Inovio Pharmaceuticals (INO) 10-Q 7 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 03, 2018
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
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		91,496,835

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 15,085,643	$ 23,786,579
Short-term investments	80,509,364	103,638,844
Accounts receivable	1,712,962	6,003,205
Accounts receivable from affiliated entities	960,453	486,619
Prepaid expenses and other current assets	1,785,081	2,600,906
Prepaid expenses and other current assets from affiliated entities	1,787,297	1,846,007
Total current assets	101,840,800	138,362,160
Fixed assets, net	16,868,953	18,320,176
Investment in affiliated entity - GeneOne	9,014,490	9,069,401
Investment in affiliated entity - PLS	2,667,805	2,325,079
Intangible assets, net	5,293,271	6,009,729
Goodwill	10,513,371	10,513,371
Other assets	2,724,376	2,639,354
Total assets	148,923,066	187,239,270
Current liabilities:
Accounts payable and accrued expenses	12,609,959	23,278,798
Accounts payable and accrued expenses due to affiliated entities	600,701	926,943
Accrued clinical trial expenses	10,359,872	8,611,892
Common stock warrants	228,665	360,795
Deferred revenue	762,361	1,175,353
Deferred revenue from affiliated entities	55,125	174,110
Deferred rent	979,803	877,535
Deferred grant funding	2,620,985	0
Deferred grant funding from affiliated entities	188,800	0
Total current liabilities	28,406,271	35,405,426
Deferred revenue, net of current portion	175,157	215,853
Deferred rent, net of current portion	8,825,052	9,104,416
Deferred tax liabilities	24,766	24,766
Total liabilities	37,431,246	44,750,461
Stockholders’ equity:
Preferred stock	0	0
Common stock	91,474	90,358
Additional paid-in capital	674,017,367	665,775,504
Accumulated deficit	(562,114,904)	(523,356,317)
Accumulated other comprehensive loss	(598,386)	(117,005)
Total Inovio Pharmaceuticals, Inc. stockholders’ equity	111,395,551	142,392,540
Non-controlling interest	96,269	96,269
Total stockholders’ equity	111,491,820	142,488,809
Total liabilities and stockholders’ equity	$ 148,923,066	$ 187,239,270

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 24,448,761	$ 20,412,124	$ 25,978,405	$ 30,788,309
Operating expenses:
Research and development	22,462,620	23,878,751	47,040,371	48,421,255
General and administrative	7,189,310	6,169,106	16,887,325	13,936,695
Total operating expenses	29,651,930	30,047,857	63,927,696	62,357,950
Loss from operations	(5,203,169)	(9,635,733)	(37,949,291)	(31,569,641)
Other income (expense):
Interest and other income, net	396,681	300,021	709,204	640,362
Change in fair value of common stock warrants	259,971	(312,500)	132,130	(196,023)
Gain (loss) on investment in affiliated entities	(2,092,608)	169,096	287,815	(1,439,721)
Net loss before provision for income taxes	(6,639,125)	(9,479,116)	(36,820,142)	(32,565,023)
Provision for income taxes		0	(2,169,811)	0
Net loss	$ (6,639,125)	$ (9,479,116)	$ (38,989,953)	$ (32,565,023)
Net loss per share
Basic (dollars per share)	$ (0.07)	$ (0.13)	$ (0.43)	$ (0.44)
Diluted (dollars per share)	$ (0.08)	$ (0.13)	$ (0.43)	$ (0.44)
Weighted average number of common shares outstanding
Basic (shares)	91,153,776	75,409,702	90,804,722	74,783,791
Diluted (shares)	91,241,660	75,409,702	90,890,792	74,783,791
Revenue under collaborative research and development arrangements
Revenues:
Total revenues	$ 24,385,852	$ 16,358,316	$ 25,674,898	$ 20,646,902
Revenue under collaborative research and development arrangements with affiliated entities
Revenues:
Total revenues	60,319	176,879	208,327	410,209
Grants and miscellaneous revenue
Revenues:
Total revenues	2,590	2,797,647	95,180	8,037,880
Grants and miscellaneous revenue from affiliated entity
Revenues:
Total revenues	$ 0	$ 1,079,282	$ 0	$ 1,693,318

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,639,125)	$ (9,479,116)	$ (38,989,953)	$ (32,565,023)
Other comprehensive income (loss):
Unrealized gain (loss) on investment in affiliated entity	0	312,253	0	(437,708)
Unrealized gain (loss) on short-term investments	(137,250)	86,862	(250,015)	290,402
Comprehensive loss	$ (6,776,375)	$ (9,080,001)	$ (39,239,968)	$ (32,712,329)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (38,989,953)	$ (32,565,023)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,841,084	1,020,679
Amortization of intangible assets	716,458	810,539
Change in value of common stock warrants	(132,130)	196,023
Stock-based compensation	6,164,958	7,937,473
Amortization of premiums on investments	71,559	140,599
Loss on short-term investments	373,822	67,366
Deferred rent	(177,096)	1,869,341
Loss (gain) on equity investment in affiliated entities	(287,815)	1,439,721
Changes in operating assets and liabilities:
Accounts receivable	4,290,243	8,298,963
Accounts receivable from affiliated entities	(473,834)	(440,945)
Prepaid expenses and other current assets	815,825	(3,165,705)
Prepaid expenses and other current assets from affiliated entities	58,710	260,694
Other assets	(85,022)	438,896
Accounts payable and accrued expenses	(9,443,933)	(4,305,114)
Accrued clinical trial expenses	1,747,980	820,362
Accounts payable and accrued expenses due to affiliated entities	(326,242)	(225,158)
Deferred revenue	(453,688)	(14,325,900)
Deferred revenue from affiliated entities	(118,985)	(219,792)
Deferred grant funding	2,620,985	0
Deferred grant funding from affiliated entities	188,800	0
Net cash used in operating activities	(31,598,274)	(31,946,981)
Cash flows from investing activities:
Purchases of investments	(31,318,982)	(14,600,112)
Maturities of investments	53,753,066	32,173,342
Purchases of capital assets	(1,614,767)	(5,828,137)
Net cash provided by investing activities	20,819,317	11,745,093
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	1,973,401	24,060,196
Proceeds from stock option and warrant exercises, net of tax payments	104,620	865,857
Net cash provided by financing activities	2,078,021	24,926,053
(Decrease) Increase in cash and cash equivalents	(8,700,936)	4,724,165
Cash and cash equivalents, beginning of period	23,786,579	19,136,472
Cash and cash equivalents, end of period	15,085,643	23,860,637
Supplemental disclosure of non-cash activities
Change in amounts accrued for purchases of property and equipment	$ 1,224,906	$ 1,185,087

Organization and Operations

Organization and Operations	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operations	Organization and Operations 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 its 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; Lassa fever; 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"), ApolloBio Corporation, Regeneron Pharmaceuticals, Inc., Genentech, Inc., Plumbline Life Sciences, Inc., Drexel University, National Institute of Allergy and Infectious Diseases (“NIAID”), United States Military HIV Research Program, U.S. Army Medical Research Institute of Infectious Diseases, National Institutes of Health, HIV Vaccines Trial Network, Defense Advanced Research Projects Agency (“DARPA”), Parker Institute for Cancer Immunotherapy, and Coalition for Epidemic Preparedness Innovations (“CEPI”). Inovio was incorporated in Delaware in June 2001 and has its principal executive offices in Plymouth Meeting, Pennsylvania.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Inovio have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) as contained in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") for interim financial information and with instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of June 30, 2018 , the condensed consolidated statements of operations and condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2018 and 2017 and the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 are unaudited, but include all adjustments (consisting of normal recurring adjustments) that the Company considers necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results of operations for the three and six months ended June 30, 2018 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 , or for any other period. These unaudited financial statements, and notes thereto, should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2017 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 14, 2018. The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Company has evaluated subsequent events after the balance sheet date of June 30, 2018 through the date it filed these unaudited condensed consolidated financial statements with the SEC. These unaudited condensed consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc., VGX and GENEOS Therapeutics, Inc., and records a non-controlling interest for the 15% of VGX Animal Health, Inc., a subsidiary of VGX, that it did not own as of June 30, 2018 and December 31, 2017 . All intercompany accounts and transactions have been eliminated upon consolidation. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Critical Accounting Policies

Critical Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Critical Accounting Policies	Critical Accounting Policies Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition (“Topic 605”), including most industry-specific revenue recognition guidance throughout the Industry Topics of the ASC. All periods prior to the adoption date of Topic 606 have not been restated to reflect the impact of the adoption of Topic 606, but continue to be accounted for and presented under Topic 605. The following paragraphs in this section describe the Company's revenue recognition accounting policies under Topic 606 upon adoption on January 1, 2018. Refer to Note 2 to the consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 for revenue recognition accounting policies under Topic 605. The Company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company will assess the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable, up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company will utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements. Under certain collaborative arrangements, the Company has been reimbursed for a portion of its research and development ("R&D") expenses, including costs of drug supplies. When these R&D services are performed under a reimbursement or cost sharing model with its collaboration partner, the Company records these reimbursements as a reduction of R&D expense in its condensed consolidated statements of operations. Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605 , Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra-expense as opposed to revenue on the condensed consolidated statement of operations. 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 Pharmaceuticals, Inc. ("VGX") in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of June 30, 2018 and December 31, 2017, the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $5.3 million and $6.0 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 June 30, 2018 . 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. 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.

