Inovio Pharmaceuticals (INO) 10-Q 12 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 07, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	INOVIO PHARMACEUTICALS, INC.
Entity Central Index Key	0001055726
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		100,010,328

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 15,853,236	$ 23,693,633
Short-term investments	77,945,753	57,538,852
Accounts receivable	776,295	3,316,361
Accounts receivable from affiliated entities	978,544	738,583
Prepaid expenses and other current assets	1,677,602	1,406,590
Prepaid expenses and other current assets from affiliated entities	1,581,111	1,120,805
Total current assets	98,812,541	87,814,824
Fixed assets, net	13,516,389	15,949,014
Intangible assets, net	3,960,457	4,760,145
Goodwill	10,513,371	10,513,371
Operating lease right-of-use assets	14,002,860
Other assets	2,731,055	2,669,998
Total assets	151,533,430	131,113,265
Current liabilities:
Accounts payable and accrued expenses	9,783,964	23,134,733
Accounts payable and accrued expenses due to affiliated entities	462,596	977,792
Accrued clinical trial expenses	4,500,898	5,671,764
Deferred revenue	106,111	223,577
Deferred revenue from affiliated entities	64,825	33,575
Deferred rent		1,065,387
Operating lease liability	2,011,008
Deferred grant funding	1,896,526	4,165,848
Deferred grant funding from affiliated entities	720,925	27,083
Total current liabilities	19,546,853	35,299,759
Deferred revenue, net of current portion	124,105	150,793
Derivative liability	4,503,918	0
Deferred rent, net of current portion		8,518,207
Operating lease liability, net of current portion	20,953,308
Deferred tax liabilities	26,649	24,766
Deferred grant funding from affiliated entities	135,000	0
Other liabilities	50,343	87,333
Total liabilities	115,414,698	44,080,858
Stockholders’ equity:
Preferred stock	0	0
Common stock	99,046	97,226
Additional paid-in capital	735,017,743	707,794,215
Accumulated deficit	(702,123,617)	(620,426,436)
Accumulated other comprehensive income (loss)	700,398	(528,867)
Total Inovio Pharmaceuticals, Inc. stockholders’ equity	33,693,570	86,936,138
Non-controlling interest	2,425,162	96,269
Total stockholders’ equity	36,118,732	87,032,407
Total liabilities and stockholders’ equity	151,533,430	131,113,265
GeneOne Life Sciences
Current assets:
Investment in affiliated entity	5,707,256	6,381,926
Other assets	338,000	381,000
Plumbline Life Sciences
Current assets:
Investment in affiliated entity	2,289,501	3,023,987
6.50% Convertible Senior Notes Due 2024
Current liabilities:
Convertible debt	62,119,671	0
Korean Won Convertible Bonds Due 2024
Current liabilities:
Convertible debt	$ 7,954,851	$ 0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 866,863	$ 2,000,868	$ 3,832,442	$ 27,979,273
Operating expenses:
Research and development	19,137,209	21,851,858	66,013,364	68,892,229
General and administrative	5,681,441	6,791,693	18,506,570	23,679,018
Total operating expenses	24,818,650	28,643,551	84,519,934	92,571,247
Loss from operations	(23,951,787)	(26,642,683)	(80,687,492)	(64,591,974)
Other income (expense):
Interest income	637,438	565,039	2,018,302	1,648,987
Interest expense	(2,428,671)	0	(5,279,702)	0
Change in fair value of common stock warrants	0	228,665	0	360,795
Change in fair value of derivative liability	2,551,453	0	2,551,453	0
Gain (loss) on investment in affiliated entities	(485,841)	1,017,359	(1,409,156)	1,305,174
Other income (expense), net	140,956	(184,052)	232,629	(558,796)
Net loss before income tax benefit/(provision for income tax)	(23,536,452)	(25,015,672)	(82,573,966)	(61,835,814)
Income tax benefit/(provision for income taxes)	0	0	169,571	(2,169,811)
Net loss	(23,536,452)	(25,015,672)	(82,404,395)	(64,005,625)
Net loss attributable to non-controlling interest	445,759	0	707,214	0
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (23,090,693)	$ (25,015,672)	$ (81,697,181)	$ (64,005,625)
Net loss per share attributable to Inovio Pharmaceuticals, Inc. stockholders
Basic (dollars per share)	$ (0.23)	$ (0.27)	$ (0.83)	$ (0.70)
Diluted (dollars per share)	$ (0.25)	$ (0.27)	$ (0.83)	$ (0.70)
Weighted average number of common shares outstanding
Basic (shares)	99,007,985	92,423,122	98,204,375	91,350,117
Diluted (shares)	102,807,056	92,423,122	98,204,375	91,350,117
Revenue under collaborative research and development arrangements
Revenues:
Total revenues	$ 617,427	$ 1,813,287	$ 3,452,422	$ 27,488,185
Revenue under collaborative research and development arrangements with affiliated entities
Revenues:
Total revenues	53,014	184,990	179,984	393,317
Miscellaneous revenue
Revenues:
Total revenues	$ 196,422	$ 2,591	$ 200,036	$ 97,771

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (23,536,452)	$ (25,015,672)	$ (82,404,395)	$ (64,005,625)
Other comprehensive income (loss):
Unrealized gain (loss) on short-term investments, net of tax	(31,457)	316,626	1,229,265	66,611
Comprehensive loss	(23,567,909)	(24,699,046)	(81,175,130)	(63,939,014)
Comprehensive loss attributable to non-controlling interest	445,759	0	707,214	0
Comprehensive loss attributable to Inovio Pharmaceuticals, Inc.	$ (23,122,150)	$ (24,699,046)	$ (80,467,916)	$ (63,939,014)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($)	Total	Preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Non- controlling interest
Beginning balance (in shares) at Dec. 31, 2017		23	90,357,644
Beginning balance at Dec. 31, 2017	$ 142,488,809	$ 0	$ 90,358	$ 665,775,504	$ (523,356,317)	$ (117,005)	$ 96,269
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			347,287
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	(506,403)		$ 347	(506,750)
Stock-based compensation	3,575,750			3,575,750
Net loss attributable to common stockholders	(32,350,828)				(32,350,828)
Unrealized gain (loss) on short-term investments, net of tax	(112,765)					(112,765)
Ending balance (in shares) at Mar. 31, 2018		23	90,704,931
Ending balance at Mar. 31, 2018	113,094,563	$ 0	$ 90,705	668,844,504	(555,475,779)	(461,136)	96,269
Beginning balance (in shares) at Dec. 31, 2017		23	90,357,644
Beginning balance at Dec. 31, 2017	142,488,809	$ 0	$ 90,358	665,775,504	(523,356,317)	(117,005)	96,269
Net loss attributable to common stockholders	(64,005,625)
Unrealized gain (loss) on short-term investments, net of tax	66,611
Ending balance (in shares) at Sep. 30, 2018		23	94,472,389
Ending balance at Sep. 30, 2018	103,709,174	$ 0	$ 94,472	690,930,769	(587,130,576)	(281,760)	96,269
Beginning balance (in shares) at Mar. 31, 2018		23	90,704,931
Beginning balance at Mar. 31, 2018	113,094,563	$ 0	$ 90,705	668,844,504	(555,475,779)	(461,136)	96,269
Issuance of common stock for cash (in shares)			407,429
Issuance of common stock for cash	1,973,401		$ 407	1,972,994
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			362,035
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	611,061		$ 362	610,699
Stock-based compensation	2,589,170			2,589,170
Net loss attributable to common stockholders	(6,639,125)				(6,639,125)
Unrealized gain (loss) on short-term investments, net of tax	(137,250)					(137,250)
Ending balance (in shares) at Jun. 30, 2018		23	91,474,395
Ending balance at Jun. 30, 2018	111,491,820	$ 0	$ 91,474	674,017,367	(562,114,904)	(598,386)	96,269
Issuance of common stock for cash (in shares)			2,560,051
Issuance of common stock for cash	12,949,862		$ 2,560	12,947,302
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			437,943
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	1,615,147		$ 438	1,614,709
Stock-based compensation	2,351,391			2,351,391
Net loss attributable to common stockholders	(25,015,672)				(25,015,672)
Unrealized gain (loss) on short-term investments, net of tax	316,626					316,626
Ending balance (in shares) at Sep. 30, 2018		23	94,472,389
Ending balance at Sep. 30, 2018	103,709,174	$ 0	$ 94,472	690,930,769	(587,130,576)	(281,760)	96,269
Beginning balance (in shares) at Dec. 31, 2018		23	97,225,810
Beginning balance at Dec. 31, 2018	87,032,407	$ 0	$ 97,226	707,794,215	(620,426,436)	(528,867)	96,269
Issuance of common stock for cash (in shares)			183,200
Issuance of common stock for cash	907,330		$ 183	907,147
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			525,000
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	(719,397)		$ 525	(719,922)
Equity component of issuance of convertible notes	15,752,698			15,752,698
Stock-based compensation	3,432,796			3,432,796
Acquisition of non-controlling interest in Geneos	3,030,107						3,030,107
Net loss attributable to common stockholders	(29,288,867)				(29,219,262)		(69,605)
Unrealized gain (loss) on short-term investments, net of tax	819,177					819,177
Ending balance (in shares) at Mar. 31, 2019		23	97,934,010
Ending balance at Mar. 31, 2019	80,966,251	$ 0	$ 97,934	727,166,934	(649,645,698)	290,310	3,056,771
Beginning balance (in shares) at Dec. 31, 2018		23	97,225,810
Beginning balance at Dec. 31, 2018	87,032,407	$ 0	$ 97,226	707,794,215	(620,426,436)	(528,867)	96,269
Net loss attributable to common stockholders	(82,404,395)
Unrealized gain (loss) on short-term investments, net of tax	1,229,265
Ending balance (in shares) at Sep. 30, 2019		23	99,046,158
Ending balance at Sep. 30, 2019	36,118,732	$ 0	$ 99,046	735,017,743	(702,123,617)	700,398	2,425,162
Beginning balance (in shares) at Mar. 31, 2019		23	97,934,010
Beginning balance at Mar. 31, 2019	80,966,251	$ 0	$ 97,934	727,166,934	(649,645,698)	290,310	3,056,771
Issuance of common stock for cash (in shares)			476,600
Issuance of common stock for cash	1,388,986		$ 476	1,388,510
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			173,761
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	(81,259)		$ 174	(81,433)
Stock-based compensation	3,355,195			3,345,378			9,817
Cost of acquisition of non-controlling interest in Geneos	(13,569)						(13,569)
Net loss attributable to common stockholders	(29,579,076)				(29,387,226)		(191,850)
Unrealized gain (loss) on short-term investments, net of tax	441,545					441,545
Ending balance (in shares) at Jun. 30, 2019		23	98,584,371
Ending balance at Jun. 30, 2019	56,478,073	$ 0	$ 98,584	731,819,389	(679,032,924)	731,855	2,861,169
Issuance of common stock for cash (in shares)			382,800
Issuance of common stock for cash	1,128,749		$ 383	1,128,366
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (in shares)			78,987
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	0		$ 79	(79)
Stock-based compensation	2,079,819			2,070,067			9,752
Net loss attributable to common stockholders	(23,536,452)				(23,090,693)		(445,759)
Unrealized gain (loss) on short-term investments, net of tax	(31,457)					(31,457)
Ending balance (in shares) at Sep. 30, 2019		23	99,046,158
Ending balance at Sep. 30, 2019	$ 36,118,732	$ 0	$ 99,046	$ 735,017,743	$ (702,123,617)	$ 700,398	$ 2,425,162

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (23,536,452)	$ (29,288,867)	$ (25,015,672)	$ (32,350,828)	$ (82,404,395)	$ (64,005,625)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation					2,746,463	2,768,096
Amortization of intangible assets	267,000		267,000		799,688	983,021
Change in fair value of common stock warrants					0	(360,795)
Change in fair value of derivative liability					(2,551,453)	0
Stock-based compensation					8,867,810	8,516,349
Non-cash interest expense					2,587,619	0
Amortization of premiums on investments					1,962	71,707
Loss (gain) on short-term investments					(238,083)	557,875
Loss (gain) on equity investment in affiliated entities	485,841		(1,017,359)		1,409,156	(1,305,174)
Tax benefit from other unrealized gains on short-term investments					(335,228)	0
Effect of foreign exchange rates on cash and cash equivalents					183,756	0
Changes in operating assets and liabilities:
Accounts receivable					2,540,066	3,171,498
Accounts receivable from affiliated entities					(239,961)	(1,081,016)
Prepaid expenses and other current assets					(271,012)	999,047
Prepaid expenses and other current assets from affiliated entities					(460,306)	(261,187)
Other assets					(61,057)	13,695
Accounts payable and accrued expenses					(12,791,123)	(4,888,115)
Accrued clinical trial expenses					(1,170,866)	(1,258,837)
Accounts payable and accrued expenses due to affiliated entities					(515,196)	(236,023)
Deferred revenue					(144,154)	(1,006,745)
Deferred revenue from affiliated entities					31,250	(105,685)
Operating lease right-of-use assets and liabilities, net					(622,138)	(277,892)
Deferred grant funding					(2,269,322)	1,297,416
Deferred grant funding from affiliated entities					828,842	39,583
Other liabilities					(35,107)	99,669
Net cash used in operating activities					(84,112,789)	(56,269,138)
Cash flows from investing activities:
Purchases of investments					(86,950,301)	(47,869,250)
Maturities of investments					68,344,014	84,848,556
Purchases of capital assets					(873,484)	(1,741,955)
Net cash (used in) provided by investing activities					(19,479,771)	35,237,351
Cash flows from financing activities:
Proceeds from issuance of convertible senior notes and convertible bonds					93,425,973	0
Costs related to issuance of convertible senior notes and convertible bonds					(3,314,757)	0
Proceeds from issuance of common stock, net of issuance costs					3,425,065	14,923,263
Taxes paid related to net share settlement of equity awards, net of proceeds from stock option exercises					(800,656)	1,719,767
Acquisition of non-controlling interest					3,016,538	0
Net cash provided by financing activities					95,752,163	16,643,030
Decrease in cash and cash equivalents					(7,840,397)	(4,388,757)
Cash and cash equivalents, beginning of period		$ 23,693,633		$ 23,786,579	23,693,633	23,786,579	$ 23,786,579
Cash and cash equivalents, end of period	$ 15,853,236		$ 19,397,822		15,853,236	19,397,822	$ 23,693,633
Supplemental disclosures:
Amounts accrued for purchases of property and equipment					0	188,253
Interest paid					$ 2,692,083	$ 0

