Alaunos Therapeutics (TCRT) 10-Q 7 May 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 24, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Document Quarterly Report	true
Document Transition Report	false
Entity Registrant Name	ZIOPHARM ONCOLOGY INC
Entity Central Index Key	0001107421
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Trading Symbol	ZIOP
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		214,286,337
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-33038
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-1475642
Entity Address, Address Line One	One First Avenue
Entity Address, Address Line Two	Parris Building 34
Entity Address, Address Line Three	Navy Yard Plaza
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02129
City Area Code	617
Local Phone Number	259-1970

BALANCE SHEETS

BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 171,002	$ 79,741
Receivables	782	3,330
Prepaid expenses and other current assets	19,836	22,421
Total current assets	191,620	105,492
Property and equipment, net	3,784	1,110
Right of use asset	2,079	2,272
Deposits	130	130
Other non-current assets	666	110
Total assets	198,279	109,114
Current liabilities:
Accounts payable	396	906
Accrued expenses	15,355	10,846
Lease liability - current portion	828	774
Total current liabilities	16,579	12,526
Lease liability - noncurrent portion	1,363	1,578
Total liabilities	17,942	14,104
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized; 214,286,337 and 181,803,320 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	214	182
Additional paid-in capital	882,541	778,953
Accumulated deficit	(702,418)	(684,125)
Total stockholders' equity	180,337	95,010
Total liabilities and stockholders' equity	$ 198,279	$ 109,114

BALANCE SHEETS (Parenthetical)

BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	214,286,337	181,803,320
Common stock, shares outstanding	214,286,337	181,803,320

STATEMENTS OF OPERATIONS

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 12,706	$ 9,476
General and administrative	5,954	4,145
Total operating expenses	18,660	13,621
Loss from operations	(18,660)	(13,621)
Other income, net	367	187
Net loss	$ (18,293)	$ (13,434)
Basic and diluted net loss per share	$ (0.09)	$ (0.08)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	199,814,768	160,640,859

STATEMENTS OF CHANGES IN STOCKH

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ 85,564	$ 161	$ 651,732	$ (566,329)
Balance (in shares) at Dec. 31, 2018		161,066,136
Stock-based compensation	1,456		1,456
Issuance of restricted common stock		$ 1	999	1,000
Issuance of restricted common stock (in shares)		1,393,536
Cancelled restricted common stock (in shares)		(7,333)
Repurchase of restricted common stock	(370)		(370)
Repurchase of restricted common stock (Shares)		(165,178)
Net loss	(13,434)			(13,434)
Balance at Mar. 31, 2019	74,216	$ 162	653,817	(579,763)
Balance (in shares) at Mar. 31, 2019		162,287,161
Balance at Dec. 31, 2019	95,010	$ 182	778,953	(684,125)
Balance (in shares) at Dec. 31, 2019		181,803,320
Stock-based compensation	1,940		1,940
Exercise of employee stock options	$ 4		4
Exercise of employee stock options (in shares)	2,333	2,333
Issuance of restricted common stock		$ 1	(1)
Issuance of restricted common stock (in shares)		555,900
Issuance of common stock in connection with a public offering, net	$ 88,661	$ 29	88,632
Issuance of common stock in connection with a public offering, net (in shares)		29,110,111
Issuance of common stock in connection with at the market offering, net	13,015	$ 2	13,013
Issuance of common stock in connection with at the market offering, net (in shares)		2,814,673
Net loss	(18,293)			(18,293)
Balance at Mar. 31, 2020	$ 180,337	$ 214	$ 882,541	$ (702,418)
Balance (in shares) at Mar. 31, 2020		214,286,337

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Market Offering [Member]
Issuance of common stock, commissions and expenses	$ 0.4
Public Offering [Member]
Issuance of common stock, commissions and expenses	$ 5.9

STATEMENTS OF CASH FLOWS

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (18,293)	$ (13,434)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	142	140
Stock-based compensation	1,940	1,456
Bonus paid in common stock, net		630
(Increase) decrease in:
Receivables	2,548	1,009
Prepaid expenses and other current assets	2,585	(1,058)
Right of use asset	193	(1,589)
Deposits		(2)
Other noncurrent assets	(556)	2,817
Increase (decrease) in:
Accounts payable	(510)	152
Accrued expenses	2,206	(1,929)
Deferred rent		17
Lease liabilities	(161)	1,559
Net cash used in operating activities	(9,906)	(10,232)
Cash flows from investing activities:
Purchases of property and equipment	(513)	(10)
Net cash used in investing activities	(513)	(10)
Cash flows from financing activities:
Proceeds from exercise of stock options	4
Issuance of common stock in connection with a public offering, net	88,661
Issuance of common stock in connection with at the market offerings, net	13,015
Net cash provided by financing activities	101,680
Net increase (decrease) in cash and cash equivalents, and restricted cash	91,261	(10,242)
Cash and cash equivalents, and restricted cash, beginning of period	79,741	61,729
Cash and cash equivalents, and restricted cash, end of period	171,002	51,487
Supplementary disclosure of cash flow information:
Compensation paid in restricted stock, gross		$ 1,000
Property and equipment included in accrued expenses	$ 2,303