Impact of Recently Issued Accou

Impact of Recently Issued Accounting Standards	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Impact of Recently Issued Accounting Standards	Impact of Recently Issued Accounting Standards The recent accounting pronouncements below may have a significant effect on the Company's financial statements. Recent accounting pronouncements that are not anticipated to have an impact on or are unrelated to the Company's financial condition, results of operations, or related disclosures are not discussed. ASU No. 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. The impact of adoption of Topic 606 on the Company's existing agreements was as follows: Collaboration Agreement with MedImmune The Company has determined that no cumulative catch-up adjustment was required. 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 have been recorded as a contra-expense as opposed to revenue on the consolidated statement of operations. For the three and six months ended June 30, 2018 , $1.9 million and $4.1 million , respectively, would have been recorded as grant revenue but under the new guidance was instead recorded as a reduction to research and development expense. The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the three months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Three Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Three Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 24,385,852 $ — $ 24,385,852 Revenue under collaborative research and development arrangements with affiliated entities 60,319 — 60,319 Grants and miscellaneous revenue 1,459,684 (1,457,094 ) 2,590 Grants and miscellaneous revenue from affiliated entity 454,820 (454,820 ) — Total revenues 26,360,675 (1,911,914 ) 24,448,761 Operating expenses: Research and development 24,374,534 (1,911,914 ) 22,462,620 General and administrative 7,189,310 — 7,189,310 Total operating expenses $ 31,563,844 $ (1,911,914 ) $ 29,651,930 The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the six months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Six Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Six Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 25,674,898 $ — $ 25,674,898 Revenue under collaborative research and development arrangements with affiliated entities 208,327 — 208,327 Grants and miscellaneous revenue 2,016,674 (1,921,494 ) 95,180 Grants and miscellaneous revenue from affiliated entity 2,212,571 (2,212,571 ) — Total revenues 30,112,470 (4,134,065 ) 25,978,405 Operating expenses: Research and development 51,174,436 (4,134,065 ) 47,040,371 General and administrative 16,887,325 — 16,887,325 Total operating expenses $ 68,061,761 $ (4,134,065 ) $ 63,927,696 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 done under the previous 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 was effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company adopted this guidance on January 1, 2018 and recorded a $231,366 cumulative effect adjustment to reclassify the cumulative unrealized gain, net of tax effect, from its investment in Plumbline Life Sciences, Inc. ("PLS") from accumulated other comprehensive loss to accumulated deficit. After the adoption of ASU No. 2016-01, the Company recorded a (loss) gain on investment in affiliated entity related to PLS of $(639,000) and $343,000 on the condensed consolidated statement of operations for the three and six months ended June 30, 2018 , respectively. The cumulative effect of the changes made to the Company's condensed consolidated balance sheet as of January 1, 2018 for the adoption of ASU No. 2016-01 are included in the table below: Equity: Balance at December 31, 2017 Adjustments due to ASU No. 2016-01 Balance at January 1, 2018 Accumulated deficit $ (523,356,317 ) $ 231,366 $ (523,124,951 ) Accumulated other comprehensive loss $ (117,005 ) $ (231,366 ) $ (348,371 ) 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. The Company currently has three operating leases for its office and laboratory spaces in San Diego, California and Plymouth Meeting, Pennsylvania that it expects to be impacted by the new accounting standard that will result in the present values of the future lease payments being presented as right-to-use assets, with a corresponding lease liability at the date of adoption.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with the Company’s historical accounting under Topic 605. For additional details about Topic 606, refer to Note 3 above. The following table summarizes changes in the Company’s contract assets and liabilities for the six months ended June 30, 2018 : Balance at January 1, 2018 Additions Deductions Balance at June 30, 2018 Contract assets Accounts receivable from MedImmune $ 1,693,530 $ 2,541,901 $ (3,142,901 ) $ 1,092,530 Contract liabilities Deferred revenue - MedImmune 1,145,500 582,500 (882,000 ) 846,000 Deferred revenue - ApolloBio — 23,000,000 (23,000,000 ) — Deferred revenue - Other $ 271,894 $ — $ (125,251 ) $ 146,643 During the three and six months ended June 30, 2018 , the Company recognized total revenue under collaborative research and development and other agreements of $23.0 million from ApolloBio; $1.4 million and $2.7 million , respectively, from MedImmune; $32,000 and $150,000 , respectively, from its affiliated entity GeneOne Life Science Inc. ("GeneOne"); and $31,000 and $153,000 , respectively, from various other contracts. Of the total revenue recognized during the three and six months ended June 30, 2018 , $354,000 and $1.0 million, respectively, was in deferred revenue, as of December 31, 2017. All revenues recognized during the three and six months ended June 30, 2018 are attributed to the United States.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Investments at June 30, 2018 and December 31, 2017 consisted of mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entity PLS. Investments are recorded at fair value, based on current market valuations. After the adoption of ASU No. 2016-01 on January 1, 2018, unrealized gains and losses on the Company's equity securities are reported in the condensed consolidated statement of operations as non-operating other income (expense). Unrealized gains and losses on the Company's debt securities will continue to be excluded from earnings and are reported as a separate component of other comprehensive loss until realized. Realized gains and losses are included in non-operating other income (expense) on the condensed consolidated statement of operations and are derived using the specific identification method for determining the cost of the securities sold. During the three and six months ended June 30, 2018 , $121,000 and $374,000 , respectively, of net realized loss on investments was recorded. During the three and six months ended June 30, 2017 , $16,000 and $67,000 , respectively, of net realized loss on investments was recorded. The Company assessed each of its investments on an individual basis to determine if any decline in fair value was other-than-temporary. Interest and dividends on investments classified as available-for-sale are included in interest and other income, net, in the condensed consolidated statements of operations. As of June 30, 2018 , the Company had 28 available-for-sale securities in a gross unrealized loss position, of which 8 with an aggregate total unrealized loss of $91,000 were in such position for longer than 12 months . The following is a summary of available-for-sale securities as of June 30, 2018 and December 31, 2017 : As of June 30, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 69,855,486 $ — $ (532,970 ) $ 69,322,516 US corporate debt securities Less than 2 11,252,264 — (65,416 ) 11,186,848 Investment in affiliated entity (PLS) --- — 2,667,805 — 2,667,805 Total investments $ 81,107,750 $ 2,667,805 $ (598,386 ) $ 83,177,169 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

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 or 2017 . 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 June 30, 2018 : Fair Value Measurements at June 30, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 1,649,759 $ 1,649,759 $ — $ — Mutual funds 69,322,516 — 69,322,516 — US corporate debt securities 11,186,848 — 11,186,848 — Investment in affiliated entities 11,682,295 11,682,295 — — Total Assets $ 93,841,418 $ 13,332,054 $ 80,509,364 $ — Liabilities: Common stock warrants $ 228,665 $ — $ — 228,665 Total Liabilities $ 228,665 $ — $ — $ 228,665 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 — Investment 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 Level 1 assets at June 30, 2018 consisted of money market funds held by the Company that are valued at quoted market prices, as well as the Company’s investments in affiliates, GeneOne and PLS. The Company accounts for its investment in 1,644,155 common shares of GeneOne based on the closing price of the shares on the Korean Stock Exchange on the applicable balance sheet date. The Company accounts for its investment in 395,758 common shares of PLS as an equity investment with a fair value based on the closing price of the shares on the Korea New Exchange (KONEX) Market on the applicable balance sheet date. 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 condensed consolidated statements of operations. 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. After the adoption of ASU No. 2016-01 on January 1, 2018, unrealized gains and losses on the Company's equity securities are reported in the condensed consolidated statement of operations as a gain (loss) on investment in affiliated entities, as discussed in Note 4. Level 2 assets at June 30, 2018 consisted of U.S. 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 the service's assessment of the fair values of the Company's investment portfolio balance against the fair values of the Company's investment portfolio balance obtained from an independent source. There were no Level 3 assets held as of June 30, 2018 . Level 3 liabilities at June 30, 2018 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 six months ended June 30, 2018 and 2017 , no ne of these warrants were exercised. As of June 30, 2018 , the Company had a $229,000 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 June 30, 2018 are presented below: Risk-free interest rate 2.32% Expected volatility 43% Expected life in years 0.2 Dividend yield — Changes in these assumptions as well as fluctuations in the Company's stock price on the valuation date 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 $260,000 and $132,000 for the three and six months ended June 30, 2018 , respectively, and an increase in fair value of $313,000 and $196,000 for the three and six months ended June 30, 2017 , respectively. The change in fair value of common stock warrants is reflected in the Company's condensed consolidated statements of operations. The following table presents the changes in fair value of the Company’s Level 3 financial liabilities for the six months ended June 30, 2018 : Balance at December 31, 2017 $ 360,795 Decrease attributable to change in fair value of common stock warrants (132,130 ) Balance at June 30, 2018 $ 228,665

