Inovio Pharmaceuticals (INO) 10-K 14 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 08, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Entity Registrant Name	INOVIO PHARMACEUTICALS, INC.
Entity Central Index Key	1,055,726
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		90,403,853
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 608,649,117
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 23,786,579	$ 19,136,472
Short-term investments	103,638,844	85,629,412
Accounts receivable	6,003,205	15,821,511
Accounts receivable from affiliated entities	486,619	748,355
Prepaid expenses and other current assets	2,600,906	1,749,059
Prepaid expenses and other current assets from affiliated entities	1,846,007	1,512,424
Total current assets	138,362,160	124,597,233
Fixed assets, net	18,320,176	9,025,446
Investment in affiliated entity - GeneOne	9,069,401	16,052,065
Investment in affiliated entity - PLS	2,325,079	3,777,510
Intangible assets, net	6,009,729	7,628,394
Goodwill	10,513,371	10,513,371
Other assets	2,639,354	2,113,147
Total assets	187,239,270	173,707,166
Current liabilities:
Accounts payable and accrued expenses	23,278,798	19,597,787
Accounts payable and accrued expenses due to affiliated entities	926,943	1,072,579
Accrued clinical trial expenses	8,611,892	6,368,389
Common stock warrants	360,795	1,167,614
Deferred revenue	1,175,353	14,762,720
Deferred revenue from affiliated entities	174,110	407,292
Deferred rent	877,535	446,646
Total current liabilities	35,405,426	43,823,027
Deferred revenue, net of current portion	215,853	317,808
Deferred revenue from affiliated entities, net of current portion	0	86,694
Deferred rent, net of current portion	9,104,416	5,926,424
Deferred tax liabilities	24,766	174,793
Total liabilities	44,750,461	50,328,746
Commitments and contingencies
Inovio Pharmaceuticals, Inc. stockholders’ equity:
Preferred stock—par value $0.001; Authorized shares: 10,000,000, issued and outstanding shares: 23 at December 31, 2017 and December 31, 2016	0	0
Common stock—par value $0.001; Authorized shares: 600,000,000 at December 31, 2017 and December 31, 2016, issued and outstanding: 90,357,644 at December 31, 2017 and 74,062,370 at December 31, 2016	90,358	74,062
Additional paid-in capital	665,775,504	556,718,356
Accumulated deficit	(523,356,317)	(434,838,235)
Accumulated other comprehensive income (loss)	(117,005)	1,327,968
Total Inovio Pharmaceuticals, Inc. stockholders’ equity	142,392,540	123,282,151
Non-controlling interest	96,269	96,269
Total stockholders’ equity	142,488,809	123,378,420
Total liabilities and stockholders’ equity	$ 187,239,270	$ 173,707,166

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value ($ per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	23	23
Preferred stock, shares outstanding	23	23
Common stock, par value ($ per share)	$ 0.001	$ 0.001
Common stock, shares authorized (shares)	600,000,000	600,000,000
Common stock, shares issued	90,357,644	74,062,370
Common stock, shares outstanding	90,357,644	74,062,370

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Revenue under collaborative research and development arrangements	$ 28,407,388	$ 6,490,747	$ 26,876,533
Revenue under collaborative research and development arrangements with affiliated entities	765,828	1,400,594	779,167
Grants and miscellaneous revenue	10,474,539	27,136,457	12,916,411
Grants and miscellaneous revenue from affiliated entity	2,572,331	340,563	0
Total revenues	42,220,086	35,368,361	40,572,111
Operating expenses:
Research and development	98,572,618	88,712,035	57,791,923
General and administrative	28,290,369	23,892,263	18,063,890
Gain on sale of assets	(1,000,000)	(1,000,000)	(1,000,000)
Total operating expenses	125,862,987	111,604,298	74,855,813
Loss from operations	(83,642,901)	(76,235,937)	(34,283,702)
Other income (expense):
Interest and other income, net	1,612,974	1,257,257	305,071
Change in fair value of common stock warrants	806,819	127,554	177,561
Gain (loss) on investment in affiliated entity	(6,982,664)	1,110,787	2,600,467
Net loss before income tax benefit	(88,205,772)	(73,740,339)	(31,200,603)
Income tax benefit	0	0	2,097,766
Net loss	(88,205,772)	(73,740,339)	(29,102,837)
Net income attributable to non-controlling interest	0	0	(84,769)
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (88,205,772)	$ (73,740,339)	$ (29,187,606)
Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders
Basic ($ per share)	$ (1.08)	$ (1.01)	$ (0.43)
Diluted ($ per share)	$ (1.09)	$ (1.01)	$ (0.44)
Weighted average number of common shares outstanding used in per share calculations:
Basic (shares)	81,777,493	73,214,766	68,198,142
Diluted (shares)	81,918,022	73,214,766	68,365,265

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (88,205,772)	$ (73,740,339)	$ (29,102,837)
Other comprehensive income (loss):
Unrealized gain (loss) on investment in affiliated entity, net of tax	(1,452,431)	(1,268,404)	2,952,201
Unrealized gain (loss) on short-term investments, net of tax	7,458	(111,967)	7,528
Comprehensive loss	(89,650,745)	(75,120,710)	(26,143,108)
Comprehensive income attributable to non-controlling interest	0	0	(84,769)
Comprehensive loss attributable to Inovio Pharmaceuticals, Inc.	$ (89,650,745)	$ (75,120,710)	$ (26,227,877)

Consolidated Statements of Stoc

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 (shares) at Dec. 31, 2014		23	60,741,082
Beginning balance at Dec. 31, 2014	$ 111,537,594	$ 0	$ 60,741	$ 443,327,915	$ (331,910,290)	$ (251,390)	$ 310,618
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (shares)			10,925,000
Issuance of common stock for cash, net of financing costs	81,902,363		$ 10,925	81,891,438
Payment to minority stockholders	(149,559)						(149,559)
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			551,883
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	2,598,915		$ 552	2,598,363
Stock-based compensation	6,186,848			6,186,848
Net loss attributable to common stockholders	(29,102,837)				(29,187,606)		84,769
Unrealized gain (loss) on short-term investments, net of tax	7,528					7,528
Unrealized gain (loss) on investment in affiliated entity, net of tax	2,952,201					2,952,201
Ending balance (shares) at Dec. 31, 2015		23	72,217,965
Ending balance at Dec. 31, 2015	175,933,053	$ 0	$ 72,218	534,004,564	(361,097,896)	2,708,339	245,828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (shares)			658,748
Issuance of common stock for cash, net of financing costs	6,295,761		$ 659	6,295,102
Issuance of common stock for Bioject acquisition (shares)			440,122
Issuance of common stock for Bioject acquisition	4,300,000		$ 440	4,299,560
Payment to minority stockholders	(149,559)						(149,559)
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			450,045
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	1,640,740		$ 449	1,640,291
Cashless exercise of stock options and warrants (shares)			295,490
Cashless exercise of stock options and warrants	0		$ 296	(296)
Stock-based compensation	10,479,135			10,479,135
Net loss attributable to common stockholders	(73,740,339)				(73,740,339)
Unrealized gain (loss) on short-term investments, net of tax	(111,967)					(111,967)
Unrealized gain (loss) on investment in affiliated entity, net of tax	(1,268,404)					(1,268,404)
Ending balance (shares) at Dec. 31, 2016		23	74,062,370
Ending balance at Dec. 31, 2016	123,378,420	$ 0	$ 74,062	556,718,356	(434,838,235)	1,327,968	96,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	0			312,310	(312,310)
Issuance of common stock for cash, net of financing costs (shares)			15,437,406
Issuance of common stock for cash, net of financing costs	94,347,922		$ 15,437	94,332,485
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			857,868
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments	1,342,250		$ 859	1,341,391
Stock-based compensation	13,070,962			13,070,962
Net loss attributable to common stockholders	(88,205,772)				(88,205,772)
Unrealized gain (loss) on short-term investments, net of tax	7,458					7,458
Unrealized gain (loss) on investment in affiliated entity, net of tax	(1,452,431)					(1,452,431)
Ending balance (shares) at Dec. 31, 2017		23	90,357,644
Ending balance at Dec. 31, 2017	$ 142,488,809	$ 0	$ 90,358	$ 665,775,504	$ (523,356,317)	$ (117,005)	$ 96,269

Consolidated Statements of Sto7

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Issuance of common stock for cash, financing costs	$ 4,900	$ 128	$ 4,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (88,205,772)	$ (73,740,339)	$ (29,102,837)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,850,376	1,708,498	1,048,431
Amortization of intangible assets	1,618,665	1,377,466	870,199
Change in value of common stock warrants	(806,819)	(127,554)	(177,561)
Stock-based compensation	13,070,962	10,479,135	6,186,848
Amortization of premiums on investments	319,845	266,290	348,566
Deferred taxes	(150,027)	(849)	14,166
Deferred rent	3,608,881	(16,728)	383,584
Loss on short-term investments	215,423	139,249	432,174
Gain on investment in affiliated entity	6,982,664	(1,110,787)	(2,600,467)
Gain on sale of intangible assets	(1,000,000)	(1,000,000)	(1,000,000)
Income tax benefit from other unrealized gains on securities	0	0	(2,097,766)
Changes in operating assets and liabilities:
Accounts receivable	9,818,306	(8,521,899)	(4,497,225)
Accounts receivable from affiliated entity	261,736	(714,908)	(31,627)
Prepaid expenses and other current assets	(851,847)	(831,802)	(119,284)
Prepaid expenses and other current assets from affiliated entity	(333,583)	(901,772)	771,723
Other assets	(526,207)	(1,442,314)	(196,265)
Accounts payable and accrued expenses	2,829,807	6,367,965	6,456,581
Accrued clinical trial expenses	2,243,503	3,767,906	593,051
Accounts payable and accrued expenses due to affiliated entity	(145,636)	907,532	136,640
Deferred revenue	(13,689,322)	1,527,686	10,191,840
Deferred revenue from affiliated entity	(319,876)	(687,827)	(49,672)
Net cash used in operating activities	(63,208,921)	(62,555,052)	(12,438,901)
Cash flows from investing activities:
Purchases of investments	(95,700,144)	(57,317,671)	(63,526,830)
Maturities of investments	77,162,902	76,528,030	10,484,267
Purchases of capital assets	(10,293,902)	(2,738,470)	(2,781,544)
Proceeds from sale of intangible assets	1,000,000	1,000,000	1,000,000
Purchase of intangible and other assets	0	(1,200,000)	0
Net cash provided by (used in) investing activities	(27,831,144)	16,271,889	(54,824,107)
Cash flows from financing activities:
Proceeds from issuance of common stock and warrants, net of issuance costs	94,347,922	6,295,761	81,902,363
Proceeds from stock option and warrant exercises, net of tax payments	1,342,250	1,640,740	2,598,915
Expenses from other financing activities	0	(149,559)	(149,559)
Net cash provided by financing activities	95,690,172	7,786,942	84,351,719
Increase (Decrease) in cash and cash equivalents	4,650,107	(38,496,221)	17,088,711
Cash and cash equivalents, beginning of period	19,136,472	57,632,693	40,543,982
Cash and cash equivalents, end of period	23,786,579	19,136,472	57,632,693
Supplemental disclosure of non-cash activities
Common stock issued for purchase of Bioject	0	4,300,000	0
Change in amounts accrued for purchases of property and equipment	851,204	164,923	225,148
Lease incentive recorded as fixed assets and deferred rent	$ 0	$ 523,856	$ 773,000