Business

Business	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Business	1. Business Overview ZIOPHARM Oncology, Inc., which is referred to herein as “ZIOPHARM,” or the “Company,” is a biopharmaceutical company seeking to develop, acquire, and commercialize, on its own or with partners, a diverse portfolio of immuno-oncology therapies. The Company’s operations to date have consisted primarily of conducting research and development and raising capital to fund those efforts. The Company’s fiscal year ends on December 31. The Company has operated at a loss since its inception in 2003 and has no recurring revenues from operations. The Company anticipates that losses will continue for the foreseeable future. As of March 31, 2020, the Company had approximately $171.0 million of cash and cash equivalents and the Company’s accumulated deficit was approximately $702.4 million. Given its current development plans, the Company anticipates cash resources will be sufficient to fund operations into the mid-2022. Basis of Presentation The accompanying unaudited interim financial statements have been prepared in accordance with the instructions to Form 10-Q It is management’s opinion that the accompanying unaudited interim financial statements reflect all adjustments (which are normal and recurring) that are necessary for a fair statement of the results for the interim periods. The unaudited interim financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K Annual Report . The year-end The results disclosed in the statements of operations for the three months ended March 31, 2020 are not necessarily indicative of the results to be expected for the full fiscal year. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Although the Company regularly assesses these estimates, actual results could differ from those estimates. Changes in estimates are recorded in the period in which they become known. The Company’s most significant estimates and judgments used in the preparation of its financial statements are: • Clinical trial expenses; • Collaboration agreements; • Fair value measurements of stock-based compensation; and • Income taxes Impact of COVID-19 Pandemic With the global spread of the ongoing COVID-19 pandemic in the first quarter of 2020, the Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its business. The extent to which the COVID-19 pandemic impacts the Company’s business, clinical development and regulatory efforts and the value of its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements, and the effectiveness of actions taken globally to contain and treat the disease. The global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the pandemic could have a material adverse effect on the Company’s business, financial condition, results of operations and growth prospects. In addition, the Company is subject to other challenges and risks specific to its business and its ability to execute on its business plan and strategy, as well as risks and uncertainties common to companies in the biopharmaceutical industry with development and commercial operations, including, without limitation, risks and uncertainties associated with: obtaining regulatory approval of its product candidates; delays or problems in obtaining clinical supply, loss of single source suppliers or failure to comply with manufacturing regulations; identifying, acquiring or in-licensing additional products or product candidates; biopharmaceutical product development and the inherent uncertainty of clinical success; and the challenges of complying with applicable regulatory requirements. In addition, to the extent the ongoing COVID-19 pandemic adversely affects its business and results of operations, it may also have the effect of heightening many of the other risks and uncertainties discussed above. Subsequent Events The Company evaluated all events and transactions that occurred after the balance sheet date through the date of this filing. During this period, the Company did not have any material subsequent events that impacted its financial statements or disclosures.

Financings

Financings	3 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Financings	2. Financings February 2020 Public Offering On February 5, 2020, the Company entered into an underwriting agreement with Jefferies, as representative of the several underwriters named therein, relating to the issuance and sale of 27,826,086 shares of its common stock. The price to the public in the offering was $3.25 per share, and the underwriters agreed to purchase the shares from the Company pursuant to the underwriting agreement at a purchase price of $3.055 per share. Under the terms of the underwriting agreement, the Company also granted the underwriters an option, exercisable for 30 days, to purchase up to an additional 4,173,912 shares of common stock at a purchase price of $3.055 per share. The offering was made pursuant to the Company’s effective registration statement on Form S-3ASR 333-232283) On March 10, 2020, the underwriters exercised their option to purchase an additional 1,284,025 shares. The net proceeds were approximately $3.9 million after deducting underwriting discounts and offering expenses paid by the Company. At-the-Market During the three months ended March 31, 2020, the Company sold an aggregate of 2,814,673 shares of its common stock. The offering was made pursuant to the Company’s effective registration statement on Form S-3ASR 333-232283)

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies The Company’s significant accounting policies were identified in the Company’s Annual Report. There have been no material changes in those policies since the filing of its Annual Report except as noted below. New Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement 2018-03.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The Company accounts for its financial assets and liabilities using fair value measurements. The authoritative accounting guidance defines fair value, establishes a framework for measuring fair value under generally accepted accounting principles and enhances disclosures about fair value measurements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy is based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value as follows: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019 were as follows: ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 74,343 $ 74,343 $ — $ — ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 68,031 $ 68,031 $ — $ —

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share	5. Net Loss per Share Basic net loss per share is computed by dividing net loss by the weighted average number of shares of common stock outstanding for the period. The Company’s potentially dilutive shares, which include outstanding common stock options, unvested restricted stock and preferred stock, have not been included in the computation of diluted net loss per share for any of the periods presented as the result would be anti-dilutive. Such potentially dilutive shares of common stock at March 31, 2020 and 2019 consisted of the following: March 31, 2020 2019 Stock options 6,676,879 5,416,085 Inducement stock options 1,030,000 500,000 Unvested restricted stock 1,495,536 1,621,845 Warrants 22,272,727 18,939,394 31,475,142 26,477,324