Organization and Operations

Organization and Operations	9 Months Ended
	Sep. 30, 2019
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 the discovery, development, and commercialization of its synthetic DNA technology targeted against cancers and infectious diseases. The Company's DNA-based immunotherapies and vaccines, in combination with its proprietary, efficacy-enabling delivery devices, are intended to generate robust immune responses, in particular functional CD8+ killer T cells and antibodies, to fight target diseases. Inovio’s synthetic products are based on its SynCon ® immunotherapy design. The Company and its collaborators are currently conducting or planning clinical programs of its proprietary SynCon ® immunotherapies for HPV-caused pre-cancers, including cervical, vulvar and anal dysplasia; HPV-caused cancers, including head & neck, cervical, anal, penile, vulvar, and vaginal; other HPV-caused disorders, such as recurrent respiratory papillomatosis ("RRP"); glioblastoma multiforme ("GBM"); prostate cancer; hepatitis B virus; hepatitis C virus; HIV; Ebola; Middle East Respiratory Syndrome, or MERS; Lassa fever; and Zika virus. The Company also recently announced its intention to accelerate the clinical development of its dBTE (DNA-encoded bi-specific T cell engagers) technology and build on recent advances of its dMAb™ (DNA-encoded monoclonal antibody) technology. The Company's partners and collaborators include AstraZeneca PLC, Regeneron Pharmaceuticals, Inc., F. Hoffmann-La Roche AG/Genentech, Inc., ApolloBio Corporation, GeneOne Life Science Inc. ("GeneOne"), The Bill and Melinda Gates Foundation, Coalition for Epidemic Preparedness Innovations (“CEPI”), Parker Institute for Cancer Immunotherapy ("PICI"), Defense Advanced Research Projects Agency (“DARPA”), National Institutes of Health ("NIH"), National Institute of Allergy and Infectious Diseases (“NIAID”), National Cancer Institute ("NCI"), HIV Vaccines Trial Network ("HVTN"), Walter Reed Army Institute of Research, Medical CBRN Defense Consortium ("MCDC"), The Wistar Institute, and the University of Pennsylvania. Inovio was incorporated in Delaware in June 2001 and has its principal executive offices in Plymouth Meeting, Pennsylvania.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	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 September 30, 2019 , the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss and the condensed consolidated statements of stockholders' equity for the three and nine months ended September 30, 2019 and 2018 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2019 and 2018 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 and nine months ended September 30, 2019 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 , 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, 2018 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 12, 2019. The balance sheet at December 31, 2018 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 subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc. and VGX Pharmaceuticals, Inc. ("VGX") and records a non-controlling interest for 39% of its subsidiary Geneos Therapeutics, Inc. ("Geneos") as well as 15% of VGX Animal Health, Inc., a subsidiary of VGX. All intercompany accounts and transactions have been eliminated upon consolidation. Inovio incurred a net loss attributable to common stockholders of $23.1 million and $81.7 million for the three and nine months ended September 30, 2019 , respectively. Inovio had working capital of $79.3 million and an accumulated deficit of $702.1 million as of September 30, 2019 . 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. The Company’s cash, cash equivalents and short-term investments of $93.8 million and long-term investments of $8.0 million as of September 30, 2019 , are sufficient to support the Company's operations for a period of at least 12 months from the date it is issuing these financial statements. In addition, the Company could sell up to an additional $68.5 million in shares of its common stock under its At-the-Market Equity Offering Sales Agreement (the “Sales Agreement”), subject to certain conditions set forth in the Sales Agreement. In order to continue to fund future research and development activities, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements and/or future public or private debt or equity financings including use of its Sales Agreement. The Company has a history of debt and equity financings, including the receipt of net proceeds of $75.7 million from a private placement of 6.50% convertible senior notes due 2024 (the “Notes”) in the first quarter of 2019 and net proceeds of $14.5 million from the private placement of 1.0% convertible bonds due 2024 (the "Bonds") during the three months ended September 30, 2019. The Company also received net proceeds of $1.1 million and $3.4 million under the Sales Agreement during the three and nine months ended September 30, 2019 , respectively, and net proceeds of $29.2 million under the Sales Agreement and a prior at-the-market equity offering agreement during the year ended December 31, 2018. 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. In July 2019, the Company announced a strategic organizational restructuring. In order to reduce operating expenses and conserve cash resources, the Company reduced approximately 28% of its workforce and discontinued its immuno-oncology Phase 1/2 clinical trial of its product candidate INO-5401 in patients with advanced bladder cancer. In the third quarter of 2019, the Company incurred a personnel-related restructuring charge of $2.2 million in connection with one-time employee termination costs, including severance and other benefits. 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. Inovio’s condensed consolidated financial statements as of and for the three and nine months ended September 30, 2019 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.

Critical Accounting Policies

Critical Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Critical Accounting Policies	Critical Accounting Policies Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. The Company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company assesses the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) product supply services; (iii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iv) royalties on net sales of licensed products. Where a portion of non-refundable, upfront fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The standalone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company will utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Product Supply Services Arrangements that include a promise for future supply of drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company will assess if these options provide a material right to the licensee and if so, they will be accounted for as separate performance obligations. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements. Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605, Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra-expense as opposed to revenue on the condensed consolidated statement of operations. Leases The Company adopted ASU 2016‑02, Leases (Topic 842) (“Topic 842”) on January 1, 2019. For its long-term operating leases, the Company recognized an operating lease right-of-use asset and an operating lease liability on its condensed consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The Company determines the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Fixed rent expense for the Company's operating leases is recognized on a straight-line basis over the term of the lease and is included in operating expenses on the condensed consolidated statements of operations. Variable lease payments including lease operating expenses are recorded as incurred. Prior period amounts continue to be reported in accordance with the historic accounting under the previous lease guidance, ASC 840, Leases (Topic 840). See “Impact of Recently Issued Accounting Standards” below, for more information about the impact of the adoption of Topic 842. Research and Development Expenses The Company’s activities have largely consisted of research and development efforts related to developing electroporation delivery technologies and DNA immunotherapies and vaccines. Research and development expenses consist of expenses incurred in performing research and development activities including salaries and benefits, facilities and other overhead expenses, clinical trials, contract services and other outside expenses. Research and development expenses are charged to operations as they are incurred. These expenses result from the Company's independent research and development efforts as well as efforts associated with collaborations and licensing arrangements. The Company reviews and accrues clinical trial expense based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. 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. Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from two to 18 years. Acquired intangible assets are continuously being developed for the future economic viability contemplated at the time of acquisition. The Company is concurrently conducting preclinical studies and clinical trials using the acquired intangibles and has entered into licensing agreements for the use of these acquired intangibles. Historically, the Company has recorded patents at cost and amortized these costs using the straight-line method over the expected useful lives of the patents or 17 years, whichever is less. Patent cost consists of the consideration paid for patents and related legal costs. Effective as of the acquisition of VGX in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of September 30, 2019 and December 31, 2018 , the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $4.0 million and $4.8 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s condensed consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. The Company’s judgments regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of its acquired businesses, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible asset to fair value. While current and historical operating and cash flow losses are potential indicators of impairment, the Company believes the future cash flows to be received from its intangible assets will exceed the intangible assets’ carrying value, and accordingly, the Company has not recognized any impairment losses through September 30, 2019 . Goodwill represents the excess of acquisition cost over the fair value of the net assets of acquired businesses. Goodwill is reviewed for impairment at least annually at November 30, or more frequently if an event occurs indicating the potential for impairment. During its goodwill impairment review, the Company may assess qualitative factors to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying amount, including goodwill. The qualitative factors include, but are not limited to, macroeconomic conditions, industry and market considerations, and the overall financial performance of the Company. If, after assessing the totality of these qualitative factors, the Company determines that it is not more likely than not that the fair value of its reporting unit is less than its carrying amount, then no additional assessment is deemed necessary. Otherwise, the Company proceeds to perform the two-step test for goodwill impairment. The first step involves comparing the estimated fair value of the reporting unit with its carrying value, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the Company performs the second step of the goodwill impairment test to determine the amount of loss, which involves comparing the implied fair value of the goodwill to the carrying value of the goodwill. The Company may also elect to bypass the qualitative assessment in a period and elect to proceed to perform the first step of the goodwill impairment test. The Company performed its annual assessment for goodwill impairment as of November 30, 2018, identifying no impairment. Although there are inherent uncertainties in this assessment process, the estimates and assumptions the Company is using are consistent with its internal planning. If these estimates or their related assumptions change in the future, the Company may be required to record an impairment charge on all or a portion of its goodwill and intangible assets. Furthermore, the Company cannot predict the occurrence of future impairment triggering events nor the impact such events might have on its reported asset values. Future events could cause the Company to conclude that impairment indicators exist and that goodwill or other intangible assets associated with its acquired businesses are impaired. Any resulting impairment loss could have an adverse impact on the Company’s results of operations. See Note 8 for further discussion of the Company’s goodwill and intangible assets. Derivative Liabilities The Company evaluates its debt and equity issuances to determine if those contracts or embedded components of those contracts qualify as derivatives requiring separate recognition in the Company’s financial statements. The result of this accounting treatment is that the fair value of the embedded derivative is revalued at each balance sheet date and recorded as a liability, and the change in fair value during the reporting period is recorded in other income (expense) in the condensed consolidated statements of operations. In circumstances where the embedded conversion option in a convertible instrument is required to be bifurcated and there are also other embedded derivative instruments in the convertible instrument that are required to be bifurcated, the bifurcated derivative instruments are accounted for as a single, compound derivative instrument. The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is reassessed at the end of each reporting period. Derivative instrument liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement of the derivative instrument is expected within twelve months of the balance sheet date. Foreign Currency Translation The functional and presentation currency of the Company is the U.S. dollar. Transactions denominated in a currency other than the functional currency are recorded on the initial recognition at the exchange rate at the date of the transaction. After initial recognition monetary assets and liabilities denominated in foreign currency are translated at the end of each reporting period into the functional currency at the exchange rate at that date. The cumulative translation adjustment is included in the accumulated other comprehensive gain (loss) within the statement of stockholders' equity. Exchange differences are included in general and administrative expenses in the condensed consolidated statement of operations. Non- monetary assets and liabilities measured at cost are translated at the exchange rate at the date of the transaction.