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following sets forth the goodwill and intangible assets by major asset class: June 30, 2018 December 31, 2017 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 (5,711,876 ) 90,652 5,802,528 (5,681,673 ) 120,855 Licenses 8 – 17 1,323,761 (1,204,983 ) 118,778 1,323,761 (1,190,609 ) 133,152 CELLECTRA ® (b) 5 – 11 8,106,270 (7,465,649 ) 640,621 8,106,270 (7,252,108 ) 854,162 GHRH(b) 11 335,314 (287,788 ) 47,526 335,314 (271,948 ) 63,366 Bioject(c) 2 – 15 5,100,000 (1,735,556 ) 3,364,444 5,100,000 (1,405,556 ) 3,694,444 Other(d) 18 4,050,000 (3,018,750 ) 1,031,250 4,050,000 (2,906,250 ) 1,143,750 Total intangible assets 24,717,873 (19,424,602 ) 5,293,271 24,717,873 (18,708,144 ) 6,009,729 Total goodwill and intangible assets $ 35,231,244 $ (19,424,602 ) $ 15,806,642 $ 35,231,244 $ (18,708,144 ) $ 16,523,100 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition. Aggregate amortization expense on intangible assets for the three and six months ended June 30, 2018 was $312,000 and $716,000 , respectively. Aggregate amortization expense on intangible assets for the three and six months ended June 30, 2017 was $404,000 and $811,000 , respectively. Estimated aggregate amortization expense is $ 533,000 for the remainder of fiscal year 2018 , $1.1 million for 2019 , $ 547,000 for 2020 , $ 520,000 for 2021 , $ 493,000 for 2022 and $ 2.1 million for 2023 and subsequent years combined.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity The following is a summary of the Company's authorized and issued common and preferred stock as of June 30, 2018 and December 31, 2017 : Outstanding as of Authorized Issued June 30, 2018 December 31, 2017 Common Stock, par value $0.001 per share 600,000,000 91,474,395 91,474,395 90,357,644 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 23 23 Common Stock In May 2018, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “Sales Agreement”) with an outside placement agent (the “Placement Agent”) to sell shares of its common stock with aggregate gross proceeds of up to $100.0 million , from time to time, through an “at-the-market” equity offering program under which the Placement Agent will act as sales agent. Under the Sales Agreement, the Company will set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limitation on the number of shares that may be sold in any one trading day and any minimum price below which sales may not be made. The Sales Agreement provides that the Placement Agent will be entitled to compensation for its services in an amount equal to up to 3.0% of the gross proceeds from the sales of shares sold through the Placement Agent under the Sales Agreement. The Company has no obligation to sell any shares under the Sales Agreement, and may at any time suspend solicitation and offers under the Sales Agreement. During the three and six months ended June 30, 2018 , the Company sold a total of 92,479 shares of common stock under the Sales Agreement. The sales were made at a weighted average price of $4.52 per share resulting in aggregate net proceeds of $410,000 . The Company may sell up to an additional $99.6 million in shares of its common stock under the Sales Agreement. The registration statement that registered with the SEC the shares that may be sold under the Sales Agreement expires on June 8, 2021. In June 2016, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “Prior Sales Agreement”) with the same placement agent. During the six months ended June 30, 2018 , the Company sold a total of 314,950 shares of common stock under the Prior Sales Agreement. The sales were made at a weighted average price of $5.07 per share resulting in aggregate net proceeds of $1.6 million . During the six months ended June 30, 2017, the Company sold a total of 2,917,725 shares of common stock under the Prior Sales Agreement. The sales were made at a weighted average price of $8.41 per share resulting in aggregate net proceeds of $24.1 million . The registration statement that registered with the SEC the shares sold under the Prior Sales Agreement expired on June 5, 2018, and no further sales will be made under the Prior Sales Agreement. The Company sold an aggregate of 3,911,104 shares of common stock under the Prior Sales Agreement resulting in aggregate net proceeds of $32.1 million . 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. 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 condensed 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 considerable judgment, including estimating stock price volatility and expected warrant life. The Company uses the Black-Scholes pricing model to value the registered warrants. 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. Changes in the fair market value of the warrants are reflected in the condensed consolidated statement of operations as change in fair value of common stock warrants. The following table summarizes the warrants outstanding as of June 30, 2018 and December 31, 2017 : As of June 30, 2018 As of December 31, 2017 Issued in Connection With: Exercise Price Expiration Date Number of Warrants Outstanding Common Stock Warrant Liability Number of Warrants Outstanding Common Stock Warrant Liability March 2013 financing $ 3.17 September 12, 2018 284,091 $ 228,665 284,091 $ 360,795 Total 284,091 $ 228,665 284,091 $ 360,795 Stock Options 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, restricted stock units and other stock-based awards or short-term cash incentive awards 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 June 30, 2018 , there were 8,000,000 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 June 30, 2018 , the Company had 2,914,316 shares of common stock available for future grant under the 2016 Incentive Plan, 1,568,381 shares underlying outstanding but unvested restricted stock units and options outstanding to purchase 3,159,706 shares of common stock under the 2016 Incentive Plan. The awards granted and available for future grant under the 2016 Incentive Plan generally vest over three years and have a maximum contractual term of ten years. The 2016 Incentive Plan terminates by its terms on March 9, 2026. The Amended and Restated 2007 Omnibus Incentive Plan (the "2007 Incentive Plan") was adopted on March 31, 2007 and terminated by its terms on March 31, 2017. At June 30, 2018 , the Company had 192,329 shares underlying outstanding but unvested restricted stock units and options outstanding to purchase 5,894,837 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 June 30, 2018 , the Company had options outstanding to purchase 191,438 shares of common stock under the VGX Equity Compensation Plan. The options under this plan were assumed in connection with the acquisition of VGX. The terms and conditions of the options outstanding under this plan remain unchanged.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss for the year by the weighted average number of common shares outstanding during the year. Diluted net loss per share is calculated in accordance with the treasury stock method 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 options, warrants or other securities and the presumed exercise of such securities are dilutive to net loss per share for the period, an adjustment to net loss used in the calculation is required to remove the change in fair value of such securities from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any, 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: Three Months Ended June 30, 2018 2017 Numerator Net loss $ (6,639,125 ) $ (9,479,116 ) Adjustment for decrease in fair value of warrant liability (259,971 ) — Numerator for use in diluted net loss per share $ (6,899,096 ) $ (9,479,116 ) Denominator Weighted average number of common shares outstanding 91,153,776 75,409,702 Effect of dilutive potential common shares 87,884 — Denominator for use in diluted net loss per share 91,241,660 75,409,702 Net loss per share, diluted $ (0.08 ) $ (0.13 ) Six Months Ended June 30, 2018 2017 Numerator Net loss $ (38,989,953 ) $ (32,565,023 ) Adjustment for decrease in fair value of warrant liability (132,130 ) — Numerator for use in diluted net loss per share $ (39,122,083 ) $ (32,565,023 ) Denominator Weighted average number of common shares outstanding 90,804,722 74,783,791 Effect of dilutive potential common shares 86,070 — Denominator for use in diluted net loss per share 90,890,792 74,783,791 Net loss per share, diluted $ (0.43 ) $ (0.44 ) The following table summarizes potential shares of common stock that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect for the three and six months ended June 30, 2018 and 2017 : Common Stock Equivalents 2018 2017 Options to purchase common stock 9,245,981 7,888,763 Warrants to purchase common stock — 284,091 Restricted stock units 1,760,710 1,335,744 Convertible preferred stock 8,456 8,456 Total 11,015,147 9,517,054

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company incurs stock-based compensation expense related to restricted stock units and stock options. The fair value of restricted stock is determined by the closing price of the Company's common stock reported on the Nasdaq Global Select Market on the date of grant. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of 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 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: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Risk-free interest rate 2.81% 1.97% 2.73% 2.22% Expected volatility 71% 73% 72% 73% Expected life in years 6.1 6.0 6.2 6.0 Dividend yield — — — — Total employee and director stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and six months ended June 30, 2018 was $ 2.4 million and $ 5.8 million , respectively, of which $ 1.4 million and $ 3.5 million , respectively, were included in research and development expenses, and $ 1.0 million and $ 2.3 million , respectively, were included in general and administrative expenses. Total employee and director stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and six months ended June 30, 2017 was $2.4 million and $7.7 million , respectively, of which $1.2 million and $3.5 million , respectively, were included in research and development expenses, and $1.2 million and $4.2 million , respectively, were included in general and administrative expenses. At June 30, 2018 , there was $7.7 million of total unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.0 years . The weighted average grant date fair value per share, calculated using the Black-Scholes option pricing model, was $3.00 and $ 2.85 for employee and director stock options granted during the three and six months ended June 30, 2018 , respectively, and $ 4.67 and $ 4.39 for employee and director stock options granted during the three and six months ended June 30, 2017 , respectively. At June 30, 2018 , there was $7.5 million of total unrecognized compensation expense related to unvested restricted stock units, which is expected to be recognized over a weighted-average period of 2.1 years. The weighted average grant date fair value per share was $ 4.57 and $4.31 for restricted stock units granted during the three and six months ended June 30, 2018 , respectively, and $7.14 and $6.70 for restricted stock units granted during the three and six months ended June 30, 2017 , respectively. The fair value of stock options granted to non-employees at the measurement dates were estimated using the Black-Scholes pricing model. Total stock-based compensation expense for stock options and restricted stock units granted to non-employees for the three and six months ended June 30, 2018 was $35,000 and $174,000 , respectively. Total stock-based compensation expense for stock options and restricted stock units granted to non-employees for the three and six months ended June 30, 2017 was $118,000 and $249,000 , respectively.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	Related Party Transactions GeneOne Life Sciences The Company owns 1,644,155 shares of common stock in GeneOne as of June 30, 2018 ; one of the Company's directors, Dr. David B. Weiner, acts as a consultant to GeneOne. In 2010, the Company entered into a collaboration and license agreement (the “GeneOne Agreement”) with GeneOne. Under the GeneOne Agreement, the Company granted GeneOne an exclusive license to the Company's SynCon ® universal influenza vaccine delivered with electroporation to be developed in certain countries in Asia (the “Product”). As consideration for the license granted to GeneOne, the Company received an upfront payment of $3.0 million , and is entitled to receive research support, annual license maintenance fees and royalties on net Product sales. The GeneOne Agreement also provides the Company with exclusive rights to supply devices for clinical and commercial purposes (including single use components) to GeneOne for use in the Product. The term of the GeneOne Agreement commenced upon execution and will extend on a country by country basis until the last to expire of all Royalty Periods for the territory (as such term is defined in the GeneOne Agreement) for any Product in that country, unless the GeneOne Agreement is terminated earlier in accordance with its provisions as a result of breach, by mutual agreement, or by GeneOne's right to terminate without cause upon prior written notice. In 2011, the Company entered into a collaborative development and license agreement (the “Hep Agreement”) with GeneOne. Under the Hep Agreement, as originally executed, the Company and GeneOne agreed to co-develop the Company’s SynCon ® therapeutic vaccines for hepatitis B and C infections (the “Hep Products”). Under the terms of the Hep Agreement, GeneOne will receive marketing rights for the Products in Asia, excluding Japan, and in return will fully fund IND-enabling and initial Phase 1 and 2 clinical studies with respect to the Hep Products. The Company will receive from GeneOne payments based on the achievement of clinical milestones and royalties based on sales of the Hep Products in the licensed territories, retaining all commercial rights to the Hep Products in all other territories. In 2013, the Company amended the Hep Agreement to grant back to the Company the SynCon ® therapeutic vaccines targeting hepatitis B, along with all associated rights, from the collaboration in return for certain remuneration including a percentage of license fees. In 2013, the Company further amended the Hep Agreement to in part provide exclusive patent rights to IL-28 technology for use with the Hep Products in Asia, excluding Japan. The Hep Agreement shall terminate upon the later of the expiration or abandonment of the last patent that is a component of the rights or 20 years after the effective date. In May 2015, the Company entered into a Collaborative Development Agreement with GeneOne to co-develop a DNA vaccine for MERS through Phase 1 clinical trials. Under the terms of the agreement, GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the MERS immunotherapy upon achievement of the last milestone event of completion of the Phase 1 safety and immunogenicity study. The collaborative research program shall terminate upon the completion of activities under the development plan, unless sooner terminated. In January 2016, the Company and GeneOne amended the Collaborative Development Agreement for MERS to expand the agreement to test and advance the Company's DNA-based vaccine for preventing and treating Zika virus. GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the Zika immunotherapy upon achievement of the last milestone event of the completion of the Phase 1 safety and immunogenicity study. All other agreement terms remain the same. 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 . Revenue recognized from GeneOne consisted of licensing and other fees from the influenza and Zika collaborations. For the three and six months ended June 30, 2018 , the Company recognized revenue from GeneOne of $ 32,000 and $ 150,000 , respectively, and $ 155,000 and $ 322,000 for the three and six months ended June 30, 2017 , respectively. Operating expenses recorded from transactions with GeneOne relate primarily to biologics manufacturing. Operating expenses from GeneOne for the three and six months ended June 30, 2018 were $1.1 million and $2.8 million , respectively, and $722,000 and $1.2 million for the three and six months ended June 30, 2017 , respectively. At June 30, 2018 and December 31, 2017 , the Company had an accounts receivable balance of $31,000 and $0 , respectively, and an accounts payable and accrued liability balance of $75,000 and $107,000 , respectively, related to GeneOne and its subsidiaries. At June 30, 2018 and December 31, 2017 , $322,000 and $331,000 , respectively, of prepayments made to GeneOne were classified as long-term other assets on the Company's condensed consolidated balance sheet. Plumbline Life Sciences, Inc. The Company owns 395,758 shares of common stock in Plumbline Life Sciences, Inc. ("PLS") as of June 30, 2018 ; one of the Company's directors, Dr. David B. Weiner, acts as a consultant to PLS. 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 three and six months ended June 30, 2018 , the Company recognized revenue from PLS of $28,000 and $58,000 , respectively, and $21,000 and $88,000 for the three and six months ended June 30, 2017 , respectively. At June 30, 2018 and December 31, 2017 , the Company had an accounts receivable balance of $429,000 and $370,000 , respectively, related to 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 under the 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 grant from the NIAID, awarded in 2015. Deferred grant funding recognized from Wistar and recorded as contra-research and development expense, which would have been classified as grant revenue in the prior year, is related to work performed by the Company on the research sub-contract agreements. For the three and six months ended June 30, 2018 , the Company recorded $455,000 and $2.2 million , respectively, as contra-research and development expense from Wistar. For the three and six months ended June 30, 2017 , the Company recognized revenue from Wistar of $1.1 million and $1.7 million , respectively. Research and development expenses recorded from Wistar relate primarily to the collaborative research agreements and sub-contract agreements related to the DARPA Ebola grant (see Note 14). Research and development expenses recorded from Wistar for the three and six months ended June 30, 2018 were $399,000 and $802,000 , respectively. Research and development expenses recorded from Wistar for the three and six months ended June 30, 2017 were $485,000 and $1.0 million , respectively. At June 30, 2018 and December 31, 2017 , the Company had an accounts receivable balance of $500,000 and $117,000 , respectively, and an accounts payable and accrued liability balance of $526,000 and $820,000 , respectively, related to Wistar.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies San Diego Leases In April 2013, the Company entered into a lease for office space located in San Diego, California (the "San Diego Lease"). The term of the San Diego Lease commenced on December 1, 2013. The initial term of the San Diego Lease is ten years, with a right to terminate on December 1, 2019, subject to specified conditions. In June 2015, the Company amended the San Diego Lease to increase the total leased space and occupy the entire building. The commencement of the amended San Diego Lease was in January 2016 and increased monthly lease payments to range from zero to $99,000 . The Company has capitalized $3.4 million of total tenant improvements within fixed assets on the condensed consolidated balance sheet related to the entire building 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 zero 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 . 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 condensed consolidated balance sheet, offset by a corresponding amount recorded in deferred rent. Plymouth Meeting Lease In March 2014, the Company entered into a lease (the "Lease") for office space located in Plymouth Meeting, Pennsylvania. The Company occupied the space in June 2014. The initial term of the Lease is 11.5 years. The base rent adjusts periodically throughout the term of the Lease, with monthly payments ranging from zero 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 and June 2016, the Company amended the Lease to increase the total leased space. The commencement of the amended Lease in July 2015 was in the first quarter of 2016 and increased monthly lease payments to range from zero to $80,000 . The commencement of the amended lease in June 2016 was October 1, 2017 and increased monthly lease payments to range from $75,000 to $90,000 . In June 2017, the Company entered into another amendment to the Lease to extend the lease term through December 31, 2029. In connection with this amendment, the Company paid 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 future monthly lease payments for all the Plymouth Meeting office space will range from zero to $179,000 . The Company has capitalized $2.6 million of tenant improvements to the Plymouth Meeting office within fixed assets on the condensed consolidated balance sheet, offset by a corresponding amount recorded in deferred rent. The Company's future minimum lease payments under all non-cancelable operating leases as of June 30, 2018 are as follows: Remainder of 2018 $ 1,642,000 2019 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 Thereafter 19,975,000 Total $ 37,295,000 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 us under these types of agreements have not had a material effect on the Company's business, consolidated results of operations or financial condition.