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies License Agreements Exclusive License Agreement with PGEN Therapeutics On October 5, 2018, the Company entered into the License Agreement, with PGEN Therapeutics, or PGEN, a wholly owned subsidiary of Precigen Inc., or Precigen, which was formerly known as Intrexon Corporation. As between the Company and PGEN, the terms of the License Agreement replace and supersede the terms of: (a) that certain Exclusive Channel Partner Agreement by and between the Company and Precigen, dated January 6, 2011, as amended by the First Amendment to Exclusive Channel Partner Agreement effective September 13, 2011, the Second Amendment to the Exclusive Channel Partner Agreement effective March 27, 2015, and the Third Amendment to Exclusive Channel Partner Agreement effective June 29, 2016, which was subsequently assigned by Precigen to PGEN; (b) certain rights and obligations pursuant to that certain License and Collaboration Agreement effective March 27, 2015 between the Company, Precigen and ARES TRADING Trading S.A., or Ares Trading, a subsidiary of Merck KGaA, or Merck, as assigned by Precigen to PGEN, or the Ares Trading Agreement; (c) that certain License Agreement between the Company, Precigen, and MD Anderson, with an effective date of January 13, 2015, or the MD Anderson License, which was subsequently assigned by Precigen and assumed by PGEN effective as of January 1, 2018; and (d) that certain Research and Development Agreement between the Company, Precigen and MD Anderson with an effective date of August 17, 2015, or the Research and Development Agreement, and any amendments or statements of work thereto. Pursuant to the terms of the License Agreement, PGEN has granted the Company exclusive, worldwide rights to research, develop and commercialize (i) products utilizing PGEN’s RheoSwitch ® ® IL-12 T-cell sub-licensable Sleeping Beauty The Company is solely responsible for all aspects of the research, development and commercialization of the exclusively licensed products for the treatment of cancer. The Company is required to use commercially reasonable efforts to develop and commercialize IL-12 two-year PGEN has also granted the Company an exclusive, worldwide, royalty-bearing, sub-licensable IL-12 IL-12 In consideration of the licenses and other rights granted by PGEN, the Company will pay PGEN an annual license fee of $0.1 million. The Company paid $0.1 million during the three months ending March 31, 2020. The Company did not make any annual license payments for the three months ended March 31, 2019. The Company will also make milestone payments totaling up to an for each exclusively licensed program upon the initiation of later stage clinical trials and upon the approval of exclusively licensed products in various jurisdictions. In addition, the Company will pay PGEN tiered royalties ranging from low-single IL-12 low-single mid-single The Company is responsible for all development costs associated with each of the licensed products, other than Gorilla IL-12 IL-12 PGEN will pay the Company royalties ranging from low-single mid-single For License Agreement—The University of Texas MD Anderson Cancer Center On January 13, 2015, the Company, together with Precigen, entered into the MD Anderson License with MD Anderson (which Precigen subsequently assigned to PGEN). Pursuant to the MD Anderson License, the Company, together with Precigen, holds an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson including technologies relating to novel CAR T-cell non-viral The term of the MD Anderson License expires on the last to occur of (a) the expiration of all patents licensed thereunder, or (b) the twentieth anniversary of the date of the MD Anderson License; provided, however, that following the expiration of the term of the MD Anderson License, the Company, together with PGEN, shall then have a fully-paid up, royalty free, perpetual, irrevocable and sublicensable license to use the licensed intellectual property thereunder. After ten years from the date of the MD Anderson License and subject to a 90-day cure period, MD Anderson will have the right to convert the MD Anderson License into a non-exclusive license if ZIOPHARM and PGEN are not using commercially reasonable efforts to commercialize the licensed intellectual property on a case-by-case basis. After five years from the date of the MD Anderson License and subject to a 180-day cure period, MD Anderson will have the right to terminate the MD Anderson License with respect to specific technology(ies) funded by the government or subject to a third-party contract if the Company and PGEN are not meeting the diligence requirements in such funding agreement or contract, as applicable. MD Anderson may also terminate the agreement with written notice upon material breach by the Company and PGEN, if such breach has not been cured within 60 days of receiving such notice. In addition, the MD Anderson License will terminate upon the occurrence of certain insolvency events for both the Company and PGEN and may be terminated by the mutual written agreement of the Company, PGEN, and MD Anderson. On August 17, 2015, the Company, Precigen and MD Anderson entered into the Research and Development, or the 2015 Agreement to formalize the scope and process for the transfer by MD Anderson, pursuant to the terms of the MD Anderson License, of certain existing research programs and related technology rights, as well as the terms and conditions for future collaborative research and development of new and ongoing research programs. Pursuant to the 2015 Agreement, the Company, Precigen and MD Anderson formed a joint steering committee to oversee and manage the new and ongoing research programs. Under the License Agreement with PGEN, the Company and PGEN agreed that PGEN would no longer participate on the joint steering committee after the date of the License Agreement. As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $15.0 million and no greater than $20.0 million per year. On October 22, 2019, the Company entered into an amendment to the Research and Development Agreement extending its term until December 31, 2026. During the three months ended March 31, 2020 and 2019, the Company made no payments to MD Anderson. The net balance of cash resources on hand at MD Anderson available to offset expenses and future costs is $18.0 million, which is included in prepaid expenses and other current assets on the Company’s balance sheet at March 31, 2020. On October 22, 2019, the Company entered into the 2019 Research and Development Agreement, or the 2019 Agreement, with The University of Texas M.D. Anderson Cancer Center, or MD Anderson, pursuant to which the parties agreed to collaborate with respect to the Company’s Sleeping Beauty non-viral The Company will own all intellectual property developed under the 2019 Agreement and will retain all rights to intellectual property for oncology products manufactured using non-viral Sleeping Beauty non-exclusive The Company has agreed, beginning on January 1, 2021, to reimburse MD Anderson up to a total of $20.0 million for development costs under the 2019 Agreement. In addition, the Company will pay MD Anderson royalties on net sales of its TCR products at rates in the low single digits. The Company is required to make performance-based payments upon the successful completion of clinical and regulatory benchmarks relating to its TCR products. The aggregate potential benchmark payments are $36.5 million, of which only $3.0 million will be due prior to the first marketing approval of the Company’s TCR products. The royalty rates and benchmark payments owed to MD Anderson may be reduced upon the occurrence of certain events. The Company also agreed that it will sell the Company’s TCR products to MD Anderson at preferential prices and will sell its TCR products in Texas exclusively to MD Anderson for a limited period of time following the first commercial sale of the Company’s TCR products. In connection with the execution of the 2019 Agreement, the Company issued MD Anderson a warrant to purchase 3,333,333 shares of common stock. Refer to Note 9 – Warrants License Agreement with the National Cancer Institute On May 28, 2019, the Company entered into a patent license agreement, or the Patent License, with the National Cancer Institute, or the NCI. Pursuant to the Patent License, the Company holds an exclusive, worldwide license to certain intellectual property to develop and commercialize patient-derived (autologous), peripheral blood T-cell T-cell non-viral non-exclusive, Pursuant to the terms of the Patent License, the Company is required to pay the NCI a cash payment in the aggregate amount of $1.5 million payable in $0.5 million installments within sixty days, six-months, The $1.5 million was expensed in the second quarter of 2019 with $0.5 million remaining in current liabilities at Mar ch 31, 2020. The terms of the Patent License also require the Company to pay the NCI minimum annual royalties in the amount of $0.3 million, which amount will be reduced to $0.1 million once the aggregate minimum annual royalties paid by the Company equals $1.5 million. The first minimum annual royalty payment is payable on the date that is eighteen months following the date of the Patent License. As of March 31, 2020, the Company included a prepayment of $0.3 million related to the Patent License as prepaid expenses and other current assets on the Company’s Balance Sheet. The Company is also required to make performance-based payments upon successful completion of clinical and regulatory benchmarks relating to the licensed products. The aggregate potential benchmark payments are $4.3 million, of which aggregate payments of $3.0 million are due only after marketing approval in the United States or in Europe, Japan, Australia, China or India. The first benchmark payment of $0.1 million will be due upon the initiation of the Company’s first sponsored phase 1 clinical trial of a licensed product or licensed process in the field of use licensed under the Patent License. In addition, the Company is required to pay the NCI one-time mid-single The Patent License will expire upon expiration of the last patent contained in the licensed patent rights, unless terminated earlier. The NCI may terminate or modify the Patent License in the event of a material breach, including if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event. The Company may terminate the Patent License, or any portion thereof, in the Company’s sole discretion at any time upon 60 days’ written notice to the NCI. In addition, the NCI has the right to: (i) require the Company to sublicense the rights to the product candidates covered by the Patent License upon certain conditions, including if the Company is not reasonably satisfying required health and safety needs and (ii) terminate or modify the Patent License, including if the Company is not satisfying requirements for public use as specified by federal regulations. On January 8, 2020, the Company entered into an amendment to the patent license agreement which expanded the TCR library to include additional TCR’s reactive to mutated KRAS and TP53. Under the amendment, the Company paid $0.6 million during the three months ending March 31, 2020. Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute On January 10, 2017, the Company announced the signing of a CRADA, with the NCI for the development of adoptive cell transfer, or ACT,-based immunotherapies genetically modified using the Sleeping Beauty non-viral Sleeping Beauty As of March 31, 2020, the Company recorded a liability of $0.6 million in accrued expenses. The Company paid $0.6 million during the three months ended March 31, 2019. Collaboration Agreement with Solasia Pharma K.K. On March 7, 2011, the Company entered into a License and Collaboration Agreement with Solasia Pharma K.K., or Solasia , As consideration for the license, the Company is eligible to receive from Solasia development- and sales-based milestones, a royalty on net sales of darinaparsin, once commercialized, and a percentage of any sublicense revenues generated by Solasia. Solasia will be responsible for all costs related to the development, manufacturing and commercialization of darinaparsin. The Company’s Licensors, as defined in the agreement, will receive a portion of all milestone and royalty payments made by Solasia to the Company in accordance with the terms of the license agreement with the Licensors. Ares Trading License and Collaboration Agreement On March 27, 2015, the Company, together with PGEN, signed the Ares Trading Agreement, with Ares Trading S.A., a subsidiary of the biopharmaceutical business of Merck KGaA, Darmstadt, Germany, through which the parties established a collaboration for the research and development and commercialization of certain products for the prophylactic, therapeutic, palliative or diagnostic use for cancer in humans. PGEN was entitled to receive $5.0 million, from Ares Trading, payable in equal quarterly installments over two years for each identified product candidate, which will be used to fund discovery work. The Company was responsible for costs exceeding the quarterly installments and all other costs of the preclinical research and development. For the three months ended March 31, 2020 and 2019, the Company incurred no expenses under the Ares Trading Agreement. Ares Trading paid a non-refundable Patent and Technology License Agreement—The University of Texas MD Anderson Cancer Center and the Texas A&M University System On August 24, 2004, the Company entered into a patent and technology license agreement with MD Anderson and the Texas A&M University System, which the Company refers to, collectively, as the Licensors. Under this agreement, the Company was granted an exclusive, worldwide license to rights (including rights to U.S. and foreign patent and patent applications and related improvements and know-how) Under the terms of the agreement, the Company may be required to make additional payments to the Licensors upon achievement of certain other milestones in varying amounts which, on a cumulative basis could total up to an additional $4.5 million. In addition, the Licensors are entitled to receive single digit percentage royalty payments on sales from a licensed product and will also be entitled to receive a portion of any fees that the Company may receive from a possible sublicense under certain circumstances.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
Leases, Operating [Abstract]
Leases	7. Leases In June 2012, the Company entered into a master lease for the Company’s corporate office On January , , the Company entered into a lease agreement for office space in Houston at MD Anderson. Under the terms of the Houston lease agreement, the Company leases approximately two hundred and ten square feet thousand through . All future rent expense incurred in Houston, will be deducted from the Company’s prepayments at MD Anderson. On March 12, 2019, the Company entered into a lease agreement for office space in Houston. Under the terms of the Houston lease agreement, the Company leases approximately one thousand and thirty-eight square feet eight thousand four hundred and forty-three square feet . The components of lease expense were as follows: Three Months Ended March 31, (in thousands) 2020 2019 Operating lease cost $ 236 $ 178 Total lease cost $ 236 $ 178 Weighted-average remaining lease term (years) 4.39 2.40 Weighted-average discount rate 8.00 % 8.00 % As of March 31, 2020, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): Maturity of Lease Liabilities Operating Leases 2020 (excluding the three months ended March 31, 2020) $ 720 2021 701 2022 213 2023 220 2024 226 Thereafter 514 Total lease payments 2,594 Less: Imputed Interest and Adjustments (403 ) Present value of lease payments $ 2,191