Impact of Recently Issued Accou

Impact of Recently Issued Accounting Standards	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Impact of Recently Issued Accounting Standards	Impact of Recently Issued Accounting Standards The recent accounting pronouncements below may have a significant effect on the Company's financial statements. Recent accounting pronouncements that are not anticipated to have an impact on or are unrelated to the Company's financial condition, results of operations, or related disclosures are not discussed. ASU No. 2016-02 . In February 2016, the FASB issued Topic 842, which requires lessees to recognize most leases on the balance sheet as lease liabilities with corresponding right-of-use assets and to disclose key information about leasing arrangements. The Company adopted the new lease standard on January 1, 2019 using the modified retrospective approach. The Company elected the available package of practical expedients upon adoption, which allowed the Company to carry forward its historical assessment of whether existing agreements contained a lease and the classification of its existing operating leases. Upon adoption, the Company recognized an operating right-of use asset and operating lease liability in its condensed consolidated balance sheet of approximately $14.6 million and $24.2 million , respectively. The Company also classified deferred rent of $9.6 million as an offset to the Company’s operating right-of-use asset upon adoption. There were no adjustments to the Company’s opening accumulated deficit balance upon adoption. The impact of the adoption of Topic 842 on the condensed consolidated balance sheets as of January 1, 2019 was as follows: ASC 840 Topic 842 January 1, 2019 Impact of Adoption January 1, 2019 Deferred rent $ 1,065,387 $ (1,065,387 ) $ — Deferred rent, net of current portion $ 8,518,207 $ (8,518,207 ) $ — Operating right-of-use assets $ — $ 14,634,769 $ 14,634,769 Operating lease liability $ — $ 1,733,600 $ 1,733,600 Operating lease liability, net of current portion $ — $ 22,484,763 $ 22,484,763 ASU No. 2018-07 . In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting, that simplifies the accounting for stock-based payments granted to non-employees for services by generally aligning it with the accounting for stock-based payments granted to employees. The Company adopted the standard on January 1, 2019 and there was no material impact to its condensed consolidated financial statements. ASU No. 2018-13 . In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement , which amends certain disclosure requirements over Level 1, Level 2 and Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-13, but does not anticipate it will have a material impact on its disclosures. ASU No. 2018-18 . In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which clarified the interaction between Topic 808, Collaborative Arrangements , and Topic 606, Revenue from Contracts with Customers . ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-18.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition During the three and nine months ended September 30, 2019 , the Company recognized total revenue under collaborative research and development and other agreements of $255,000 and $3.0 million , respectively, from AstraZeneca and $612,000 and $803,000 , respectively, from various other contracts. The Company defers revenue when a contract is entered into with a collaborator and cash payments are received prior to satisfaction of the related performance obligation. Of the total revenue recognized during the three and nine months ended September 30, 2019 , $41,000 and $256,000 , respectively, was in deferred revenue as of December 31, 2018. Of the total revenue recognized during the three and nine months ended September 30, 2018 , $316,000 and $1.3 million , respectively, was in deferred revenue as of December 31, 2017. Performance obligations are generally satisfied within 12 months of the initial contract date.

Investments

Investments	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Investments at September 30, 2019 consisted of mutual funds. Investments at December 31, 2018 consisted of mutual funds and United States corporate debt securities. Investments are recorded at fair value, based on current market valuations. Unrealized gains and losses on the Company's debt securities will continue to be excluded from earnings and are reported as a separate component of other comprehensive loss until realized. Realized gains and losses are included in non-operating other income (expense) on the condensed consolidated statements of operations and are derived using the specific identification method for determining the cost of the securities sold. During the three and nine months ended September 30, 2019 , $145,000 and $238,000 , respectively, of net realized gain on investments was recorded. During the three and nine months ended September 30, 2018 , $(184,000) and $(558,000) , respectively, of net realized loss on investments was recorded. Interest and dividends on investments classified as available-for-sale are included in interest income in the condensed consolidated statements of operations. As of September 30, 2019 , the Company had no available-for-sale securities in an unrealized loss position for longer than 12 months . The following is a summary of available-for-sale securities as of September 30, 2019 and December 31, 2018 : As of September 30, 2019 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 76,910,152 $ 1,038,733 $ (3,132 ) $ 77,945,753 As of December 31, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 57,842,955 $ — $ (528,084 ) $ 57,314,871 US corporate debt securities Less than 2 224,633 — (652 ) 223,981 Total investments $ 58,067,588 $ — $ (528,736 ) $ 57,538,852

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value Measurements	Marketable Securities and Fair Value Measurements The guidance regarding fair value measurements establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets that are accessible at the measurement date; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Assets are classified based on the lowest level of input that is significant to the fair value measurements. The Company reviews the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy. The Company did not have any transfer of assets between Level 1, Level 2 and Level 3 of the fair value hierarchy during the nine months ended September 30, 2019 or 2018 . The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis, and are determined using the following inputs as of September 30, 2019 : Fair Value Measurements at September 30, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 3,317,462 $ 3,317,462 $ — $ — Mutual funds 77,945,753 — 77,945,753 — Investment in affiliated entities 7,996,757 7,996,757 — — Total assets $ 89,259,972 $ 11,314,219 $ 77,945,753 $ — Liabilities: Derivative liability (Note 9) $ 4,503,918 $ — $ — 4,503,918 Total liabilities $ 4,503,918 $ — $ — $ 4,503,918 The following table presents the Company’s assets that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2018 : Fair Value Measurements at December 31, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,646,507 $ 9,646,507 $ — $ — Mutual funds 57,314,871 — 57,314,871 — US corporate debt securities 223,981 — 223,981 — Investment in affiliated entities 9,405,913 9,405,913 — — Total assets $ 76,591,272 $ 19,052,420 $ 57,538,852 $ — Level 1 assets at September 30, 2019 consisted of money market funds held by the Company that are valued at quoted market prices, as well as the Company’s investments in affiliates, GeneOne and PLS. The Company accounts for its investment in 1,644,155 common shares of GeneOne based on the closing price of the shares on the Korean Stock Exchange on the applicable balance sheet date. The Company accounts for its investment in 395,758 common shares of PLS based on the closing price of the shares on the Korea New Exchange (KONEX) Market on the applicable balance sheet date. Unrealized gains and losses on the Company's equity securities are reported in the condensed consolidated statement of operations as a gain (loss) on investment in affiliated entities. Level 2 assets at September 30, 2019 consisted of mutual funds 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 September 30, 2019 . Level 3 liabilities held as of September 30, 2019 consisted of the embedded conversion option contained in the Bonds that met the criteria to be bifurcated and accounted for separately from the Bonds (the "Derivative Liability"). The Derivative Liability was recorded at fair value of $ 7.1 million upon the issuance of the Bonds and is subsequently remeasured to fair value at each reporting period. The Derivative Liability was initially valued and remeasured using a "with-and-without" method. The "with-and-without" methodology involves valuing the whole instrument on an as-is basis and then valuing the instrument without the embedded conversion option. The difference between the entire instrument with the embedded conversion option compared to the instrument without the embedded conversion option is the fair value of the derivative, recorded as the Derivative Liability. The fair value of the Bonds with the conversion option is estimated using a Monte Carlo simulation approach. The key inputs to valuing the Bonds with the conversion option as of September 30, 2019 include the Company’s stock price on the valuation date; the expected annual volatility of the Company’s common stock, and the discount yield, which was derived by making the fair value of the Bonds equal to the face value on the issuance date. Fair value measurements are highly sensitive to changes in these inputs and significant changes in these inputs could result in a significantly higher or lower fair value. The following table presents the changes in fair value of the Company's derivative liability for the nine months ended September 30, 2019: Balance at December 31, 2018 $ — Initial fair value upon issuance of the Bonds 7,055,371 Change in fair value (2,551,453 ) Balance at September 30, 2019 $ 4,503,918

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following sets forth the goodwill and intangible assets by major asset class: September 30, 2019 December 31, 2018 Useful Life (Yrs) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Indefinite lived: Goodwill(a) $ 10,513,371 $ — $ 10,513,371 $ 10,513,371 $ — $ 10,513,371 Definite lived: Patents 8 – 17 5,802,528 (5,787,384 ) 15,144 5,802,528 (5,742,079 ) 60,449 Licenses 8 – 17 1,323,761 (1,240,917 ) 82,844 1,323,761 (1,219,357 ) 104,404 CELLECTRA ® (b) 5 – 11 8,106,270 (7,999,501 ) 106,769 8,106,270 (7,679,190 ) 427,080 GHRH(b) 11 335,314 (327,392 ) 7,922 335,314 (303,630 ) 31,684 Bioject(c) 2 – 15 5,100,000 (2,102,222 ) 2,997,778 5,100,000 (1,882,222 ) 3,217,778 Other(d) 18 4,050,000 (3,300,000 ) 750,000 4,050,000 (3,131,250 ) 918,750 Total intangible assets 24,717,873 (20,757,416 ) 3,960,457 24,717,873 (19,957,728 ) 4,760,145 Total goodwill and intangible assets $ 35,231,244 $ (20,757,416 ) $ 14,473,828 $ 35,231,244 $ (19,957,728 ) $ 15,273,516 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition. Aggregate amortization expense on intangible assets for the three and nine months ended September 30, 2019 was $267,000 and $800,000 , respectively. Aggregate amortization expense on intangible assets for the three and nine months ended September 30, 2018 was $267,000 and $983,000 , respectively. Estimated aggregate amortization expense is $ 267,000 for the remainder of fiscal year 2019 , $547,000 for 2020 , $ 520,000 for 2021 , $ 493,000 for 2022 , $ 276,000 for 2023 and $ 1.9 million for 2024 and subsequent years combined.