Collaborative Agreements

Collaborative Agreements	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Agreements	Collaborative Agreements ApolloBio Corporation On December 29, 2017, the Company entered into an Amended and Restated License and Collaboration Agreement (the "ApolloBio Agreement"), with ApolloBio Corporation ("ApolloBio"), with an effective date of March 20, 2018. Under the terms of the ApolloBio Agreement, the Company has granted to ApolloBio the exclusive right to develop and commercialize VGX-3100, its DNA immunotherapy product designed to treat pre-cancers caused by HPV, within the territories of China, Hong Kong, Macao, Taiwan, and may include Korea in the event that no patent covering VGX-3100 is issued in China within the three years following the effective date of the ApolloBio Agreement. Under the ApolloBio Agreement, the Company received proceeds of $19.4 million in March 2018 which comprised the up-front payment of $23.0 million less $2.2 million in foreign income taxes and $1.4 million in certain foreign non-income taxes. The foreign income taxes were recorded as a provision for income taxes and the foreign non-income taxes were recorded as a general and administrative expense, on the condensed consolidated statement of operations during the quarter ended March 31, 2018. The Company also incurred advisory fees of $960,000 in connection with receiving the up-front payment from ApolloBio. These fees were determined to be incremental costs of obtaining the contract. The Company applied the practical expedient that permits a company to expense incremental costs to obtain a contract when the expected amortization period is one year or less and recorded the fees in general and administrative expense during the quarter ended March 31, 2018. No additional advisory fees are due related to the ApolloBio Agreement. In addition to the upfront payment, the Company is entitled to receive up to an aggregate of $20.0 million , less required income, withholding or other taxes, upon the achievement of specified milestones related to the regulatory approval of VGX-3100 in the United States, China and Korea. In the event that VGX-3100 is approved for marketing, the Company will be entitled to receive royalty payments based on a tiered percentage of annual net sales, with such percentage being in the low- to mid-teens, subject to reduction in the event of generic competition in a particular territory. ApolloBio’s obligation to pay royalties will continue for 10 years after the first commercial sale in a particular territory or, if later, until the expiration of the last-to-expire patent covering the licensed products in the specified territory. The ApolloBio Agreement will continue in force until ApolloBio has no remaining royalty obligations. Either party may terminate the ApolloBio Agreement in the event the other party shall materially breach or default in the performance of its material obligations thereunder and such default continues for a specified period after written notice thereof. In addition, ApolloBio may terminate the ApolloBio Agreement at any time beginning one year after the effective date for any reason upon 90 days written notice to the Company The Company identified the promised goods or services at the effective date of the ApolloBio agreement and determined that the license to VGX-3100 in the territories represents a distinct performance obligation on a standalone basis. The Company has determined that during the three months ended June 30, 2018, the transfer of technology occurred and accordingly, the performance obligation was satisfied. The Company has recorded the gross up-front payment received from ApolloBio of $23.0 million as revenue under collaborative research and development arrangements on the condensed consolidated statement of operations during the three months ended June 30, 2018. 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, with the ability to sublicense those license rights. MedImmune made an upfront payment of $27.5 million to the Company in September 2015 and has agreed to make potential future development and regulatory event-based payments totaling up to $355 million and potential future commercial event-based payments totaling up to $345 million , in each case upon the achievement of specified milestones set forth in the license and collaboration agreement. 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, at MedImmune’s discretion, MedImmune and the Company will 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. These additional development services would be provided by the Company at an industry standard full-time-equivalent rate. Under the agreement, MedImmune can also request the Company to provide certain clinical manufacturing at an agreed upon price. The Company determined these options did not represent material rights at the inception of the agreement. As of December 31, 2017, the Company had recognized all of the $27.5 million upfront payment as revenue, as all identified material performance obligations had been met with respect to that payment. In December 2017, the Company received and recognized as revenue a $7.0 million milestone payment from MedImmune triggered by MedImmune’s initiation of the Phase 2 portion of an ongoing clinical trial under the agreement. During the three and six months ended June 30, 2018 , the Company recognized revenues of $1.4 million and $2.7 million , respectively, from MedImmune primarily for manufacturing services. As of June 30, 2018 , the Company had deferred revenue and accounts receivable related to MedImmune of $846,000 and $1.1 million , respectively. The deferred revenue relates to advanced payments made by the Company to a third-party biologics manufacturer for which MedImmune is obligated to pay. Prior to January 1, 2018 the Company accounted for the arrangement under Topic 605, which resulted in revenue of $14.2 million and $14.5 million from MedImmune for the three and six months ended June 30, 2017 , respectively. Roche In September 2013, the Company entered into a Collaborative, License, and Option Agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. (together, “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 which were completed during the quarter ended June 30, 2017, associated with the termination of the agreement. During the three and six months ended June 30, 2018 , the Company recognized no revenues from Roche. During the three and six months ended June 30, 2017 , the Company recognized revenues of $2.1 million and $6.1 million , respectively, from Roche. Coalition for Epidemic Preparedness Innovations On April 11, 2018, the Company announced that it has entered into agreements with the Coalition for Epidemic Preparedness Innovations ("CEPI"), pursuant to which the Company intends to develop vaccine candidates against Lassa fever and MERS. The goal of the collaboration between the Company and CEPI is to conduct research and development so that investigational stockpiles will be ready for clinical efficacy trial testing during potential disease outbreaks. The agreements with CEPI contemplate preclinical studies, as well as Phase 1 and Phase 2 clinical trials, occurring over the next few years. As part of the arrangement between the parties, CEPI has agreed to fund up to an aggregate of $56 million of costs over a five -year period for preclinical studies, as well as planned Phase 1 and Phase 2 clinical trials, to be conducted by the Company and collaborators, with funding from CEPI based on the achievement of identified milestones. The Company's vaccine candidate for Lassa fever will be known as INO-4500 and its vaccine candidate for MERS will be known as INO-4700. During the three and six months ended June 30, 2018 , the Company received funding of $834,000 related to the CEPI grant and recorded it as contra-research and development expense. As of June 30, 2018, the Company had a deferred grant funding balance related to the CEPI grant of $2.4 million recorded as deferred grant funding on the condensed consolidated balance sheet. 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 initial funding period covers a base award of $19.6 million and an option award of $24.6 million , which was exercised in September 2015. During the three and six months ended June 30, 2018 , the Company received funding of $496,000 and $872,000 , respectively, related to the DARPA grant and recorded it as contra-research and development expense. During the three and six months ended June 30, 2017 , the Company recognized revenues of $2.7 million and $7.8 million , respectively, from DARPA related to the grant. As of June 30, 2018, the Company has received total funding of $43.4 million related to the DARPA grant. As of June 30, 2018 , the Company had a deferred grant funding balance and accounts receivable balance of $130,000 and $569,000 , respectively, related to the DARPA grant.