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Stock-Based Compensation	8 The Company recognized stock-based compensation expense on all employee and non-employee For the three months ended March 31, (in thousands) 2020 2019 Research and development $ 530 $ 433 General and administrative 1,410 1,023 Stock-based compensation expense $ 1,940 $ 1,456 The Company granted an aggregate of 896,000 stock options during the three months ended March 31, 2020 with a weighted-average grant date fair value of $2.64 per share. The Company granted an aggregate of 1,496,333 stock options during the three months ended March 31, 2019 with a weighted average grant date fair value of $1.62 per share. On January 6, 2019, the Company paid an accrued annual performance bonus by issuing 446,428 shares of common stock. For the three months ended March 31, 2020 and 2019, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions: For the three months ended March 31 , 2020 2019 Risk-free interest rate 0.50 - 2.28 - Expected life in years 6 - 6.25 6 - 6.25 Expected volatility 71.11 - 78.87 - Expected dividend yield 0% 0% Stock option activity under the Company’s stock option plan for the three months ended March 31, 2020 is as follows: (in thousands, except share and per share data) Number of Weighted- Weighted- Aggregate Outstanding, December 31, 2019 5,842,879 $ 3.21 Granted 896,000 4.17 Exercised (2,333 ) 1.87 Cancelled (59,667 ) 4.67 Outstanding, March 31, 2020 6,676,879 $ 3.95 8.15 $ 864 Options exercisable, March 31, 2020 3,024,728 $ 4.05 6.83 $ 509 Options exercisable, December 31, 2019 2,765,357 $ 4.39 6.70 $ 3,603 Options available for future grant 1,066,275 At March 31, 2020, total unrecognized compensation costs related to unvested stock options outstanding amounted to $10.1 million. The cost is expected to be recognized over a weighted-average period of 1.78 years. A summary of the status of unvested restricted stock for the three Number of Shares Weighted-Average Non-vested, 9 939,636 $ 2.93 Granted 555,900 4.21 Vested — — Cancelled — — Non-vested, 1,495,536 $ 3.41 At March 31, 2020, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $4.5 million. The cost is expected to be recognized over a weighted-average period of 1.59 years.