Convertible Debt

Convertible Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Convertible Debt	Convertible Debt Convertible Bonds On August 1, 2019, the Company closed a private placement of the Bonds with an aggregate principal amount of 18 billion Korean Won (KRW) (approximately USD $15.0 million based on the exchange rate on the date of issuance) issued to institutional investors led by Korea Investment Partners (KIP), a global venture capital and private equity firm based in Seoul, Korea. Net proceeds from the offering were approximately $14.5 million . The Company also announced its intent to pursue a listing of its securities on the KOSDAQ Market of the Korea Exchange (KOSDAQ) in the form of Korean Depositary Receipts (KDRs) representing shares of common stock. The Bonds, which are unsecured obligations of the Company, were issued on August 1, 2019 and will accrue interest at a coupon rate of 1.00% per annum, payable quarterly. The Bonds will mature on July 31, 2024, unless earlier converted or repurchased. The outstanding Bonds will be repaid at maturity at a price equal to the principal of the outstanding bonds to be repaid plus a premium on such bonds to provide an internal rate of return with respect to such bonds of 6.00% . Commencing on August 1, 2020, the Bonds will be convertible until the date that is one month prior to maturity date. Upon conversion, the Company will deliver KDRs, if the Company has any such securities listed on the KOSDAQ at that time, or otherwise shares of common stock, if KDRs are not listed on KOSDAQ at that time or the converting holder requests delivery of shares of common stock. The initial conversion rate is 211.0595 shares per KRW 1,000,000 in principal amount (equivalent to an initial conversion price of approximately USD $4.00 per share based on the exchange rate as of July 30, 2019), subject to adjustment upon the occurrence of specified events. The conversion rate is subject to reset on January 2, 2020 and on each three month anniversary thereafter until the maturity date to the then current market price if the current market price is lower than the conversion price then in effect; provided that the conversion rate will not exceed 351.7658 shares per KRW 1,000,000 (equivalent to a conversion price of approximately USD $2.40 per share based on the exchange rates as of July 30, 2019). The Bonds will be subject to repurchase by the Company at the option of the bondholders from and including July 31, 2022 up to the date that is one month prior to the maturity date at a repurchase price equal to the principal of the Bonds to be repurchased plus a premium in order to provide an internal rate of return with respect to the Bonds of 6.00% . In addition, upon the occurrence of a fundamental change (as defined in the Bonds), the Company will be required to offer to repurchase the Bonds at a repurchase price equal to the principal amount thereof plus accrued and unpaid interest thereon to but excluding the applicable repurchase date. Upon the occurrence of an event of default (as defined in the Bonds), with the approval of at least 25% of the bondholders, the Company will be required to offer to repurchase the Bonds at a repurchase price equal to the principal amount thereof plus a premium in order to provide an internal rate of return with respect to the Bonds of 8.00% . The Company evaluated the accounting for the issuance of the Bonds and concluded that the embedded conversion feature is considered a derivative requiring bifurcation from the Bonds as it does not meet the equity scope exception due to the fact that it is denominated in a currency other than the Company's functional currency. The fair value of the conversion feature at August 1, 2019 was $7.1 million , which was recorded as a reduction to the carrying value of the debt. This debt discount is being amortized to interest expense over the term of the debt using the effective interest method. The conversion option is accounted for as a derivative liability, which is revalued each reporting period with the resulting change in fair value reflected in other income (expense), net, in the condensed consolidated statements of operations. The Company determined that all other features of the Bonds were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's condensed consolidated financial statements. The balance of the Bonds at September 30, 2019 is as follows: Principal amount $ 15,052,055 Unamortized debt discount (6,945,328 ) Unamortized debt issuance cost (262,013 ) Accretion of premium associated with the Bonds 84,569 Accrued interest 25,568 Net carrying amount $ 7,954,851 The Company determined that the expected life of the Bonds was equal to the period through August 1, 2022 as this represents the point at which the Bonds are initially subject to repurchase by the Company at the option of the holders. Accordingly, the total debt discount of $7.3 million, inclusive of the fair value of the embedded conversion feature derivative at issuance, is being amortized using the effective interest method through August 1, 2022. The effective interest rate of the Bonds is 29.4% . For the three and nine months ended September 30, 2019, the Company recognized $374,000 of interest expense related to the Bonds, of which $26,000 related to the contractual interest coupon. As of September 30, 2019, there have not been any conversions or redemptions of the Bonds. The derivative liability is valued at $4.5 million as of September 30, 2019. The change in fair value of the derivative liability was $2.6 million for the three and nine months ended September 30, 2019. 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 approximately $75.7 million . The Notes are senior unsecured obligations of the Company and accrue interest payable in cash semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2019, at a rate of 6.50% per annum. The Notes will mature on March 1, 2024, unless earlier converted, redeemed or repurchased. Prior to the close of business on the business day immediately preceding November 1, 2023, the Notes will be convertible at the option of the holders only upon the satisfaction of certain circumstances. Thereafter, the Notes will be convertible at the option of the holders at any time until the close of business on the scheduled trading day immediately before the maturity date. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at its election. The initial conversion rate will be 185.8045 shares per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $5.38 per share), subject to adjustment upon the occurrence of specified events. The Company may not redeem the Notes prior to March 1, 2022. On or after March 1, 2022, the Company may redeem all, or any portion, of the Notes for cash if the last reported sale price per share of the Company's common stock exceeds 130% of the conversion price on (i) each of at least 20 trading days (whether or not consecutive) during the 30 consecutive trading days ending on, and including, the trading day immediately before the Company sends the related redemption notice; and (ii) the trading day immediately before the date the Company sends such redemption notice. The redemption price will be equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. The Company evaluated the accounting for the issuance of the Notes and concluded that the embedded conversion features meet the requirements for a derivative scope exception for instruments that are both indexed to an entity’s own stock and classified in stockholders’ equity in its condensed consolidated balance sheet, and that the cash conversion guidance applies. Therefore, the Notes issuance proceeds of $78.5 million are allocated first to the liability component based on the fair value of non-convertible debt with otherwise identical residual terms with the residual proceeds allocated to equity for the conversion features. The Company determined that the fair value of the non-convertible debt upon issuance of the Notes was $62.2 million and recorded this amount as a liability and the offsetting amount as a debt discount as a reduction to the carrying value of the Notes on the closing date. The debt issuance costs associated with the Notes of $2.8 million are allocated to the liability and equity component in the same proportion as the issuance proceeds. The Company determined that all other features of the Notes were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's condensed consolidated financial statements. The balance of the Notes at September 30, 2019 is as follows: Principal amount $ 78,500,000 Unamortized debt discount on the liability component (14,772,356 ) Unamortized debt issuance cost (2,033,181 ) Accrued interest 425,208 Net carrying amount $ 62,119,671 The Company determined that the expected life of the Notes was equal to the period through November 1, 2023 as this represents the point at which the Notes are initially subject to repurchase by the Company at the option of the holders. Accordingly, the total debt discount of $18.6 million , inclusive of the fair value of the embedded conversion feature derivative at issuance, is being amortized using the effective interest method through November 1, 2023. The effective interest rate of the liability component is 13.1% . For the three and nine months ended September 30, 2019 , the Company recognized $2.1 million and $4.9 million, respectively, of interest expense related to the Notes, of which $1.3 million and $3.1 million , respectively, related to the contractual interest coupon. As of September 30, 2019 , there have not been any conversions or redemptions of the Notes.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019 and December 31, 2018 : Outstanding as of Authorized Issued September 30, 2019 December 31, 2018 Common Stock, par value $0.001 per share 600,000,000 99,046,158 99,046,158 97,225,810 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 23 23 Common Stock In May 2018, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “Sales Agreement”) with an outside placement agent (the “Placement Agent”) to sell shares of its common stock with aggregate gross proceeds of up to $100.0 million , from time to time, through an “at-the-market” equity offering program under which the Placement Agent will act as sales agent. Under the Sales Agreement, the Company will set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limitation on the number of shares that may be sold in any one trading day and any minimum price below which sales may not be made. The Sales Agreement provides that the Placement Agent will be entitled to compensation for its services in an amount equal to up to 3.0% of the gross proceeds from the sales of shares sold through the Placement Agent under the Sales Agreement. The Company has no obligation to sell any shares under the Sales Agreement, and may at any time suspend solicitation and offers under the Sales Agreement. During the three and nine months ended September 30, 2019 , the Company sold 382,800 and 1,042,600 shares of common stock, respectively, under the Sales Agreement. The sales were made at a weighted average price of $3.01 and $3.35 per share, respectively, resulting in aggregate net proceeds of $1.1 million and $3.4 million , respectively. The Company may sell up to an additional $68.5 million in shares of its common stock under the Sales Agreement. The registration statement that registered with the SEC the shares that may be sold under the Sales Agreement expires on June 8, 2021. Stock Options and Restricted Stock Units The Company has a stock-based incentive plan, the 2016 Omnibus Incentive Plan (as amended to date, the "2016 Incentive Plan"), pursuant to which the Company may grant stock options, restricted stock awards, restricted stock units and other stock-based awards or short-term cash incentive awards to employees, directors and consultants. The 2016 Incentive Plan was originally approved by the Company's stockholders on May 13, 2016, and an amendment to the plan to increase the number of shares available for issuance was approved by the stockholders on May 8, 2019. The maximum number of shares of the Company’s common stock available for issuance over the term of the 2016 Incentive Plan may not exceed 16,000,000 shares, provided that commencing with the first business day of each calendar year beginning January 1, 2020, such maximum number of shares shall be increased by 2,000,000 shares of common stock unless the Board determines, prior to January 1 for any such calendar year, to increase such maximum amount by a fewer number of shares or not to increase the maximum amount at all for such year. At September 30, 2019 , there were 16,000,000 shares of common stock reserved for issuance upon exercise of incentive awards granted and to be granted at future dates under the 2016 Incentive Plan. At September 30, 2019 , the Company had 7,849,847 shares of common stock available for future grant under the 2016 Incentive Plan, 2,118,026 shares underlying outstanding but unvested restricted stock units and options outstanding to purchase 4,817,921 shares of common stock under the 2016 Incentive Plan. The awards granted and available for future grant under the 2016 Incentive Plan generally vest over three years and have a maximum contractual term of ten years. The 2016 Incentive Plan terminates by its terms on March 9, 2026. The Amended and Restated 2007 Omnibus Incentive Plan (the "2007 Incentive Plan") was adopted on March 31, 2007 and terminated by its terms on March 31, 2017. At September 30, 2019 , the Company had 3,333 shares underlying outstanding but unvested restricted stock units and options outstanding to purchase 5,153,376 shares of common stock under the 2007 Incentive Plan. The awards granted under the 2007 Incentive Plan generally vest over three years and have a maximum contractual term of ten years.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2019
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 year by the weighted average number of common shares outstanding during the year. Diluted net loss per share is calculated in accordance with the treasury stock method for the outstanding stock options and restricted stock units and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. For the three and nine months ended September 30, 2019 , the dilutive impact of the outstanding Notes and Bonds issued by the Company (discussed in Note 9) has been 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 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. The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Three Months Ended September 30, 2019 2018 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. (numerator for use in basic net loss per share) $ (23,090,693 ) $ (25,015,672 ) Adjustment for decrease in fair value of derivative liability and interest expense (2,177,250 ) — Numerator for use in diluted net loss per share $ (25,267,943 ) $ (25,015,672 ) Denominator Weighted average number of common shares outstanding (denominator for use in basic net loss per share) 99,007,985 92,423,122 Effect of dilutive potential common shares 3,799,071 — Denominator for use in diluted net loss per share 102,807,056 92,423,122 Net loss per share, diluted $ (0.25 ) $ (0.27 ) Net loss per share, basic $ (0.23 ) $ (0.27 ) Nine Months Ended September 30, 2019 2018 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. (numerator for use in basic net loss per share) $ (81,697,181 ) $ (64,005,625 ) Adjustment for decrease in fair value of derivative liability and interest expense — — — Numerator for use in diluted net loss per share $ (81,697,181 ) $ (64,005,625 ) Denominator Weighted average number of common shares outstanding (denominator for use in basic net loss per share) 98,204,375 91,350,117 Effect of dilutive potential common shares — — Denominator for use in diluted net loss per share 98,204,375 91,350,117 Net loss per share, diluted $ (0.83 ) $ (0.70 ) Net loss per share, basic $ (0.83 ) $ (0.70 ) 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 for the three months ended September 30, 2019 and 2018 : Common Stock Equivalents 2019 2018 Options to purchase common stock 9,971,297 8,945,275 Restricted stock units 2,121,359 1,711,213 Convertible preferred stock 8,456 8,456 Convertible notes 14,585,653 — Convertible bonds — — Total 26,686,765 10,664,944 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 for the nine months ended September 30, 2019 and 2018 : Common Stock Equivalents 2019 2018 Options to purchase common stock 9,971,297 8,945,275 Restricted stock units 2,121,359 1,711,213 Convertible preferred stock 8,456 8,456 Convertible notes 14,585,653 — Convertible bonds 3,799,071 — Total 30,485,836 10,664,944

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company incurs stock-based compensation expense related to restricted stock units 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 Global Select 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 weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Risk-free interest rate 1.75% 2.86% 2.43% 2.73% Expected volatility 65% 71% 70% 72% Expected life in years 6.1 6.1 6.2 6.2 Dividend yield — — — — Total employee and director stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and nine months ended September 30, 2019 was $ 1.8 million and $8.1 million , respectively, of which $ 922,000 and $5.1 million , respectively, was included in research and development expenses, and $ 885,000 and $3.0 million , respectively, was included in general and administrative expenses. Total employee and director stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and nine months ended September 30, 2018 was $ 2.2 million and $8.0 million , respectively, of which $ 1.2 million and $4.7 million , respectively, was included in research and development expenses, and $ 1.0 million and $3.3 million , respectively, was included in general and administrative expenses. At September 30, 2019 , 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 1.9 years . The weighted average grant date fair value per share, calculated using the Black-Scholes option pricing model, was $1.65 and $2.20 for employee and director stock options granted during the three and nine months ended September 30, 2019 , respectively, and $ 2.96 and $2.85 for employee and director stock options granted during the three and nine months ended September 30, 2018 , respectively. At September 30, 2019 , there was $5.3 million of total unrecognized compensation expense related to unvested restricted stock units, which is expected to be recognized over a weighted-average period of 1.7 years. The weighted average grant date fair value per share was $2.68 and $3.09 for restricted stock units granted during the three and nine months ended September 30, 2019 , respectively, and $4.31 for restricted stock units granted during the nine months ended September 30, 2018. There were no restricted stock units granted during the three months ended September 30, 2018. The Company adopted ASU 2018-07 on January 1, 2019, which generally aligned the accounting for stock-based compensation for non-employees with that of employees. The fair value of stock options granted to non-employees was estimated using the Black-Scholes pricing model. Total stock-based compensation expense for stock options and restricted stock units granted to non-employees for the three and nine months ended September 30, 2019 was $264,000 and $744,000 , respectively. Total stock-based compensation expense for stock options and restricted stock units granted to non-employees for the three and nine months ended September 30, 2018 was $160,000 and $334,000 respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	Related Party Transactions GeneOne Life Sciences The Company owns 1,644,155 shares of common stock in GeneOne as of September 30, 2019 and one of the Company's directors, Dr. David B. Weiner, acts as a consultant to GeneOne. In 2010, the Company entered into a collaboration and license agreement (the “GeneOne Agreement”) with GeneOne. Under the GeneOne Agreement, the Company granted GeneOne an exclusive license to the Company's SynCon ® universal influenza vaccine delivered with electroporation to be developed in certain countries in Asia (the “Product”). As consideration for the license granted to GeneOne, the Company received an upfront payment of $3.0 million , and is entitled to receive research support, annual license maintenance fees and royalties on net Product sales. The GeneOne Agreement also provides the Company with exclusive rights to supply devices for clinical and commercial purposes (including single use components) to GeneOne for use in the Product. The term of the GeneOne Agreement commenced upon execution and will extend on a country by country basis until the last to expire of all Royalty Periods for the territory (as such term is defined in the GeneOne Agreement) for any Product in that country, unless the GeneOne Agreement is terminated earlier in accordance with its provisions as a result of breach, by mutual agreement, or by GeneOne's right to terminate without cause upon prior written notice. In 2011, the Company entered into a collaborative development and license agreement (the “Hep Agreement”) with GeneOne. Under the Hep Agreement, as originally executed, the Company and GeneOne agreed to co-develop the Company’s SynCon ® therapeutic vaccines for hepatitis B and C infections (the “Hep Products”). Under the terms of the Hep Agreement, GeneOne will receive marketing rights for the Products in Asia, excluding Japan, and in return will fully fund IND-enabling and initial Phase 1 and 2 clinical studies with respect to the Hep Products. The Company will receive from GeneOne payments based on the achievement of clinical milestones and royalties based on sales of the Hep Products in the licensed territories, retaining all commercial rights to the Hep Products in all other territories. In 2013, the Company amended the Hep Agreement to grant back to the Company the SynCon ® therapeutic vaccines targeting hepatitis B, along with all associated rights, from the collaboration in return for certain remuneration including a percentage of license fees. In 2013, the Company further amended the Hep Agreement to in part provide exclusive patent rights to IL-28 technology for use with the Hep Products in Asia, excluding Japan. The Hep Agreement shall terminate upon the later of the expiration or abandonment of the last patent that is a component of the rights or 20 years after the effective date. In May 2015, the Company entered into a Collaborative Development Agreement with GeneOne to co-develop a DNA vaccine for MERS through Phase 1 clinical trials. Under the terms of the agreement, GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the MERS immunotherapy upon achievement of the last milestone event of completion of the Phase 1 safety and immunogenicity study. The collaborative research program shall terminate upon the completion of activities under the development plan, unless sooner terminated. In January 2016, the Company and GeneOne amended the Collaborative Development Agreement for MERS to expand the agreement to test and advance the Company's DNA-based vaccine for preventing and treating Zika virus. GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the Zika immunotherapy upon achievement of the last milestone event of the completion of the Phase 1 safety and immunogenicity study. All other agreement terms remain the same. Revenue recognized from GeneOne consisted of patent and device maintenance fees. For the three and nine months ended September 30, 2019 , the Company recognized revenue from GeneOne of $31,000 and $94,000 , respectively, and $155,000 and $305,000 for the three and nine months ended September 30, 2018 , respectively. Operating expenses recorded from transactions with GeneOne related primarily to biologics manufacturing were $232,000 and $2.1 million for the three and nine months ended September 30, 2019 , respectively and $1.9 million and $4.7 million for the three and nine months ended September 30, 2018 , respectively. At September 30, 2019 and December 31, 2018 , the Company had an accounts receivable balance of $128,000 and $0 , respectively, and an accounts payable and accrued liability balance of $107,000 and $372,000 , respectively, related to GeneOne and its subsidiaries. At September 30, 2019 and December 31, 2018 , $338,000 and $381,000 , respectively, of prepayments made to GeneOne were classified as long-term other assets on the Company's condensed consolidated balance sheet. Plumbline Life Sciences, Inc. The Company owns 395,758 shares of common stock in Plumbline Life Sciences, Inc. ("PLS") as of September 30, 2019 and one of the Company's directors, Dr. David B. Weiner, acts as a consultant to PLS. Revenue recognized from PLS consisted of license and patent fees. For the three and nine months ended September 30, 2019 , the Company recognized revenue from PLS of $22,000 and $86,000 , respectively, and $30,000 and $88,000 for the three and nine months ended September 30, 2018 , respectively. At September 30, 2019 and December 31, 2018 , the Company had an accounts receivable balance of $564,000 and $478,000 , respectively, related to PLS. The Wistar Institute Two of the Company's directors, Dr. David B. Weiner and Dr. Morton Collins, are Directors of the Vaccine Center of The Wistar Institute ("Wistar"). Dr. Weiner is also the 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 will reimburse 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 agreement. The Company will have the exclusive right to in-license new intellectual property developed under the agreement. In November 2016, the Company received a $6.1 million sub-grant through Wistar to develop a DNA-based monoclonal antibody against the Zika infection, with funding through July 2020. The Company is also a collaborator with Wistar on an Integrated Preclinical/Clinical AIDS Vaccine Development grant from the NIAID, with funding through February 2020. 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 and nine months ended September 30, 2019 , the Company recorded $482,000 and $1.7 million , respectively, and for the three and nine months ended September 30, 2018 the Company recorded $952,000 and $3.2 million , respectively, as contra-research and development expense from Wistar. Research and development expenses recorded from Wistar relate primarily to the collaborative research agreements and sub-contract agreements related to the Bill and Melinda Gates Foundation and CEPI (see Note 15). Research and development expenses recorded from Wistar for the three and nine months ended September 30, 2019 were $313,000 and $1.1 million , respectively. Research and development expenses recorded from Wistar for the three and nine months ended September 30, 2018 were $615,000 and $1.4 million , respectively. At September 30, 2019 and December 31, 2018 , the Company had an accounts receivable balance of $287,000 and $258,000 , respectively, and an accounts payable and accrued liability balance of $355,000 and $554,000 , respectively, related to Wistar. As of September 30, 2019 , the Company had $856,000 recorded as deferred grant funding on the condensed consolidated balance sheet related to Wistar.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases The Company leases approximately 82,200 square feet of office, laboratory, and manufacturing space in San Diego, California and 57,360 square feet of office space in Plymouth Meeting, Pennsylvania under various non-cancellable operating lease agreements with remaining lease terms of 4.2 to 10.3 years, 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. The Company has evaluated all of its leases and determined that, effective upon the adoption of Topic 842, they were all operating leases. The Company performed an evaluation of its other contracts with customers and suppliers in accordance with 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 September 30, 2019 , the maturities of the Company's operating lease liabilities were as follows: Remainder of 2019 $ 959,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 Thereafter 15,952,000 Total remaining lease payments 32,856,000 Less: present value adjustment (9,891,684 ) Total operating lease liabilities 22,964,316 Less: current portion (2,011,008 ) Long-term operating lease liabilities $ 20,953,308 Weighted-average remaining lease term 8.5 years Weighted-average discount rate 8.4 % Lease costs included in operating expenses in the condensed consolidated statements of operations for the three and nine months ended September 30, 2019 were $820,000 and $2.5 million , respectively. Lease costs included in operating expenses in the condensed consolidated statements of operations for the three and nine months ended September 30, 2018 were $827,000 and $2.5 million , 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 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.