The Company

The Company	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company Inovio Pharmaceuticals, Inc. (the “Company” or “Inovio”), a clinical stage biopharmaceutical company, develops active SynCon ® DNA immunotherapies and vaccines focused on preventing and treating cancers and infectious diseases. Inovio’s DNA-based immunotherapies, in combination with proprietary CELLECTRA ® delivery devices, are intended to generate optimal antigen production in vivo, in particular functional CD8+ killer T cell and antibody responses, 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 and cancers; prostate, breast, lung and pancreatic cancers; hepatitis B virus ("HBV"); HIV; Ebola; Middle East Respiratory Syndrome ("MERS"); and Zika virus. The Company's partners and collaborators include MedImmune, LLC, The Wistar Institute, University of Pennsylvania, GeneOne Life Science Inc. ("GeneOne"), Regeneron Pharmaceuticals, Inc., Genentech, Inc., Plumbline Life Sciences, Inc., the Parker Institute for Cancer Immunotherapy, Drexel University, National Microbiology Laboratory of the Public Health Agency of Canada, National Institute of Allergy and Infectious Diseases (“NIAID”), United States Military HIV Research Program (“USMHRP”), U.S. Army Medical Research Institute of Infectious Diseases (“USAMRIID”), National Institutes of Health ("NIH"), HIV Vaccines Trial Network (“HVTN”) and Defense Advanced Research Projects Agency (“DARPA”). Inovio was incorporated in Delaware in June 2001 and has its principal executive offices in Plymouth Meeting, Pennsylvania.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation Inovio incurred a net loss attributable to common stockholders of $88.2 million for the year ended December 31, 2017 . Inovio had working capital of $103.0 million and an accumulated deficit of $523.4 million as of December 31, 2017 . 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 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 consolidated financial statements as of and for the year ended December 31, 2017 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 financial statements. Consolidation These consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. In conjunction with the acquisition in June 2009 of VGX Pharmaceuticals, the Company acquired a majority interest in VGX Animal Health and an equity interest in GeneOne, a publicly-traded company in South Korea. In addition to VGX Pharmaceuticals and VGX Animal Health, the Company consolidates its wholly owned subsidiaries Genetronics, Inc. and GENEOS Therapeutics, Inc., and recorded a non-controlling interest for the 15% of VGX Animal Health it did not own as of December 31, 2017 and 2016 . The Company's investment in GeneOne is recorded as investment in affiliated entity within the consolidated balance sheets and is accounted for at fair value at each reporting date, with changes in fair value recorded on the consolidated statements of operations within gain (loss) on investment in affiliated entity. All intercompany accounts and transactions have been eliminated upon consolidation. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one segment operating primarily within the United States. Use of Estimates The preparation of consolidated financial statements in accordance with United States generally accepted accounting principles requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. Inovio bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, the Company reviews its estimates to ensure that these estimates appropriately reflect changes in the business or as new information becomes available. Concentration of Credit Risk Financial instruments, that potentially subject the Company to concentrations of credit risk, consist primarily of cash and short-term investments. The Company limits its exposure to credit loss by placing its cash and investments with high credit quality financial institutions. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities which are designed to maintain principal and maximize liquidity. The Company has contracts with certain of its customers that have represented more than 10% of the Company's total revenues, as discussed in Note 6. Fair value of Financial Instruments The Company’s financial instruments consist principally of cash equivalents, short-term investments and investments in affiliated entities. The carrying amounts of cash equivalents approximate the related fair values due to the short-term maturities of these instruments. Investments consist of available-for-sale securities that are reported at fair value with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of consolidated stockholders’ equity. The Company's investment in Plumbline Life Sciences, Inc. (“PLS”), an affiliated entity, is accounted for as an available-for sale security. The Company’s investment in GeneOne, an affiliated entity, is accounted for at fair value on a recurring basis, with changes in fair value recorded on the consolidated statements of operations within gain (loss) from investment in affiliated entity. Cash and Cash Equivalents Cash equivalents are considered by the Company to be highly liquid investments purchased with original maturities of three months or less from the date of purchase. Cash and cash equivalents include certain money market accounts at December 31, 2017 and 2016 . Investments The Company defines investments as income-yielding securities that can be readily converted into cash or equity investments classified as available-for-sale. Investments include mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entity PLS at December 31, 2017 and 2016 . Accounts Receivable Accounts receivable are recorded at invoiced amounts and do not bear interest. The Company performs ongoing credit evaluations of its customers’ financial condition. Credit is extended to customers as deemed necessary and generally does not require collateral. Management believes that the risk of loss is significantly reduced due to the quality and financial position of the Company's customers. No allowance for doubtful accounts was deemed necessary at December 31, 2017 and 2016 . Fixed Assets Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the remaining term of the related leases or the estimated economic useful lives of the improvements. Repairs and maintenance are expensed as incurred. Long-Lived Assets All long-lived assets are reviewed for impairment in value when changes in circumstances dictate, based upon undiscounted future operating cash flows, and appropriate losses are recognized and reflected in current earnings, to the extent the carrying amount of an asset exceeds its estimated fair value determined by the use of appraisals, discounted cash flow analyses or comparable fair values of similar assets. The Company has not recognized any losses on long-lived assets through December 31, 2017 . Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from 2 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 being 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 December 31, 2017 and 2016 , the Company’s intangible assets resulting from the acquisition of VGX, Inovio AS and Bioject, and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $6.0 million and $ 7.6 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s 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 December 31, 2017 . 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, 2017 , 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. Income Taxes The Company recognizes deferred tax assets and liabilities for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities along with net operating loss and tax credit carry forwards. The Company records a valuation allowance against its deferred tax assets to reduce the net carrying value to an amount that it believes is more likely than not to be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made. Valuation allowances against the Company’s deferred tax assets were $94.0 million and $113.4 million at December 31, 2017 and 2016 , respectively. Changes in the valuation allowances, when they are recognized in the provision for income taxes, are included as a component of the estimated annual effective tax rate. Revenue Recognition The Company recognizes revenues when all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectability is reasonably assured. Grant revenue The Company receives non-refundable grants under available government programs. Government grants towards current expenditures are recorded as revenue when there is reasonable assurance that the Company has complied with all conditions necessary to receive the grants, collectability is reasonably assured and the related expenditures are incurred. License fee and milestone revenue The Company has adopted a strategy of co-developing or licensing its gene delivery technology for specific genes or specific medical indications. Accordingly, the Company has entered into collaborative research and development agreements and has received third-party funding for pre-clinical research and clinical trials. Agreements that contain multiple elements are analyzed to determine whether the deliverables within the agreement can be separated or whether they must be accounted for as a single unit of accounting in accordance with the FASB's Accounting Standards Update (“ASU”) No. 2009-13, Revenue Recognition (Topic 605): Multiple-Deliverable Revenue Arrangements. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. The delivered item(s) were considered a separate unit of accounting if all of the following criteria were met: (1) the delivered item(s) has value to the customer on a standalone basis; (2) there is objective and reliable evidence of the fair value of the undelivered item(s); and (3) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control. If these criteria were not met, the deliverable was combined with other deliverables in the arrangement and accounted for as a combined unit of accounting. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, the Company uses its best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the price to the collaborator is fixed or determinable, and collectability is reasonably assured. Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have an impact on the amount of revenue recognized in a given period. The Company applies ASU No. 2010-17, Revenue Recognition (Topic 605): Milestone Method of Revenue Recognition (“Milestone Method”). Under the Milestone Method, the Company will recognize consideration that is contingent upon the achievement of a milestone in its entirety as revenue in the period in which the milestone is achieved only if the milestone is substantive in its entirety. A milestone is considered substantive when it meets all of the following criteria: 1. The consideration is commensurate with either the entity's performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity's performance to achieve the milestone, 2. The consideration relates solely to past performance, and 3. The consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity's performance or on the occurrence of a specific outcome resulting from the entity's performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company. Business Combinations The cost of an acquired business is assigned to the tangible and identifiable intangible assets acquired and liabilities assumed on the basis of the estimated fair values at the date of acquisition. The Company assesses fair value, which is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, using a variety of methods including, but not limited to, an income approach and a market approach such as the estimation of future cash flows of acquired business and current selling prices of similar assets. Fair value of the assets acquired and liabilities assumed, including intangible assets, are measured based on the assumptions and estimations with regards to the variable factors such as the amount and timing of future cash flows for the asset or liability being measured, appropriate risk-adjusted discount rates, nonperformance risk, or other factors that market participants would consider. Upon acquisition, the Company determines the estimated economic lives of the acquired intangible assets for amortization purposes, which are based on the underlying expected cash flows of such assets. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that is not individually identified and separately recognized. Actual results may vary from projected results and assumptions used in the fair value assessments. 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. 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 and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. 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 warrants 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 the warrants from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any, under the treasury stock method. The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Year Ended December 31, 2017 2016 2015 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. $ (88,205,772 ) $ (73,740,339 ) $ (29,187,606 ) Adjustment for decrease in fair value of warrant liability (806,819 ) — (721,591 ) Numerator for use in diluted net loss per share $ (89,012,591 ) $ (73,740,339 ) $ (29,909,197 ) Denominator Weighted average number of common shares outstanding 81,777,493 73,214,766 68,198,142 Effect of dilutive potential common shares from warrants 140,529 — 167,123 Denominator for use in diluted net loss per share 81,918,022 73,214,766 68,365,265 Net loss per share, diluted $ (1.09 ) $ (1.01 ) $ (0.44 ) The following table summarizes potential shares of common stock that were excluded from diluted net loss per share calculation because of their anti-dilutive effect: Year Ended December 31, 2017 2016 2015 Options to purchase common stock 7,694,870 6,806,183 5,862,364 Warrants to purchase common stock — 284,091 276,813 Restricted stock units 1,234,168 798,834 230,000 Convertible preferred stock 8,456 8,456 8,456 Total 8,937,494 7,897,564 6,377,633 Leases Leases are classified as either capital or operating leases. Leases which transfer substantially all of the benefits and risks incidental to the ownership of assets are accounted for as if there was an acquisition of an asset and incurrence of an obligation at the inception of the lease. All other leases are accounted for as operating leases. Inovio’s Plymouth Meeting, PA headquarters and San Diego, CA facility leases, which have escalating payments, are expensed on a straight-line basis over the term of the lease. The allowance provided by the lessor for non-structural, normal leasehold improvements are considered tenant incentives and are amortized on a straight-line basis over the term of the lease. These leases represent the primary expense and commitment as indicated in Note 11, “Commitments”. Other leases exist for office machinery, such as copiers, wherein lease expense is recorded as incurred. Stock-Based Compensation The Company incurs stock-based compensation expense related to restricted stock units and stock options. The fair value of restricted stock units 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 highly 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 of zero is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. Upon adoption of ASU 2016-09 on January 1, 2017, the Company elected to remove the forfeiture rate from the calculation and recorded a cumulative catch-up adjustment to accumulated deficit with a corresponding offset to additional paid-in-capital of $312,000 . Previously, the forfeiture rate was based on historical data and the Company recorded stock-based compensation expense only for those awards that were expected to vest. The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.20% 0.91% 0.99% Expected volatility 73% 76% 74% Expected life in years 6 5 5 Dividend yield — — — Forfeiture rate N/A 7% 7% Stock‑based compensation expense related to stock options granted to non‑employees is recognized based on the fair value of the stock options, determined using the Black‑Scholes option pricing model, as they are earned. The fair value of the non-employee options is remeasured at each reporting period. Assumptions used in the Black-Scholes model for non-employees are presented below: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.4%-2.6% 2.3%-2.5% 2.1%-2.3% Expected volatility 97%-102% 71%-104% 105%-108% Expected life in years 9-10 7-10 7-10 Dividend yield — — — Recent Accounting Pronouncements - Recently Adopted ASU No. 2016-09. In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation-Improvements to Employee Share-Based Payment Accounting . The new guidance simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this standard were effective for the Company's annual year and first fiscal quarter beginning on January 1, 2017 with early adoption permitted. The Company adopted this guidance as of January 1, 2017 using a modified retrospective transition method. As a result of the adoption of this standard, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures when they occur. The Company recorded an adjustment of $312,000 to accumulated deficit with a corresponding offset to additional paid-in-capital at January 1, 2017. The Company also reversed a deferred tax asset related to the balance of unrecognized excess tax benefits of $1.1 million , with an offsetting adjustment to the valuation allowance. Recent Accounting Pronouncements 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. 2014-09. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers ("Topic 606”), which amended the existing accounting standards for revenue recognition, outlines a comprehensive revenue recognition model and supersedes most current revenue recognition guidance. The new standard requires a company to recognize revenue upon transfer of goods or services to a customer at an amount that reflects the expected consideration to be received in exchange for those goods or services. The amended guidance defines a five-step approach for recognizing revenue, which will require a company to use more judgment and make more estimates than under the current guidance. The Company adopted this new standard effective January 1, 2018, using the modified retrospective transition method. Under this method, the Company’s results will remain as reported and starting in 2018 will be under the new method. The Company has completed its preliminary evaluation of the impact of adoption of Topic 606 on certain of its existing agreements as follows: Collaboration Agreement with MedImmune The Company has determined that no cumulative catch-up adjustment is required. The Company expects the accounting for contingent milestone payments to be a significant change in accounting for its license and collaboration agreements. Topic 605 provides guidance specific to the accounting for milestone payments, including the ability to defer the recognition of any milestones until received and, if certain criteria are met, the ability to recognize milestone payments as revenue when received. However, Topic 606 does not contain guidance specific to milestone payments, thereby requiring potential milestone payments to be considered in accordance with the overall model of Topic 606. As a result, revenues from contingent milestone payments may be recognized earlier under Topic 606 than under Topic 605, based on an assessment of the probability of achievement of the milestone and the likelihood of a significant reversal of such milestone revenue at each reporting date. This assessment may result in recognizing milestone revenue before the milestone event has been achieved. In addition, Topic 606 changes guidance regarding the accounting for variable consideration received from licensees, which may impact the estimation of, and determination of the timing of, the related revenue recognition Grant Agreements 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 will be recorded as a contra-expense as opposed to revenue on the consolidated statement of operations. New grant agreements will be evaluated to determine if they represent contribution transactions or exchange transactions. If the Company performs research and development services with no performance obligations to provide the agency granting the funds reciprocal value for the contributions received, then the consideration received under the grant would result in amounts recognized as contra expense, as opposed to revenue. ASU No. 2016-01. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . The amended guidance requires the Company to measure and record equity investments, except those accounted for under the equity method of accounting that have a readily determinable fair value, at fair value and for the Company to recognize the changes in fair value in its consolidated statements of operations, instead of recognizing unrealized

Collaborative Agreements

Collaborative Agreements	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Agreements	Collaborative Agreements MedImmune On August 7, 2015, The Company entered into a license and collaboration agreement with MedImmune, the global biologics research and development arm of AstraZeneca. Under the agreement, MedImmune 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. MedImmune made an upfront payment of $27.5 million to the Company in September 2015 and has agreed to make additional future development, regulatory and commercial event based payments totaling up to $700 million . MedImmune will fund all development costs associated with INO-3112 immunotherapy. The Company is entitled to receive up to mid-single to double-digit tiered royalties on INO-3112 product sales. Within the broader collaboration, the Company and MedImunne will attempt to develop up to two additional DNA-based cancer vaccine products not included in the Company's current product pipeline, which MedImmune will have the exclusive rights to develop and commercialize. The Company has assessed event-based payments under the authoritative guidance for research and development milestones and determined that none of the event- based payments represent a milestone under the milestone method of accounting. The Company identified the deliverables at the inception of the agreement. The Company has determined that the license to INO-3112, the license for the research collaboration products with related research and development services and the product development services for INO-3112 individually represent separate units of accounting because each deliverable has standalone basis. The Company considered the provisions of the multiple-element arrangement guidance in determining whether the deliverables outlined above have standalone basis and thus should be treated as separate units of accounting. The Company determined that the license for INO-3112, the license for the research collaboration products with related research and development services, and the product development services for INO-3112 have standalone basis and represent separate units of accounting because the rights conveyed permit MedImmune to perform all efforts necessary to complete development, commercialize and begin selling the product upon regulatory approval. In addition, MedImmune has the appropriate development, regulatory and commercial expertise with products similar to the product licensed under the agreement and has the ability to engage third parties to manufacture the product allowing MedImmune to realize the value of the license without receiving any of the remaining deliverables. MedImmune can also sublicense its license rights to third parties. Also, the Company determined that the product development services for INO-3112 represents an individual unit of accounting as MedImmune could perform such services and/or could acquire these on a separate basis. The best estimated selling prices for these units of accounting were determined based on market conditions, the terms of comparable collaborative agreements for similar technology in the pharmaceutical and biotechnology industry, the Company's pricing practices and pricing objectives and the nature of the research and development services to be provided. While market data and the cost-to-recreate method under the cost approach were considered throughout the valuation process, ultimately, the estimated selling prices of the licenses were determined utilizing two forms of the relief from royalty method under the income approach. The arrangement consideration was allocated to the deliverables based on the relative selling price method. The amount allocable to the delivered unit or units of accounting is limited to the amount that is considered fixed and determinable and is not contingent upon the delivery of additional items or meeting other specified performance conditions. Based on the results of the Company's analysis, the $27.5 million up-front payment was allocated as follows: $15.0 million to the product license to INO-3112 and $12.5 million for the license to the research collaboration products and related research and developments services. The amount allocated to the license for INO-3112 was recognized as revenue under collaborative research and development arrangements during the year ended December 31, 2015 as this was determined to be earned upon the granting of the license and delivery of the related knowledge and data. The remaining amount related to the research collaboration products and related research and development services of $12.5 million was recognized as revenue under collaboration research and development arrangements during the quarter ended June 30, 2017, upon selection of the first research collaboration product candidate by MedImmune. The Company believes that no substantive value related to the research collaboration products license and research services was transferred to MedImmune prior to their selection of the first research collaboration product since there was no economic benefit from the research unless such product candidate was selected. Therefore, the Company believes the license for the research collaboration products was delivered and the research services were completed upon the selection of the product candidate by MedImmune in June 2017. The Company performs certain product development services for INO-3112 and is reimbursed by MedImmune for these services. The Company recognizes revenues associated with these services as revenues under collaborative arrangements as the related services are performed and according to the relative selling price method of the allocable arrangement consideration. In December 2017, the Company received a $7.0 million milestone payment from MedImmune triggered by the initiation of the Phase 2 portion of an ongoing clinical trial under the agreement. This amount was recognized in full as revenue for the year ended December 31, 2017. During the years ended December 31, 2017 and 2016 , the Company recognized revenues of $22.3 million and $1.5 million from MedImmune, respectively. As of December 31, 2017 and 2016 , the Company has a deferred revenue balance of $1.1 million and $13.7 million , respectively, related to the Agreement. As of December 31, 2017 and 2016 , the Company had an accounts receivable balance of $1.7 million and $1.2 million , respectively, related to the collaboration agreement with MedImmune. Roche In September 2013, the Company entered into a Collaborative, License, and Option Agreement with Roche and received an upfront payment of $10.0 million . The parties agreed to co-develop multi-antigen DNA immunotherapies targeting prostate cancer and hepatitis B. On November 14, 2014, Roche provided notice to the Company that it would be partially terminating the agreement with respect to the development of the Company’s DNA immunotherapy targeting prostate cancer. The termination was effective in February 2015. All of Roche’s rights to the Company’s DNA immunotherapy targeting prostate cancer, including the right to license the product to other parties, have been returned to the Company. On July 28, 2016, Roche provided notice to the Company that it would be discontinuing the agreement and its development of INO-1800, the Company’s DNA immunotherapy against the hepatitis B virus. The termination was effective in October 2016. All of Roche’s rights to INO-1800, including the right to license the product to other parties, have been returned to the Company. In February 2017, the Company received full payment of $8.5 million from Roche for its past and future obligations associated with the termination of the agreement. The Company identified the deliverables at the inception of the agreement. The Company determined that the license to the targets, the option right to license additional vaccines, research and development services, manufacturing and drug supply, and participation in the joint steering committee individually represented separate units of accounting because each deliverable had standalone value. The amount allocable to the delivered unit or units of accounting using the best estimated selling price was limited to the amount that was considered fixed and determinable and was not contingent upon the delivery of additional items or meeting other specified performance conditions. Based on the results of the Company's analysis, the $10.0 million up-front payment was allocated as follows: $8.4 million to the license to the targets, $1.5 million to the option right and $155,000 to the joint steering committee obligation. The amounts allocated to the licenses for the targets was recognized as revenue in 2013 as these were determined to be earned upon the granting of the license and delivery of the related knowledge and data. The Company recognized revenues associated with research and development services and manufacturing and drug supply as revenues under collaborative arrangements as the related services were performed and according to the relative selling price method of the allocable arrangement consideration. During the years ended December 31, 2017 and 2016 , the Company recognized revenues of $6.1 million and $4.9 million from Roche, respectively. As of December 31, 2017 and 2016 , the Company has an accounts receivable balance of $0 and $2.4 million , respectively, related to the Roche Agreement. DARPA- Ebola In April 2015, the Company received a grant from the Defense Advanced Research Projects Agency ("DARPA") to lead a collaborative team to develop multiple treatment and prevention approaches against Ebola. The consortium, led by the Company, is taking a multi-faceted approach to develop products to prevent and treat Ebola infection. The award covers pre-clinical development costs as well as good manufacturing practice manufacturing costs and the Phase 1 clinical study costs. The funding period is over two years and covers a base award of $19.6 million and an option award of $24.6 million , which was exercised in September 2015. The development proposal includes a second option of $11.1 million to support additional product supply and clinical development activities. The options are contingent upon the successful completion of certain pre-clinical development milestones. During the years ended December 31, 2017 and 2016 , the Company recognized revenues of $9.8 million and $22.4 million, respectively, from DARPA related to the grant. As of December 31, 2017 and 2016 , the Company had a deferred revenue balance of $149,000 and $1.2 million , respectively, related to the DARPA grant. As of December 31, 2017 and 2016 , the Company had an accounts receivable balance of $4.1 million and $9.2 million, respectively, related to the DARPA grant. ApolloBio Corporation On December 29, 2017, the Company entered into an Amended and Restated License and Collaboration Agreement, or the ApolloBio Agreement, with ApolloBio Corporation, or ApolloBio. 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 and Taiwan. The territory may be expanded to include Korea in the event that no patent covering VGX-3100 issues in China within the three years following the Effective Date of the ApolloBio Agreement, as defined below. Under the ApolloBio Agreement, ApolloBio will pay the Company an upfront payment of $23.0 million , and such payment is to be made within three business days following the date of approval of the ApolloBio Agreement by ApolloBio’s board of directors and shareholders, or the Effective Date, which the Company expects to occur in the first quarter of 2018. In the event that such upfront payment is not made on or before April 7, 2018, the Company has the right to terminate the Agreement in its entirety. In addition to the upfront payment, the Company is entitled to receive up to an aggregate of $20.0 million 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.