Warrants

Warrants	3 Months Ended
	Mar. 31, 2020
Warrants Disclosure [Abstract]
Warrant	9 In connection with the Company’s November 2018 private placement which provided net proceeds of approximately $47.1 million, the Company issued warrants to purchase an aggregate of 18,939,394 shares of common stock which became exercisable six months after the closing of the private placement. The warrants have an exercise price of $3.01 per share and have a five-year term. The relative fair value of the warrants was estimated at $18.4 million using a Black-Scholes model with the following assumptions: expected volatility of 71%, risk free interest rate of 2.99%, expected life of five years and no dividends. The Company assessed whether the warrants require accounting as derivatives. The Company determined that the warrants were (1) indexed to the Company’s own stock and (2) classified in stockholders’ equity in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 815, Derivatives and Hedging On July 26, 2019 and September 12, 2019, the Company entered into agreements with existing investors for the exercise of previously issued warrants to purchase common stock in a private placement. Pursuant to the terms of the agreements, investors exercised their 2018 warrants for an aggregate of 17,803,031 shares of common stock, at an exercise price of $3.01 per share. The warrants exercised were originally issued by the Company in the November 2018 non-cash On October 22, 2019, the Company entered into the 2019 Agreement with MD Anderson. In connection with the execution of the 2019 Agreement, the Company issued MD Anderson a warrant to purchase 3,333,333 shares of common stock. The warrant has an initial exercise price of $0.001 per share and grant date fair value of $14.5 million. The warrant expires on December 31, 2026 and vests upon the occurrence of certain clinical milestones. The Company will recognize expense on the warrant in the same manner as if the Company paid cash for services to be rendered. For the three months ended March 31, 2020, work related to the clinical milestones has not been started and therefore the Company did not recognize any expense related to the warrant.