Collaborative Agreements

Collaborative Agreements	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Agreements	Collaborative Agreements 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"), with an effective date of March 20, 2018. Under the terms of the ApolloBio Agreement, the Company has granted to ApolloBio the exclusive right to develop and commercialize VGX-3100, its DNA immunotherapy product designed to treat pre-cancers caused by HPV, within the territories of China, Hong Kong, Macao, Taiwan, and may include Korea in the event that no patent covering VGX-3100 is issued in China within the three years following the effective date of the ApolloBio Agreement. Under the ApolloBio Agreement, the Company received proceeds of $19.4 million in March 2018 which comprised the upfront payment of $23.0 million less $2.2 million in foreign income taxes and $1.4 million in certain foreign non-income taxes. The foreign income taxes were recorded as a provision for income taxes and the foreign non-income taxes were recorded as a general and administrative expense, on the condensed consolidated statement of operations during the quarter ended March 31, 2018. The Company also incurred advisory fees of $960,000 in connection with receiving the upfront payment from ApolloBio. These fees were determined to be incremental costs of obtaining the contract. The Company applied the practical expedient that permits a company to expense incremental costs to obtain a contract when the expected amortization period is one year or less and recorded the fees in general and administrative expense during the quarter ended March 31, 2018. No additional advisory fees are due related to the ApolloBio Agreement. In addition to the upfront payment, 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 the United States, China and Korea. 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. The Company evaluated the terms of the ApolloBio Agreement under Topic 606, and the license to VGX-3100 in the territories was identified as the only distinct performance obligation on a standalone basis as of the inception of the agreement. The Company concluded that the license was distinct from potential future manufacturing and supply obligations. The Company further determined that the transaction price under the agreement consisted of the $23.0 million upfront payment. The future potential milestone amounts were not included in the transaction price, as they were all determined to be fully constrained. As part of the evaluation of the development and regulatory milestones constraint, the Company determined that the achievement of such milestones is contingent upon success in future clinical trials and regulatory approvals, each of which is uncertain at this time. Future potential milestone amounts may be recognized as revenue under the ApolloBio Agreement, as well as under other collaborative research and development arrangements, if unconstrained. Reimbursable program costs will be recognized proportionately with the performance of the underlying services or delivery of drug supply and are excluded from the transaction price. The ApolloBio Agreement will continue in force until ApolloBio has no remaining royalty obligations. Either party may terminate the ApolloBio Agreement in the event the other party shall materially breach or default in the performance of its material obligations thereunder and such default continues for a specified period after written notice thereof. In addition, ApolloBio may terminate the ApolloBio Agreement at any time beginning one year after the effective date for any reason upon 90 days written notice to the Company. Under Topic 606, the entire transaction price of $23.0 million was allocated to the license performance obligation. The Company determined that during the quarter ended June 30, 2018, the transfer of technology occurred and accordingly, the performance obligation was fully satisfied. The Company has recorded the gross upfront payment received from ApolloBio of $23.0 million as revenue under collaborative research and development arrangements on the condensed consolidated statement of operations during the three months ended June 30, 2018. AstraZeneca On August 7, 2015, the Company entered into a license and collaboration agreement with MedImmune, the global biologics research and development arm of AstraZeneca ("AstraZeneca"). Under the agreement, AstraZeneca acquired exclusive rights to the Company's INO-3112 immunotherapy, renamed as MEDI0457, which targets cancers caused by human papillomavirus (HPV) types 16 and 18, with the ability to sublicense those license rights. AstraZeneca made an upfront payment of $27.5 million to the Company in September 2015. AstraZeneca may be obligated to make potential future development and regulatory event-based payments to the Company totaling up to $125 million and potential future commercial event-based payments totaling up to $115 million , in each case upon the achievement of specified milestones related to MEDI0457 set forth in the license and collaboration agreement. AstraZeneca will fund all development costs associated with MEDI0457 immunotherapy. The Company is entitled to receive up to mid-single to double-digit tiered royalties on MEDI0457 product sales. Under the agreement, AstraZeneca can also request the Company to provide certain clinical manufacturing at an agreed upon price. The Company determined these options did not represent material rights at the inception of the agreement. Within the broader collaboration, AstraZeneca had rights to co-develop up to two additional DNA-based cancer vaccine product candidates not included in the Company's current product pipeline. The Company has received notice that AstraZeneca intends to discontinue activities with respect to the research collaboration programs, other than MEDI0457, that were covered by the collaboration agreement. As of December 31, 2017, the Company had recognized all of the $27.5 million upfront payment as revenue, as all identified material performance obligations had been met with respect to that payment. During the three and nine months ended September 30, 2019 , the Company recognized revenues of $255,000 and $3.0 million , respectively, from AstraZeneca primarily from a milestone achieved in the first quarter of 2019 triggered by the initiation of a Phase 2 portion of an ongoing clinical trial in the third major indication, as well as for manufacturing services. During the three and nine months ended September 30, 2018 , the Company recognized revenues of $1.8 million and $4.5 million , respectively, from AstraZeneca primarily for manufacturing services. As of September 30, 2019 , the Company had deferred revenue and accounts receivable of $118,000 and $122,000 , respectively, related to AstraZeneca. The deferred revenue relates to advanced payments made by the Company to a third-party biologics manufacturer for which AstraZeneca is obligated to reimburse the Company. Coalition for Epidemic Preparedness Innovations On April 11, 2018, the Company entered into agreements with CEPI, pursuant to which the Company intends to develop vaccine candidates against Lassa fever and MERS. The goal of the collaboration between the Company and CEPI is to conduct research and development so that investigational stockpiles will be ready for clinical efficacy trial testing during potential disease outbreaks. The agreements with CEPI contemplate preclinical studies, as well as Phase 1 and Phase 2 clinical trials, occurring over multiple years. As part of the arrangement between the parties, CEPI has 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. During the three and nine months ended September 30, 2019 , the Company received funding of $1.5 million and $4.6 million , respectively, related to the CEPI grant and recorded it as contra-research and development expense. During the three and nine months ended September 30, 2018 , the Company received funding of $1.2 million and $2.0 million , respectively, related to the CEPI grant and recorded it as contra-research and development expense. As of September 30, 2019 , the Company had $829,000 recorded as deferred grant funding on the condensed consolidated balance sheet related to the CEPI grant.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
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. The income tax benefit recorded during the nine months ended September 30, 2019 is principally due to a requirement under ASC 740, Accounting for Income Taxes , that a company must consider all sources of income in order to determine the tax benefit resulting from a loss from continuing operations. As a result of the requirement under ASC 740-20-45-7, the pretax income which the Company generated from other comprehensive income (loss) was a source of income which resulted in the partial realization of the current year loss from continuing operations. During the nine months ended September 30, 2019 the Company has recorded a tax benefit of approximately $170,000 and an offsetting $335,000 charge included in other comprehensive income (loss).

Geneos Therapeutics, Inc.