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Investments at December 31, 2017 and 2016 consisted of mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entity PLS. The Company classifies all investments as available-for-sale, as the sale of such investments may be required prior to maturity to implement management strategies. Available-for-sale securities are recorded at fair value, based on current market valuations. Unrealized gains and losses on available-for-sale securities are 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 consolidated statement of operations and are derived using the specific identification method for determining the cost of the securities sold. During the years ended December 31, 2017 and 2016 , net realized loss on investments of $215,000 and $139,000 was recorded, respectively. The Company assessed each of its investments on an individual basis to determine if any decline in fair value was other-than-temporary. There were no impairments considered to be other-than-temporary during the years ended December 31, 2017 and 2016 . Interest and dividends on investments classified as available-for-sale are included in interest and other income, net, in the consolidated statements of operations. As of December 31, 2017 , the Company had 42 available-for-sale securities in a gross unrealized loss position, of which 16 with an aggregate total unrealized loss of $108,000 were in such position for longer than 12 months. The following is a summary of available-for-sale securities as of December 31, 2017 and 2016 : As of December 31, 2017 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 68,776,165 $ 42,097 $ (252,373 ) $ 68,565,889 US corporate debt securities Less than 2 35,210,121 3,032 (140,198 ) 35,072,955 Investment in affiliated entity (PLS) --- — 2,325,079 — 2,325,079 Total investments $ 103,986,286 $ 2,370,208 $ (392,571 ) $ 105,963,923 As of December 31, 2016 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 60,883,065 $ 94,374 $ (387,693 ) $ 60,589,746 US corporate debt securities Less than 2 25,098,122 6,853 (65,309 ) 25,039,666 Investment in affiliated entity (PLS) --- — 3,777,510 — 3,777,510 Total investments $ 85,981,187 $ 3,878,737 $ (453,002 ) $ 89,406,922

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
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 and liabilities 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 and liabilities between Level 1, Level 2 and Level 3 of the fair value hierarchy during the years ended December 31, 2017 and 2016 . 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 December 31, 2017 : Fair Value Measurements at December 31, 2017 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,843,482 $ 9,843,482 $ — $ — Mutual funds 68,565,889 — 68,565,889 — US corporate debt securities 35,072,955 — 35,072,955 — Investments in affiliated entities 11,394,480 11,394,480 — — Total assets $ 124,876,806 $ 21,237,962 $ 103,638,844 $ — Liabilities: Common stock warrants $ 360,795 $ — $ 360,795 Total liabilities $ 360,795 $ — $ 360,795 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 December 31, 2016 : Fair Value Measurements at December 31, 2016 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 10,300,813 $ 10,300,813 $ — $ — Mutual funds 60,589,746 — 60,589,746 — US corporate debt securities 25,039,666 — 25,039,666 — Investments in affiliated entities 19,829,575 19,829,575 — — Total assets $ 115,759,800 $ 30,130,388 $ 85,629,412 $ — Liabilities: Common stock warrants $ 1,167,614 $ — $ — $ 1,167,614 Total liabilities $ 1,167,614 $ — $ — $ 1,167,614 Level 1 assets at December 31, 2017 and 2016 consisted of money market funds held by the Company that are valued at quoted market prices, as well as the Company’s investments in GeneOne and PLS (see Note 12 for additional information about the Company’s investments in these affiliated entities). Level 2 assets at December 31, 2017 and 2016 consisted of US corporate debt securities and 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 their 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 December 31, 2017 . Level 3 assets held at December 31, 2016 consisted of a warrant received by the Company in 2012 to purchase shares of common stock of OncoSec Medical Incorporated (“OncoSec”). This warrant expired unexercised in March 2017 and was considered to have zero value as of December 31, 2016. Another warrant to purchase shares of common stock of OncoSec held by the Company expired unexercised in September 2016. The Company recorded a change in fair value of the OncoSec warrants of $0 , $(6,000) and $(544,000) for the years ended December 31, 2017 , 2016 and 2015 , respectively. The change in fair value is reflected in the Company's consolidated statement of operations as a component of change in fair value of common stock warrants. Level 3 liabilities held as of December 31, 2017 and 2016 consisted of common stock warrant liabilities associated with warrants to purchase the Company's common stock issued in March 2013. If unexercised, the warrants will expire in September 2018 . During the years ended December 31, 2017 and 2016 , none of these warrants were exercised. See Note 10 for additional information about the warrants. As of December 31, 2017 the Company had a $361,000 common stock warrant liability. The Company reassesses the fair value of the common stock warrants at each reporting date utilizing a Black-Scholes pricing model. Inputs used in the pricing model include estimates of stock price volatility, expected warrant life and risk-free interest rate. The Company develops its estimates based on historical data. The assumptions used to estimate the fair value of common stock warrants at December 31, 2017 and 2016 are presented below: Year Ended December 31, 2017 2016 Risk-free interest rate 1.75% 1.1% Expected volatility 55% 61% Expected life in years 0.70 1.70 Dividend yield — — Changes in these assumptions as well as fluctuations in the Company's stock price between the valuation dates can have a significant impact on the fair value of the common stock warrant liability. As a result of these calculations, the Company recorded a decrease in fair value of $(807,000) , $(134,000) and $(722,000) for the years ended December 31, 2017 , 2016 and 2015 , respectively. The change in fair value is reflected in the Company's consolidated statement of operations as a component of change in fair value of common stock warrants. The following table presents the changes in fair value of the Company’s total Level 3 financial liabilities for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 2016 Balance at beginning of year $ 1,167,614 $ 1,301,138 Decrease in fair value included in change in fair value of common stock warrants (806,819 ) (133,524 ) Balance at end of year $ 360,795 $ 1,167,614

Major Customers and Concentrati

Major Customers and Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Major Customers and Concentration of Credit Risk	Major Customers and Concentration of Credit Risk Customer 2017 Revenue % of Total Revenue 2016 Revenue % of Total Revenue 2015 Revenue % of Total Revenue MedImmune $ 22,269,773 53 % $ 1,518,639 4 % $ 16,037,731 40 % DARPA 9,983,927 24 26,602,183 75 11,582,623 28 Roche 6,107,254 14 4,917,929 14 10,778,688 27 NIAID — — 118,171 — 901,475 2 GeneOne (affiliated entity) 551,208 1 1,188,432 4 450,000 1 All other 3,307,924 8 1,023,007 3 821,594 2 Total revenue $ 42,220,086 100 % $ 35,368,361 100 % $ 40,572,111 100 % During the years ended December 31, 2017 , 2016 and 2015 , the Company recognized revenue from various license fees, collaborative research and development agreements, grants and government contracts. As of December 31, 2017 , $ 4.1 million, or 69% , and $1.7 million , or 28% , of the Company's accounts receivable was attributable to DARPA and MedImmune, respectively. As of December 31, 2016 , $12.1 million , or 73% , $2.4 million , or 15% , and $ 1.2 million , or 7% , of accounts receivable was attributable to DARPA, Roche and MedImmune, respectively. The Company’s accounts receivable from DARPA includes $1.6 million of amounts that are unbilled as of December 31, 2017 . Unbilled amounts range from 1 to 9 months in age and are attributable to the fact that the Company is awaiting an invoice from its sub-contractor prior to submission of an aggregate invoice to DARPA. The Company believes that all criteria for revenue recognition under SAB 104 have been met, and also anticipates that all such amounts will be invoiced and collected within the next 12 months and has included these amounts as current assets in its consolidated balance sheet. There is minimal credit risk with these customers based upon collection history, their size and financial condition. Accordingly, the Company does not consider it necessary to record a reserve for uncollectible accounts receivable.

Fixed Assets

Fixed Assets	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Fixed Assets	Fixed Assets Fixed assets at December 31, 2017 and 2016 consist of the following: Cost Accumulated Depreciation and Amortization Net Book Value As of December 31, 2017 Leasehold improvements $ 14,553,993 $ (2,042,871 ) $ 12,511,122 Laboratory equipment 3,787,578 (1,724,946 ) 2,062,632 Office furniture and fixtures 3,366,896 (1,471,705 ) 1,895,191 Computer equipment and other 3,718,266 (1,867,035 ) 1,851,231 $ 25,426,733 $ (7,106,557 ) $ 18,320,176 As of December 31, 2016 Leasehold improvements $ 5,248,311 $ (1,199,415 ) $ 4,048,896 Laboratory equipment 3,534,302 (1,072,188 ) 2,462,114 Office furniture and fixtures 1,814,493 (1,108,187 ) 706,306 Computer equipment and other 3,684,521 (1,876,391 ) 1,808,130 $ 14,281,627 $ (5,256,181 ) $ 9,025,446 Depreciation expense for the years ended December 31, 2017 , 2016 and 2015 was $1.9 million , $1.7 million and $1.0 million , respectively. The Company determined that the carrying value of these long-lived assets was not impaired during the periods presented.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following sets forth goodwill and intangible assets by major asset class: December 31, 2017 December 31, 2016 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 (5,681,673 ) 120,855 5,802,528 (5,618,854 ) 183,674 Licenses 8 – 17 1,323,761 (1,190,609 ) 133,152 1,323,761 (1,161,861 ) 161,900 CELLECTRA ® (b) 5 – 11 8,106,270 (7,252,108 ) 854,162 8,106,270 (6,825,028 ) 1,281,242 GHRH(b) 11 335,314 (271,948 ) 63,366 335,314 (240,264 ) 95,050 Bioject (c) 2 – 15 5,100,000 (1,405,556 ) 3,694,444 5,100,000 (562,222 ) 4,537,778 Other(d) 18 4,050,000 (2,906,250 ) 1,143,750 4,050,000 (2,681,250 ) 1,368,750 Total intangible assets 24,717,873 (18,708,144 ) 6,009,729 24,717,873 (17,089,479 ) 7,628,394 Total goodwill and intangible assets $ 35,231,244 $ (18,708,144 ) $ 16,523,100 $ 35,231,244 $ (17,089,479 ) $ 18,141,765 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX Pharmaceuticals 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 Pharmaceuticals. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the acquisition of Bioject. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition. Aggregate amortization expense on intangible assets was $1.6 million , $1.4 million and $870,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. Amortization expense related to intangible assets at December 31, 2017 is expected to be incurred as follows: Year ending December 31, 2018 $ 1,249,584 2019 1,066,251 2020 547,081 2021 520,414 2022 492,818 Thereafter 2,133,581 $ 6,009,729 There were no impairment or impairment indicators present and no losses were recorded during the years ended December 31, 2017 , 2016 and 2015 , respectively.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts Payable and Accrued Expenses Accounts payable and accrued expenses at December 31, 2017 and 2016 consist of the following: As of December 31, 2017 2016 Trade accounts payable, including from affiliated entity $ 7,564,830 $ 5,920,642 Accrued compensation 7,997,152 6,531,983 Accrued subcontract costs 3,746,937 5,475,359 Other accrued expenses 3,969,879 1,669,803 $ 23,278,798 $ 19,597,787

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock Shares Outstanding as of December 31, Shares Authorized Shares Issued 2017 2016 Series C Preferred Stock, par $0.001 1,091 1,091 23 23 The shares of the Company’s Series C Preferred Stock have the following pertinent rights and privileges, as set forth in the Company’s Amended and Restated Certificate of Incorporation and its Certificates of Designations, Rights and Preferences related to the various series of preferred stock. Rights on Liquidation In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company (a “liquidation event”), before any distribution of assets of the Company shall be made to or set apart for the holders of common stock, the holders of Series C Preferred Stock, pari passu, are entitled to receive payment of such assets of the Company in an amount equal to $10,000 per share of such series of preferred stock, plus any accumulated and unpaid dividends thereon (whether or not earned or declared). If the assets of the Company available for distribution to stockholders exceed the aggregate amount of the liquidation preferences payable with respect to all shares of each series of preferred stock then outstanding, then, after the payment of such preferences is made or irrevocably set aside, the holders of the Company’s common stock are entitled to receive a pro rata portion of such assets based on the aggregate number of shares of common stock held by each such holder. The holders of the Company’s outstanding preferred stock shall participate in such a distribution on a pro-rata basis, computed based on the number of shares of common stock which would be held by such preferred holders if immediately prior to the liquidation event all of the outstanding shares of the preferred stock had been converted into shares of common stock at the then current conversion value applicable to each series. A Change of Control of the Company (as defined in the Certificates of Designations, Rights and Preferences) is not a liquidation event triggering the preferences described above, and is instead addressed by separate terms in the Series C Certificates of Designations, Rights, and Preferences. Although the liquidation preferences are in excess of the par value of $0.001 per share of the Company’s preferred stock, these preferences are equal to or less than the stated value of such shares based on their original purchase price. Voting Rights The holders of Series C Preferred Stock have full voting rights and powers equal to the voting rights and powers of holders of the Company’s common stock and are entitled to notice of any stockholders’ meeting in accordance with the Company’s Bylaws. Holders are entitled to vote on any matter upon which holders of the Company’s common stock have the right to vote, including, without limitation, the right to vote for the election of directors together with the holders of common stock as one class. Series C Preferred holders are entitled to 368 votes for each share of Series C Preferred Stock held. Holder Optional Conversion Right The holder of any share or shares of Series C Preferred Stock has the right at any time, at such holder’s option, to convert all or any lesser portion of such holder’s shares of the Preferred Stock into such number of fully paid and non-assessable shares of Common Stock as is determined by dividing (i) the aggregate Liquidation Preference applicable to the particular series of preferred shares, plus accrued and unpaid dividends thereon by (ii) the applicable Conversion Value (as defined in the relevant series’ Certificate of Designations, Rights and Preferences) then in effect for such series of preferred shares. As of December 31, 2017, the Conversion Value was $27.20 , such that the outstanding shares of Series C Preferred Stock were convertible into 8,456 shares of common stock. The Company is not obligated to issue any fractional shares or scrip representing fractional shares upon such conversion and instead shall pay the holder an amount in cash equal to such fraction multiplied by the current market price per share of the Company’s common stock. Company Mandatory Conversion Option The Company has the option upon thirty (30) days prior written notice, to convert all of the outstanding shares of the Series C Preferred Stock into such number of fully paid and non-assessable shares of common stock as is determined by dividing (i) the aggregate Liquidation Preference of the shares of the relevant series of preferred stock to be converted, plus accrued and unpaid dividends thereon by (ii) the applicable Conversion Value (as defined in the relevant series’ Certificate of Designations, Rights and Preferences) then in effect, if the following triggering events have occurred: (i) the price of the Company’s common stock exceeds $72.00 per share for 20 out of 30 consecutive trading days; and (ii) the average daily trading volume (subject to adjustment for stock dividends, subdivisions and combinations) of the common stock exceeds 6,250 shares for at least 20 out of 30 consecutive trading days. Common Stock On July 25, 2017, the Company closed an underwritten public offering of 12,500,000 shares of common stock at a public offering price of $6.00 per share. The net proceeds to the Company, after deducting the underwriters' discounts and commissions and other offering expenses, were $70.1 million. In June 2016, 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 $50.0 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 2.0% 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 year ended December 31, 2017 , the Company sold a total of 2,937,406 shares of common stock under the Sales Agreement. The sales were made at a weighted average price of $8.41 per share with net proceeds to the Company of $24.2 million. As of December 31, 2017, the Company has sold an aggregate of 3,596,154 shares of common stock under the Sales Agreement for net proceeds of $30.5 million . Accordingly, as of December 31, 2017 the Company may sell up to an additional $18.9 million in shares of its common stock under the Sales Agreement. Warrants The Company accounts for registered common stock warrants issued in March 2013 under the authoritative guidance on accounting for derivative financial instruments indexed to, and potentially settled in, a company’s own stock, on the understanding that in compliance with applicable securities laws, the registered warrants require the issuance of registered securities upon exercise and do not sufficiently preclude an implied right to net cash settlement. The Company classifies registered warrants on the consolidated balance sheet as a current liability which is revalued at each balance sheet date subsequent to the initial issuance. Determining the appropriate fair-value model and calculating the fair value of registered warrants requires some judgment, including estimating stock price volatility and expected warrant life. The Company develops its estimates based on historical data. A small change in the estimates used may have a relatively large change in the estimated valuation. The Company uses the Black-Scholes pricing model to value the registered warrants. Changes in the fair market value of the warrants are reflected in the consolidated statement of operations as “Change in fair value of common stock warrants". The following table summarizes the warrants outstanding as of December 31, 2017 and 2016 : As of December 31, 2017 As of December 31, 2016 Issued in Connection With: Exercise Price Expiration Date Number of Warrants Common Stock Warrant Liability Number of Warrants Common Stock Warrant Liability March 2013 financing $ 3.17 September 12, 2018 284,091 $ 360,795 284,091 $ 1,167,614 Total 284,091 $ 360,795 284,091 $ 1,167,614 During the years ended December 31, 2017 and 2016 , no warrants to purchase shares of the Company's common stock which were issued in connection with the March 2013 financing were exercised. Stock Options and Restricted Stock Units The Company has a stock-based incentive plan, the 2016 Omnibus Incentive Plan (the "2016 Incentive Plan"), pursuant to which the Company may grant stock options, restricted stock awards and restricted stock unit awards (“RSUs”) to employees, directors and consultants. The 2016 Incentive Plan was approved by the Company's stockholders on May 13, 2016. 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 6,000,000 shares, provided that commencing with the first business day of each calendar year beginning January 1, 2018, 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. On January 1, 2018, the maximum number of shares to be issued was increased by 2,000,000 . At December 31, 2017 , there were 6,000,000 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 December 31, 2017 , the Company had 3,994,511 shares of common stock available for future grant under the 2016 Incentive Plan, 819,507 shares underlying outstanding but unvested RSUs and options outstanding to purchase 1,136,057 shares of common stock under the 2016 Incentive Plan. The awards granted 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 Company’s previous stock-based incentive plan, 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 December 31, 2017 , the Company had 414,661 shares underlying outstanding but unvested RSUs and options outstanding to purchase 6,357,071 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. At December 31, 2017 , the Company also had options outstanding to purchase 201,742 shares of common stock under the VGX Equity Compensation Plan, which the Company assumed in connection with its acquisition of VGX in 2009. The terms and conditions of the options outstanding under this plan remain unchanged. Total stock-based compensation cost recognized in the consolidated statement of operations for the years ended December 31, 2017 , 2016 and 2015 was $12.9 million , $10.2 million and $5.8 million , respectively, of which $5.8 million , $4.8 million and $3.2 million was included in research and development expenses and $7.1 million , $5.4 million and $2.6 million was included in general and administrative expenses, respectively. At December 31, 2017 and 2016 , there was $5.9 million and $5.8 million of total unrecognized compensation cost, respectively, related to unvested stock options, which is expected to be recognized over a weighted-average period of 1.8 years and 1.9 years respectively. At December 31, 2017 and 2016 , there was $5.3 million and $4.0 million of total unrecognized compensation cost, respectively, related to unvested RSUs, which is expected to be recognized over a weighted-average period of 1.8 years and 2.0 years, respectively. The fair value of options granted to non-employees at the measurement dates were estimated using the Black-Scholes pricing model. Total stock-based compensation for options granted to non-employees for the years ended December 31, 2017 , 2016 and 2015 was $201,000 , $321,000 and $385,000 , respectively. As of December 31, 2017 , options to purchase 701,367 shares of common stock granted to non-employees remained outstanding. The following table summarizes total stock options outstanding at December 31, 2017 : Options Outstanding Options Exercisable Exercise Price Shares Underlying Options Outstanding Weighted-Average Remaining Contractual Life (in Years) Weighted Average Exercise Price Shares Underlying Options Exercisable Weighted Average Exercise Price $1.48-$3.00 1,177,183 4.6 $ 2.25 1,177,183 $ 2.25 $3.01-$6.00 753,932 3.4 $ 4.64 668,244 $ 4.57 $6.01-$9.00 4,709,442 7.6 $ 7.09 2,639,454 $ 7.23 $9.01-$12.00 357,603 8.0 $ 9.79 263,180 $ 9.83 $12.01-$15.00 696,710 6.2 $ 12.96 696,710 $ 12.96 7,694,870 6.6 $ 6.77 5,444,771 $ 6.68 At December 31, 2017 , the aggregate intrinsic value of options outstanding was $2.3 million , the aggregate intrinsic value of options exercisable was $2.3 million , and the weighted average remaining contractual term of options exercisable was 5.9 years. At December 31, 2017 , the aggregate intrinsic value of unvested RSUs was $5.1 million and the aggregate intrinsic value of RSUs which vested during the year ended December 31, 2017 was $3.6 million. At December 31, 2017 , options to purchase 7,694,870 shares of common stock and 1,234,168 RSUs are expected to vest. Stock option activity under the Company’s equity incentive plans during the year ended December 31, 2017 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2016 6,806,183 $ 6.81 Granted 1,788,121 6.62 Exercised (452,973 ) 5.18 Cancelled (446,461 ) 8.49 Balance, December 31, 2017 7,694,870 $ 6.77 RSU activity under the Company’s equity incentive plans during the year ended December 31, 2017 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2016 798,834 $ — Granted 1,035,443 — Vested (561,462 ) — Cancelled (38,647 ) — Balance, December 31, 2017 1,234,168 $ — The weighted average exercise price per share was $9.67 for the 200,501 options which expired during the year ended December 31, 2017 , $9.01 for the 69,570 options which expired during the year ended December 31, 2016 and $10.89 for the 83,696 options which expired during the year ended December 31, 2015 . The weighted average grant date fair value per share was $4.33 , $4.59 and $4.60 for options granted during the years ended December 31, 2017 , 2016 and 2015 , respectively. The weighted average grant date fair value was $6.66 , $7.41 and $7.76 per share for RSUs granted during the years ended December 31, 2017 , 2016 and 2015 , respectively. The Company received $2.3 million , $1.8 million and $552,000 in proceeds from the exercise of stock options during the years ended December 31, 2017 , 2016 and 2015 , respectively. The aggregate intrinsic value of options exercised was $519,000 , $3.5 million and $456,000 during the years ended December 31, 2017 , 2016 and 2015 , respectively.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments	Commitments San Diego Leases In April 2013, the Company entered into a lease for office space located in San Diego, California. The term of the Lease commenced on December 1, 2013. The initial term of the Lease is ten years, with a right to terminate on December 1, 2019, subject to specified conditions. In June 2015, the Company amended the lease for this space to increase the total leased space and occupy the entire building. The commencement of the amended lease was in January 2016 and increased monthly lease payments to range from free rent to $99,000 . The Company has capitalized $822,000 of tenant improvements within fixed assets on the consolidated balance sheet related to this additional space, and has recorded a corresponding increase to deferred rent. In October 2016, the Company entered into an office lease (the “new Lease”) for a second property located in San Diego, California. The total space under the new Lease is approximately 51,000 square feet. The Company is using the facility for office, manufacturing and research and development purposes. The term of the new Lease commenced on June 1, 2017. The initial term of the new Lease is ten years, with a right to terminate on November 30, 2023, subject to specified conditions. The base rent adjusts periodically throughout the term of the new Lease, with monthly payments ranging from free rent to $95,000 , with a portion of the rent abated for certain periods during the first two years of the initial term. In addition, the Company is obligated to reimburse the landlord its share of operating and other expenses, and has paid a security deposit of $95,000 . As of December 31, 2017 , the Company has capitalized $2.3 million of reimbursable tenant improvements to the new office which has been recorded as a leasehold improvement within fixed assets on the consolidated balance sheet, offset by a corresponding amount recorded in deferred rent. Plymouth Meeting Lease and Sublease In March 2014, the Company entered into a lease (the "Lease") with a publicly owned real estate investment trust for office space located in Plymouth Meeting, Pennsylvania. The Company occupied the space in June 2014. The initial term of the Lease was 11.5 years. The base rent adjusts periodically throughout the term of the Lease, with monthly payments ranging from free rent to $58,000 . In addition, the Company is obligated to reimburse the landlord its share of operating and other expenses and a property management fee, and has paid a security deposit of $49,000 . In July 2015, the Company amended the Lease to increase the total leased space. The commencement of the amended Lease was in the first quarter of 2016 and increased monthly lease payments to range between free rent to $80,000 . In June 2017, the Company entered into a sublease (the “Sublease”) for additional space in its current office in Plymouth Meeting, Pennsylvania. The total additional space subject to the Sublease is approximately 30,000 square feet, which the Company intends to use for office purposes. The Sublease commenced on October 1, 2017 and will end on June 30, 2027. The base rent adjusts periodically throughout the term of the Sublease, with monthly payments ranging from $75,000 to $90,000 . In addition, the Company is obligated to reimburse the sub-landlord its share of operating and other expenses. In December 2017, the Sublease was reassigned by the sub-landlord back to the landlord, with no change in the underlying terms of the Sublease. In June 2017, the Company entered into a second amendment to the Lease to extend the lease term and term of the Sublease through December 31, 2029. In connection with the second amendment, the Company will pay the landlord an additional security deposit of $75,000 . Total monthly rent payments for the additional term will range between $173,000 and $179,000 . The Company has capitalized $2.6 million of tenant improvements to the Plymouth Meeting office within fixed assets on the consolidated balance sheet, offset by a corresponding amount recorded in deferred rent. Rent expense was $2.4 million , $1.6 million and $1.3 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Future minimum lease payments under non-cancelable operating leases as of December 31, 2017 are as follows: Year ending December 31, 2018 $ 3,251,000 2019 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 Thereafter 19,975,000 Total $ 38,904,000 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.