Joint Venture

Joint Venture	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture	1 0 On December 18, 2018, the Company entered into a Framework Agreement with TriArm Therapeutics, Ltd., or TriArm, pursuant to which the parties agreed to launch Eden BioCell, Ltd., or Eden BioCell, to lead clinical development and commercialization of certain Sleeping Beauty-generated CAR-T therapies as set forth in a separate license agreement. On January 3, 2019, Eden BioCell was incorporated in Hong Kong as a private company. Eden BioCell, the Company and TriArm entered into a Share Subscription Agreement on January 23, 2019, where the Company and TriArm agreed to contribute certain intellectual property, services and cash (only with respect to TriArm) to Eden BioCell to subscribe for a certain number of newly issued ordinary shares in the share capital of Eden BioCell. On the closing date, upon the issuance and subscription of the shares, in respect of the aforementioned consideration, 10,000,000 ordinary shares were issued to the Company and 10,000,000 ordinary shares were issued to TriArm. The closing of the transaction occurred on July 5, 2019. The Framework Agreement and Share Subscription Agreements were each respectively amended to be effective as of this date. Upon consummation of the joint venture, Eden BioCell and the Company also entered into a license agreement, pursuant to which the Company licensed the rights to Eden BioCell for third-generation Sleeping Beauty CAR-T 6 As of July 5, 2019, as a result of the design and purpose of Eden BioCell, the Company determined that Eden BioCell was considered a variable interest entity, or VIE, and concluded that it is not the primary beneficiary of the VIE as it did not have the power to direct the activities of the VIE that most significantly impact its performance. Rather, the Company accounts for the equity interest in Eden BioCell under the equity method of accounting as it has the ability to exercise significant influence over the operations of Eden BioCell. The Company determined that Eden BioCell was not a customer and therefore, accounted for the transaction as the transfer of nonfinancial assets to be recognized at their fair value on the contribution date. The fair value of the intellectual property contributed to Eden BioCell had a de minimis value due to the early stage of the technology and the likelihood of clinical success. Due to the de minimis fair value of the intellectual property contributed, the Company did not record a gain or loss on this transaction and recognized no value for its equity-method investment.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement 2018-03.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019 were as follows: ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 74,343 $ 74,343 $ — $ — ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 68,031 $ 68,031 $ — $ —

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share	Such potentially dilutive shares of common stock at March 31, 2020 and 2019 consisted of the following: March 31, 2020 2019 Stock options 6,676,879 5,416,085 Inducement stock options 1,030,000 500,000 Unvested restricted stock 1,495,536 1,621,845 Warrants 22,272,727 18,939,394 31,475,142 26,477,324

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Leases, Operating [Abstract]
Components of Lease Expense	The components of lease expense were as follows: Three Months Ended March 31, (in thousands) 2020 2019 Operating lease cost $ 236 $ 178 Total lease cost $ 236 $ 178 Weighted-average remaining lease term (years) 4.39 2.40 Weighted-average discount rate 8.00 % 8.00 %
Lessee, Operating Lease, Liability, Maturity	As of March 31, 2020, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): Maturity of Lease Liabilities Operating Leases 2020 (excluding the three months ended March 31, 2020) $ 720 2021 701 2022 213 2023 220 2024 226 Thereafter 514 Total lease payments 2,594 Less: Imputed Interest and Adjustments (403 ) Present value of lease payments $ 2,191

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Stock-Based Compensation Expense on All Employee and Non-Employee Awards	The Company recognized stock-based compensation expense on all employee and non-employee For the three months ended March 31, (in thousands) 2020 2019 Research and development $ 530 $ 433 General and administrative 1,410 1,023 Stock-based compensation expense $ 1,940 $ 1,456
Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model	For the three months ended March 31, 2020 and 2019, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions: For the three months ended March 31 , 2020 2019 Risk-free interest rate 0.50 - 2.28 - Expected life in years 6 - 6.25 6 - 6.25 Expected volatility 71.11 - 78.87 - Expected dividend yield 0% 0%
Stock Option Activity under Stock Option Plan	Stock option activity under the Company’s stock option plan for the three months ended March 31, 2020 is as follows: (in thousands, except share and per share data) Number of Weighted- Weighted- Aggregate Outstanding, December 31, 2019 5,842,879 $ 3.21 Granted 896,000 4.17 Exercised (2,333 ) 1.87 Cancelled (59,667 ) 4.67 Outstanding, March 31, 2020 6,676,879 $ 3.95 8.15 $ 864 Options exercisable, March 31, 2020 3,024,728 $ 4.05 6.83 $ 509 Options exercisable, December 31, 2019 2,765,357 $ 4.39 6.70 $ 3,603 Options available for future grant 1,066,275
Summary of Unvested Restricted Stock	A summary of the status of unvested restricted stock for the three Number of Shares Weighted-Average Non-vested, 9 939,636 $ 2.93 Granted 555,900 4.21 Vested — — Cancelled — — Non-vested, 1,495,536 $ 3.41

Business - Additional Informati

Business - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 171,002	$ 79,741
Accumulated deficit	$ 702,418	$ 684,125

Financings - Additional Informa

Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 10, 2020	Feb. 05, 2020	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Sale of stock consideration received on transaction			$ 88,661
At The Market Offering [Member]
Class of Stock [Line Items]
Stock issued during period			2,814,673	0
Sale of stock consideration received on transaction			$ 13,000
Underwriting Agreement [Member]
Class of Stock [Line Items]
Stock issued during period		27,826,086
Issuance & sale of common stock in public offering price per share		$ 3.25
Sale of stock consideration received on transaction		$ 84,800
par value per share		$ 3.055
Underwriting Agreement [Member] | Maximum
Class of Stock [Line Items]
Stock issued during period		4,173,912
par value per share		$ 3.055
Underwriting Agreement [Member] | Stock Option [Member]
Class of Stock [Line Items]
Stock issued during period	1,284,025
Sale of stock consideration received on transaction	$ 3,900