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements of Inovio have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) as contained in the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") for interim financial information and with instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of June 30, 2018 , the condensed consolidated statements of operations and condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2018 and 2017 and the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 are unaudited, but include all adjustments (consisting of normal recurring adjustments) that the Company considers necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results of operations for the three and six months ended June 30, 2018 shown herein are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 , or for any other period. These unaudited financial statements, and notes thereto, should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2017 , included in the Company's Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 14, 2018. The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Company has evaluated subsequent events after the balance sheet date of June 30, 2018 through the date it filed these unaudited condensed consolidated financial statements with the SEC. These unaudited condensed consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc., VGX and GENEOS Therapeutics, Inc., and records a non-controlling interest for the 15% of VGX Animal Health, Inc., a subsidiary of VGX, that it did not own as of June 30, 2018 and December 31, 2017 . All intercompany accounts and transactions have been eliminated upon consolidation. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition (“Topic 605”), including most industry-specific revenue recognition guidance throughout the Industry Topics of the ASC. All periods prior to the adoption date of Topic 606 have not been restated to reflect the impact of the adoption of Topic 606, but continue to be accounted for and presented under Topic 605. The following paragraphs in this section describe the Company's revenue recognition accounting policies under Topic 606 upon adoption on January 1, 2018. Refer to Note 2 to the consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 for revenue recognition accounting policies under Topic 605. The Company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company will assess the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable, up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company will utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements. Under certain collaborative arrangements, the Company has been reimbursed for a portion of its research and development ("R&D") expenses, including costs of drug supplies. When these R&D services are performed under a reimbursement or cost sharing model with its collaboration partner, the Company records these reimbursements as a reduction of R&D expense in its condensed consolidated statements of operations.
Grants	Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605 , Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra-expense as opposed to revenue on the condensed consolidated statement of operations.
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 Pharmaceuticals, Inc. ("VGX") in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of June 30, 2018 and December 31, 2017, the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $5.3 million and $6.0 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 June 30, 2018 . 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.
Research and Development Expense	Research and Development Expenses The Company’s activities have largely consisted of research and development efforts related to developing electroporation delivery technologies and DNA immunotherapies and vaccines. Research and development expenses consist of expenses incurred in performing research and development activities including salaries and benefits, facilities and other overhead expenses, clinical trials, contract services and other outside expenses. Research and development expenses are charged to operations as they are incurred. These expenses result from the Company's independent research and development efforts as well as efforts associated with collaborations and licensing arrangements. The Company reviews and accrues clinical trial expense based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical trial costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however, a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to the Company's results of operations.
Recently Issued Accounting Standards	The recent accounting pronouncements below may have a significant effect on the Company's financial statements. Recent accounting pronouncements that are not anticipated to have an impact on or are unrelated to the Company's financial condition, results of operations, or related disclosures are not discussed. ASU No. 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. The impact of adoption of Topic 606 on the Company's existing agreements was as follows: Collaboration Agreement with MedImmune The Company has determined that no cumulative catch-up adjustment was required. 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 have been recorded as a contra-expense as opposed to revenue on the consolidated statement of operations. For the three and six months ended June 30, 2018 , $1.9 million and $4.1 million , respectively, would have been recorded as grant revenue but under the new guidance was instead recorded as a reduction to research and development expense. The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the three months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Three Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Three Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 24,385,852 $ — $ 24,385,852 Revenue under collaborative research and development arrangements with affiliated entities 60,319 — 60,319 Grants and miscellaneous revenue 1,459,684 (1,457,094 ) 2,590 Grants and miscellaneous revenue from affiliated entity 454,820 (454,820 ) — Total revenues 26,360,675 (1,911,914 ) 24,448,761 Operating expenses: Research and development 24,374,534 (1,911,914 ) 22,462,620 General and administrative 7,189,310 — 7,189,310 Total operating expenses $ 31,563,844 $ (1,911,914 ) $ 29,651,930 The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the six months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Six Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Six Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 25,674,898 $ — $ 25,674,898 Revenue under collaborative research and development arrangements with affiliated entities 208,327 — 208,327 Grants and miscellaneous revenue 2,016,674 (1,921,494 ) 95,180 Grants and miscellaneous revenue from affiliated entity 2,212,571 (2,212,571 ) — Total revenues 30,112,470 (4,134,065 ) 25,978,405 Operating expenses: Research and development 51,174,436 (4,134,065 ) 47,040,371 General and administrative 16,887,325 — 16,887,325 Total operating expenses $ 68,061,761 $ (4,134,065 ) $ 63,927,696 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 done under the previous 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 was effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods. The Company adopted this guidance on January 1, 2018 and recorded a $231,366 cumulative effect adjustment to reclassify the cumulative unrealized gain, net of tax effect, from its investment in Plumbline Life Sciences, Inc. ("PLS") from accumulated other comprehensive loss to accumulated deficit. After the adoption of ASU No. 2016-01, the Company recorded a (loss) gain on investment in affiliated entity related to PLS of $(639,000) and $343,000 on the condensed consolidated statement of operations for the three and six months ended June 30, 2018 , respectively. The cumulative effect of the changes made to the Company's condensed consolidated balance sheet as of January 1, 2018 for the adoption of ASU No. 2016-01 are included in the table below: Equity: Balance at December 31, 2017 Adjustments due to ASU No. 2016-01 Balance at January 1, 2018 Accumulated deficit $ (523,356,317 ) $ 231,366 $ (523,124,951 ) Accumulated other comprehensive loss $ (117,005 ) $ (231,366 ) $ (348,371 ) 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. The Company currently has three operating leases for its office and laboratory spaces in San Diego, California and Plymouth Meeting, Pennsylvania that it expects to be impacted by the new accounting standard that will result in the present values of the future lease payments being presented as right-to-use assets, with a corresponding lease liability at the date of adoption.

Impact of Recently Issued Acc21

Impact of Recently Issued Accounting Standards (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The cumulative effect of the changes made to the Company's condensed consolidated balance sheet as of January 1, 2018 for the adoption of ASU No. 2016-01 are included in the table below: Equity: Balance at December 31, 2017 Adjustments due to ASU No. 2016-01 Balance at January 1, 2018 Accumulated deficit $ (523,356,317 ) $ 231,366 $ (523,124,951 ) Accumulated other comprehensive loss $ (117,005 ) $ (231,366 ) $ (348,371 ) The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the three months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Three Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Three Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 24,385,852 $ — $ 24,385,852 Revenue under collaborative research and development arrangements with affiliated entities 60,319 — 60,319 Grants and miscellaneous revenue 1,459,684 (1,457,094 ) 2,590 Grants and miscellaneous revenue from affiliated entity 454,820 (454,820 ) — Total revenues 26,360,675 (1,911,914 ) 24,448,761 Operating expenses: Research and development 24,374,534 (1,911,914 ) 22,462,620 General and administrative 7,189,310 — 7,189,310 Total operating expenses $ 31,563,844 $ (1,911,914 ) $ 29,651,930 The following table illustrates the impact that adopting Topic 606 has had on the Company's reported results in the condensed consolidated statement of operations for the six months ended June 30, 2018 . Balances Without Adoption of Topic 606 for the Six Months Ended June 30, 2018 Impact of Adopting Topic 606 As Reported for the Six Months Ended June 30, 2018 Revenues: Revenue under collaborative research and development arrangements $ 25,674,898 $ — $ 25,674,898 Revenue under collaborative research and development arrangements with affiliated entities 208,327 — 208,327 Grants and miscellaneous revenue 2,016,674 (1,921,494 ) 95,180 Grants and miscellaneous revenue from affiliated entity 2,212,571 (2,212,571 ) — Total revenues 30,112,470 (4,134,065 ) 25,978,405 Operating expenses: Research and development 51,174,436 (4,134,065 ) 47,040,371 General and administrative 16,887,325 — 16,887,325 Total operating expenses $ 68,061,761 $ (4,134,065 ) $ 63,927,696

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset and Liability	The following table summarizes changes in the Company’s contract assets and liabilities for the six months ended June 30, 2018 : Balance at January 1, 2018 Additions Deductions Balance at June 30, 2018 Contract assets Accounts receivable from MedImmune $ 1,693,530 $ 2,541,901 $ (3,142,901 ) $ 1,092,530 Contract liabilities Deferred revenue - MedImmune 1,145,500 582,500 (882,000 ) 846,000 Deferred revenue - ApolloBio — 23,000,000 (23,000,000 ) — Deferred revenue - Other $ 271,894 $ — $ (125,251 ) $ 146,643

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of investments	The following is a summary of available-for-sale securities as of June 30, 2018 and December 31, 2017 : As of June 30, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 69,855,486 $ — $ (532,970 ) $ 69,322,516 US corporate debt securities Less than 2 11,252,264 — (65,416 ) 11,186,848 Investment in affiliated entity (PLS) --- — 2,667,805 — 2,667,805 Total investments $ 81,107,750 $ 2,667,805 $ (598,386 ) $ 83,177,169 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

