness Innovations | Collaborative Arrangement, Product
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, funding to be received	$ 6,900,000
Coalition for Epidemic Preparedness Innovations | Collaborative Arrangement, Product | Lassa Fever and MERS Vaccine
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, funding to be received					$ 56,000,000
Collaborative agreement, period to receive funding for research and development (in years)					5 years
Collaborative agreement, funding received						0	1,600,000
Accrued liabilities						2,200,000		$ 2,200,000
Coalition for Epidemic Preparedness Innovations | Collaborative Arrangement, Product | INO-4800
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, funding to be received	1,300,000	$ 9,000,000
Collaborative agreement, funding received						0	53,000
Coalition for Epidemic Preparedness Innovations | Collaborative Arrangement, Product | CELLECTRA 3PSP Proprietary Smart Device
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, funding to be received	$ 5,000,000
Bill and Melinda Gates Foundation | Collaborative Arrangement, Product | DNA-Encoded Monoclonal Antibody Technology
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, funding received			$ 1,100,000	$ 2,200,000		39,000	$ 59,000
Accrued liabilities						$ 49,000

Geneos Therapeutics, Inc. - Nar

Geneos Therapeutics, Inc. - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2023	Feb. 28, 2021
Geneos Therapeutics, Inc.
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by parent (in percent)	28%		23%	35%
Series A-2 One Preferred Stock
Noncontrolling Interest [Line Items]
Share of net loss in Geneos	$ 2,200
Investment in Geneos	0
Resulting in again on remeasurement	165
Geneos Therapeutics, Inc.
Noncontrolling Interest [Line Items]
Loss from equity method investment, recorded and allocated to investment		$ 1,500
Share of net loss in Geneos		434
Investment in Geneos		0
Geneos Therapeutics, Inc. | Series A One Preferred Stock
Noncontrolling Interest [Line Items]
Share of net loss in Geneos		819
Geneos Therapeutics, Inc. | Common stock
Noncontrolling Interest [Line Items]
Investment in Geneos		0
Geneos Therapeutics, Inc. | Preferred stock
Noncontrolling Interest [Line Items]
Share of net loss in Geneos		4,200
Investment in Geneos		$ 0
Payments to acquire additional interest in subsidiaries	$ 2,000

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 18, 2024	Mar. 31, 2024	Dec. 31, 2023
Subsequent Event [Line Items]
Common stock, par value (in dollars per share)		$ 0.001	$ 0.001
Subsequent Event | Underwritten Registered Direct Offering
Subsequent Event [Line Items]
Proceeds from sale of stock	$ 33.2
Class of warrant or right, common stock ownership (in percent)	19.99%
Subsequent Event | Underwritten Registered Direct Offering | Common stock
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares)	2,536,258
Common stock, par value (in dollars per share)	$ 0.001
Sale of stock, price per share (in dollars per share)	$ 7.693
Class of warrant or right, common stock ownership (in percent)	9.99%
Subsequent Event | Underwritten Registered Direct Offering | Warrant
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares)	2,135,477
Warrant exercise price (in dollars per share)	$ 0.001
Sale of stock, price per share (in dollars per share)	$ 7.692