Investments in Affiliated Entit

Investments in Affiliated Entities	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Investments in Affiliated Entities	Investments in Affiliated Entities The Company held 1,644,155 common shares, representing a 7.8% and 10.2% ownership interest in GeneOne as of December 31, 2017 and 2016 , respectively, and 395,758 common shares, representing a 16.4% ownership interest in PLS as of each of December 31, 2017 and 2016 . The Company's investment in GeneOne is measured at fair value on a recurring basis. The Company elected the fair value option in conjunction with the investment in GeneOne at the inception of the investment; therefore, changes in the fair value of the investment are reflected as other income (expense) in the consolidated statements of operations. The fair market value of the Company’s interest in GeneOne was determined using the closing price of GeneOne's shares of common stock as listed on the Korean Stock Exchange as of December 31, 2017 and 2016 . The Company accounts for its investment in PLS as an available-for sale security by which the fair value was determined using the closing price of the common shares on the Korea New Exchange (KONEX) Market. The Company did not elect the fair value option for the investment in PLS at the inception of the investment, but rather recorded the investment under the equity method until its ownership interest dropped below 20% in June 2015 and accordingly began recording the investment under the cost method using the carryover basis from the equity method of zero . Once shares of PLS began trading on the KONEX, the Company classified the investment as available-for-sale and began recording the investment at fair value with changes in fair value reflected in other comprehensive income (loss).

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combination	Business Combination On April 29, 2016, the Company acquired all of the assets of Bioject Medical Technologies Inc.’s ("Bioject"), including its needle-free injection technology, products and intellectual property. The transaction, which was accounted for as a business combination, provided the Company with further opportunities in device development. The Company paid Bioject aggregate consideration of $5.5 million , consisting of $4.3 million in shares of the Company's common stock and $1.2 million in cash upon closing. The acquisition consideration was allocated to the estimated fair vales of the assets acquired as follows: Developed technology $ 3,800,000 Customer-related intangible assets 1,000,000 Trademarks 200,000 Covenants not-to-compete 100,000 Goodwill 400,000 Total purchase consideration $ 5,500,000 The fair value of the acquired intangible assets was estimated based on the discounted cash flow method that estimated the present value of a revenue stream derived from the licensing of the Bioject technology. These projected cash flows were discounted to present value using a discount rate of 14% . The fair value of the developed technology is being amortized on a straight-line basis over the estimated useful life of 15 years . The fair value of the remaining intangible assets acquired is being amortized on a straight-line basis over the estimated useful lives of between 2 - 5 years. The excess of the acquisition date consideration over the fair values assigned to the assets acquired was recorded as goodwill. The goodwill resulting from the acquisition consists primarily of the synergies expected from combining the technologies and know-how of Bioject with the Company's existing business. This includes synergies expected from combining Bioject's needle-free injection technology with the Company's existing electroporation delivery devices.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In accordance with the guidance pursuant to accounting for income taxes, a deferred tax asset or liability is determined based on the difference between the financial statement and tax basis of assets and liabilities as measured by the enacted tax rates which will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax asset will be realized. The components of the provision for income taxes are presented in the following table: Year Ended December 31, 2017 2016 2015 Current: Federal $ — $ — $ — State — — — — — — Deferred: Federal — — (1,594,000 ) State — — (504,000 ) — — (2,098,000 ) $ — $ — $ (2,098,000 ) The reconciliation of income taxes attributable to continuing operations computed at the statutory tax rates to income tax expense (recovery), using a 35% statutory tax rate, is as follows: Year Ended December 31, 2017 2016 2015 Income (benefit) taxes at statutory rates $ (30,872,000 ) $ (25,809,000 ) $ (10,920,000 ) State income tax, net of federal benefit (4,000 ) (4,000 ) (2,640,000 ) Change in valuation allowance (20,965,000 ) 29,678,000 7,882,000 Research and development tax credits (3,456,000 ) (3,117,000 ) (1,537,000 ) Fair value warrant (282,000 ) (47,000 ) (253,000 ) Stock compensation 2,332,000 113,000 2,288,000 Uncertain tax positions 846,000 1,367,000 1,968,000 Expired NOLs and credits 454,000 4,269,000 339,000 Limited NOLs and credits (165,000 ) (6,456,000 ) (297,000 ) Change in state tax rate 50,019,000 (495,000 ) 676,000 Other 2,093,000 501,000 396,000 $ — $ — $ (2,098,000 ) The income tax benefit recorded during the year ended December 31, 2015 of $2.1 million is principally due to a requirement under Accounting Standards Codification ("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 was a source of income which resulted in the partial realization of the current year loss from continuing operations. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2017 and 2016 are shown below: As of December 31, 2017 2016 Deferred tax assets: Capitalized research expense 8,546,000 $ 567,000 Net operating loss carryforwards 71,665,000 95,500,000 Research and development and other tax credits 7,531,000 5,300,000 Deferred revenue 297,000 5,452,000 Deferred rent 2,097,000 2,231,000 Stock-based compensation 3,091,000 4,511,000 Acquired intangibles 858,000 989,000 Other 1,906,000 3,783,000 95,991,000 118,333,000 Valuation allowance (94,039,000 ) (113,407,000 ) Total deferred tax assets 1,952,000 4,926,000 Deferred tax liabilities: Acquired intangibles (124,000 ) (175,000 ) Investment in affiliated entity (422,000 ) (3,624,000 ) Fixed assets (1,430,000 ) (1,302,000 ) Net deferred tax liabilities $ (24,000 ) $ (175,000 ) As of December 31, 2017 , the Company had federal, California and Pennsylvania tax net operating loss carry forwards of approximately $298.9 million , $68.6 million and $75.6 million , respectively, net of the net operating losses that will expire due to IRC Section 382 limitations. The federal, California and Pennsylvania net operating loss carry forwards will begin to expire in 2018 , 2028 and 2021 , respectively, unless previously utilized. The Company adopted ASU 2016-09 in the first quarter of 2017. Under the new guidance, companies will no longer record excess tax benefits and certain tax deficiencies related to share-based payment to employees in additional paid-in capital. Instead, the Company will recognize all income tax effects of awards in its income statement when awards vest or are settled. All excess tax benefits not previously recognized were to be recorded to retained earnings as a cumulative effect adjustment upon adoption. Upon adoption, no adjustment to retained earnings was necessary due to the Company's valuation allowance position. Approximately $1.1 million attributable to excess tax benefits on stock compensation that had not been previously recognized was added to the deferred tax asset for NOLs with a corresponding increase to the valuation allowance. In addition, the Company had federal and state research tax credit carryforwards of approximately $11.1 million and $2.1 million , respectively. The federal tax credit carryforwards will begin to expire in 2018. The California research tax credits do not expire. Utilization of the NOL and tax credit carryforwards is subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986, and similar state provisions due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes will limit the amount of NOL and tax credit carryforwards and other deferred tax assets that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing ownership of certain stock holders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. The Company and VGX both experienced ownership changes under Section 382 as a result of their 2009 merger. The ownership change resulted in annual limitations on the utilizations of tax attributes, including net operating loss carryforwards and tax credits. The Company estimates that approximately $13.4 million of tax benefits related to NOL and tax credit carryforwards will expire unused. Accordingly, the related NOL and R&D credit carryforwards have been removed from deferred tax assets accompanied by a corresponding reduction of the valuation allowance. Due to the existence of the valuation allowance, limitations created by current and future ownership changes, if any, related to the Company's operations in the United States will not impact its effective tax rate. Any additional ownership changes, may further limit the ability to use the net operating losses and credits carryovers. The Tax Cuts and Jobs Act ("the Act") was enacted on December 22, 2017. The Act includes a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. federal corporate tax rate from a maximum of 35% to a flat 21%, effective January 1, 2018. In conjunction with the tax law changes, the SEC staff issued Staff Accounting Bulletin 118 ("SAB 118") to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. In these instances, a Company can record provisional amounts in its financial statements for the income tax effects for which a reasonable estimate can be determined. For items for which a reasonable estimate cannot be determined, a company should continue to apply ASC 740 based on the provisions of the tax laws that were in effect immediately prior to the Act being enacted. As a result of the new law, the Company has revalued its deferred tax assets, which represent a reduction in the amount of corporate taxes that are expected to be paid in the future, by $50.0 million . The Company has also reduced its valuation allowance by $(50.2) million for a net impact of $(0.2) million as a result of the Act. This impact is considered to be a provisional amount as the Company is still analyzing certain aspects of the Act and refining our calculations. The ultimate impact may differ from this provisional amount, due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of the Act. In addition, as there is some uncertainty around the grandfathering provisions related to performance-based executive compensation, the Company has not estimated a provisional amount for deferred tax assets related to performance-based executive compensation and continue to apply ASC 740 based on the provisions of the tax laws that were in effect immediately prior to the Act being enacted. Upon the issuance of additional guidance by the U.S. Treasury Department and other standard-setting bodies, the Company plans to adjust its deferred tax assets accordingly. The following table summarizes the activity related to the Company's unrecognized tax benefits: Year ended December 31, 2017 2016 2015 Balance at beginning of the year $ 6,855,000 $ 5,455,000 $ 2,759,000 Increases related to current year tax positions 1,532,000 1,183,000 615,000 Increases (decreases) related to prior year tax positions (74,000 ) 217,000 2,081,000 Balance at end of the year $ 8,313,000 $ 6,855,000 $ 5,455,000 The amount of unrecognized tax benefit that, if recognized and realized, would affect the effective tax rate was $7.1 million as of December 31, 2017 . The Company has not recorded any interest and penalties on the unrecognized tax positions as the Company has continued to generate net operating losses after accounting for the unrecognized tax benefits. The Company does not anticipate that the total amount of unrecognized tax benefits will significantly increase or decrease within twelve months of the reporting date. The Company and its subsidiaries are subject to United States federal income tax as well as income tax in multiple state jurisdictions. With few exceptions, the Company is no longer subject to United States federal income tax examinations for years before 2014 and state and local income tax examinations before 2013. However, to the extent allowed by law, the tax authorities may have the right to examine prior periods where net operating losses were generated and carried forward, and make adjustments up to the amount of the net operating loss carryforward amount. The Company is not currently under Internal Revenue Service (“IRS”), state or local tax examination.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
401(k) Plan	401(k) Plan The Company has adopted a 401(k) Profit Sharing Plan covering substantially all of its employees. The defined contribution plan allows the employees to contribute a percentage of their compensation each year. The Company currently matches 50% of its employees’ contributions, up to 6% of their annual compensation. The Company’s contributions are recorded as expense in the accompanying consolidated statements of operations and totaled $822,000 , $496,000 and $328,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	Related Party Transactions GeneOne Life Sciences In December 2017, the Company completed the sale of certain assets related to its compound VGX-1027 to GeneOne for a purchase price of $1.0 million . In May 2015, the Company entered into a Collaborative Development Agreement with GeneOne to co-develop a DNA vaccine for MERS (Middle East Respiratory Syndrome) 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 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 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 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. In 2014, the Company entered into a Collaborative Development Agreement with GeneOne to co-develop an Ebola vaccine through Phase 1 clinical trials. In 2015, the Company amended the Agreement to change control of development back to Inovio in return for the Company’s payment of certain expenses relating to GeneOne's contribution to the clinical trials. 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 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 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 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 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 will receive research support, annual license maintenance fees and royalties on net Product sales. The Company recorded the $3.0 million as deferred revenue from affiliated entity, and will recognize it as revenue over the eight year expected period of the Company’s performance obligation. In addition, contingent upon achievement of clinical and regulatory milestones, the Company will receive development payments over the term of the GeneOne Agreement. 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. One of the Company's directors, Dr. David B. Weiner, acts as a consultant to GeneOne. Revenue recognized from GeneOne consists of licensing and other fees from the influenza and Zika collaborations. For the years ended December 31, 2017 , 2016 and 2015 , the Company recognized revenue from GeneOne of $551,000 , $1.2 million and $450,000 , respectively. Operating expenses recorded from transactions with GeneOne relate primarily to biologics manufacturing. Operating expenses related to the transactions with GeneOne for the years ended December 31, 2017 , 2016 and 2015 were $2.3 million , $2.8 million and $6.9 million , respectively. At December 31, 2017 and 2016 , the Company had an accounts receivable balance of $0 and $441,000 , respectively, and an accounts payable and accrued liability balance of $107,000 and $379,000 , respectively, related to GeneOne and its subsidiaries. At December 31, 2017 and 2016 , $331,000 and $571,000 of prepayments made to GeneOne, respectively, were classified as long-term other assets on the consolidated balance sheet. Plumbline Life Sciences, Inc. In May 2014, the Company's 85% owned subsidiary VGX Animal Health entered into an agreement for the sale of its animal health assets to PLS. The assets transferred included an exclusive license with the Company for animal applications of its growth hormone-releasing hormone ("GHRH") technology and animal DNA vaccines plus a non-exclusive license to Inovio electroporation delivery systems. In return, VGX Animal Health received $2.0 million in cash, of which $1.0 million was received in May 2015 and the remainder in May 2016, and 465,364 shares of PLS, of which the Company received 395,758 shares or approximately 16.4% of PLS's common stock. During each of the years ended December 31, 2016 and 2015, VGX Animal Health distributed $1.0 million cash received to its shareholders, of which $850,000 was received by the Company and $150,000 was paid to minority shareholders in each year. One of the Company's directors, Dr. David B Weiner, acts as a consultant to PLS. As of December 31, 2017 the Company accounts for its ownership interest in PLS under the accounting guidance for investments considered available-for-sale (Accounting Standards Codification (ASC) 320). The original carrying value of the Company's investment in PLS was $0 . On July 28, 2015, PLS registered on the Korea New Exchange (KONEX) Market. The total carrying value of the Company's investment in PLS was $2.3 million as of December 31, 2017 . The fair value is based on the market value of the common shares as listed on the KONEX. The changes in carrying value of PLS are recorded in the Company's consolidated statements of comprehensive loss as an unrealized gain (loss) on investment in affiliated entity. In August 2016, the Company licensed a veterinary vaccine for foot and mouth disease (FMD) to PLS. PLS will fund all development activities for this FMD vaccine. The Company will receive milestone payments as well as royalties on product sales from PLS for commercial rights to this FMD synthetic vaccine in Asia, excluding Japan. For the years ended December 31, 2017 and 2016 , the Company recognized revenue from PLS of $215,000 and $212,000 , respectively. At December 31, 2017 and 2016 , the Company had an accounts receivable balance of $370,000 and $155,000 , respectively, related to its license agreement with PLS. The Wistar Institute One of the Company's directors, Dr. David B. Weiner, is the Executive Vice President and Director of the Vaccine Center of The Wistar Institute ("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 in this agreement. In December 2016 the Company received a $6.1 million sub-grant through Wistar to develop a DNA-based monoclonal antibody against the Zika infection. The Company is also a collaborator with Wistar on an Integrated Preclinical/Clinical AIDS Vaccine Development (IPCAVD) grant from the National Institute of Allergy and Infectious Diseases (NIAID), awarded in 2015. Revenue recognized from Wistar is related to work performed by the Company on the research sub-contract agreements. For the years ended December 31, 2017 and 2016 , the Company recognized revenue from Wistar of $2.6 million and $341,000 , respectively. Operating expenses recorded as a result of the relationship with Wistar relate primarily to the collaborative research agreements and sub-contract related to the DARPA Ebola grant. Operating expenses related to the Wistar relationship for the years ended December 31, 2017 and 2016 were $2.3 million and $985,000 , respectively. At December 31, 2017 and 2016 , the Company had an accounts receivable balance of $117,000 and $152,000 , respectively, and an accounts payable and accrued liability balance of $820,000 and $671,000 , respectively, related to Wistar.