Marketable Securities and Fai24

Marketable Securities and Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 : Fair Value Measurements at June 30, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 1,649,759 $ 1,649,759 $ — $ — Mutual funds 69,322,516 — 69,322,516 — US corporate debt securities 11,186,848 — 11,186,848 — Investment in affiliated entities 11,682,295 11,682,295 — — Total Assets $ 93,841,418 $ 13,332,054 $ 80,509,364 $ — Liabilities: Common stock warrants $ 228,665 $ — $ — 228,665 Total Liabilities $ 228,665 $ — $ — $ 228,665 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 — Investment 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
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 June 30, 2018 are presented below: Risk-free interest rate 2.32% Expected volatility 43% Expected life in years 0.2 Dividend yield —
Changes in fair value of the financial liabilities	The following table presents the changes in fair value of the Company’s Level 3 financial liabilities for the six months ended June 30, 2018 : Balance at December 31, 2017 $ 360,795 Decrease attributable to change in fair value of common stock warrants (132,130 ) Balance at June 30, 2018 $ 228,665

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of intangible assets by major asset class	The following sets forth the goodwill and intangible assets by major asset class: June 30, 2018 December 31, 2017 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 (5,711,876 ) 90,652 5,802,528 (5,681,673 ) 120,855 Licenses 8 – 17 1,323,761 (1,204,983 ) 118,778 1,323,761 (1,190,609 ) 133,152 CELLECTRA ® (b) 5 – 11 8,106,270 (7,465,649 ) 640,621 8,106,270 (7,252,108 ) 854,162 GHRH(b) 11 335,314 (287,788 ) 47,526 335,314 (271,948 ) 63,366 Bioject(c) 2 – 15 5,100,000 (1,735,556 ) 3,364,444 5,100,000 (1,405,556 ) 3,694,444 Other(d) 18 4,050,000 (3,018,750 ) 1,031,250 4,050,000 (2,906,250 ) 1,143,750 Total intangible assets 24,717,873 (19,424,602 ) 5,293,271 24,717,873 (18,708,144 ) 6,009,729 Total goodwill and intangible assets $ 35,231,244 $ (19,424,602 ) $ 15,806,642 $ 35,231,244 $ (18,708,144 ) $ 16,523,100 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Summary of common and preferred stock authorized, issued and outstanding	The following is a summary of the Company's authorized and issued common and preferred stock as of June 30, 2018 and December 31, 2017 : Outstanding as of Authorized Issued June 30, 2018 December 31, 2017 Common Stock, par value $0.001 per share 600,000,000 91,474,395 91,474,395 90,357,644 Series C Preferred Stock, par value $0.001 per share 1,091 1,091 23 23
Summary of warrants outstanding	The following table summarizes the warrants outstanding as of June 30, 2018 and December 31, 2017 : As of June 30, 2018 As of December 31, 2017 Issued in Connection With: Exercise Price Expiration Date Number of Warrants Outstanding Common Stock Warrant Liability Number of Warrants Outstanding Common Stock Warrant Liability March 2013 financing $ 3.17 September 12, 2018 284,091 $ 228,665 284,091 $ 360,795 Total 284,091 $ 228,665 284,091 $ 360,795

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Diluted Earnings Per Share	The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Three Months Ended June 30, 2018 2017 Numerator Net loss $ (6,639,125 ) $ (9,479,116 ) Adjustment for decrease in fair value of warrant liability (259,971 ) — Numerator for use in diluted net loss per share $ (6,899,096 ) $ (9,479,116 ) Denominator Weighted average number of common shares outstanding 91,153,776 75,409,702 Effect of dilutive potential common shares 87,884 — Denominator for use in diluted net loss per share 91,241,660 75,409,702 Net loss per share, diluted $ (0.08 ) $ (0.13 ) Six Months Ended June 30, 2018 2017 Numerator Net loss $ (38,989,953 ) $ (32,565,023 ) Adjustment for decrease in fair value of warrant liability (132,130 ) — Numerator for use in diluted net loss per share $ (39,122,083 ) $ (32,565,023 ) Denominator Weighted average number of common shares outstanding 90,804,722 74,783,791 Effect of dilutive potential common shares 86,070 — Denominator for use in diluted net loss per share 90,890,792 74,783,791 Net loss per share, diluted $ (0.43 ) $ (0.44 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes potential shares of common stock that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect for the three and six months ended June 30, 2018 and 2017 : Common Stock Equivalents 2018 2017 Options to purchase common stock 9,245,981 7,888,763 Warrants to purchase common stock — 284,091 Restricted stock units 1,760,710 1,335,744 Convertible preferred stock 8,456 8,456 Total 11,015,147 9,517,054

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of weighted average assumptions	The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Risk-free interest rate 2.81% 1.97% 2.73% 2.22% Expected volatility 71% 73% 72% 73% Expected life in years 6.1 6.0 6.2 6.0 Dividend yield — — — —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The Company's future minimum lease payments under all non-cancelable operating leases as of June 30, 2018 are as follows: Remainder of 2018 $ 1,642,000 2019 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 Thereafter 19,975,000 Total $ 37,295,000

Basis of Presentation (Details)

Basis of Presentation (Details)	Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Noncontrolling interest, ownership percentage by noncontrolling owners	15.00%	15.00%

Critical Accounting Policies (D

Critical Accounting Policies (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 5,293,271	$ 6,009,729
Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	18 years
Patents
Finite-Lived Intangible Assets [Line Items]
Useful life	17 years
Patents | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	8 years
Patents | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	17 years

Impact of Recently Issued Acc32

Impact of Recently Issued Accounting Standards - Narrative (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)lease	Dec. 31, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contra-research and development expense	$ 1,900,000	$ 4,100,000
Number of operating leases | lease		3
Accounting Standards Update 2016-01 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect			$ (231,366)
Accounting Standards Update 2016-01 | AOCI Attributable to Parent
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect			$ (231,366)
Plumbline Life Sciences
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain (loss) on investment in affiliated entities	$ (639,000)	$ 343,000

Impact of Recently Issued Acc33

Impact of Recently Issued Accounting Standards - Impact of Adopting ASU 2014-09 (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues [Abstract]
Total revenues	$ 24,448,761	$ 20,412,124	$ 25,978,405	$ 30,788,309
Operating Expenses [Abstract]
Research and development	22,462,620	23,878,751	47,040,371	48,421,255
General and administrative	7,189,310	6,169,106	16,887,325	13,936,695
Total operating expenses	29,651,930	30,047,857	63,927,696	62,357,950
Calculated under Revenue Guidance in Effect before Topic 606
Revenues [Abstract]
Total revenues	26,360,675		30,112,470
Operating Expenses [Abstract]
Research and development	24,374,534		51,174,436
General and administrative	7,189,310		16,887,325
Total operating expenses	31,563,844		68,061,761
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenues [Abstract]
Total revenues	(1,911,914)		(4,134,065)
Operating Expenses [Abstract]
Research and development	(1,911,914)		(4,134,065)
General and administrative	0		0
Total operating expenses	(1,911,914)		(4,134,065)
Revenue under collaborative research and development arrangements
Revenues [Abstract]
Total revenues	24,385,852	16,358,316	25,674,898	20,646,902
Revenue under collaborative research and development arrangements | Calculated under Revenue Guidance in Effect before Topic 606
Revenues [Abstract]
Total revenues	24,385,852		25,674,898
Revenue under collaborative research and development arrangements | Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenues [Abstract]
Total revenues	0		0
Revenue under collaborative research and development arrangements with affiliated entities
Revenues [Abstract]
Total revenues	60,319	176,879	208,327	410,209
Revenue under collaborative research and development arrangements with affiliated entities | Calculated under Revenue Guidance in Effect before Topic 606
Revenues [Abstract]
Total revenues	60,319		208,327
Revenue under collaborative research and development arrangements with affiliated entities | Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenues [Abstract]
Total revenues	0		0
Grants and miscellaneous revenue
Revenues [Abstract]
Total revenues	2,590	2,797,647	95,180	8,037,880
Grants and miscellaneous revenue | Calculated under Revenue Guidance in Effect before Topic 606
Revenues [Abstract]
Total revenues	1,459,684		2,016,674
Grants and miscellaneous revenue | Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenues [Abstract]
Total revenues	(1,457,094)		(1,921,494)
Grants and miscellaneous revenue from affiliated entity
Revenues [Abstract]
Total revenues	0	$ 1,079,282	0	$ 1,693,318
Grants and miscellaneous revenue from affiliated entity | Calculated under Revenue Guidance in Effect before Topic 606
Revenues [Abstract]
Total revenues	454,820		2,212,571
Grants and miscellaneous revenue from affiliated entity | Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenues [Abstract]
Total revenues	$ (454,820)		$ (2,212,571)

Impact of Recently Issued Acc34

Impact of Recently Issued Accounting Standards - Cumulative Effect of ASU 2016-01 (Details) - USD ($)	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Equity [Abstract]
Accumulated deficit	$ (562,114,904)	$ (523,124,951)	$ (523,356,317)
Accumulated other comprehensive loss	$ (598,386)	(348,371)	$ (117,005)
Accounting Standards Update 2016-01
Equity [Abstract]
Accumulated deficit		231,366
Accumulated other comprehensive loss		$ (231,366)

Revenue Recognition - Summary o

Revenue Recognition - Summary of Changes in Contract Assets and Liabilities (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Contract liabilities
Deductions	$ (354,000)	$ (1,000,000)
MedImmune
Contract assets
Balance at January 1, 2018		1,693,530
Additions		2,541,901
Deductions		(3,142,901)
Balance at June 30, 2018	1,092,530	1,092,530
Contract liabilities
Balance at January 1, 2018		1,145,500
Additions		582,500
Deductions		(882,000)
Balance at June 30, 2018	846,000	846,000
ApolloBio
Contract liabilities
Balance at January 1, 2018		0
Additions		23,000,000
Deductions		(23,000,000)
Balance at June 30, 2018	0	0
Other Counterparty
Contract liabilities
Balance at January 1, 2018		271,894
Additions		0
Deductions		(125,251)
Balance at June 30, 2018	$ 146,643	$ 146,643

