Alaunos Therapeutics (TCRT) 10-Q 6 Aug 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
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		214,150,940
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	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 153,521	$ 79,741
Receivables	4,072	3,330
Prepaid expenses and other current assets	15,583	22,421
Total current assets	173,176	105,492
Property and equipment, net	5,746	1,110
Right of use asset	1,883	2,272
Deposits	130	130
Other non-current assets	744	110
Total assets	181,679	109,114
Current liabilities:
Accounts payable	1,082	906
Accrued expenses	15,192	10,846
Lease liability—current portion	838	774
Total current liabilities	17,112	12,526
Lease liability—noncurrent portion	1,153	1,578
Total liabilities	18,265	14,104
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized; 214,292,170 and 181,803,320 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	214	182
Additional paid-in capital	884,214	778,953
Accumulated deficit	(721,014)	(684,125)
Total stockholders' equity	163,414	95,010
Total liabilities and stockholders' equity	$ 181,679	$ 109,114

BALANCE SHEETS (Parenthetical)

BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 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	214,292,170	181,803,320
Common stock, shares outstanding	214,292,170	181,803,320

STATEMENTS OF OPERATIONS

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 12,051	$ 9,998	$ 24,757	$ 19,474
General and administrative	6,555	4,755	12,509	8,900
Total operating expenses	18,606	14,753	37,266	28,374
Loss from operations	(18,606)	(14,753)	(37,266)	(28,374)
Other income, net	10	133	377	320
Net loss	$ (18,596)	$ (14,620)	$ (36,889)	$ (28,054)
Basic and diluted net loss per share	$ (0.09)	$ (0.09)	$ (0.18)	$ (0.17)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	212,792,403	160,789,272	206,303,586	160,718,313

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	3,255		3,255
Exercise of employee stock options	600		600
Exercise of employee stock options (in shares)		258,068
Issuance of restricted common stock	1,000	$ 1	999
Issuance of restricted common stock (in shares)		1,393,536
Cancelled restricted common stock (in shares)		(74,599)
Repurchase of restricted common stock	(370)		(370)
Repurchase of restricted common stock (in shares)		(165,178)
Net loss	(28,054)			(28,054)
Balance at Jun. 30, 2019	61,995	$ 162	656,216	(594,383)
Balance (in shares) at Jun. 30, 2019		162,477,963
Balance at Mar. 31, 2019	74,216	$ 162	653,817	(579,763)
Balance (in shares) at Mar. 31, 2019		162,287,161
Stock-based compensation	1,799		1,799
Exercise of employee stock options	600		600
Exercise of employee stock options (in shares)		258,068
Cancelled restricted common stock (in shares)		(67,266)
Net loss	(14,620)			(14,620)
Balance at Jun. 30, 2019	61,995	$ 162	656,216	(594,383)
Balance (in shares) at Jun. 30, 2019		162,477,963
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	3,601		3,601
Exercise of employee stock options	$ 16		16
Exercise of employee stock options (in shares)	8,166	8,166
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	(36,889)			(36,889)
Balance at Jun. 30, 2020	163,414	$ 214	884,214	(721,014)
Balance (in shares) at Jun. 30, 2020		214,292,170
Balance at Mar. 31, 2020	180,337	$ 214	882,541	(702,418)
Balance (in shares) at Mar. 31, 2020		214,286,337
Stock-based compensation	1,661		1,661
Exercise of employee stock options	12		12
Exercise of employee stock options (in shares)		5,833
Net loss	(18,596)			(18,596)
Balance at Jun. 30, 2020	$ 163,414	$ 214	$ 884,214	$ (721,014)
Balance (in shares) at Jun. 30, 2020		214,292,170

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	6 Months Ended
	Jun. 30, 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	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (36,889)	$ (28,054)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	390	296
Stock-based compensation	3,601	4,255
(Increase) decrease in:
Receivables	(742)	404
Prepaid expenses and other current assets	6,838	(144)
Right of use asset	389
Deposits		(2)
Other noncurrent assets	(634)	4,672
Increase (decrease) in:
Accounts payable	176	234
Accrued expenses	3,320	36
Deferred rent		17
Lease liabilities	(361)	(33)
Net cash used in operating activities	(23,912)	(18,319)
Cash flows from investing activities:
Purchases of property and equipment	(4,000)	(77)
Net cash used in investing activities	(4,000)	(77)
Cash flows from financing activities:
Repurchase of common stock		(370)
Proceeds from exercise of stock options	16	600
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	101,692	230
Net increase (decrease) in cash and cash equivalents, and restricted cash	73,780	(18,166)
Cash and cash equivalents, and restricted cash, beginning of period	79,741	61,729
Cash and cash equivalents, and restricted cash, end of period	153,521	43,563
Supplementary disclosure of cash flow information:
Compensation paid in restricted stock, gross		$ 1,000
Property and equipment included in accrued expenses	$ 1,026