Geneos Therapeutics, Inc.	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Geneos Therapeutics, Inc.	Geneos Therapeutics, Inc. In August 2016, the Company incorporated a subsidiary, Geneos Therapeutics, Inc. (“Geneos”), to develop and commercialize neoantigen-based personalized cancer therapies. In February 2019, the Company completed a spin-out of Geneos, after Geneos completed the initial closing of a $4.5 million preferred stock financing. The Company invested $1.2 million in the preferred stock financing, which was led by an outside investor. The terms of the stock purchase agreement include a commitment for an additional investment of $800,000 by the Company as well as commitments from the other investors upon the occurrence of a specified regulatory event, as well as an option for the Company to purchase $800,000 of additional preferred stock of Geneos upon the achievement of a specified milestone. Following the initial closing of the financing transaction, the Company holds 61% of the outstanding equity, on an as-converted to common stock basis, of Geneos. The Company's ownership percentage of Geneos would decrease in the event of additional purchases of preferred stock of Geneos by the other investors under the terms of the stock purchase agreement. The Company has exclusively licensed its SynCon ® immunotherapy and CELLECTRA ® technology platform to Geneos to be used in the field of personalized, neoantigen-based therapy for cancer. The license agreement provides for potential royalty payments to the Company in the event that Geneos commercializes any products using the licensed technology.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events From October 1 through November 8, 2019, the Company sold 967,862 shares of common stock under its Sales Agreement for net proceeds of $2.4 million . The sales were made at a weighted average price of $2.49 per share.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
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 September 30, 2019 , the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss and the condensed consolidated statements of stockholders' equity for the three and nine months ended September 30, 2019 and 2018 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2019 and 2018 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 and nine months ended September 30, 2019 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 , 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, 2018 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 12, 2019. The balance sheet at December 31, 2018 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 subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc. and VGX Pharmaceuticals, Inc. ("VGX") and records a non-controlling interest for 39% of its subsidiary Geneos Therapeutics, Inc. ("Geneos") as well as 15% of VGX Animal Health, Inc., a subsidiary of VGX. All intercompany accounts and transactions have been eliminated upon consolidation. Inovio incurred a net loss attributable to common stockholders of $23.1 million and $81.7 million for the three and nine months ended September 30, 2019 , respectively. Inovio had working capital of $79.3 million and an accumulated deficit of $702.1 million as of September 30, 2019 . 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. The Company’s cash, cash equivalents and short-term investments of $93.8 million and long-term investments of $8.0 million as of September 30, 2019 , are sufficient to support the Company's operations for a period of at least 12 months from the date it is issuing these financial statements. In addition, the Company could sell up to an additional $68.5 million in shares of its common stock under its At-the-Market Equity Offering Sales Agreement (the “Sales Agreement”), subject to certain conditions set forth in the Sales Agreement. In order to continue to fund future research and development activities, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements and/or future public or private debt or equity financings including use of its Sales Agreement. The Company has a history of debt and equity financings, including the receipt of net proceeds of $75.7 million from a private placement of 6.50% convertible senior notes due 2024 (the “Notes”) in the first quarter of 2019 and net proceeds of $14.5 million from the private placement of 1.0% convertible bonds due 2024 (the "Bonds") during the three months ended September 30, 2019. The Company also received net proceeds of $1.1 million and $3.4 million under the Sales Agreement during the three and nine months ended September 30, 2019 , respectively, and net proceeds of $29.2 million under the Sales Agreement and a prior at-the-market equity offering agreement during the year ended December 31, 2018. 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. In July 2019, the Company announced a strategic organizational restructuring. In order to reduce operating expenses and conserve cash resources, the Company reduced approximately 28% of its workforce and discontinued its immuno-oncology Phase 1/2 clinical trial of its product candidate INO-5401 in patients with advanced bladder cancer. In the third quarter of 2019, the Company incurred a personnel-related restructuring charge of $2.2 million in connection with one-time employee termination costs, including severance and other benefits. 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. Inovio’s condensed consolidated financial statements as of and for the three and nine months ended September 30, 2019 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.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. The Company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company assesses the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) product supply services; (iii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iv) royalties on net sales of licensed products. Where a portion of non-refundable, upfront fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The standalone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company will utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Product Supply Services Arrangements that include a promise for future supply of drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company will assess if these options provide a material right to the licensee and if so, they will be accounted for as separate performance obligations. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements.
Grants	Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605, Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra-expense as opposed to revenue on the condensed consolidated statement of operations.
Leases	Leases The Company adopted ASU 2016‑02, Leases (Topic 842) (“Topic 842”) on January 1, 2019. For its long-term operating leases, the Company recognized an operating lease right-of-use asset and an operating lease liability on its condensed consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The Company determines the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Fixed rent expense for the Company's operating leases is recognized on a straight-line basis over the term of the lease and is included in operating expenses on the condensed consolidated statements of operations. Variable lease payments including lease operating expenses are recorded as incurred. Prior period amounts continue to be reported in accordance with the historic accounting under the previous lease guidance, ASC 840, Leases (Topic 840). See “Impact of Recently Issued Accounting Standards” below, for more information about the impact of the adoption of Topic 842.
Research and Development Expense	Research and Development Expenses The Company’s activities have largely consisted of research and development efforts related to developing electroporation delivery technologies and DNA immunotherapies and vaccines. Research and development expenses consist of expenses incurred in performing research and development activities including salaries and benefits, facilities and other overhead expenses, clinical trials, contract services and other outside expenses. Research and development expenses are charged to operations as they are incurred. These expenses result from the Company's independent research and development efforts as well as efforts associated with collaborations and licensing arrangements. The Company reviews and accrues clinical trial expense based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. 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.
Valuation of Intangible Assets and Goodwill	Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from two to 18 years. Acquired intangible assets are continuously being developed for the future economic viability contemplated at the time of acquisition. The Company is concurrently conducting preclinical studies and clinical trials using the acquired intangibles and has entered into licensing agreements for the use of these acquired intangibles. Historically, the Company has recorded patents at cost and amortized these costs using the straight-line method over the expected useful lives of the patents or 17 years, whichever is less. Patent cost consists of the consideration paid for patents and related legal costs. Effective as of the acquisition of VGX in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of September 30, 2019 and December 31, 2018 , the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $4.0 million and $4.8 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s condensed consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. The Company’s judgments regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of its acquired businesses, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible asset to fair value. While current and historical operating and cash flow losses are potential indicators of impairment, the Company believes the future cash flows to be received from its intangible assets will exceed the intangible assets’ carrying value, and accordingly, the Company has not recognized any impairment losses through September 30, 2019 . Goodwill represents the excess of acquisition cost over the fair value of the net assets of acquired businesses. Goodwill is reviewed for impairment at least annually at November 30, or more frequently if an event occurs indicating the potential for impairment. During its goodwill impairment review, the Company may assess qualitative factors to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying amount, including goodwill. The qualitative factors include, but are not limited to, macroeconomic conditions, industry and market considerations, and the overall financial performance of the Company. If, after assessing the totality of these qualitative factors, the Company determines that it is not more likely than not that the fair value of its reporting unit is less than its carrying amount, then no additional assessment is deemed necessary. Otherwise, the Company proceeds to perform the two-step test for goodwill impairment. The first step involves comparing the estimated fair value of the reporting unit with its carrying value, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the Company performs the second step of the goodwill impairment test to determine the amount of loss, which involves comparing the implied fair value of the goodwill to the carrying value of the goodwill. The Company may also elect to bypass the qualitative assessment in a period and elect to proceed to perform the first step of the goodwill impairment test. The Company performed its annual assessment for goodwill impairment as of November 30, 2018, identifying no impairment. Although there are inherent uncertainties in this assessment process, the estimates and assumptions the Company is using are consistent with its internal planning. If these estimates or their related assumptions change in the future, the Company may be required to record an impairment charge on all or a portion of its goodwill and intangible assets. Furthermore, the Company cannot predict the occurrence of future impairment triggering events nor the impact such events might have on its reported asset values. Future events could cause the Company to conclude that impairment indicators exist and that goodwill or other intangible assets associated with its acquired businesses are impaired. Any resulting impairment loss could have an adverse impact on the Company’s results of operations.
Derivative Liabilities	Derivative Liabilities The Company evaluates its debt and equity issuances to determine if those contracts or embedded components of those contracts qualify as derivatives requiring separate recognition in the Company’s financial statements. The result of this accounting treatment is that the fair value of the embedded derivative is revalued at each balance sheet date and recorded as a liability, and the change in fair value during the reporting period is recorded in other income (expense) in the condensed consolidated statements of operations. In circumstances where the embedded conversion option in a convertible instrument is required to be bifurcated and there are also other embedded derivative instruments in the convertible instrument that are required to be bifurcated, the bifurcated derivative instruments are accounted for as a single, compound derivative instrument. The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is reassessed at the end of each reporting period. Derivative instrument liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement of the derivative instrument is expected within twelve months of the balance sheet date.
Foreign Currency Translation	Foreign Currency Translation The functional and presentation currency of the Company is the U.S. dollar. Transactions denominated in a currency other than the functional currency are recorded on the initial recognition at the exchange rate at the date of the transaction. After initial recognition monetary assets and liabilities denominated in foreign currency are translated at the end of each reporting period into the functional currency at the exchange rate at that date. The cumulative translation adjustment is included in the accumulated other comprehensive gain (loss) within the statement of stockholders' equity. Exchange differences are included in general and administrative expenses in the condensed consolidated statement of operations. Non- monetary assets and liabilities measured at cost are translated at the exchange rate at the date of the transaction.
Recently Issued Accounting Standards	The recent accounting pronouncements below may have a significant effect on the Company's financial statements. Recent accounting pronouncements that are not anticipated to have an impact on or are unrelated to the Company's financial condition, results of operations, or related disclosures are not discussed. ASU No. 2016-02 . In February 2016, the FASB issued Topic 842, which requires lessees to recognize most leases on the balance sheet as lease liabilities with corresponding right-of-use assets and to disclose key information about leasing arrangements. The Company adopted the new lease standard on January 1, 2019 using the modified retrospective approach. The Company elected the available package of practical expedients upon adoption, which allowed the Company to carry forward its historical assessment of whether existing agreements contained a lease and the classification of its existing operating leases. Upon adoption, the Company recognized an operating right-of use asset and operating lease liability in its condensed consolidated balance sheet of approximately $14.6 million and $24.2 million , respectively. The Company also classified deferred rent of $9.6 million as an offset to the Company’s operating right-of-use asset upon adoption. There were no adjustments to the Company’s opening accumulated deficit balance upon adoption. The impact of the adoption of Topic 842 on the condensed consolidated balance sheets as of January 1, 2019 was as follows: ASC 840 Topic 842 January 1, 2019 Impact of Adoption January 1, 2019 Deferred rent $ 1,065,387 $ (1,065,387 ) $ — Deferred rent, net of current portion $ 8,518,207 $ (8,518,207 ) $ — Operating right-of-use assets $ — $ 14,634,769 $ 14,634,769 Operating lease liability $ — $ 1,733,600 $ 1,733,600 Operating lease liability, net of current portion $ — $ 22,484,763 $ 22,484,763 ASU No. 2018-07 . In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting, that simplifies the accounting for stock-based payments granted to non-employees for services by generally aligning it with the accounting for stock-based payments granted to employees. The Company adopted the standard on January 1, 2019 and there was no material impact to its condensed consolidated financial statements. ASU No. 2018-13 . In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement , which amends certain disclosure requirements over Level 1, Level 2 and Level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-13, but does not anticipate it will have a material impact on its disclosures. ASU No. 2018-18 . In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which clarified the interaction between Topic 808, Collaborative Arrangements , and Topic 606, Revenue from Contracts with Customers . ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-18.

Impact of Recently Issued Acc_2

Impact of Recently Issued Accounting Standards (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The impact of the adoption of Topic 842 on the condensed consolidated balance sheets as of January 1, 2019 was as follows: ASC 840 Topic 842 January 1, 2019 Impact of Adoption January 1, 2019 Deferred rent $ 1,065,387 $ (1,065,387 ) $ — Deferred rent, net of current portion $ 8,518,207 $ (8,518,207 ) $ — Operating right-of-use assets $ — $ 14,634,769 $ 14,634,769 Operating lease liability $ — $ 1,733,600 $ 1,733,600 Operating lease liability, net of current portion $ — $ 22,484,763 $ 22,484,763

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of available-for-sale securities	The following is a summary of available-for-sale securities as of September 30, 2019 and December 31, 2018 : As of September 30, 2019 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 76,910,152 $ 1,038,733 $ (3,132 ) $ 77,945,753 As of December 31, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 57,842,955 $ — $ (528,084 ) $ 57,314,871 US corporate debt securities Less than 2 224,633 — (652 ) 223,981 Total investments $ 58,067,588 $ — $ (528,736 ) $ 57,538,852

Marketable Securities and Fai_2

Marketable Securities and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis, and are determined using the following inputs as of September 30, 2019 : Fair Value Measurements at September 30, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 3,317,462 $ 3,317,462 $ — $ — Mutual funds 77,945,753 — 77,945,753 — Investment in affiliated entities 7,996,757 7,996,757 — — Total assets $ 89,259,972 $ 11,314,219 $ 77,945,753 $ — Liabilities: Derivative liability (Note 9) $ 4,503,918 $ — $ — 4,503,918 Total liabilities $ 4,503,918 $ — $ — $ 4,503,918 The following table presents the Company’s assets that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2018 : Fair Value Measurements at December 31, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,646,507 $ 9,646,507 $ — $ — Mutual funds 57,314,871 — 57,314,871 — US corporate debt securities 223,981 — 223,981 — Investment in affiliated entities 9,405,913 9,405,913 — — Total assets $ 76,591,272 $ 19,052,420 $ 57,538,852 $ —
Changes in fair value of the company's derivative liability	The following table presents the changes in fair value of the Company's derivative liability for the nine months ended September 30, 2019: Balance at December 31, 2018 $ — Initial fair value upon issuance of the Bonds 7,055,371 Change in fair value (2,551,453 ) Balance at September 30, 2019 $ 4,503,918

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of intangible assets by major asset class	The following sets forth the goodwill and intangible assets by major asset class: September 30, 2019 December 31, 2018 Useful Life (Yrs) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Indefinite lived: Goodwill(a) $ 10,513,371 $ — $ 10,513,371 $ 10,513,371 $ — $ 10,513,371 Definite lived: Patents 8 – 17 5,802,528 (5,787,384 ) 15,144 5,802,528 (5,742,079 ) 60,449 Licenses 8 – 17 1,323,761 (1,240,917 ) 82,844 1,323,761 (1,219,357 ) 104,404 CELLECTRA ® (b) 5 – 11 8,106,270 (7,999,501 ) 106,769 8,106,270 (7,679,190 ) 427,080 GHRH(b) 11 335,314 (327,392 ) 7,922 335,314 (303,630 ) 31,684 Bioject(c) 2 – 15 5,100,000 (2,102,222 ) 2,997,778 5,100,000 (1,882,222 ) 3,217,778 Other(d) 18 4,050,000 (3,300,000 ) 750,000 4,050,000 (3,131,250 ) 918,750 Total intangible assets 24,717,873 (20,757,416 ) 3,960,457 24,717,873 (19,957,728 ) 4,760,145 Total goodwill and intangible assets $ 35,231,244 $ (20,757,416 ) $ 14,473,828 $ 35,231,244 $ (19,957,728 ) $ 15,273,516 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition.