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 74,343	$ 68,031
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 74,343	$ 68,031

Potential Dilutive Shares Exclu

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	31,475,142	26,477,324
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	22,272,727	18,939,394
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	6,676,879	5,416,085
Stock Options | Two Thousand Twelve Stock Option Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,030,000	500,000
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,495,536	1,621,845

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands

May 28, 2019

Oct. 05, 2018

Aug. 17, 2015

Jan. 13, 2015

Jul. 31, 2015

Mar. 31, 2020

Jun. 30, 2019

Mar. 31, 2019

Jan. 01, 2021

Nov. 28, 2020

Dec. 31, 2019

Oct. 22, 2019

Feb. 19, 2019

Aug. 24, 2004

Accrued Payments

Research and development expense

$ 12,706

$ 9,476

Cash balance

171,002

$ 79,741

Agreement commencement date

2015-05

MD Anderson License and the Research and Development Agreement Member [Member]

Accrued Payments

Research and development service agreement aggregate quarterly payments

15,000

Reimbursement of historical costs

$ 20,000

Accrued Payments

3,000

Number of Warrants

3,333,333

CRADA Agreement [Member]

Accrued Payments

Obligations due under contract

600

$ 5,000

Quarterly payments under contract

600

Aggregate potential benchmark payments

$ 36,500

Gorilla IL12 Products [Member] | Parent [Member]

Accrued Payments

Percentage of development costs

80.00%

Percentage of operating profits

80.00%

CAR Products [Member]

Accrued Payments

Amount of royalties receivable

$ 50,000

License Agreement with the National Cancer Institute [Member]

Accrued Payments

Expected cash payment payable per installments

$ 500

The University of Texas MD Anderson Cancer Center and The Texas A & M University System

Accrued Payments

Milestone maximum payment

$ 4,500

License Agreement with the National Cancer Institute [Member]

Accrued Payments

Reimbursement of historical costs

46

Expected Cash Payment Payable

1,500

500

Minimum Royalties Amount Payable

$ 300

Description Of First Annual Royalty Payable

The first minimum annual royalty payment is payable on the date that is eighteen months following the date of the Patent License.

Description Of First Benchmark Payable

The first benchmark payment of $0.1 million will be due upon the initiation of the Company’s first sponsored phase 1 clinical trial of a licensed product or licensed process in the field of use licensed under the Patent License.

Description Of option To terminate Agreement

The NCI may terminate or modify the Patent License in the event of a material breach, including if the Company does not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event.

Agreement termination, notice period

60 days

Payments under patent license

600

$ 1,500

License Agreement with the National Cancer Institute [Member] | Performance Based Payments Member [Member]

Accrued Payments

Aggregate Benchmark Payments Payable

$ 4,300

License Agreement with the National Cancer Institute [Member] | One Time Benchmark Payments [Member]

Accrued Payments

Potential Benchmark Payments Payable

12,000

License Agreement with the National Cancer Institute [Member] | Scenario, Forecast [Member]

Accrued Payments

Expected Cash Payment Payable

$ 1,500

Minimum Royalties Amount Payable

$ 100

License Agreement with the National Cancer Institute [Member] | Post Marketing Approval [Member] | Performance Based Payments Member [Member]

Accrued Payments

Aggregate Benchmark Payments Payable

3,000

License Agreement with the National Cancer Institute [Member] | licensed products [Member] | One Time Benchmark Payments [Member]

Accrued Payments

Maximum Sales Revenue On Which Benchmark Payments Payable

$ 1,000,000

Prepaid Expenses and Other Current Assets | MD Anderson License

Accrued Payments

Cash balance

$ 18,000

Prepaid Expenses and Other Current Assets | License Agreement with the National Cancer Institute [Member]

Accrued Payments

Prepaid Royalties

300

Intrexon Corporation

Accrued Payments

Licensing fee

$ 115,000

Research and development expense

1,200

Milestone payment receivable

5,000

Upfront payment received

$ 57,500

Percentage of upfront fee Payable

50.00%

Annual Licensing fee

100

Expected additional milestones payable

$ 52,500

Expected Cash Payment Payable

900

Annual Licensing fee paid

$ 100

$ 0

Intrexon Corporation | Gorilla IL12 Products [Member]

Accrued Payments

Percentage of development costs

20.00%

Percentage of operating profits

20.00%

Intrexon Corporation | T-cell receptor

Accrued Payments

Maximum royalty amount

$ 100,000

Portion of income payable to related party

20.00%

Maximum | MD Anderson License and the Research and Development Agreement Member [Member]

Accrued Payments

Research and development expense

$ 20,000

Lease expense (Detail)

Lease expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating lease cost	$ 236	$ 178
Total lease cost	$ 236	$ 178
Weighted-average remaining lease term (years)	4 years 4 months 20 days	2 years 4 months 24 days
Weighted-average discount rate	8.00%	8.00%

Operating lease liabilities (De

Operating lease liabilities (Detail) $ in Thousands	Mar. 31, 2020USD ($)
2020 (excluding the three months ended March 31, 2020)	$ 720
2021	701
2022	213
2023	220
2024	226
Thereafter	514
Total lease payments	2,594
Less: Imputed Interest and Adjustments	(403)
Present value of lease payments	$ 2,191