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) The following is a summary of the quarterly results of operations of the Company for the years ended December 31, 2017 and 2016 (unaudited): Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenue: Revenue under collaborative research and development arrangements $ 7,409,214 $ 351,272 $ 16,358,316 $ 4,288,586 Revenue under collaborative research and development arrangements with affiliated entity 226,486 129,133 176,879 233,330 Grants and miscellaneous revenue 980,443 1,456,216 2,797,647 5,240,233 Grants and miscellaneous revenue from affiliated entity 171,091 707,922 1,079,282 614,036 Total revenues 8,787,234 2,644,543 20,412,124 10,376,185 Operating Expenses: Research and development 24,641,124 25,510,239 23,878,751 24,542,504 General and administrative 8,033,899 6,319,775 6,169,106 7,767,589 Gain on sale of assets (1,000,000 ) — — — Total operating expenses 31,675,023 31,830,014 30,047,857 32,310,093 Loss from operations (22,887,789 ) (29,185,471 ) (9,635,733 ) (21,933,908 ) Interest and other income, net 509,266 463,346 300,021 340,341 Change in fair value of common stock warrants 579,546 423,296 (312,500 ) 116,477 Gain (Loss) from investment in affiliated entity 292,798 (5,835,741 ) 169,096 (1,608,817 ) Net loss attributable to Inovio Pharmaceuticals, Inc. $ (21,506,179 ) $ (34,134,570 ) $ (9,479,116 ) $ (23,085,907 ) Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders Basic $ (0.24 ) $ (0.39 ) $ (0.13 ) $ (0.31 ) Diluted $ (0.24 ) $ (0.40 ) $ (0.13 ) $ (0.31 ) Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenue: Revenue under collaborative research and development arrangements $ 476,586 $ 2,327,316 $ 1,889,988 $ 1,796,857 Revenue under collaborative research and development arrangements with affiliated entity 189,278 574,596 499,720 137,000 Grants and miscellaneous revenue 7,735,428 9,410,648 3,814,083 6,176,298 Grants and miscellaneous revenue from affiliated entity 112,660 227,903 — — Total revenues 8,513,952 12,540,463 6,203,791 8,110,155 Operating Expenses: Research and development 23,911,731 26,980,343 19,630,801 18,189,160 General and administrative 6,965,517 5,755,603 5,799,530 5,371,613 Gain on sale of assets — — (1,000,000 ) — Total operating expenses 30,877,248 32,735,946 24,430,331 23,560,773 Loss from operations (22,363,296 ) (20,195,483 ) (18,226,540 ) (15,450,618 ) Interest and other income, net 191,460 391,596 341,131 333,070 Change in fair value of common stock warrants 644,888 2,690 (113,775 ) (406,249 ) Gain (Loss) from investment in affiliated entity (4,706,522 ) (958,141 ) (705,527 ) 7,480,977 Net loss attributable to Inovio Pharmaceuticals, Inc. $ (26,233,470 ) $ (20,759,338 ) $ (18,704,711 ) $ (8,042,820 ) Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders Basic $ (0.35 ) $ (0.28 ) $ (0.26 ) $ (0.11 ) Diluted $ (0.36 ) $ (0.28 ) $ (0.26 ) $ (0.11 )

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Inovio incurred a net loss attributable to common stockholders of $88.2 million for the year ended December 31, 2017 . Inovio had working capital of $103.0 million and an accumulated deficit of $523.4 million as of December 31, 2017 . 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 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 consolidated financial statements as of and for the year ended December 31, 2017 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 financial statements.
Consolidation	Consolidation These consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. In conjunction with the acquisition in June 2009 of VGX Pharmaceuticals, the Company acquired a majority interest in VGX Animal Health and an equity interest in GeneOne, a publicly-traded company in South Korea. In addition to VGX Pharmaceuticals and VGX Animal Health, the Company consolidates its wholly owned subsidiaries Genetronics, Inc. and GENEOS Therapeutics, Inc., and recorded a non-controlling interest for the 15% of VGX Animal Health it did not own as of December 31, 2017 and 2016 . The Company's investment in GeneOne is recorded as investment in affiliated entity within the consolidated balance sheets and is accounted for at fair value at each reporting date, with changes in fair value recorded on the consolidated statements of operations within gain (loss) on investment in affiliated entity. All intercompany accounts and transactions have been eliminated upon consolidation.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one segment operating primarily within the United States.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with United States generally accepted accounting principles requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. Inovio bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, the Company reviews its estimates to ensure that these estimates appropriately reflect changes in the business or as new information becomes available.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, that potentially subject the Company to concentrations of credit risk, consist primarily of cash and short-term investments. The Company limits its exposure to credit loss by placing its cash and investments with high credit quality financial institutions. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities which are designed to maintain principal and maximize liquidity.
Fair value of Financial Instruments	Fair value of Financial Instruments The Company’s financial instruments consist principally of cash equivalents, short-term investments and investments in affiliated entities. The carrying amounts of cash equivalents approximate the related fair values due to the short-term maturities of these instruments. Investments consist of available-for-sale securities that are reported at fair value with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of consolidated stockholders’ equity.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are considered by the Company to be highly liquid investments purchased with original maturities of three months or less from the date of purchase. Cash and cash equivalents include certain money market accounts at December 31, 2017 and 2016 .
Investments	Investments The Company defines investments as income-yielding securities that can be readily converted into cash or equity investments classified as available-for-sale. Investments include mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entity PLS at December 31, 2017 and 2016 .
Accounts Receivable	Accounts Receivable Accounts receivable are recorded at invoiced amounts and do not bear interest. The Company performs ongoing credit evaluations of its customers’ financial condition. Credit is extended to customers as deemed necessary and generally does not require collateral. Management believes that the risk of loss is significantly reduced due to the quality and financial position of the Company's customers.
Fixed Assets	Fixed Assets Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the remaining term of the related leases or the estimated economic useful lives of the improvements. Repairs and maintenance are expensed as incurred.
Long-Lived Assets	Long-Lived Assets All long-lived assets are reviewed for impairment in value when changes in circumstances dictate, based upon undiscounted future operating cash flows, and appropriate losses are recognized and reflected in current earnings, to the extent the carrying amount of an asset exceeds its estimated fair value determined by the use of appraisals, discounted cash flow analyses or comparable fair values of similar assets.
Valuation of Intangible Assets and Goodwill	Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from 2 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 being 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 December 31, 2017 and 2016 , the Company’s intangible assets resulting from the acquisition of VGX, Inovio AS and Bioject, and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $6.0 million and $ 7.6 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s 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 December 31, 2017 . 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, 2017 , 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.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities along with net operating loss and tax credit carry forwards. The Company records a valuation allowance against its deferred tax assets to reduce the net carrying value to an amount that it believes is more likely than not to be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made. Valuation allowances against the Company’s deferred tax assets were $94.0 million and $113.4 million at December 31, 2017 and 2016 , respectively. Changes in the valuation allowances, when they are recognized in the provision for income taxes, are included as a component of the estimated annual effective tax rate.
Revenue Recognition	Revenue Recognition The Company recognizes revenues when all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectability is reasonably assured. Grant revenue The Company receives non-refundable grants under available government programs. Government grants towards current expenditures are recorded as revenue when there is reasonable assurance that the Company has complied with all conditions necessary to receive the grants, collectability is reasonably assured and the related expenditures are incurred. License fee and milestone revenue The Company has adopted a strategy of co-developing or licensing its gene delivery technology for specific genes or specific medical indications. Accordingly, the Company has entered into collaborative research and development agreements and has received third-party funding for pre-clinical research and clinical trials. Agreements that contain multiple elements are analyzed to determine whether the deliverables within the agreement can be separated or whether they must be accounted for as a single unit of accounting in accordance with the FASB's Accounting Standards Update (“ASU”) No. 2009-13, Revenue Recognition (Topic 605): Multiple-Deliverable Revenue Arrangements. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. The delivered item(s) were considered a separate unit of accounting if all of the following criteria were met: (1) the delivered item(s) has value to the customer on a standalone basis; (2) there is objective and reliable evidence of the fair value of the undelivered item(s); and (3) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control. If these criteria were not met, the deliverable was combined with other deliverables in the arrangement and accounted for as a combined unit of accounting. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, the Company uses its best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the price to the collaborator is fixed or determinable, and collectability is reasonably assured. Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have an impact on the amount of revenue recognized in a given period. The Company applies ASU No. 2010-17, Revenue Recognition (Topic 605): Milestone Method of Revenue Recognition (“Milestone Method”). Under the Milestone Method, the Company will recognize consideration that is contingent upon the achievement of a milestone in its entirety as revenue in the period in which the milestone is achieved only if the milestone is substantive in its entirety. A milestone is considered substantive when it meets all of the following criteria: 1. The consideration is commensurate with either the entity's performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity's performance to achieve the milestone, 2. The consideration relates solely to past performance, and 3. The consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity's performance or on the occurrence of a specific outcome resulting from the entity's performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company.
Business Combinations	Business Combinations The cost of an acquired business is assigned to the tangible and identifiable intangible assets acquired and liabilities assumed on the basis of the estimated fair values at the date of acquisition. The Company assesses fair value, which is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, using a variety of methods including, but not limited to, an income approach and a market approach such as the estimation of future cash flows of acquired business and current selling prices of similar assets. Fair value of the assets acquired and liabilities assumed, including intangible assets, are measured based on the assumptions and estimations with regards to the variable factors such as the amount and timing of future cash flows for the asset or liability being measured, appropriate risk-adjusted discount rates, nonperformance risk, or other factors that market participants would consider. Upon acquisition, the Company determines the estimated economic lives of the acquired intangible assets for amortization purposes, which are based on the underlying expected cash flows of such assets. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that is not individually identified and separately recognized. Actual results may vary from projected results and assumptions used in the fair value assessments.
Research and Development Expenses	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.
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 and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. 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 warrants 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 the warrants from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any, under the treasury stock method.
Leases	Leases Leases are classified as either capital or operating leases. Leases which transfer substantially all of the benefits and risks incidental to the ownership of assets are accounted for as if there was an acquisition of an asset and incurrence of an obligation at the inception of the lease. All other leases are accounted for as operating leases. Inovio’s Plymouth Meeting, PA headquarters and San Diego, CA facility leases, which have escalating payments, are expensed on a straight-line basis over the term of the lease. The allowance provided by the lessor for non-structural, normal leasehold improvements are considered tenant incentives and are amortized on a straight-line basis over the term of the lease. These leases represent the primary expense and commitment as indicated in Note 11, “Commitments”. Other leases exist for office machinery, such as copiers, wherein lease expense is recorded as incurred.
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 units 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 highly 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 of zero is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. Upon adoption of ASU 2016-09 on January 1, 2017, the Company elected to remove the forfeiture rate from the calculation and recorded a cumulative catch-up adjustment to accumulated deficit with a corresponding offset to additional paid-in-capital of $312,000 . Previously, the forfeiture rate was based on historical data and the Company recorded stock-based compensation expense only for those awards that were expected to vest.
Recent Accounting Pronouncements - Recently Adopted, Recent Accounting Pronouncements	Recent Accounting Pronouncements - Recently Adopted ASU No. 2016-09. In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation-Improvements to Employee Share-Based Payment Accounting . The new guidance simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amendments in this standard were effective for the Company's annual year and first fiscal quarter beginning on January 1, 2017 with early adoption permitted. The Company adopted this guidance as of January 1, 2017 using a modified retrospective transition method. As a result of the adoption of this standard, the Company elected to change its policy from estimating forfeitures to recognizing forfeitures when they occur. The Company recorded an adjustment of $312,000 to accumulated deficit with a corresponding offset to additional paid-in-capital at January 1, 2017. The Company also reversed a deferred tax asset related to the balance of unrecognized excess tax benefits of $1.1 million , with an offsetting adjustment to the valuation allowance. Recent Accounting Pronouncements 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. 2014-09. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers ("Topic 606”), which amended the existing accounting standards for revenue recognition, outlines a comprehensive revenue recognition model and supersedes most current revenue recognition guidance. The new standard requires a company to recognize revenue upon transfer of goods or services to a customer at an amount that reflects the expected consideration to be received in exchange for those goods or services. The amended guidance defines a five-step approach for recognizing revenue, which will require a company to use more judgment and make more estimates than under the current guidance. The Company adopted this new standard effective January 1, 2018, using the modified retrospective transition method. Under this method, the Company’s results will remain as reported and starting in 2018 will be under the new method. The Company has completed its preliminary evaluation of the impact of adoption of Topic 606 on certain of its existing agreements as follows: Collaboration Agreement with MedImmune The Company has determined that no cumulative catch-up adjustment is required. The Company expects the accounting for contingent milestone payments to be a significant change in accounting for its license and collaboration agreements. Topic 605 provides guidance specific to the accounting for milestone payments, including the ability to defer the recognition of any milestones until received and, if certain criteria are met, the ability to recognize milestone payments as revenue when received. However, Topic 606 does not contain guidance specific to milestone payments, thereby requiring potential milestone payments to be considered in accordance with the overall model of Topic 606. As a result, revenues from contingent milestone payments may be recognized earlier under Topic 606 than under Topic 605, based on an assessment of the probability of achievement of the milestone and the likelihood of a significant reversal of such milestone revenue at each reporting date. This assessment may result in recognizing milestone revenue before the milestone event has been achieved. In addition, Topic 606 changes guidance regarding the accounting for variable consideration received from licensees, which may impact the estimation of, and determination of the timing of, the related revenue recognition Grant Agreements 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 will be recorded as a contra-expense as opposed to revenue on the consolidated statement of operations. New grant agreements will be evaluated to determine if they represent contribution transactions or exchange transactions. If the Company performs research and development services with no performance obligations to provide the agency granting the funds reciprocal value for the contributions received, then the consideration received under the grant would result in amounts recognized as contra expense, as opposed to revenue. ASU No. 2016-01. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . The amended guidance requires the Company to measure and record equity investments, except those accounted for under the equity method of accounting that have a readily determinable fair value, at fair value and for the Company to recognize the changes in fair value in its consolidated statements of operations, instead of recognizing unrealized gains and losses through accumulated other comprehensive income (loss), as currently done under the existing guidance. The amended guidance also changes several disclosure requirements for financial instruments, including the methods and significant assumptions used to estimate fair value. The standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company will adopt this guidance on January 1, 2018 and will make any adjustments to beginning balances through a cumulative-effect adjustment to accumulated deficit on that date. The Company has evaluated the impact of the adoption of this accounting standard and expects it to have no impact on its financial statements and related disclosures. ASU No. 2016-02. In February 2016, the FASB issued ASU No. 2016-02, Leases . Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (a) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (b) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The ASU will be effective for the Company beginning January 1, 2019 with early adoption permitted. The Company is currently evaluating the impact of the application of this accounting standard update on its financial statements and related disclosures.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Year Ended December 31, 2017 2016 2015 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. $ (88,205,772 ) $ (73,740,339 ) $ (29,187,606 ) Adjustment for decrease in fair value of warrant liability (806,819 ) — (721,591 ) Numerator for use in diluted net loss per share $ (89,012,591 ) $ (73,740,339 ) $ (29,909,197 ) Denominator Weighted average number of common shares outstanding 81,777,493 73,214,766 68,198,142 Effect of dilutive potential common shares from warrants 140,529 — 167,123 Denominator for use in diluted net loss per share 81,918,022 73,214,766 68,365,265 Net loss per share, diluted $ (1.09 ) $ (1.01 ) $ (0.44 )
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect	The following table summarizes potential shares of common stock that were excluded from diluted net loss per share calculation because of their anti-dilutive effect: Year Ended December 31, 2017 2016 2015 Options to purchase common stock 7,694,870 6,806,183 5,862,364 Warrants to purchase common stock — 284,091 276,813 Restricted stock units 1,234,168 798,834 230,000 Convertible preferred stock 8,456 8,456 8,456 Total 8,937,494 7,897,564 6,377,633
Summary of assumptions used to estimate the fair value of stock options	The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.20% 0.91% 0.99% Expected volatility 73% 76% 74% Expected life in years 6 5 5 Dividend yield — — — Forfeiture rate N/A 7% 7% Assumptions used in the Black-Scholes model for non-employees are presented below: Year Ended December 31, 2017 2016 2015 Risk-free interest rate 2.4%-2.6% 2.3%-2.5% 2.1%-2.3% Expected volatility 97%-102% 71%-104% 105%-108% Expected life in years 9-10 7-10 7-10 Dividend yield — — —