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 24,448,761	$ 20,412,124	$ 25,978,405	$ 30,788,309
Revenue recognized from deferred revenue beginning balance	354,000		1,000,000
ApolloBio
Disaggregation of Revenue [Line Items]
Total revenues	23,000,000		23,000,000
Revenue recognized from deferred revenue beginning balance			23,000,000
MedImmune
Disaggregation of Revenue [Line Items]
Total revenues	1,400,000		2,700,000
Revenue recognized from deferred revenue beginning balance			882,000
GeneOne
Disaggregation of Revenue [Line Items]
Total revenues	32,000		150,000
Other Counterparty
Disaggregation of Revenue [Line Items]
Total revenues	$ 31,000		153,000
Revenue recognized from deferred revenue beginning balance			$ 125,251

Investments - Narrative (Detail

Investments - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)investment	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)investment	Jun. 30, 2017USD ($)
Investments, Debt and Equity Securities [Abstract]
Investment impairment charges | $	$ 121	$ 16	$ 374	$ 67
Number of securities in gross unrealized loss position | investment	28		28
Number of securities in gross unrealized loss position for longer than 12 months | investment	8		8
Total unrealized loss | $	$ 91		$ 91

Investments - Summary of Availa

Investments - Summary of Available-for-sale Securities (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2015
Debt Securities, Available-for-sale [Abstract]
Cost	$ 81,107,750
Gross Unrealized Losses	(598,386)
Gross Unrealized Gains	2,667,805	$ 2,325,079
Fair Market Value	83,177,169
Cost		0	$ 0
Gross Unrealized Gains		2,325,079
Gross Unrealized Losses		0
Fair Market Value		2,325,079
Cost		103,986,286
Gross Unrealized Gains		2,370,208
Gross Unrealized Losses		(392,571)
Fair Market Value		105,963,923
Mutual funds
Debt Securities, Available-for-sale [Abstract]
Cost	69,855,486	68,776,165
Gross Unrealized Gains	0	42,097
Gross Unrealized Losses	(532,970)	(252,373)
Fair Market Value	69,322,516	68,565,889
US corporate debt securities
Debt Securities, Available-for-sale [Abstract]
Cost	11,252,264	35,210,121
Gross Unrealized Gains	0	3,032
Gross Unrealized Losses	(65,416)	(140,198)
Fair Market Value	$ 11,186,848	$ 35,072,955
Maximum | US corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Contractual maturity, less than	2 years	2 years

Marketable Securities and Fai39

Marketable Securities and Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - Fair Value, Measurements, Recurring - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	$ 93,841,418	$ 124,876,806
Liabilities, fair value	228,665	360,795
Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	13,332,054	21,237,962
Liabilities, fair value	0	0
Using Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	80,509,364	103,638,844
Liabilities, fair value	0	0
Using 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	228,665	360,795
Money market funds
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	1,649,759	9,843,482
Money market funds | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	1,649,759	9,843,482
Money market funds | Using 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 | Using 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	69,322,516	68,565,889
Mutual funds | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Mutual funds | Using Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	69,322,516	68,565,889
Mutual funds | Using 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	11,186,848	35,072,955
US corporate debt securities | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
US corporate debt securities | Using Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	11,186,848	35,072,955
US corporate debt securities | Using Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Investment in affiliated entity
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	11,682,295	11,394,480
Investment in affiliated entity | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	11,682,295	11,394,480
Investment in affiliated entity | Using Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Assets, fair value	0	0
Investment in affiliated entity | Using 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	228,665	360,795
Common stock warrants | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value	0	0
Common stock warrants | Using 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 | Using Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Liabilities, fair value	$ 228,665	$ 360,795

Marketable Securities and Fai40

Marketable Securities and Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Jun. 30, 2015
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Carryover basis					$ 0	$ 0
Stock warrants exercised (shares)			0	0
Common stock warrants	$ 228,665		$ 228,665		$ 360,795
Decrease attributable to change in fair value of common stock warrants	$ (260,000)	$ 313,000	$ (132,000)	$ 196,000
Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Number of shares held in an affiliated entity (shares)	1,644,155		1,644,155
Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Investment owned (shares)	395,758		395,758

Marketable Securities and Fai41

Marketable Securities and Fair Value Measurements - Assumptions Used to Estimate Fair Value of Common Stock Warrants (Details)	Jun. 30, 2018$ / shares
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warranty liability	0.0232
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warranty liability	0.43
Expected Term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, expected life in years	2 months 12 days
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warranty liability	0

Marketable Securities and Fai42

Marketable Securities and Fair Value Measurements - Changes of Fair Value of Level 3 Financial Liabilities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Decrease attributable to change in fair value of common stock warrants	$ (260,000)	$ 313,000	$ (132,000)	$ 196,000
Using Significant Unobservable Inputs (Level 3)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2017			360,795
Decrease attributable to change in fair value of common stock warrants			(132,130)
Balance at June 30, 2018	$ 228,665		$ 228,665

Goodwill and Intangible Asset43

Goodwill and Intangible Assets - Schedule Goodwill and Intangible Assets (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Apr. 30, 2016	Jun. 30, 2009	Jan. 31, 2005
Indefinite lived:
Goodwill, gross	$ 10,513,371	$ 10,513,371
Goodwill, net book value	10,513,371	10,513,371
Definite lived:
Intangible assets, gross	24,717,873	24,717,873
Intangible assets, accumulated amortization	(19,424,602)	(18,708,144)
Intangible assets, net book value	5,293,271	6,009,729
Total goodwill and intangible assets, gross	35,231,244	35,231,244
Total goodwill and intangible assets, net book value	$ 15,806,642	16,523,100
Minimum
Definite lived:
Useful Life	2 years
Maximum
Definite lived:
Useful Life	18 years
Inovio AS
Indefinite lived:
Goodwill, net book value					$ 3,900,000
VGX
Indefinite lived:
Goodwill, net book value				$ 6,200,000
Bioject
Indefinite lived:
Goodwill, net book value			$ 400,000
Patents
Definite lived:
Useful Life	17 years
Intangible assets, gross	$ 5,802,528	5,802,528
Intangible assets, accumulated amortization	(5,711,876)	(5,681,673)
Intangible assets, net book value	$ 90,652	120,855
Patents | Minimum
Definite lived:
Useful Life	8 years
Patents | Maximum
Definite lived:
Useful Life	17 years
Licenses
Definite lived:
Intangible assets, gross	$ 1,323,761	1,323,761
Intangible assets, accumulated amortization	(1,204,983)	(1,190,609)
Intangible assets, net book value	$ 118,778	133,152
Licenses | Minimum
Definite lived:
Useful Life	8 years
Licenses | Maximum
Definite lived:
Useful Life	17 years
CELLECTRA
Definite lived:
Intangible assets, gross	$ 8,106,270	8,106,270
Intangible assets, accumulated amortization	(7,465,649)	(7,252,108)
Intangible assets, net book value	$ 640,621	854,162
CELLECTRA | Minimum
Definite lived:
Useful Life	5 years
CELLECTRA | Maximum
Definite lived:
Useful Life	11 years
GHRH
Definite lived:
Useful Life	11 years
Intangible assets, gross	$ 335,314	335,314
Intangible assets, accumulated amortization	(287,788)	(271,948)
Intangible assets, net book value	47,526	63,366
Bioject
Definite lived:
Intangible assets, gross	5,100,000	5,100,000
Intangible assets, accumulated amortization	(1,735,556)	(1,405,556)
Intangible assets, net book value	$ 3,364,444	3,694,444
Bioject | Minimum
Definite lived:
Useful Life	2 years
Bioject | Maximum
Definite lived:
Useful Life	15 years
Other
Definite lived:
Useful Life	18 years
Intangible assets, gross	$ 4,050,000	4,050,000
Intangible assets, accumulated amortization	(3,018,750)	(2,906,250)
Intangible assets, net book value	$ 1,031,250	$ 1,143,750

Goodwill and Intangible Asset44

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill and Intangible Assets (Textual) [Abstract]
Aggregate amortization expense on intangible assets	$ 312,000	$ 404,000	$ 716,458	$ 810,539
Estimated aggregate amortization expense for remainder of 2018	533,000		533,000
Estimated aggregate amortization expense for 2019	1,100,000		1,100,000
Estimated aggregate amortization expense for 2020	547,000		547,000
Estimated aggregate amortization expense for 2021	520,000		520,000
Estimated aggregate amortization expense for 2022	493,000		493,000
Estimated aggregate amortization expense for 2023 and the years after	$ 2,100,000		$ 2,100,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Authorized and Issued Common and Preferred Stock (Details) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Summary of common and preferred stock authorized, issued and outstanding
Common stock, par value (dollars per share)	$ 0.001	$ 0.001
Common stock, shares, authorized (shares)	600,000,000
Common stock, shares, issued (shares)	91,474,395
Common stock, shares, outstanding (shares)	91,474,395	90,357,644
Series C Preferred Stock
Summary of common and preferred stock authorized, issued and outstanding
Preferred stock, par value (dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (shares)	1,091
Preferred stock, shares issued (shares)	1,091
Preferred stock, shares outstanding (shares)	23	23

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($)	Jun. 05, 2018	Jan. 01, 2018	Jul. 25, 2017	May 31, 2018	Jun. 30, 2018	Jun. 30, 2017	May 13, 2016
Class of Stock [Line Items]
Proceeds					$ 1,973,401	$ 24,060,196
Award vesting period					3 years
Maximum contractual term					10 years
VGX Equity Compensation Plan
Class of Stock [Line Items]
Options outstanding (shares)					191,438
Stock and Cash Based Incentive Plan
Class of Stock [Line Items]
Common stock, other shares, outstanding (shares)					5,894,837
Award vesting period					3 years
Maximum contractual term					10 years
Number of shares of unvested restricted stock units (shares)					192,329
2016 Incentive Plan
Class of Stock [Line Items]
Number of shares authorized (shares)					8,000,000		6,000,000
Number of potential shares authorized for issuance under share based compensation plan (shares)							2,000,000
Increase in number of shares authorized, share-based compensation arrangement (shares)		2,000,000
Number of shares available for grant (shares)					2,914,316
Number of shares of unvested restricted stock units and options outstanding (shares)					1,568,381
Common stock, other shares, outstanding (shares)					3,159,706
Common Stock | Sales Agreement
Class of Stock [Line Items]
Maximum authorized amount				$ 100,000,000
Agent fee				3.00%
Aggregate number of shares issued (shares)					92,479
Common shares sold (dollars per share)					$ 4.52
Aggregate proceeds					$ 410,000
Remaining authorized amount					$ 99,600,000
Common Stock | ATM Sales Agreement
Class of Stock [Line Items]
Aggregate number of shares issued (shares)	3,911,104				314,950	2,917,725
Common shares sold (dollars per share)					$ 5.07	$ 8.41
Aggregate proceeds	$ 32,100,000				$ 1,600,000	$ 24,100,000
Common Stock | Public Offering, Not IPO
Class of Stock [Line Items]
Common shares sold (dollars per share)			$ 6
Number of common shares sold (shares)			12,500,000
Proceeds			$ 70,100,000