Convertible Debt (Tables)

Convertible Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Convertible Debt	The balance of the Notes at September 30, 2019 is as follows: Principal amount $ 78,500,000 Unamortized debt discount on the liability component (14,772,356 ) Unamortized debt issuance cost (2,033,181 ) Accrued interest 425,208 Net carrying amount $ 62,119,671 The balance of the Bonds at September 30, 2019 is as follows: Principal amount $ 15,052,055 Unamortized debt discount (6,945,328 ) Unamortized debt issuance cost (262,013 ) Accretion of premium associated with the Bonds 84,569 Accrued interest 25,568 Net carrying amount $ 7,954,851

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
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 September 30, 2019 and December 31, 2018 : Outstanding as of Authorized Issued September 30, 2019 December 31, 2018 Common Stock, par value $0.001 per share 600,000,000 99,046,158 99,046,158 97,225,810 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 23 23

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
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 for the three months ended September 30, 2019 and 2018 : Common Stock Equivalents 2019 2018 Options to purchase common stock 9,971,297 8,945,275 Restricted stock units 2,121,359 1,711,213 Convertible preferred stock 8,456 8,456 Convertible notes 14,585,653 — Convertible bonds — — Total 26,686,765 10,664,944 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 for the nine months ended September 30, 2019 and 2018 : Common Stock Equivalents 2019 2018 Options to purchase common stock 9,971,297 8,945,275 Restricted stock units 2,121,359 1,711,213 Convertible preferred stock 8,456 8,456 Convertible notes 14,585,653 — Convertible bonds 3,799,071 — Total 30,485,836 10,664,944

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Risk-free interest rate 1.75% 2.86% 2.43% 2.73% Expected volatility 65% 71% 70% 72% Expected life in years 6.1 6.1 6.2 6.2 Dividend yield — — — —

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	As of September 30, 2019 , the maturities of the Company's operating lease liabilities were as follows: Remainder of 2019 $ 959,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 Thereafter 15,952,000 Total remaining lease payments 32,856,000 Less: present value adjustment (9,891,684 ) Total operating lease liabilities 22,964,316 Less: current portion (2,011,008 ) Long-term operating lease liabilities $ 20,953,308 Weighted-average remaining lease term 8.5 years Weighted-average discount rate 8.4 %

Basis of Presentation (Details)

Basis of Presentation (Details)	Aug. 01, 2019USD ($)	Mar. 01, 2019USD ($)	Jul. 31, 2019	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Aug. 01, 2019KRW (₩)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss				$ 23,090,693	$ 25,015,672	$ 81,697,181	$ 64,005,625
Working capital				79,300,000		79,300,000
Retained earnings (accumulated deficit)				(702,123,617)		(702,123,617)		$ (620,426,436)
Cash, cash equivalents, and short-term investments				93,800,000		93,800,000
Long-term investments				8,000,000		8,000,000
Proceeds from issuance of stock						$ 3,425,065	$ 14,923,263
Expected number of positions to be eliminated, percent			28.00%
Restructuring charges				$ 2,200,000
Geneos Therapeutics, Inc.
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Non-controlling interest				39.00%		39.00%
VGX Animal Health, Inc
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Non-controlling interest				15.00%		15.00%
Common stock | Sales Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock sales agreement, remaining authorized sales amount				$ 68,500,000		$ 68,500,000
Proceeds from issuance of stock				1,100,000		3,400,000		$ 29,200,000
6.50% Convertible Senior Notes Due 2024 | Convertible Debt
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from issuance of debt		$ 75,700,000				75,700,000
Principal amount		$ 78,500,000		$ 78,500,000		$ 78,500,000
Debt instrument, interest rate, stated percentage		6.50%		6.50%		6.50%
Korean Won Convertible Bonds Due 2024 | Convertible Debt
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from issuance of debt	$ 14,500,000
Principal amount	$ 15,000,000			$ 15,052,055		$ 15,052,055			₩ 18,000,000,000
Debt instrument, interest rate, stated percentage	1.00%								1.00%

Critical Accounting Policies (D

Critical Accounting Policies (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 3,960,457	$ 4,760,145
Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	18 years
Patents
Finite-Lived Intangible Assets [Line Items]
Useful life	17 years
Patents | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	8 years
Patents | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	17 years

Impact of Recently Issued Acc_3

Impact of Recently Issued Accounting Standards - Narrative (Details) - USD ($)	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 14,002,860	$ 14,634,769
Operating lease liability	$ 22,964,316
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		14,600,000
Operating lease liability		24,200,000
Deferred rent credit		$ 9,600,000

Impact of Recently Issued Acc_4

Impact of Recently Issued Accounting Standards - Impact of Adopting ASU 2016-02 (Details) - USD ($)	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent			$ 1,065,387
Deferred rent, net of current portion			$ 8,518,207
Operating lease right-of-use assets	$ 14,002,860	$ 14,634,769
Operating lease liability	2,011,008	1,733,600
Operating lease liability, net of current portion	$ 20,953,308	22,484,763
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		14,600,000
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent		1,065,387
Deferred rent, net of current portion		8,518,207
Impact of Adoption | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent		(1,065,387)
Deferred rent, net of current portion		(8,518,207)
Operating lease right-of-use assets		14,634,769
Operating lease liability		1,733,600
Operating lease liability, net of current portion		$ 22,484,763

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 866,863	$ 2,000,868	$ 3,832,442	$ 27,979,273
Revenue recognized from deferred revenue beginning balance	41,000	316,000	256,000	1,300,000
AstraZeneca
Disaggregation of Revenue [Line Items]
Total revenues	255,000	$ 1,800,000	3,000,000	$ 4,500,000
Other Counterparty
Disaggregation of Revenue [Line Items]
Total revenues	$ 612,000		$ 803,000

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Realized net gain (loss) on investments	$ 145	$ (184)	$ 238	$ (558)

Investments - Summary of Availa

Investments - Summary of Available-for-sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2019
Debt Securities, Available-for-sale [Abstract]
Cost	$ 58,067,588
Gross Unrealized Gains	0
Gross Unrealized Losses	(528,736)
Fair Market Value	57,538,852
Mutual funds
Debt Securities, Available-for-sale [Abstract]
Cost	57,842,955	$ 76,910,152
Gross Unrealized Gains	0	1,038,733
Gross Unrealized Losses	(528,084)	(3,132)
Fair Market Value	57,314,871	$ 77,945,753
US corporate debt securities
Debt Securities, Available-for-sale [Abstract]
Cost	224,633
Gross Unrealized Gains	0
Gross Unrealized Losses	(652)
Fair Market Value	$ 223,981
Maximum | US corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Contractual maturity, less than	2 years

Marketable Securities and Fai_3

Marketable Securities and Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		$ 57,538,852
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	$ 4,503,918	0
Significant Unobservable Inputs (Level 3)
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	7,100,000
Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities	77,945,753	57,314,871
Fair Value, Measurements, Recurring
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		223,981
Investment in affiliated entities	7,996,757	9,405,913
Total assets	89,259,972	76,591,272
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	4,503,918
Total liabilities	4,503,918
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		0
Investment in affiliated entities	7,996,757	9,405,913
Total assets	11,314,219	19,052,420
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	0
Total liabilities	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		223,981
Investment in affiliated entities	0	0
Total assets	77,945,753	57,538,852
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	0
Total liabilities	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		0
Investment in affiliated entities	0	0
Total assets	0	0
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability (Note 9)	4,503,918
Total liabilities	4,503,918
Fair Value, Measurements, Recurring | Money market funds
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	3,317,462	9,646,507
Fair Value, Measurements, Recurring | Money market funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	3,317,462	9,646,507
Fair Value, Measurements, Recurring | Money market funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	0	0
Fair Value, Measurements, Recurring | Money market funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	0	0
Fair Value, Measurements, Recurring | Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	77,945,753	57,314,871
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
Cash and cash equivalents, fair value	0	0
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
Cash and cash equivalents, fair value	77,945,753	57,314,871
Fair Value, Measurements, Recurring | Mutual funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents, fair value	$ 0	$ 0

Marketable Securities and Fai_4

Marketable Securities and Fair Value Measurements - Narrative (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Derivative liability	$ 4,503,918	$ 0
Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Number of shares held in an affiliated entity (in shares)	1,644,155
Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Common stock
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Investment owned (in shares)	395,758
Fair Value, Inputs, Level 3
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Derivative liability	$ 7,100,000

Marketable Securities and Fai_5

Marketable Securities and Fair Value Measurements - Fair Value of the Company's Derivative Liability (Details)	9 Months Ended
	Sep. 30, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0
Initial fair value upon issuance of the Bonds	7,055,371,000
Change in fair value	(2,551,453,000)
Ending balance	$ 4,503,918,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Schedule Goodwill and Intangible Assets (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Apr. 30, 2016	Jun. 30, 2009	Jan. 31, 2005
Indefinite lived:
Goodwill, gross	$ 10,513,371	$ 10,513,371
Goodwill, net book value	10,513,371	10,513,371
Definite lived:
Intangible assets, gross	24,717,873	24,717,873
Intangible assets, accumulated amortization	(20,757,416)	(19,957,728)
Intangible assets, net book value	3,960,457	4,760,145
Total goodwill and intangible assets, gross	35,231,244	35,231,244
Total goodwill and intangible assets, net book value	$ 14,473,828	15,273,516
Minimum
Definite lived:
Useful life	2 years
Maximum
Definite lived:
Useful life	18 years
Inovio AS
Indefinite lived:
Goodwill, net book value					$ 3,900,000
VGX
Indefinite lived:
Goodwill, net book value				$ 6,200,000
Bioject
Indefinite lived:
Goodwill, net book value			$ 400,000
Patents
Definite lived:
Useful life	17 years
Intangible assets, gross	$ 5,802,528	5,802,528
Intangible assets, accumulated amortization	(5,787,384)	(5,742,079)
Intangible assets, net book value	$ 15,144	60,449
Patents | Minimum
Definite lived:
Useful life	8 years
Patents | Maximum
Definite lived:
Useful life	17 years
Licenses
Definite lived:
Intangible assets, gross	$ 1,323,761	1,323,761
Intangible assets, accumulated amortization	(1,240,917)	(1,219,357)
Intangible assets, net book value	$ 82,844	104,404
Licenses | Minimum
Definite lived:
Useful life	8 years
Licenses | Maximum
Definite lived:
Useful life	17 years
CELLECTRA
Definite lived:
Intangible assets, gross	$ 8,106,270	8,106,270
Intangible assets, accumulated amortization	(7,999,501)	(7,679,190)
Intangible assets, net book value	$ 106,769	427,080
CELLECTRA | Minimum
Definite lived:
Useful life	5 years
CELLECTRA | Maximum
Definite lived:
Useful life	11 years
GHRH
Definite lived:
Useful life	11 years
Intangible assets, gross	$ 335,314	335,314
Intangible assets, accumulated amortization	(327,392)	(303,630)
Intangible assets, net book value	7,922	31,684
Bioject
Definite lived:
Intangible assets, gross	5,100,000	5,100,000
Intangible assets, accumulated amortization	(2,102,222)	(1,882,222)
Intangible assets, net book value	$ 2,997,778	3,217,778
Bioject | Minimum
Definite lived:
Useful life	2 years
Bioject | Maximum
Definite lived:
Useful life	15 years
Other
Definite lived:
Useful life	18 years
Intangible assets, gross	$ 4,050,000	4,050,000
Intangible assets, accumulated amortization	(3,300,000)	(3,131,250)
Intangible assets, net book value	$ 750,000	$ 918,750

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Aggregate amortization expense on intangible assets	$ 267,000	$ 267,000	$ 799,688	$ 983,021
Estimated aggregate amortization expense for remainder of 2019	267,000		267,000
Estimated aggregate amortization expense for 2020	547,000		547,000
Estimated aggregate amortization expense for 2021	520,000		520,000
Estimated aggregate amortization expense for 2022	493,000		493,000
Estimated aggregate amortization expense for 2023	276,000		276,000
Estimated aggregate amortization expense for 2024	$ 1,900,000		$ 1,900,000