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Summary of investments	The following is a summary of available-for-sale securities as of December 31, 2017 and 2016 : As of December 31, 2017 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 68,776,165 $ 42,097 $ (252,373 ) $ 68,565,889 US corporate debt securities Less than 2 35,210,121 3,032 (140,198 ) 35,072,955 Investment in affiliated entity (PLS) --- — 2,325,079 — 2,325,079 Total investments $ 103,986,286 $ 2,370,208 $ (392,571 ) $ 105,963,923 As of December 31, 2016 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 60,883,065 $ 94,374 $ (387,693 ) $ 60,589,746 US corporate debt securities Less than 2 25,098,122 6,853 (65,309 ) 25,039,666 Investment in affiliated entity (PLS) --- — 3,777,510 — 3,777,510 Total investments $ 85,981,187 $ 3,878,737 $ (453,002 ) $ 89,406,922

Marketable Securities and Fai29

Marketable Securities and Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
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 December 31, 2017 : Fair Value Measurements at December 31, 2017 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,843,482 $ 9,843,482 $ — $ — Mutual funds 68,565,889 — 68,565,889 — US corporate debt securities 35,072,955 — 35,072,955 — Investments in affiliated entities 11,394,480 11,394,480 — — Total assets $ 124,876,806 $ 21,237,962 $ 103,638,844 $ — Liabilities: Common stock warrants $ 360,795 $ — $ 360,795 Total liabilities $ 360,795 $ — $ 360,795 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 December 31, 2016 : Fair Value Measurements at December 31, 2016 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 10,300,813 $ 10,300,813 $ — $ — Mutual funds 60,589,746 — 60,589,746 — US corporate debt securities 25,039,666 — 25,039,666 — Investments in affiliated entities 19,829,575 19,829,575 — — Total assets $ 115,759,800 $ 30,130,388 $ 85,629,412 $ — Liabilities: Common stock warrants $ 1,167,614 $ — $ — $ 1,167,614 Total liabilities $ 1,167,614 $ — $ — $ 1,167,614
Assumptions used to estimate the fair values of the common stock warrants	The assumptions used to estimate the fair value of common stock warrants at December 31, 2017 and 2016 are presented below: Year Ended December 31, 2017 2016 Risk-free interest rate 1.75% 1.1% Expected volatility 55% 61% Expected life in years 0.70 1.70 Dividend yield — —
Changes in fair value of the financial liabilities	The following table presents the changes in fair value of the Company’s total Level 3 financial liabilities for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 2016 Balance at beginning of year $ 1,167,614 $ 1,301,138 Decrease in fair value included in change in fair value of common stock warrants (806,819 ) (133,524 ) Balance at end of year $ 360,795 $ 1,167,614

Major Customers and Concentra30

Major Customers and Concentration of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Schedule of major customers and concentration risks	Customer 2017 Revenue % of Total Revenue 2016 Revenue % of Total Revenue 2015 Revenue % of Total Revenue MedImmune $ 22,269,773 53 % $ 1,518,639 4 % $ 16,037,731 40 % DARPA 9,983,927 24 26,602,183 75 11,582,623 28 Roche 6,107,254 14 4,917,929 14 10,778,688 27 NIAID — — 118,171 — 901,475 2 GeneOne (affiliated entity) 551,208 1 1,188,432 4 450,000 1 All other 3,307,924 8 1,023,007 3 821,594 2 Total revenue $ 42,220,086 100 % $ 35,368,361 100 % $ 40,572,111 100 %

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of fixed assets	Fixed assets at December 31, 2017 and 2016 consist of the following: Cost Accumulated Depreciation and Amortization Net Book Value As of December 31, 2017 Leasehold improvements $ 14,553,993 $ (2,042,871 ) $ 12,511,122 Laboratory equipment 3,787,578 (1,724,946 ) 2,062,632 Office furniture and fixtures 3,366,896 (1,471,705 ) 1,895,191 Computer equipment and other 3,718,266 (1,867,035 ) 1,851,231 $ 25,426,733 $ (7,106,557 ) $ 18,320,176 As of December 31, 2016 Leasehold improvements $ 5,248,311 $ (1,199,415 ) $ 4,048,896 Laboratory equipment 3,534,302 (1,072,188 ) 2,462,114 Office furniture and fixtures 1,814,493 (1,108,187 ) 706,306 Computer equipment and other 3,684,521 (1,876,391 ) 1,808,130 $ 14,281,627 $ (5,256,181 ) $ 9,025,446

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of intangible assets by major asset class	The following sets forth goodwill and intangible assets by major asset class: December 31, 2017 December 31, 2016 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 (5,681,673 ) 120,855 5,802,528 (5,618,854 ) 183,674 Licenses 8 – 17 1,323,761 (1,190,609 ) 133,152 1,323,761 (1,161,861 ) 161,900 CELLECTRA ® (b) 5 – 11 8,106,270 (7,252,108 ) 854,162 8,106,270 (6,825,028 ) 1,281,242 GHRH(b) 11 335,314 (271,948 ) 63,366 335,314 (240,264 ) 95,050 Bioject (c) 2 – 15 5,100,000 (1,405,556 ) 3,694,444 5,100,000 (562,222 ) 4,537,778 Other(d) 18 4,050,000 (2,906,250 ) 1,143,750 4,050,000 (2,681,250 ) 1,368,750 Total intangible assets 24,717,873 (18,708,144 ) 6,009,729 24,717,873 (17,089,479 ) 7,628,394 Total goodwill and intangible assets $ 35,231,244 $ (18,708,144 ) $ 16,523,100 $ 35,231,244 $ (17,089,479 ) $ 18,141,765 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX Pharmaceuticals 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 Pharmaceuticals. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the acquisition of Bioject. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition.
Schedule of finite-lived intangible assets, future amortization expense	Amortization expense related to intangible assets at December 31, 2017 is expected to be incurred as follows: Year ending December 31, 2018 $ 1,249,584 2019 1,066,251 2020 547,081 2021 520,414 2022 492,818 Thereafter 2,133,581 $ 6,009,729

Accounts Payable and Accrued 33

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Schedule of accounts payable and accrued expenses	Accounts payable and accrued expenses at December 31, 2017 and 2016 consist of the following: As of December 31, 2017 2016 Trade accounts payable, including from affiliated entity $ 7,564,830 $ 5,920,642 Accrued compensation 7,997,152 6,531,983 Accrued subcontract costs 3,746,937 5,475,359 Other accrued expenses 3,969,879 1,669,803 $ 23,278,798 $ 19,597,787

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Summary of preferred stock authorized, issued and outstanding	Shares Outstanding as of December 31, Shares Authorized Shares Issued 2017 2016 Series C Preferred Stock, par $0.001 1,091 1,091 23 23
Summary of warrants outstanding	The following table summarizes the warrants outstanding as of December 31, 2017 and 2016 : As of December 31, 2017 As of December 31, 2016 Issued in Connection With: Exercise Price Expiration Date Number of Warrants Common Stock Warrant Liability Number of Warrants Common Stock Warrant Liability March 2013 financing $ 3.17 September 12, 2018 284,091 $ 360,795 284,091 $ 1,167,614 Total 284,091 $ 360,795 284,091 $ 1,167,614
Schedule of shares authorized under stock option plans, by exercise price range	The following table summarizes total stock options outstanding at December 31, 2017 : Options Outstanding Options Exercisable Exercise Price Shares Underlying Options Outstanding Weighted-Average Remaining Contractual Life (in Years) Weighted Average Exercise Price Shares Underlying Options Exercisable Weighted Average Exercise Price $1.48-$3.00 1,177,183 4.6 $ 2.25 1,177,183 $ 2.25 $3.01-$6.00 753,932 3.4 $ 4.64 668,244 $ 4.57 $6.01-$9.00 4,709,442 7.6 $ 7.09 2,639,454 $ 7.23 $9.01-$12.00 357,603 8.0 $ 9.79 263,180 $ 9.83 $12.01-$15.00 696,710 6.2 $ 12.96 696,710 $ 12.96 7,694,870 6.6 $ 6.77 5,444,771 $ 6.68
Schedule of stock options, activity	Stock option activity under the Company’s equity incentive plans during the year ended December 31, 2017 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2016 6,806,183 $ 6.81 Granted 1,788,121 6.62 Exercised (452,973 ) 5.18 Cancelled (446,461 ) 8.49 Balance, December 31, 2017 7,694,870 $ 6.77
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	RSU activity under the Company’s equity incentive plans during the year ended December 31, 2017 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2016 798,834 $ — Granted 1,035,443 — Vested (561,462 ) — Cancelled (38,647 ) — Balance, December 31, 2017 1,234,168 $ —

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future minimum lease payments under non-cancelable operating leases	Future minimum lease payments under non-cancelable operating leases as of December 31, 2017 are as follows: Year ending December 31, 2018 $ 3,251,000 2019 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 Thereafter 19,975,000 Total $ 38,904,000

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The acquisition consideration was allocated to the estimated fair vales of the assets acquired as follows: Developed technology $ 3,800,000 Customer-related intangible assets 1,000,000 Trademarks 200,000 Covenants not-to-compete 100,000 Goodwill 400,000 Total purchase consideration $ 5,500,000

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of components of income tax expense (benefit)	The components of the provision for income taxes are presented in the following table: Year Ended December 31, 2017 2016 2015 Current: Federal $ — $ — $ — State — — — — — — Deferred: Federal — — (1,594,000 ) State — — (504,000 ) — — (2,098,000 ) $ — $ — $ (2,098,000 )
Schedule of effective income tax rate reconciliation	The reconciliation of income taxes attributable to continuing operations computed at the statutory tax rates to income tax expense (recovery), using a 35% statutory tax rate, is as follows: Year Ended December 31, 2017 2016 2015 Income (benefit) taxes at statutory rates $ (30,872,000 ) $ (25,809,000 ) $ (10,920,000 ) State income tax, net of federal benefit (4,000 ) (4,000 ) (2,640,000 ) Change in valuation allowance (20,965,000 ) 29,678,000 7,882,000 Research and development tax credits (3,456,000 ) (3,117,000 ) (1,537,000 ) Fair value warrant (282,000 ) (47,000 ) (253,000 ) Stock compensation 2,332,000 113,000 2,288,000 Uncertain tax positions 846,000 1,367,000 1,968,000 Expired NOLs and credits 454,000 4,269,000 339,000 Limited NOLs and credits (165,000 ) (6,456,000 ) (297,000 ) Change in state tax rate 50,019,000 (495,000 ) 676,000 Other 2,093,000 501,000 396,000 $ — $ — $ (2,098,000 )
Schedule of deferred tax assets and liabilities	Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2017 and 2016 are shown below: As of December 31, 2017 2016 Deferred tax assets: Capitalized research expense 8,546,000 $ 567,000 Net operating loss carryforwards 71,665,000 95,500,000 Research and development and other tax credits 7,531,000 5,300,000 Deferred revenue 297,000 5,452,000 Deferred rent 2,097,000 2,231,000 Stock-based compensation 3,091,000 4,511,000 Acquired intangibles 858,000 989,000 Other 1,906,000 3,783,000 95,991,000 118,333,000 Valuation allowance (94,039,000 ) (113,407,000 ) Total deferred tax assets 1,952,000 4,926,000 Deferred tax liabilities: Acquired intangibles (124,000 ) (175,000 ) Investment in affiliated entity (422,000 ) (3,624,000 ) Fixed assets (1,430,000 ) (1,302,000 ) Net deferred tax liabilities $ (24,000 ) $ (175,000 )
Schedule of unrecognized tax benefits rollforward	The following table summarizes the activity related to the Company's unrecognized tax benefits: Year ended December 31, 2017 2016 2015 Balance at beginning of the year $ 6,855,000 $ 5,455,000 $ 2,759,000 Increases related to current year tax positions 1,532,000 1,183,000 615,000 Increases (decreases) related to prior year tax positions (74,000 ) 217,000 2,081,000 Balance at end of the year $ 8,313,000 $ 6,855,000 $ 5,455,000

Quarterly Financial Informati38

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information (unaudited)	The following is a summary of the quarterly results of operations of the Company for the years ended December 31, 2017 and 2016 (unaudited): Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenue: Revenue under collaborative research and development arrangements $ 7,409,214 $ 351,272 $ 16,358,316 $ 4,288,586 Revenue under collaborative research and development arrangements with affiliated entity 226,486 129,133 176,879 233,330 Grants and miscellaneous revenue 980,443 1,456,216 2,797,647 5,240,233 Grants and miscellaneous revenue from affiliated entity 171,091 707,922 1,079,282 614,036 Total revenues 8,787,234 2,644,543 20,412,124 10,376,185 Operating Expenses: Research and development 24,641,124 25,510,239 23,878,751 24,542,504 General and administrative 8,033,899 6,319,775 6,169,106 7,767,589 Gain on sale of assets (1,000,000 ) — — — Total operating expenses 31,675,023 31,830,014 30,047,857 32,310,093 Loss from operations (22,887,789 ) (29,185,471 ) (9,635,733 ) (21,933,908 ) Interest and other income, net 509,266 463,346 300,021 340,341 Change in fair value of common stock warrants 579,546 423,296 (312,500 ) 116,477 Gain (Loss) from investment in affiliated entity 292,798 (5,835,741 ) 169,096 (1,608,817 ) Net loss attributable to Inovio Pharmaceuticals, Inc. $ (21,506,179 ) $ (34,134,570 ) $ (9,479,116 ) $ (23,085,907 ) Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders Basic $ (0.24 ) $ (0.39 ) $ (0.13 ) $ (0.31 ) Diluted $ (0.24 ) $ (0.40 ) $ (0.13 ) $ (0.31 ) Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenue: Revenue under collaborative research and development arrangements $ 476,586 $ 2,327,316 $ 1,889,988 $ 1,796,857 Revenue under collaborative research and development arrangements with affiliated entity 189,278 574,596 499,720 137,000 Grants and miscellaneous revenue 7,735,428 9,410,648 3,814,083 6,176,298 Grants and miscellaneous revenue from affiliated entity 112,660 227,903 — — Total revenues 8,513,952 12,540,463 6,203,791 8,110,155 Operating Expenses: Research and development 23,911,731 26,980,343 19,630,801 18,189,160 General and administrative 6,965,517 5,755,603 5,799,530 5,371,613 Gain on sale of assets — — (1,000,000 ) — Total operating expenses 30,877,248 32,735,946 24,430,331 23,560,773 Loss from operations (22,363,296 ) (20,195,483 ) (18,226,540 ) (15,450,618 ) Interest and other income, net 191,460 391,596 341,131 333,070 Change in fair value of common stock warrants 644,888 2,690 (113,775 ) (406,249 ) Gain (Loss) from investment in affiliated entity (4,706,522 ) (958,141 ) (705,527 ) 7,480,977 Net loss attributable to Inovio Pharmaceuticals, Inc. $ (26,233,470 ) $ (20,759,338 ) $ (18,704,711 ) $ (8,042,820 ) Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders Basic $ (0.35 ) $ (0.28 ) $ (0.26 ) $ (0.11 ) Diluted $ (0.36 ) $ (0.28 ) $ (0.26 ) $ (0.11 )

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Narrative (Details)	Jan. 01, 2017USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Accounting Policies [Abstract]
Net loss from operations		$ (21,506,179)	$ (34,134,570)	$ (9,479,116)	$ (23,085,907)	$ (26,233,470)	$ (20,759,338)	$ (18,704,711)	$ (8,042,820)	$ (88,205,772)	$ (73,740,339)	$ (29,187,606)
Working capital		103,000,000								103,000,000
Accumulated deficit		$ (523,356,317)				$ (434,838,235)				$ (523,356,317)	$ (434,838,235)
Non-controlling interest		15.00%				15.00%				15.00%	15.00%
Number of operating segments | segment										1
Allowance for doubtful accounts		$ 0				$ 0				$ 0	$ 0
Property, Plant and Equipment [Line Items]
Intangible assets, net		6,009,729				7,628,394				6,009,729	7,628,394
Deferred tax assets, valuation allowance		$ 94,039,000				113,407,000				$ 94,039,000	113,407,000
Cumulative effect of accounting change						0					0
Excess tax benefits on stock compensation					$ 1,100,000
Minimum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, useful life										3 years
Intangible asset, useful life										2 years
Maximum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, useful life										5 years
Intangible asset, useful life										18 years
Patents | Minimum
Property, Plant and Equipment [Line Items]
Intangible asset, useful life										8 years
Patents | Maximum
Property, Plant and Equipment [Line Items]
Intangible asset, useful life										17 years
Accounting Standards Update 2016-09
Property, Plant and Equipment [Line Items]
Deferred tax assets, valuation allowance						1,100,000					1,100,000
Excess tax benefits on stock compensation	$ 1,100,000
Retained earnings
Property, Plant and Equipment [Line Items]
Cumulative effect of accounting change						(312,310)					(312,310)
Retained earnings | Accounting Standards Update 2016-09
Property, Plant and Equipment [Line Items]
Cumulative effect of accounting change						312,000					312,000
Additional paid-in capital
Property, Plant and Equipment [Line Items]
Cumulative effect of accounting change						312,310					312,310
Additional paid-in capital | Accounting Standards Update 2016-09
Property, Plant and Equipment [Line Items]
Cumulative effect of accounting change						$ (312,000)					$ (312,000)
Options to purchase common stock | Employees and Directors
Property, Plant and Equipment [Line Items]
Dividend yield										0.00%	0.00%	0.00%

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Calculation of Net Loss Per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator [Abstract]
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (21,506,179)	$ (34,134,570)	$ (9,479,116)	$ (23,085,907)	$ (26,233,470)	$ (20,759,338)	$ (18,704,711)	$ (8,042,820)	$ (88,205,772)	$ (73,740,339)	$ (29,187,606)
Adjustment for decrease in fair value of warrant liability									(806,819)	0	(721,591)
Numerator for use in diluted net loss per share									$ (89,012,591)	$ (73,740,339)	$ (29,909,197)
Denominator [Abstract]
Weighted average number of common shares outstanding (shares)									81,777,493	73,214,766	68,198,142
Effect of dilutive potential common shares from warrants (shares)									140,529	0	167,123
Denominator for use in diluted loss per share (shares)									81,918,022	73,214,766	68,365,265
Net loss per share, Diluted ($ per share)	$ (0.24)	$ (0.40)	$ (0.13)	$ (0.31)	$ (0.36)	$ (0.28)	$ (0.26)	$ (0.11)	$ (1.09)	$ (1.01)	$ (0.44)

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Antidilutive Securities Table (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	8,937,494	7,897,564	6,377,633
Options to purchase common stock
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	7,694,870	6,806,183	5,862,364
Warrants to purchase common stock
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	0	284,091	276,813
Restricted stock units
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	1,234,168	798,834	230,000
Convertible preferred stock
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	8,456	8,456	8,456