Stockholders' Equity - Summar47

Stockholders' Equity - Summary of Warrants Outstanding (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Summary of warrants outstanding
Number of Warrants Outstanding (shares)	284,091	284,091
Common Stock Warrant Liability	$ 228,665	$ 360,795
March 2013 financing
Summary of warrants outstanding
Exercise price (dollars per share)	$ 3.17
Expiration Date	Sep. 12, 2018
Number of Warrants Outstanding (shares)	284,091	284,091
Common Stock Warrant Liability	$ 228,665	$ 360,795

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Diluted Loss Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator
Net loss	$ (6,639,125)	$ (9,479,116)	$ (38,989,953)	$ (32,565,023)
Adjustment for decrease in fair value of warrant liability	(259,971)	0	(132,130)	0
Numerator for use in diluted net loss per share	$ (6,899,096)	$ (9,479,116)	$ (39,122,083)	$ (32,565,023)
Denominator
Weighted average number of common shares outstanding (shares)	91,153,776	75,409,702	90,804,722	74,783,791
Effect of dilutive potential common shares (shares)	87,884	0	86,070	0
Denominator for use in diluted net loss per share (shares)	91,241,660	75,409,702	90,890,792	74,783,791
Net loss per share, diluted (dollars per share)	$ (0.08)	$ (0.13)	$ (0.43)	$ (0.44)

Net Loss Per Share - Schedule49

Net Loss Per Share - Schedule of Anti-Dilutive Securities (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (shares)	11,015,147	9,517,054	11,015,147	9,517,054
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (shares)	9,245,981	7,888,763	9,245,981	7,888,763
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (shares)	0	284,091	0	284,091
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (shares)	1,760,710	1,335,744	1,760,710	1,335,744
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded (shares)	8,456	8,456	8,456	8,456

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation			$ 6,164,958	$ 7,937,473
Total unrecognized compensation cost related to unvested stock options	$ 7,700,000		$ 7,700,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized			2 years
Weighted average grant date fair value (dollars per share)	$ 3	$ 4.67	$ 2.85	$ 4.39
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested stock options	$ 7,500,000		$ 7,500,000
Period over which total unrecognized compensation cost related to unvested stock options will be recognized			2 years 1 month
Weighted average grant date fair value, restricted stock units (dollars per share)	$ 4.57	$ 7.14	$ 4.31	$ 6.70
Employees and Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,400,000	$ 2,400,000	$ 5,800,000	$ 7,700,000
Employees and Directors | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.81%	1.97%	2.73%	2.22%
Expected volatility	71.00%	73.00%	72.00%	73.00%
Expected life in years	6 years 1 month	6 years	6 years 2 months	6 years
Dividend yield	0.00%	0.00%	0.00%	0.00%
Non Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 35,000	$ 118,000	$ 174,000	$ 249,000
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	1,400,000	1,200,000	3,500,000	3,500,000
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 1,000,000	$ 1,200,000	$ 2,300,000	$ 4,200,000
Additional Paid-in Capital | Accounting Standards Update 2016-09
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cumulative effect					$ (312,000)
Retained Earnings | Accounting Standards Update 2016-09
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cumulative effect					$ 312,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended					3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Jan. 31, 2016	May 31, 2015	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2013	Dec. 31, 2010
Related-Party Transactions (Textual) [Abstract]
Long-term other assets	$ 2,639,354					$ 2,724,376		$ 2,724,376
Contra-research and development expense						$ 1,900,000		$ 4,100,000
GeneOne Life Sciences
Related-Party Transactions (Textual) [Abstract]
Investment owned (shares)						1,644,155		1,644,155
Payment received for license granted											$ 3,000,000
Term										20 years
Milestone-based ownership target				35.00%	35.00%
Proceeds from sale of intangible assets	1,000,000
Revenue from related parties						$ 32,000	$ 155,000	$ 150,000	$ 322,000
Operating expenses related to affiliated entity						1,100,000	722,000	2,800,000	1,200,000
Accounts receivable	0					31,000		31,000
Accounts payable and accrued liability	107,000					75,000		75,000
Long-term other assets	331,000					322,000		322,000
Director
Related-Party Transactions (Textual) [Abstract]
Term			5 years
Revenue from related parties							1,100,000		1,700,000
Operating expenses related to affiliated entity						399,000	485,000	802,000	1,000,000
Accounts receivable	117,000					500,000		500,000
Expenses to reimburse			$ 3,100,000
Award		$ 6,100,000
Contra-research and development expense						455,000		2,200,000
Accounts payable/accrued liabilities	820,000					526,000		526,000
Plumbline Life Sciences
Related-Party Transactions (Textual) [Abstract]
Revenue from related parties						28,000	$ 21,000	58,000	$ 88,000
Accounts receivable	$ 370,000					$ 429,000		$ 429,000
Plumbline Life Sciences | Available-for-sale Securities
Related-Party Transactions (Textual) [Abstract]
Investment owned (shares)						395,758		395,758

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) ft² in Thousands	Oct. 01, 2017USD ($)	Jun. 30, 2017USD ($)	Oct. 31, 2016USD ($)ft²	Jan. 31, 2016USD ($)	Mar. 31, 2014USD ($)	Apr. 30, 2013	Mar. 31, 2016USD ($)	Jun. 30, 2018USD ($)
San Diego Office
Loss Contingencies [Line Items]
Initial lease term						10 years
Tenant improvements								$ 3,400,000
San Diego, California
Loss Contingencies [Line Items]
Initial lease term			10 years
Tenant improvements								2,300,000
Area leased (in square feet) | ft²			51
Adjustable rent period			2 years
Security deposit			$ 95,000
Plymouth Meeting, Pennsylvania
Loss Contingencies [Line Items]
Initial lease term					11 years 6 months
Tenant improvements								2,600,000
Security deposit		$ 75,000			$ 49,000
Minimum | San Diego Office
Loss Contingencies [Line Items]
Increase to monthly payment				$ 0
Minimum | San Diego, California
Loss Contingencies [Line Items]
Monthly payments under the lease			0
Minimum | Plymouth Meeting, Pennsylvania
Loss Contingencies [Line Items]
Monthly payments under the lease	$ 75,000				0		$ 0
Additional amendment, periodic payments		173,000						0
Maximum | San Diego Office
Loss Contingencies [Line Items]
Increase to monthly payment				$ 99,000
Maximum | San Diego, California
Loss Contingencies [Line Items]
Monthly payments under the lease			$ 95,000
Maximum | Plymouth Meeting, Pennsylvania
Loss Contingencies [Line Items]
Monthly payments under the lease	$ 90,000				$ 58,000		$ 80,000
Additional amendment, periodic payments		$ 179,000						$ 179,000

Commitments and Contingencies53

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Details) $ in Thousands	Jun. 30, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2018	$ 1,642
2,019	3,756
2,020	3,891
2,021	3,979
2,022	4,052
Thereafter	19,975
Total	$ 37,295

Collaborative Agreements (Detai

Collaborative Agreements (Details)	Apr. 11, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 29, 2017	Aug. 07, 2015product	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Feb. 28, 2017USD ($)	Sep. 30, 2015USD ($)	Apr. 30, 2015USD ($)	Sep. 30, 2013USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized											$ 354,000		$ 1,000,000
Deferred grant funding		$ 0				$ 0					2,620,985		2,620,985
ApolloBio
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue		0				0					0		0
Revenue recognized													23,000,000
MedImmune
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue		1,145,500				1,145,500					846,000		846,000
Accounts receivable		1,693,530				1,693,530					1,092,530		1,092,530
Revenue recognized													882,000
Collaborative Arrangement, Product | ApolloBio
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Territory expansion option period			3 years
Proceeds received in upfront payment					$ 19,400,000
Upfront payment received					23,000,000						23,000,000
Advisory fees					960,000
Additional revenue to be achieved													$ 20,000,000
Royalty period													10 years
Period from effective date for termination													1 year
Number of days written notice defore termination													90 days
Collaborative Arrangement, Product | MedImmune
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received		$ 27,500,000						$ 27,500,000
Anticipated development and regulatory event based payment receivable milestones													$ 355,000,000
Anticipated commercial event based payment receivable milestones													345,000,000
Number of additional products to be developed | product				2
Milestone payment, revenue recognized						$ 7,000,000
Revenue under collaborative research and development arrangements											1,400,000	$ 14,200,000	2,700,000	$ 14,500,000
Deferred revenue											846,000		846,000
Accounts receivable											1,100,000		1,100,000
Collaborative Arrangement, Product | Roche
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Full payment							$ 8,500,000
Collaborative Arrangement, Product | Hoffman-La Roche
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received										$ 10,000,000
Revenue recognized											0	2,100,000	0	6,100,000
Collaborative Arrangement, Product | Coalition for Epidemic Preparedness Innovations
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement, funding to be received	$ 56,000,000
Collaborative agreement, period to receive funding for research and development	5 years
Funding received for research and development											834,000		834,000
Deferred grant funding											2,400,000		2,400,000
Collaborative Arrangement, Product | Defense Advanced Research Projects Agency (DARPA)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable											569,000		569,000
Funding received for research and development											496,000	$ 2,700,000	872,000	$ 7,800,000
Deferred grant funding											130,000		130,000
Base award									$ 19,600,000
Option award									$ 24,600,000
Total funding received for research and development											$ 43,400,000		$ 43,400,000
Foreign Tax Authority | Collaborative Arrangement, Product | ApolloBio
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Foreign corporate income taxes reducing upfront payment					2,200,000
Foreign non-corporate income taxes reducing upfront payment					$ 1,400,000