Leases - Additional Information

Leases - Additional Information (Details)	Mar. 12, 2019USD ($)ft²	Sep. 30, 2020	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Oct. 15, 2019USD ($)ft²	Jan. 30, 2018USD ($)ft²
Land Subject to Ground Leases | ft²	1,038
Lessee Operating Lease Monthly Average Rental Payment | $	$ 2,000
Boston, MA
Security Deposit | $			$ 100,000	$ 100,000
Sublease term amendment			Aug. 31, 2021
Operating lease expiration month and year			2016-08
Houston, TX
Land Subject to Ground Leases | ft²					8,443
Operating Lease Area | ft²						210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021 | $					$ 17,000	$ 1,000
Annual Base Rent		3.00%

Stock-Based Compensation Expens

Stock-Based Compensation Expense Included in Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,940	$ 1,456
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	530	433
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,410	$ 1,023

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Jan. 06, 2019	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, granted		896,000	1,496,333
Weighted-average grant date fair value		$ 2.64	$ 1.62
Number of shares issued for accrued annual performance bonus	446,428
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding		$ 10,100,000
Expected recognition period		1 year 9 months 10 days
Unvested Restricted Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding		$ 4,500,000
Expected recognition period		1 year 7 months 2 days

Fair Value of Stock Options Ass

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Detail)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Risk-free interest rate, Minimum	0.50%	2.28%
Risk-free interest rate, Maximum	1.68%	2.53%
Expected volatility, Minimum	71.11%	78.87%
Expected volatility, Maximum	73.01%	85.00%
Expected dividend yield	0.00%	0.00%
Maximum [Member]
Expected life in years	6 years 3 months	6 years 3 months
Minimum [Member]
Expected life in years	6 years	6 years

Stock Option Activity Under Sto

Stock Option Activity Under Stock Option Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Number of Shares
Beginning Balance	5,842,879
Granted	896,000	1,496,333
Exercised	(2,333)
Cancelled	(59,667)
Ending Balance	6,676,879
Options exercisable, at end of period	3,024,728		2,765,357
Options available for future grant	1,066,275
Weighted Average Exercise Price
Beginning Balance	$ 3.21
Granted	4.17
Exercised	1.87
Cancelled	4.67
Ending Balance	3.95
Options exercisable, at end of period	$ 4.05		$ 4.39
Weighted Average Contractual Term (Years)
Outstanding, at end of period	8 years 1 month 24 days
Options exercisable, at end of period	6 years 9 months 29 days	6 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 864
Options exercisable, at end of period	$ 509		$ 3,603

Summary of Non-Vested Restricte

Summary of Non-Vested Restricted Stock (Detail) - Unvested Restricted Common Stock	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Number of Shares
Beginning Balance | shares	939,636
Granted | shares	555,900
Vested | shares	0
Cancelled | shares	0
Ending Balance | shares	1,495,536
Weighted Average Grant Date Fair Value
Beginning Balance | $ / shares	$ 2.93
Granted | $ / shares	4.21
Vested | $ / shares	0
Cancelled | $ / shares	0
Ending Balance | $ / shares	$ 3.41

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 12, 2019	Mar. 31, 2020	Mar. 31, 2019
Fair Value Assumptions Expected volatility Rate Maximum		73.01%	85.00%
Fair Value Assumptions Risk Free Interest Rate Maximum		1.68%	2.53%
Fair Value Assumptions Expected Dividend Rate		0.00%	0.00%
Net Proceeds from Underwriting		$ 13,015
Proceeds from private placement	$ 52,500
MD Anderson Warrant [Member]
Number of securities into which the class of warrant converted		3,333,333
Warrant Exercise Per share		$ 0.001
fair value of adjustment of warrants		$ 14,500
Warrant Expiry date		Dec. 31, 2026
Securities Purchase Agreement [Member]
Net Proceeds from Underwriting		$ 47,100
Private Placement [Member]
Number of securities into which the class of warrant converted	17,803,031	18,939,394
Warrant Exercise Per share	$ 3.01	$ 3.01
fair value of adjustment of warrants		$ 18,400
Fair Value Assumptions Expected volatility Rate Maximum		71.00%
Fair Value Assumptions Risk Free Interest Rate Maximum		2.99%
Fair Value Assumptions Expected Term1		5 years
Fair Value Assumptions Expected Dividend Rate		0.00%
Placement agent fees and other expenses	$ 1,100
Private Placement [Member] | New Warrants [Member]
Number of securities into which the class of warrant converted	17,803,031
Warrant Exercise Per share	$ 7
Non-cash inducement warrant expense		$ 60,800

Joint Venture - Additional Inf

Joint Venture - Additional Information (Detail) - USD ($) $ in Millions	Jul. 05, 2019	Mar. 31, 2020	Dec. 31, 2019	Jan. 03, 2019
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued		214,286,337	181,803,320
Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments		$ 0
Ziopharm [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity interest in affilated entity	50.00%
Tri Arm [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity interest in affilated entity	50.00%
Tri Arm [Member] | License Agreement Terms [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Milestone payment made	$ 10
Conditional milestone amount payable	$ 25
Share Subscription Agreement [Member] | Ziopharm [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued				10,000,000
Share Subscription Agreement [Member] | Tri Arm [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued				10,000,000