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Summary of Stock-Based Compensation Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employees and Directors
Summary of assumptions used to estimate the fair value of stock options
Risk-free interest rate	2.20%	0.91%	0.99%
Expected volatility	73.00%	76.00%	74.00%
Expected life in years	6 years	5 years	5 years
Dividend yield	0.00%	0.00%	0.00%
Forfeiture rate		7.00%	7.00%
Non Employee
Summary of assumptions used to estimate the fair value of stock options
Risk-free interest rate (minimum)	2.40%	2.30%	2.10%
Risk-free interest rate (maximum)	2.60%	2.50%	2.30%
Dividend yield	0.00%	0.00%	0.00%
Non Employee | Minimum
Summary of assumptions used to estimate the fair value of stock options
Expected volatility	97.00%	71.00%	105.00%
Expected life in years	9 years	7 years	7 years
Non Employee | Maximum
Summary of assumptions used to estimate the fair value of stock options
Expected volatility	102.00%	104.00%	108.00%
Expected life in years	10 years	10 years	10 years

Collaborative Agreements (Detai

Collaborative Agreements (Details)	Dec. 29, 2017	Aug. 07, 2015USD ($)product	Dec. 31, 2017USD ($)	Feb. 28, 2017USD ($)	Sep. 30, 2015USD ($)	Apr. 30, 2015USD ($)	Sep. 30, 2013USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue under collaborative research and development arrangements									$ 7,409,214	$ 351,272	$ 16,358,316	$ 4,288,586	$ 476,586	$ 2,327,316	$ 1,889,988	$ 1,796,857	$ 28,407,388	$ 6,490,747	$ 26,876,533
Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received							$ 10,000,000
MedImmune | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received		$ 27,500,000			$ 27,500,000
Additional revenue to be achieved		$ 700,000,000
Number of additional products | product		2
Revenue recognized			$ 7,000,000
Revenue under collaborative research and development arrangements																	22,300,000	1,500,000
Deferred revenue			1,100,000						1,100,000				13,700,000				1,100,000	13,700,000
Accounts receivable			1,700,000						1,700,000				1,200,000				1,700,000	1,200,000
Roche | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received							10,000,000
Revenue under collaborative research and development arrangements																	6,100,000	4,900,000
Accounts receivable			0						0				2,400,000				0	2,400,000
Full payment				$ 8,500,000
DARPA | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue			149,000						149,000				1,200,000				149,000	1,200,000
Accounts receivable			$ 4,100,000						$ 4,100,000				$ 9,200,000				4,100,000	9,200,000
Term						2 years
Base award						$ 19,600,000
Previously deferred revenue recognized																	$ 9,800,000	$ 22,400,000
Option award						24,600,000
Second option award						$ 11,100,000
ApolloBio | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Territory expansion option period	3 years
INO-3112 | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized		$ 15,000,000
INO 5150 | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized							8,400,000
Nonsoftware License Arrangement | License To Research Collaboration Products | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue, additions		$ 12,500,000
Nonsoftware License Arrangement | Option Right | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue, additions							1,500,000
Nonsoftware License Arrangement | Joint Steering Committee Obligation | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue, additions							$ 155,000
Scenario, Forecast | ApolloBio | Collaborative Arrangement, Product
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received								$ 23,000,000
Additional revenue to be achieved								$ 20,000,000
Duration for upfront payment to be made following date of approval of collaborative agreement								3 days
Obligation period to pay royalties								10 years

Investments - Narrative (Detail

Investments - Narrative (Details)	12 Months Ended
	Dec. 31, 2017USD ($)investment	Dec. 31, 2016USD ($)
Investments, Debt and Equity Securities [Abstract]
Investment impairment charges	$ 215,000	$ 139,000
Other than temporary impairments	$ 0	$ 0
Number of securities in a gross unrealized loss position | investment	42
Number of securities in a gross unrealized loss position for more than twelve months | investment	16
Unrealized loss	$ 108,000

Investments - Summary of Availa

Investments - Summary of Available-for-sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Summary of investments
Cost	$ 103,986,286	$ 85,981,187
Gross Unrealized Gains	2,370,208	3,878,737
Gross Unrealized Losses	(392,571)	(453,002)
Fair Market Value	105,963,923	89,406,922
Mutual funds
Summary of investments
Cost	68,776,165	60,883,065
Gross Unrealized Gains	42,097	94,374
Gross Unrealized Losses	(252,373)	(387,693)
Fair Market Value	68,565,889	60,589,746
US corporate debt securities
Summary of investments
Cost	35,210,121	25,098,122
Gross Unrealized Gains	3,032	6,853
Gross Unrealized Losses	(140,198)	(65,309)
Fair Market Value	35,072,955	25,039,666
Investment in affiliated entity (PLS)
Summary of investments
Cost	0	0
Gross Unrealized Gains	2,325,079	3,777,510
Gross Unrealized Losses	0	0
Fair Market Value	$ 2,325,079	$ 3,777,510
Maximum | US corporate debt securities
Summary of investments
Contractual maturity	2 years	2 years

Marketable Securities and Fai46

Marketable Securities and Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	$ 124,876,806	$ 115,759,800
Liabilities, fair value	360,795	1,167,614
Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	21,237,962	30,130,388
Liabilities, fair value		0
Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	103,638,844	85,629,412
Liabilities, fair value	0	0
Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Liabilities, fair value	360,795	1,167,614
Money market funds
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	9,843,482	10,300,813
Money market funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	9,843,482	10,300,813
Money market funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Money market funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	68,565,889	60,589,746
Mutual funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Mutual funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	68,565,889	60,589,746
Mutual funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
US corporate debt securities
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	35,072,955	25,039,666
US corporate debt securities | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
US corporate debt securities | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	35,072,955	25,039,666
US corporate debt securities | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Investments in affiliated entities
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	11,394,480	19,829,575
Investments in affiliated entities | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	11,394,480	19,829,575
Investments in affiliated entities | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Investments in affiliated entities | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Common stock warrants
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value	360,795	1,167,614
Common stock warrants | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value		0
Common stock warrants | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value	0	0
Common stock warrants | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value	$ 360,795	$ 1,167,614

Marketable Securities and Fai47

Marketable Securities and Fair Value Measurements - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Common stock warrants	$ 360,795	$ 1,167,614
Change in the fair value	$ (807,000)	$ (134,000)	$ (722,000)
Number of warrants exercised (shares)	0	0
First warrant
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Change in the fair value	$ 0	$ (6,000)	$ (544,000)
Significant Unobservable Inputs (Level 3)
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Change in the fair value	$ (806,819)	(133,524)
Significant Unobservable Inputs (Level 3) | Second warrant
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Common stock warrants		$ 0

Marketable Securities and Fai48

Marketable Securities and Fair Value Measurements - Assumptions Used to Estimate Fair Value of Common Stock Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Risk-free interest rate	1.75%	1.10%
Expected volatility	55.00%	61.00%
Expected life in years	8 months 12 days	1 year 8 months 12 days
Dividend yield	$ 0	$ 0

Marketable Securities and Fai49

Marketable Securities and Fair Value Measurements - Changes in Fair Value of Level 3 Financial Liabilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in fair value of the financial liabilities
Decrease in fair value included in change in fair value of common stock warrants	$ (807,000)	$ (134,000)	$ (722,000)
Significant Unobservable Inputs (Level 3)
Changes in fair value of the financial liabilities
Balance at beginning of year	1,167,614	1,301,138
Decrease in fair value included in change in fair value of common stock warrants	(806,819)	(133,524)
Balance at end of year	$ 360,795	$ 1,167,614	$ 1,301,138

Major Customers and Concentra50

Major Customers and Concentration of Credit Risk (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Revenue	$ 42,220,086	$ 35,368,361	$ 40,572,111
Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%
MedImmune
Concentration Risk [Line Items]
Revenue	$ 22,269,773	$ 1,518,639	$ 16,037,731
Accounts receivable	$ 1,700,000	$ 1,200,000
MedImmune | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	53.00%	4.00%	40.00%
MedImmune | Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	28.00%	7.00%
DARPA
Concentration Risk [Line Items]
Revenue	$ 9,983,927	$ 26,602,183	$ 11,582,623
Accounts receivable	4,100,000	$ 12,100,000
Unbilled receivables	$ 1,600,000
Estimated collection period for unbilled receivables	12 months
DARPA | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%	75.00%	28.00%
DARPA | Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	69.00%	73.00%
Roche
Concentration Risk [Line Items]
Revenue	$ 6,107,254	$ 4,917,929	$ 10,778,688
Accounts receivable		$ 2,400,000
Roche | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	14.00%	27.00%
Roche | Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage		15.00%
NIAID
Concentration Risk [Line Items]
Revenue	$ 0	$ 118,171	$ 901,475
NIAID | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	0.00%	0.00%	2.00%
GeneOne (affiliated entity)
Concentration Risk [Line Items]
Revenue	$ 551,208	$ 1,188,432	$ 450,000
GeneOne (affiliated entity) | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	1.00%	4.00%	1.00%
All other
Concentration Risk [Line Items]
Revenue	$ 3,307,924	$ 1,023,007	$ 821,594
All other | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	8.00%	3.00%	2.00%
Minimum | DARPA
Concentration Risk [Line Items]
Age of unbilled receivables	1 month
Maximum | DARPA
Concentration Risk [Line Items]
Age of unbilled receivables	9 months

Fixed Assets (Details)

Fixed Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Cost	$ 25,426,733	$ 14,281,627
Accumulated Depreciation and Amortization	(7,106,557)	(5,256,181)
Net Book Value	18,320,176	9,025,446
Depreciation	1,850,376	1,708,498	$ 1,048,431
Leasehold improvements
Property, Plant and Equipment [Line Items]
Cost	14,553,993	5,248,311
Accumulated Depreciation and Amortization	(2,042,871)	(1,199,415)
Net Book Value	12,511,122	4,048,896
Laboratory equipment
Property, Plant and Equipment [Line Items]
Cost	3,787,578	3,534,302
Accumulated Depreciation and Amortization	(1,724,946)	(1,072,188)
Net Book Value	2,062,632	2,462,114
Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Cost	3,366,896	1,814,493
Accumulated Depreciation and Amortization	(1,471,705)	(1,108,187)
Net Book Value	1,895,191	706,306
Computer equipment and other
Property, Plant and Equipment [Line Items]
Cost	3,718,266	3,684,521
Accumulated Depreciation and Amortization	(1,867,035)	(1,876,391)
Net Book Value	$ 1,851,231	$ 1,808,130

Goodwill and Intangible Asset52

Goodwill and Intangible Assets - Summary of Goodwill and Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2016	Jun. 30, 2009	Jan. 31, 2005
Indefinite lived:
Goodwill, Gross	$ 10,513,371	$ 10,513,371
Goodwill	10,513,371	10,513,371
Definite lived:
Intangible assets, Gross	24,717,873	24,717,873
Intangible assets, Accumulated Amortization	(18,708,144)	(17,089,479)
Intangible assets, net book value	6,009,729	7,628,394
Total goodwill and intangible assets, Gross	35,231,244	35,231,244
Total goodwill and intangible assets, Net Book Value	$ 16,523,100	18,141,765
Inovio AS
Indefinite lived:
Goodwill					$ 3,900,000
VGX
Indefinite lived:
Goodwill				$ 6,200,000
Bioject
Indefinite lived:
Goodwill			$ 400,000
Minimum
Schedule of intangible assets by major asset class
Intangible asset, useful life	2 years
Maximum
Schedule of intangible assets by major asset class
Intangible asset, useful life	18 years
Patents
Definite lived:
Intangible assets, Gross	$ 5,802,528	5,802,528
Intangible assets, Accumulated Amortization	(5,681,673)	(5,618,854)
Intangible assets, net book value	$ 120,855	183,674
Patents | Minimum
Schedule of intangible assets by major asset class
Intangible asset, useful life	8 years
Patents | Maximum
Schedule of intangible assets by major asset class
Intangible asset, useful life	17 years
Licenses
Definite lived:
Intangible assets, Gross	$ 1,323,761	1,323,761
Intangible assets, Accumulated Amortization	(1,190,609)	(1,161,861)
Intangible assets, net book value	$ 133,152	161,900
Licenses | Minimum
Schedule of intangible assets by major asset class
Intangible asset, useful life	8 years
Licenses | Maximum
Schedule of intangible assets by major asset class
Intangible asset, useful life	17 years
CELLECTRA
Definite lived:
Intangible assets, Gross	$ 8,106,270	8,106,270
Intangible assets, Accumulated Amortization	(7,252,108)	(6,825,028)
Intangible assets, net book value	$ 854,162	1,281,242
CELLECTRA | Minimum
Schedule of intangible assets by major asset class
Intangible asset, useful life	5 years
CELLECTRA | Maximum
Schedule of intangible assets by major asset class
Intangible asset, useful life	11 years
GHRH
Schedule of intangible assets by major asset class
Intangible asset, useful life	11 years
Definite lived:
Intangible assets, Gross	$ 335,314	335,314
Intangible assets, Accumulated Amortization	(271,948)	(240,264)
Intangible assets, net book value	63,366	95,050
Bioject
Definite lived:
Intangible assets, Gross	5,100,000	5,100,000
Intangible assets, Accumulated Amortization	(1,405,556)	(562,222)
Intangible assets, net book value	$ 3,694,444	4,537,778
Bioject | Minimum
Schedule of intangible assets by major asset class
Intangible asset, useful life	2 years
Bioject | Maximum
Schedule of intangible assets by major asset class
Intangible asset, useful life	15 years
Other
Schedule of intangible assets by major asset class
Intangible asset, useful life	18 years
Definite lived:
Intangible assets, Gross	$ 4,050,000	4,050,000
Intangible assets, Accumulated Amortization	(2,906,250)	(2,681,250)
Intangible assets, net book value	$ 1,143,750	$ 1,368,750

Goodwill and Intangible Asset53

Goodwill and Intangible Assets - Schedule of Amortization Expense (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets (Textual) [Abstract]
2,018	$ 1,249,584
2,019	1,066,251
2,020	547,081
2,021	520,414
2,022	492,818
Thereafter	2,133,581
Intangible assets, net book value	$ 6,009,729	$ 7,628,394

Goodwill and Intangible Asset54

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 1,618,665	$ 1,377,466	$ 870,199
Impairment	$ 0	$ 0	$ 0

Accounts Payable and Accrued 55

Accounts Payable and Accrued Expenses (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Trade accounts payable, including from affiliated entity	$ 7,564,830	$ 5,920,642
Accrued compensation	7,997,152	6,531,983
Accrued subcontract costs	3,746,937	5,475,359
Other accrued expenses	3,969,879	1,669,803
Accounts payable and accrued liabilities	$ 23,278,798	$ 19,597,787

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Preferred Stock (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Summary of common and preferred stock authorized, issued and outstanding
Preferred Stock, par value ($ per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	23	23
Preferred stock, shares outstanding	23	23
Series C Preferred Stock
Summary of common and preferred stock authorized, issued and outstanding
Preferred Stock, par value ($ per share)	$ 0.001
Preferred stock, shares authorized	1,091
Preferred stock, shares issued	1,091
Preferred stock, shares outstanding	23	23

Stockholders' Equity - Summar57

Stockholders' Equity - Summary of Warrants Outstanding (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Summary of warrants outstanding
Number of warrants (shares)	284,091	284,091
Common Stock Warrant Liability	$ 360,795	$ 1,167,614
March 2013 financing
Summary of warrants outstanding
Exercise price ($ per share)	$ 3.17
Expiration Date	Sep. 12, 2018
Number of warrants (shares)	284,091	284,091
Common Stock Warrant Liability	$ 360,795	$ 1,167,614

Stockholders' Equity - Summar58

Stockholders' Equity - Summary of Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (shares) | shares	7,694,870
Weighted-Average Remaining Contractual Life (in Years)	6 years 6 months 27 days
Weighted average exercise price ($ per share)	$ 6.77
Options exercisable (shares) | shares	5,444,771
Weighted-average exercise price ($ per share)	$ 6.68
$1.48-$3.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit	1.48
Exercise price, upper range limit	$ 3
Options outstanding (shares) | shares	1,177,183
Weighted-Average Remaining Contractual Life (in Years)	4 years 6 months 27 days
Weighted average exercise price ($ per share)	$ 2.25
Options exercisable (shares) | shares	1,177,183
Weighted-average exercise price ($ per share)	$ 2.25
$3.01-$6.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit	3.01
Exercise price, upper range limit	$ 6
Options outstanding (shares) | shares	753,932
Weighted-Average Remaining Contractual Life (in Years)	3 years 4 months 9 days
Weighted average exercise price ($ per share)	$ 4.64
Options exercisable (shares) | shares	668,244
Weighted-average exercise price ($ per share)	$ 4.57
$6.01-$9.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit	6.01
Exercise price, upper range limit	$ 9
Options outstanding (shares) | shares	4,709,442
Weighted-Average Remaining Contractual Life (in Years)	7 years 6 months 25 days
Weighted average exercise price ($ per share)	$ 7.09
Options exercisable (shares) | shares	2,639,454
Weighted-average exercise price ($ per share)	$ 7.23
$9.01-$12.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit	9.01
Exercise price, upper range limit	$ 12
Options outstanding (shares) | shares	357,603
Weighted-Average Remaining Contractual Life (in Years)	8 years 1 day
Weighted average exercise price ($ per share)	$ 9.79
Options exercisable (shares) | shares	263,180
Weighted-average exercise price ($ per share)	$ 9.83
$12.01-$15.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit	12.01
Exercise price, upper range limit	$ 15
Options outstanding (shares) | shares	696,710
Weighted-Average Remaining Contractual Life (in Years)	6 years 2 months 20 days
Weighted average exercise price ($ per share)	$ 12.96
Options exercisable (shares) | shares	696,710
Weighted-average exercise price ($ per share)	$ 12.96

Stockholders' Equity - Summar59

Stockholders' Equity - Summary of Stock Option Activity Under Equity Incentive Plan (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Number of Shares
Beginning Balance (shares) | shares	6,806,183
Granted (shares) | shares	1,788,121
Exercised (shares) | shares	(452,973)
Cancelled (shares) | shares	(446,461)
Ending Balance (shares) | shares	7,694,870
Weighted-Average Exercise Price
Beginning Balance ($ per share) | $ / shares	$ 6.81
Granted ($ per share) | $ / shares	6.62
Exercised ($ per share) | $ / shares	5.18
Cancelled ($ per share) | $ / shares	8.49
Ending Balance ($ per share) | $ / shares	$ 6.77