Convertible Debt - Narrative (D

Convertible Debt - Narrative (Details)	Aug. 01, 2019USD ($)$ / shares	Mar. 01, 2019USD ($)day$ / shares	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Aug. 01, 2019KRW (₩)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Non-cash interest expense			$ 2,428,671	$ 0	$ 5,279,702	$ 0
Derivative liability			4,503,918		4,503,918			$ 0
Change in fair value of derivative liability			2,551,453	$ 0	2,551,453	$ 0
Korean Won Convertible Bonds Due 2024 | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.00%						1.00%
Principal amount	$ 15,000,000		15,052,055		15,052,055		₩ 18,000,000,000
Proceeds from issuance of debt	$ 14,500,000
Debt instrument, convertible, internal rate of return	6.00%						6.00%
Debt Instrument, Convertible, Required Bondholder Approval, Percentage	25.00%
Debt instrument, convertible, carrying amount of equity component	$ 7,100,000
Unamortized debt issuance cost			262,013		262,013
Debt instrument, unamortized discount	$ 7,300,000		$ 6,945,328		$ 6,945,328
Debt instrument, effective interest rate			29.40%		29.40%
Non-cash interest expense			$ 374,000		$ 307,000
Interest expense, contractual interest			26,000		26,000
Derivative liability			4,500,000		4,500,000
Change in fair value of derivative liability			$ 2,600,000		$ 2,400,000
6.50% Convertible Senior Notes Due 2024 | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		6.50%	6.50%		6.50%
Principal amount		$ 78,500,000	$ 78,500,000		$ 78,500,000
Proceeds from issuance of debt		75,700,000			75,700,000
Debt instrument, convertible, carrying amount of equity component		$ 62,200,000
Debt instrument, convertible, conversion ratio		0.1858045
Debt instrument, convertible conversion price (in dollars per share) | $ / shares		$ 5.38
Debt instrument, convertible, threshold percentage of stock price trigger		130.00%
Debt instrument, convertible, threshold trading days | day		20
Debt instrument, convertible, threshold consecutive trading days | day		30
Debt instrument, redemption price percentage		100.00%
Unamortized debt issuance cost		$ 2,800,000	2,033,181		2,033,181
Debt instrument, unamortized discount		$ 18,600,000	$ 14,772,356		$ 14,772,356
Debt instrument, effective interest rate			13.10%		13.10%
Non-cash interest expense			$ 2,100,000		$ 4,900,000
Interest expense, contractual interest			$ 1,300,000		$ 3,100,000
Initial Conversion Price | Korean Won Convertible Bonds Due 2024 | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, convertible conversion price (in dollars per share) | $ / shares	$ 4
Event Of Default | Korean Won Convertible Bonds Due 2024 | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, convertible, internal rate of return	8.00%						8.00%
Maximum | After January 2, 2020 Conversion Price | Korean Won Convertible Bonds Due 2024 | Convertible Debt
Debt Instrument [Line Items]
Debt instrument, convertible conversion price (in dollars per share) | $ / shares	$ 2.40

Convertible Debt - Balance of C

Convertible Debt - Balance of Convertible Bonds and Notes (Details) - Convertible Debt	Sep. 30, 2019USD ($)	Aug. 01, 2019USD ($)	Aug. 01, 2019KRW (₩)	Mar. 01, 2019USD ($)
Korean Won Convertible Bonds Due 2024
Debt Instrument [Line Items]
Principal amount	$ 15,052,055	$ 15,000,000	₩ 18,000,000,000
Unamortized debt discount	(6,945,328)	$ (7,300,000)
Unamortized debt issuance cost	(262,013)
Accretion of premium associated with the Bonds	84,569
Accrued interest	25,568
Net carrying amount	7,954,851
6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Principal amount	78,500,000			$ 78,500,000
Unamortized debt discount	(14,772,356)			(18,600,000)
Unamortized debt issuance cost	(2,033,181)			$ (2,800,000)
Accrued interest	425,208
Net carrying amount	$ 62,119,671

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Authorized and Issued Common and Preferred Stock (Details) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
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)	99,046,158
Common stock, shares, outstanding (in shares)	99,046,158	97,225,810
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)	23	23

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	May 31, 2018	Sep. 30, 2019	Sep. 30, 2019	May 13, 2016
2016 Incentive Plan
Class of Stock [Line Items]
Number of shares authorized (in shares)		16,000,000	16,000,000	16,000,000
Number of potential shares authorized for issuance under share based compensation plan (in shares)				2,000,000
Number of shares available for grant (in shares)		7,849,847	7,849,847
Number of shares of unvested restricted stock units and options outstanding (in shares)		2,118,026	2,118,026
Common stock, other shares, outstanding (in shares)		4,817,921	4,817,921
Award vesting period			3 years
Maximum contractual term			10 years
2007 Incentive Plan
Class of Stock [Line Items]
Common stock, other shares, outstanding (in shares)		5,153,376	5,153,376
Award vesting period			3 years
Maximum contractual term			10 years
Number of shares of unvested restricted stock units (in shares)			3,333
Common stock | Sales Agreement
Class of Stock [Line Items]
Maximum authorized amount	$ 100,000,000
Agent fee	3.00%
Aggregate number of shares issued (in shares)		382,800	1,042,600
Stock Sale Agreement weighted average price per share		$ 3.01	$ 3.35
Aggregate proceeds		$ 1,100,000	$ 3,400,000
Stock sales agreement, remaining authorized sales amount		$ 68,500,000	$ 68,500,000

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Diluted Net Loss Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net loss attributable to Inovio Pharmaceuticals, Inc. (numerator for use in basic net loss per share)	$ (23,090,693)	$ (25,015,672)	$ (81,697,181)	$ (64,005,625)
Adjustment for decrease in fair value of derivative liability and interest expense	(2,177,250)	0	0	0
Numerator for use in diluted net loss per share	$ (25,267,943)	$ (25,015,672)	$ (81,697,181)	$ (64,005,625)
Denominator
Weighted average number of common shares outstanding (denominator for use in basic net loss per share) (shares)	99,007,985	92,423,122	98,204,375	91,350,117
Effect of dilutive potential common shares (shares)	3,799,071	0	0	0
Denominator for use in diluted net loss per share (shares)	102,807,056	92,423,122	98,204,375	91,350,117
Net loss per share, diluted (dollars per share)	$ (0.25)	$ (0.27)	$ (0.83)	$ (0.70)
Net loss per share, basic (dollars per share)	$ (0.23)	$ (0.27)	$ (0.83)	$ (0.70)

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Anti-Dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	26,686,765	10,664,944	30,485,836	10,664,944
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	9,971,297	8,945,275	9,971,297	8,945,275
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	2,121,359	1,711,213	2,121,359	1,711,213
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	8,456	8,456	8,456	8,456
6.50% Convertible Senior Notes Due 2024 | Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	14,585,653	0	14,585,653	0
Korean Won Convertible Bonds Due 2024 | Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (in shares)	0	0	3,799,071	0

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation			$ 8,867,810	$ 8,516,349
Total unrecognized compensation cost related to unvested stock options	$ 4,300,000		$ 4,300,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized			1 year 10 months 30 days
Weighted average grant date fair value (in dollars per share)	$ 1.65	$ 2.96	$ 2.20	$ 2.85
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested stock options	$ 5,300,000		$ 5,300,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized			1 year 8 months
Weighted average grant date fair value, restricted stock units (in dollars per share)	$ 2.68	$ 0	$ 3.09	$ 4.31
Employees and Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,800,000	$ 2,200,000	$ 8,100,000	$ 8,000,000
Employees and Directors | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.75%	2.86%	2.43%	2.73%
Expected volatility	65.00%	71.00%	70.00%	72.00%
Expected life in years	6 years 1 month	6 years 1 month	6 years 2 months	6 years 2 months
Dividend yield	0.00%	0.00%	0.00%	0.00%
Non Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 264,000	$ 160,000	$ 744,000	$ 334,000
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	922,000	1,200,000	5,100,000	4,700,000
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 885,000	$ 1,000,000	$ 3,000,000	$ 3,300,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2016	Mar. 31, 2016	Jan. 31, 2016	May 31, 2015	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2013	Dec. 31, 2010	Dec. 31, 2018
Related-Party Transactions (Textual) [Abstract]
Long-term other assets					$ 2,731,055		$ 2,731,055				$ 2,669,998
GeneOne Life Sciences
Related-Party Transactions (Textual) [Abstract]
Investment owned (in shares)					1,644,155		1,644,155
Payment received for license granted										$ 3,000,000
Term									20 years
Milestone-based ownership target			35.00%	35.00%
Revenue from related parties					$ 31,000	$ 155,000	$ 94,000	$ 305,000
Operating expenses related to affiliated entity					232,000	1,900,000	2,100,000	4,700,000
Accounts receivable					128,000		128,000				0
Accounts payable and accrued liability					107,000		107,000				372,000
Long-term other assets					338,000		338,000				381,000
Director
Related-Party Transactions (Textual) [Abstract]
Term		5 years
Revenue from related parties						952,000		3,200,000
Operating expenses related to affiliated entity					313,000	615,000	1,100,000	1,400,000
Accounts receivable					287,000		287,000				258,000
Expenses to reimburse		$ 3,100,000
Awarded amount	$ 6,100,000
Contra-research and development expense					482,000		1,700,000
Accounts payable/accrued liabilities					355,000		355,000				554,000
Deferred Grant Funding, From Affiliate					856,000		856,000
Plumbline Life Sciences
Related-Party Transactions (Textual) [Abstract]
Revenue from related parties					22,000	$ 30,000	86,000	$ 88,000
Accounts receivable					$ 564,000		$ 564,000				$ 478,000
Plumbline Life Sciences | Available-for-sale Securities
Related-Party Transactions (Textual) [Abstract]
Investment owned (in shares)					395,758		395,758

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)ft²	Sep. 30, 2018USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	8 years 6 months		8 years 6 months
Lease cost | $	$ 820	$ 827	$ 2,500	$ 2,500
San Diego, California
Lessee, Lease, Description [Line Items]
Area leased (in square feet)			82,200
Plymouth Meeting, Pennsylvania
Lessee, Lease, Description [Line Items]
Area leased (in square feet)			57,360
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	4 years 2 months 12 days		4 years 2 months 12 days
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term	10 years 3 months 18 days		10 years 3 months 18 days

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments (Details) - USD ($)	Sep. 30, 2019	Jan. 01, 2019
Leases [Abstract]
Remainder of 2019	$ 959,000
2020	3,891,000
2021	3,979,000
2022	4,052,000
2023	4,023,000
Thereafter	15,952,000
Total remaining lease payments	32,856,000
Less: present value adjustment	(9,891,684)
Total operating lease liabilities	22,964,316
Less: current portion	(2,011,008)	$ (1,733,600)
Long-term operating lease liabilities	$ 20,953,308	$ 22,484,763
Weighted-average remaining lease term	8 years 6 months
Weighted-average discount rate	8.40%

Collaborative Agreements (Detai

Collaborative Agreements (Details)	Apr. 11, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 29, 2017	Aug. 07, 2015product	Mar. 31, 2018USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues							$ 866,863	$ 2,000,868		$ 3,832,442	$ 27,979,273
Deferred grant funding							1,896,526			1,896,526		$ 4,165,848
AstraZeneca
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues							255,000	1,800,000		3,000,000	4,500,000
Collaborative Arrangement, Product | ApolloBio
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Territory expansion option period			3 years
Proceeds received in upfront payment					$ 19,400,000
Upfront payment received					23,000,000				$ 23,000,000	23,000,000
Advisory fees					960,000
Additional revenue to be achieved										$ 20,000,000
Royalty period										10 years
Period from effective date for termination										1 year
Number of days written notice before termination										90 days
Collaborative Arrangement, Product | AstraZeneca
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received		$ 27,500,000				$ 27,500,000
Anticipated development and regulatory event based payment receivable milestones										$ 125,000,000
Anticipated commercial event based payment receivable milestones										115,000,000
Number of additional products to be developed | product				2
Deferred revenue							118,000			118,000
Accounts receivable							122,000			122,000
Collaborative Arrangement, Product | Coalition for Epidemic Preparedness Innovations
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	5 years
Funding received for research and development							1,500,000	$ 1,200,000		4,600,000	$ 2,000,000
Deferred grant funding							$ 829,000			$ 829,000
Foreign Tax Authority | Collaborative Arrangement, Product | ApolloBio
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Foreign corporate income taxes reducing upfront payment					2,200,000
Foreign non-corporate income taxes reducing upfront payment					$ 1,400,000

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0	$ (169,571)	$ 2,169,811
Other comprehensive income (loss), tax			$ 335,000

Geneos Therapeutics, Inc. (Deta

Geneos Therapeutics, Inc. (Details) $ in Thousands	1 Months Ended
	Feb. 28, 2019USD ($)
Geneos Therapeutics, Inc.
Noncontrolling Interest [Line Items]
Sale of stock, consideration received	$ 4,500
Geneos Therapeutics, Inc.
Noncontrolling Interest [Line Items]
Payments to acquire additional interest in subsidiaries	1,200
Stock purchase agreement, commitment of additional investment	800
Stock purchase agreement, commitment of additional investment upon milestone	$ 800
Noncontrolling interest, ownership percentage by parent	61.00%

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Nov. 08, 2019	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs			$ 3,425,065	$ 14,923,263
Common stock | Sales Agreement
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs		$ 1,100,000	$ 3,400,000		$ 29,200,000
Common stock | Sales Agreement | Subsequent Events
Subsequent Event [Line Items]
Number of common shares sold (in shares)	967,862
Proceeds from issuance of common stock, net of issuance costs	$ 2,400,000
Common shares sold (in dollars per share)	$ 2.49

Uncategorized Items - ino-20190

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(231,366)
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 231,366