Business

Business	6 Months Ended
	Jun. 30, 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 June 30, 2020, the Company had approximately $153.5 million of cash and cash equivalents and the Company’s accumulated deficit was approximately $721.0 million. Given its current development plans, the Company anticipates cash resources will be sufficient to fund operations into mid-2022. The 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 The year-end The results disclosed in the statements of operations for the three and six months ended June 30, 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 COVID-19 COVID-19 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 COVID-19 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	6 Months Ended
	Jun. 30, 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 No. 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- m In June 2019, the Company entered into an Open Market Sale Agreement with Jefferies LLC, as agent (“Jefferies”), pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Shares will be sold pursuant to the Company’s effective registration statement on Form S-3ASR (File No. 333-232283), as previously filed with the Securities and Exchange Commission. During the six months ended June 30, 2020, the Company issued and sold an aggregate of 2,814,673 shares of its common stock under the sales agreement for aggregate net proceeds of $ million after deducting commissions and offering expenses of $0.4 million.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 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. L

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 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 June 30, 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 $ 74,438 $ 74,438 $ — $ — ($ 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 $ — $ — The cash equivalents represent deposits in short-term United States treasury money market mutual funds quoted in an active market and classified as a Level 1 asset.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 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 June 30, 2020 and 2019 consisted of the following: June 30, 2020 2019 Stock options 6,561,513 5,077,591 Inducement stock options 863,333 500,000 Unvested restricted stock 1,354,306 1,554,579 Warrants 22,272,727 18,939,394 31,051,879 26,071,564

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 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, Inc. 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 ZIOPHARM, Precigen and ARES 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 (iii) 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 Company will also make milestone payments totaling up to an additional $52.5 million 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 As of and for the six months ended June 30, 2020, there were no liabilities or had 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 later 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 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 non-exclusive case-by-case 180-day 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 six months ended June 30, 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 $14.1 million, which is included in prepaid expenses and other current assets on the Company’s balance sheet at June 30, 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 incurred starting after January 1, 2021 . 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 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, 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 six months ending June 30, 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 June 30, 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. 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 to this program. The Company paid the NCI for the six months ended June 30, 2020 and 2019. 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 six June 0 Ares Trading paid a non-refundable Under the License Agreement, PGEN agreed to perform all future obligations of the Company under the Ares Trading Agreement other than certain payment obligations. Accordingly, the Company recognized the remaining deferred revenue as part of the settlement of a related party relationship in 2018 as described above. 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. 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, which was amended on July 31, 2014 to include an exclusive worldwide license. Pursuant to the License and Collaboration Agreement, the Company granted Solasia an exclusive license to develop and commercialize darinaparsin in both intravenous and oral forms and related organic arsenic molecules, in all indications for human use. 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.

Leases

Leases	6 Months Ended
	Jun. 30, 2020
Leases, Operating [Abstract]
Leases	7. Leases In June 2012, the Company entered into a master lease for the Company’s corporate office headquarters in Boston, which was originally set to expire in August 2016, but renewed through August 31, 2021. As of June 30, 2020 and December 31, 2019, a total security deposit of $0.1 million is included in deposits on the Company’s balance sheet. On January 30, 2018, 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 lease d two hundred and ten w e . This lease was terminated effective March 31, 2020. 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 , from MD Anderson, approximately eight thousand four hundred and forty-three The components of lease expense were as follows: Three Months Ended Six Months Ended (in thousands) 2020 2020 Operating lease cost $ 236 $ 471 Total lease cost $ 236 $ 471 Weighted-average remaining lease term (years) 4.36 4.36 Weighted-average discount rate 8.00 % 8.00 % Three Months Ended Six Months Ended (in thousands) 2019 2019 Operating lease cost $ 182 $ 360 Total lease cost $ 182 $ 360 Weighted-average remaining lease term (years) 2.40 2.40 Weighted-average discount rate 8.00 % 8.00 % As of June 30, 2020, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): 2020 (excluding the six months ended June 30, 2020) $ 540 2021 739 2022 213 2023 220 2024 226 Thereafter 514 Total lease payments 2,452 Less: Imputed interest and adjustments (461 ) Present value of lease payments $ 1,991