Stockholders' Equity - Summar60

Stockholders' Equity - Summary of RSU Activity Under Equity Incentive Plan (Details) - Restricted stock units	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
December 31, 2016 (shares) | shares	798,834
Granted (shares) | shares	1,035,443
Vested (shares) | shares	(561,462)
Cancelled (shares) | shares	(38,647)
December 31, 2017 (shares) | shares	1,234,168
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
December 31, 2016 ($ per share) | $ / shares	$ 0
Granted ($ per share) | $ / shares	0
Vested ($ per share) | $ / shares	0
Cancelled ($ per share) | $ / shares	0
December 31, 2016 ($ per share) | $ / shares	$ 0

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details)	Jul. 25, 2017USD ($)$ / sharesshares	Jun. 30, 2016USD ($)	Dec. 31, 2017USD ($)dayvote$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2017USD ($)vote$ / sharesshares	Jan. 01, 2018shares	May 13, 2016shares
Class of Stock [Line Items]
Preferred stock, par value ($ per share) | $ / shares			$ 0.001	$ 0.001		$ 0.001
Convertible preferred stock, shares issued upon conversion, conversion price ($ per share) | $ / shares			27.20
Daily market price triggering mandatory conversion ($ per share) | $ / shares			$ 72
Number of trading days | day			20
Number of consecutive trading days | day			30
Proceeds from issuance of common stock | $			$ 94,347,922	$ 6,295,761	$ 81,902,363
Share-based compensation | $			13,070,962	10,479,135	$ 6,186,848
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized | $			$ 5,900,000	$ 5,800,000		$ 5,900,000
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition			1 year 9 months 15 days	1 year 10 months 15 days
Number of options outstanding to purchase common stock (shares) | shares			7,694,870	6,806,183		7,694,870
Aggregate intrinsic value of options outstanding | $			$ 2,300,000
Aggregate intrinsic value for options exercisable | $			$ 2,300,000			$ 2,300,000
Options exercisable, remaining contractual term			5 years 10 months 15 days
Number of options expected to vest (shares) | shares			7,694,870			7,694,870
Options, expirations in period, weighted average exercise price ($ per share) | $ / shares			$ 9.67	$ 9.01	$ 10.89
Options, expirations in period | shares			200,501	69,570	83,696
Options, grants in period, weighted average grant date fair value ($ per share) | $ / shares			$ 4.33	$ 4.59	$ 4.60
Proceeds from stock options exercised | $			$ 2,300,000	$ 1,800,000	$ 552,000
Options, exercises in period, aggregate intrinsic value | $			519,000	3,500,000	456,000
Employee
Class of Stock [Line Items]
Share-based compensation | $			12,900,000	10,200,000	5,800,000
Research and Development Expense
Class of Stock [Line Items]
Share-based compensation | $			5,800,000	4,800,000	3,200,000
General and Administrative Expense
Class of Stock [Line Items]
Share-based compensation | $			7,100,000	5,400,000	2,600,000
Non Employee
Class of Stock [Line Items]
Allocated share-based compensation expense | $			$ 201,000	321,000	$ 385,000
Number of options outstanding to purchase common stock (shares) | shares			701,367			701,367
Restricted Stock Units (RSUs)
Class of Stock [Line Items]
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized | $			$ 5,300,000	$ 4,000,000		$ 5,300,000
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition			1 year 9 months	2 years
Aggregate intrinsic value of unvested | $			$ 5,100,000			$ 5,100,000
Aggregate intrinsic value of vested | $			$ 3,600,000
RSU's expected to vest (shares) | shares			1,234,168			1,234,168
Weighted average grant date fair value ($ per share) | $ / shares			$ 6.66	$ 7.41	$ 7.76
At-the-Market Exchange
Class of Stock [Line Items]
Proceeds from issuance of common stock | $			$ 24,200,000			$ 30,500,000
Authorized amount | $		$ 50,000,000
Agent fee		2.00%
Issuance of common stock for cash, net of financing costs (shares) | shares			2,937,406			3,596,154
Offering price ($ per share) | $ / shares			$ 8.41			$ 8.41
Stock sales agreement, remaining authorized shares (shares) | $			$ 18,900,000			$ 18,900,000
Minimum
Class of Stock [Line Items]
Average daily trading volume triggering mandatory conversion (shares) | shares			6,250
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price ($ per share) | $ / shares			$ 10,000			$ 10,000
Preferred stock, par value ($ per share) | $ / shares			$ 0.001			$ 0.001
Number of votes per share | vote			368			368
Convertible preferred stock, shares issued upon conversion (shares) | shares			8,456			8,456
Notice period for mandatory conversion of preferred stock			30 days
Common stock | Public Offering, Not IPO
Class of Stock [Line Items]
Sale of stock, number of shares issued in transaction (shares) | shares	12,500,000
Sale of stock, price per share ($ per share) | $ / shares	$ 6
Proceeds from issuance of common stock | $	$ 70,100,000
2016 Incentive Plan
Class of Stock [Line Items]
Reserved number of shares under the Incentive Plan (shares) | shares			6,000,000			6,000,000
Number of potential shares authorized for issuance under a share-based compensation plan (shares) | shares								2,000,000
Number of shares available for grants under the Incentive Plan (shares) | shares			3,994,511			3,994,511
Number of shares of vested restricted stock outstanding under the plan (shares) | shares			819,507
Number of common stock shares outstanding under the Incentive Plan (shares) | shares			1,136,057			1,136,057
Vesting period of Incentive Plan			3 years
Contractual year term of Incentive Plan			10 years
2007 Incentive Plan
Class of Stock [Line Items]
Number of shares of vested restricted stock outstanding under the plan (shares) | shares			414,661
Number of common stock shares outstanding under the Incentive Plan (shares) | shares			6,357,071			6,357,071
Vesting period of Incentive Plan			3 years
Contractual year term of Incentive Plan			10 years
VGX Equity Compensation Plan
Class of Stock [Line Items]
Number of common stock shares outstanding under the Incentive Plan (shares) | shares			201,742			201,742
Subsequent Event | 2016 Incentive Plan
Class of Stock [Line Items]
Increase in number of shares authorized (shares) | shares							2,000,000

Commitments - Narrative (Detail

Commitments - Narrative (Details) ft² in Thousands, $ in Thousands	1 Months Ended					3 Months Ended	12 Months Ended			13 Months Ended
	Jun. 30, 2017USD ($)	Oct. 31, 2016USD ($)ft²	Jan. 31, 2016USD ($)	Mar. 31, 2014USD ($)	Apr. 30, 2013	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2017USD ($)ft²
Operating Leased Assets [Line Items]
Rent expense, net							$ 2,400	$ 1,600	$ 1,300
San Diego Office
Operating Leased Assets [Line Items]
Term of contract					10 years
Tenant Improvements			$ 822
San Diego, California
Operating Leased Assets [Line Items]
Term of contract		10 years
Tenant Improvements							$ 2,300
Area (square feet) | ft²		51
Adjustable rent period		2 years
Security deposit		$ 95
Plymouth Meeting, Pennsylvania
Operating Leased Assets [Line Items]
Term of contract				11 years 6 months
Tenant Improvements	$ 2,600									$ 2,600
Area (square feet) | ft²										30
Security deposit	75			$ 49						$ 75
Minimum | Plymouth Meeting, Pennsylvania
Operating Leased Assets [Line Items]
Monthly payments under the lease										75
Lease amendment, periodic payments, amount	173
Maximum | San Diego Office
Operating Leased Assets [Line Items]
Monthly payments under the lease			$ 99
Maximum | San Diego, California
Operating Leased Assets [Line Items]
Monthly payments under the lease		$ 95
Maximum | Plymouth Meeting, Pennsylvania
Operating Leased Assets [Line Items]
Monthly payments under the lease				$ 58						$ 90
Increase in monthly lease payments						$ 80
Lease amendment, periodic payments, amount	$ 179

Commitments - Summary of Future

Commitments - Summary of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 3,251
2,019	3,756
2,020	3,891
2,021	3,979
2,022	4,052
Thereafter	19,975
Total	$ 38,904

Investments in Affiliated Ent64

Investments in Affiliated Entities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Jul. 01, 2015
Related Party Transaction [Line Items]
Carryover basis			$ 0
GeneOne Life Sciences
Related Party Transaction [Line Items]
Percentage of ownership	7.80%	10.20%
GeneOne Life Sciences | Common stock
Related Party Transaction [Line Items]
Number of shares owned (shares)	1,644,155	1,644,155
Plumbline Life Sciences
Related Party Transaction [Line Items]
Percentage of ownership	16.40%	16.40%
Plumbline Life Sciences | Common stock
Related Party Transaction [Line Items]
Number of shares owned (shares)	395,758	395,758

Business Combination - Narrativ

Business Combination - Narrative (Details) - Bioject $ in Millions	Apr. 29, 2016USD ($)
Business Acquisition [Line Items]
Consideration transferred	$ 5.5
Equity issued	4.3
Cash paid for acquisition	$ 1.2
Developed technology
Business Acquisition [Line Items]
Discount rate	14.00%
Amortization period	15 years
Minimum
Business Acquisition [Line Items]
Amortization period	2 years
Maximum
Business Acquisition [Line Items]
Amortization period	5 years

Business Combination - Summary

Business Combination - Summary of Assets Acquired (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Apr. 29, 2016
Business Acquisition [Line Items]
Goodwill	$ 10,513,371	$ 10,513,371
Bioject
Business Acquisition [Line Items]
Goodwill			$ 400,000
Total purchase consideration			5,500,000
Trademarks | Bioject
Business Acquisition [Line Items]
Intangible assets			200,000
Developed technology | Bioject
Business Acquisition [Line Items]
Intangible assets			3,800,000
Customer-related intangible assets | Bioject
Business Acquisition [Line Items]
Intangible assets			1,000,000
Covenants not-to-compete | Bioject
Business Acquisition [Line Items]
Intangible assets			$ 100,000

Income Taxes - Summary of the P

Income Taxes - Summary of the Provision for Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 0	$ 0	$ 0
State	0	0	0
Current income tax expense (benefit)	0	0	0
Deferred:
Federal	0	0	(1,594,000)
State	0	0	(504,000)
Deferred income tax expense (benefit)	0	0	(2,098,000)
Income tax expense (benefit)	$ 0	$ 0	$ (2,097,766)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income (benefit) taxes at statutory rates	$ (30,872)	$ (25,809)	$ (10,920)
State income tax, net of federal benefit	(4)	(4)	(2,640)
Change in valuation allowance	(20,965)	29,678	7,882
Research and development tax credits	(3,456)	(3,117)	(1,537)
Fair value warrant	(282)	(47)	(253)
Stock compensation	2,332	113	2,288
Uncertain tax positions	846	1,367	1,968
Expired NOLs and credits	454	4,269	339
Limited NOLs and credits	(165)	(6,456)	(297)
Change in state tax rate	50,019	(495)	676
Other	2,093	501	396
Income tax expense (benefit)	$ 0	$ 0	$ (2,098)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Income tax benefit		$ 0	$ 0	$ 2,097,766
Excess tax benefits on stock compensation	$ 1,100,000
Tax benefits expired		13,400,000
Decrease in deferred tax assets		50,000,000
Decrease in valuation allowance		50,200,000
Provisional income tax benefit		(200,000)
Unrecognized tax benefits that would impact effective tax rate		7,100,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations		298,900,000
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations		68,600,000
Pennsylvania
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations		75,600,000
Research Tax Credit Carryforward | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount		11,100,000
Research Tax Credit Carryforward | State
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount		$ 2,100,000

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Capitalized research expense	$ 8,546	$ 567
Net operating loss carryforwards	71,665	95,500
Research and development and other tax credits	7,531	5,300
Deferred revenue	297	5,452
Deferred rent	2,097	2,231
Stock-based compensation	3,091	4,511
Acquired intangibles	858	989
Other	1,906	3,783
Deferred tax assets, gross	95,991	118,333
Valuation allowance	(94,039)	(113,407)
Total deferred tax assets	1,952	4,926
Deferred tax liabilities:
Acquired intangibles	(124)	(175)
Investment in affiliated entity	(422)	(3,624)
Fixed assets	(1,430)	(1,302)
Net deferred tax liabilities	$ (24)	$ (175)

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 6,855,000	$ 5,455,000	$ 2,759,000
Increases related to current year tax positions	1,532,000	1,183,000	615,000
Decreases related to prior year tax positions	74,000
Increases (decreases) related to prior year tax positions		217,000	2,081,000
Balance at end of the year	$ 8,313,000	$ 6,855,000	$ 5,455,000

401(k) Plan (Details)

401(k) Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Employer matching contribution, percent	50.00%
Maximum annual contribution per employee, percent	6.00%
Company's contribution to 401(k) plan	$ 822	$ 496	$ 328

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended					12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Jan. 31, 2016	May 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2010	May 31, 2016	May 31, 2014
Related Party Transaction [Line Items]
Full payment						$ 1,000,000	$ 1,000,000	$ 1,000,000
Long-term other assets	$ 2,639,354	$ 2,113,147				2,639,354	2,113,147
Ownership percentage by parent												85.00%
Payment of receivable											$ 2,000,000
Future payments to be received					$ 1,000,000
Ownership											16.40%
Payment of cash distribution							1,000,000	1,000,000
Investment in affiliated entity - PLS	2,325,079	3,777,510				2,325,079	3,777,510
Parent
Related Party Transaction [Line Items]
Payment of cash distribution							850,000	850,000
Minority shareholders
Related Party Transaction [Line Items]
Payment of cash distribution							150,000	150,000
Plumbline Life Sciences
Related Party Transaction [Line Items]
Revenue from related parties						215,000	212,000
Carrying value of investment												$ 0
Accounts receivable	370,000	155,000				370,000	155,000
Available-for-sale Securities
Related Party Transaction [Line Items]
Number of shares owned (shares)											395,758
VGX Pharmaceuticals | Available-for-sale Securities
Related Party Transaction [Line Items]
Number of shares owned (shares)											465,364
GeneOne (affiliated entity)
Related Party Transaction [Line Items]
Full payment	1,000,000
Ownership target				35.00%	35.00%
Term									20 years
Payment received for license granted										$ 3,000,000
Deferred revenue from affiliated entity										$ 3,000,000
Period over which deferred revenue from affiliated entity will be recognized in years										8 years
Revenue from related parties						551,000	1,200,000	450,000
Operating expenses related to affiliated entity						2,300,000	2,800,000	$ 6,900,000
Accounts receivable from related parties	0	441,000				0	441,000
Accounts payable/accrued liability	107,000	379,000				107,000	379,000
Long-term other assets	331,000	571,000				331,000	571,000
Director
Related Party Transaction [Line Items]
Term			5 years
Revenue from related parties						2,600,000	341,000
Operating expenses related to affiliated entity						2,300,000	985,000
Accounts receivable	117,000	152,000				117,000	152,000
Expenses to reimburse			$ 3,100,000
Proceeds from sub-grant		6,100,000
Due to related parties	$ 820,000	$ 671,000				$ 820,000	$ 671,000

Quarterly Financial Informati74

Quarterly Financial Information (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue under collaborative research and development arrangements	$ 7,409,214	$ 351,272	$ 16,358,316	$ 4,288,586	$ 476,586	$ 2,327,316	$ 1,889,988	$ 1,796,857	$ 28,407,388	$ 6,490,747	$ 26,876,533
Revenue under collaborative research and development arrangements with affiliated entity	226,486	129,133	176,879	233,330	189,278	574,596	499,720	137,000	765,828	1,400,594	779,167
Grants and miscellaneous revenue	980,443	1,456,216	2,797,647	5,240,233	7,735,428	9,410,648	3,814,083	6,176,298	10,474,539	27,136,457	12,916,411
Grants and miscellaneous revenue from affiliated entity	171,091	707,922	1,079,282	614,036	112,660	227,903	0	0	2,572,331	340,563	0
Total revenues	8,787,234	2,644,543	20,412,124	10,376,185	8,513,952	12,540,463	6,203,791	8,110,155	42,220,086	35,368,361	40,572,111
Research and development	24,641,124	25,510,239	23,878,751	24,542,504	23,911,731	26,980,343	19,630,801	18,189,160	98,572,618	88,712,035	57,791,923
General and administrative	8,033,899	6,319,775	6,169,106	7,767,589	6,965,517	5,755,603	5,799,530	5,371,613	28,290,369	23,892,263	18,063,890
Gain on sale of assets	(1,000,000)	0	0	0	0	0	(1,000,000)	0	(1,000,000)	(1,000,000)	(1,000,000)
Total operating expenses	31,675,023	31,830,014	30,047,857	32,310,093	30,877,248	32,735,946	24,430,331	23,560,773	125,862,987	111,604,298	74,855,813
Loss from operations	(22,887,789)	(29,185,471)	(9,635,733)	(21,933,908)	(22,363,296)	(20,195,483)	(18,226,540)	(15,450,618)	(83,642,901)	(76,235,937)	(34,283,702)
Interest and other income, net	509,266	463,346	300,021	340,341	191,460	391,596	341,131	333,070	1,612,974	1,257,257	305,071
Change in fair value of common stock warrants	579,546	423,296	(312,500)	116,477	644,888	2,690	(113,775)	(406,249)	806,819	127,554	177,561
Gain (Loss) from investment in affiliated entity	292,798	(5,835,741)	169,096	(1,608,817)	(4,706,522)	(958,141)	(705,527)	7,480,977	(6,982,664)	1,110,787	2,600,467
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (21,506,179)	$ (34,134,570)	$ (9,479,116)	$ (23,085,907)	$ (26,233,470)	$ (20,759,338)	$ (18,704,711)	$ (8,042,820)	$ (88,205,772)	$ (73,740,339)	$ (29,187,606)
Net loss per common share attributable to Inovio Pharmaceuticals, Inc. stockholders
Basic ($ per share)	$ (0.24)	$ (0.39)	$ (0.13)	$ (0.31)	$ (0.35)	$ (0.28)	$ (0.26)	$ (0.11)	$ (1.08)	$ (1.01)	$ (0.43)
Diluted ($ per share)	$ (0.24)	$ (0.40)	$ (0.13)	$ (0.31)	$ (0.36)	$ (0.28)	$ (0.26)	$ (0.11)	$ (1.09)	$ (1.01)	$ (0.44)