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2020
Text Block [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation The Company recognized stock-based compensation expense on all employee and non-employee For the three months ended June 30, For the six months ended June 30, (in thousands) 2020 2019 2020 2019 Research and development $ 535 $ 297 $ 1,065 $ 729 General and administrative 1,126 1,502 2,536 2,526 Stock-based compensation expense $ 1,661 $ 1,799 $ 3,601 $ 3,255 The Company granted an aggregate of 153,000 and 1,049,000 stock options during the three and six months ended June 30, 2020 with a weighted-average grant date fair value of $1.99 and $2.55 per share, respectively. The Company granted an aggregate of 199,422 and 1,695,755 stock options during the three and six months ended June 30, 2019 with a weighted average grant date fair value of $3.13 and $1.80 per share, respectively. On January 6, 2019, the Company paid an accrued annual performance bonus by issuing 446,428 shares of common stock. On May 26, 2020 the Company extended the contractual life of 448,130 fully vested stock options and 31,220 stock options that vested on June 30, 2020, held by an officer of the Company. Additionally, on May 26, 2020, the Company accelerated the vesting of 45,277 shares of restricted stock held by a For the three months ended June 30, 2020 and 2019, the fair value of stock options was estimated on the date of grant using a Black- option valuation model with the following assumptions: For the three months ended June 30, 2020 2019 Risk-free interest rate 0.43 - 0.60 % 1.89 - 2.42 % Expected life in years 6 - 6.25 5.75 - 6.25 Expected volatility 73.10 - 73.90 % 72.68 - 78.85 % Expected dividend yield 0 % 0 % At June 30, 2020, there were 863,333 stock options that had been issued outside the 2012 Plan. These options are excluded from the schedule below. Stock option activity under the Company’s stock option plans for the six months ended June 30, 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 1,049,000 4.01 Exercised (8,166 ) 1.87 Cancelled (322,200 ) 3.49 Outstanding, June 30, 2020 6,561,513 $ 3.96 7.90 $ 2,900 Options exercisable, June 30, 2020 3,453,006 $ 3.83 6.68 $ 1,700 Options exercisable, December 31, 2019 2,765,357 $ 4.39 6.70 $ 3,603 Options available for future grant 6,032,404 At June 30, 2020, total unrecognized compensation costs related to unvested stock options outstanding amounted to $7.7 million. The cost is expected to be recognized over a weighted-average period of 1.81 years. A summary of the status of unvested restricted stock for the six months ended June 30, 2020 is as follows: Number of Shares Weighted-Average Non-vested, 939,636 $ 2.93 Granted 555,900 4.21 Vested — — Cancelled 141,230 3.15 Non-vested, 1,354,306 $ 3.43 At June 30, 2020, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $3.1 million. The cost is expected to be recognized over a weighted-average period of 1.56 years. At the Company’s annual meeting held on June 29, 2020, the shareholders approved the 2020 Equity Incentive Plan, or the 2020 Plan, which is a successor to and continuation of the Company’s 2012 Equity Incentive Plan, or the 2012 plan. The 2020 Plan has 21 million shares plus the shares remaining for issuance under the 2012 Plan. Our ability to utilize the total shares authorized under the 2020 Plan will be limited by the total number of authorized shares authorized in our certificate of incorporation. No additional awards can be granted from the 2012 Plan or the Company’s 2003 Stock Option Plan.

Warrants

Warrants	6 Months Ended
	Jun. 30, 2020
Warrants Disclosure [Abstract]
Warrant	9. Warrants 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 sto ck , or the 2018 warrants, whic per share and have a five-year term. The relative fair value of the warrants was estimated at $ million using a Black- model with the following assumptions: expected volatility of %, risk free interest rate of %, expected life of and 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 the , or the 2019 warrants , 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 and six months ended June 30, 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	6 Months Ended
	Jun. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture	10. Joint Venture 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- CAR-T 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 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)	6 Months Ended
	Jun. 30, 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. L

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 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 June 30, 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 $ 74,438 $ 74,438 $ — $ — ($ 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)	6 Months Ended
	Jun. 30, 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 June 30, 2020 and 2019 consisted of the following: June 30, 2020 2019 Stock options 6,561,513 5,077,591 Inducement stock options 863,333 500,000 Unvested restricted stock 1,354,306 1,554,579 Warrants 22,272,727 18,939,394 31,051,879 26,071,564

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2020
Leases, Operating [Abstract]
Components of Lease Expense	The components of lease expense were as follows: Three Months Ended Six Months Ended (in thousands) 2020 2020 Operating lease cost $ 236 $ 471 Total lease cost $ 236 $ 471 Weighted-average remaining lease term (years) 4.36 4.36 Weighted-average discount rate 8.00 % 8.00 % Three Months Ended Six Months Ended (in thousands) 2019 2019 Operating lease cost $ 182 $ 360 Total lease cost $ 182 $ 360 Weighted-average remaining lease term (years) 2.40 2.40 Weighted-average discount rate 8.00 % 8.00 %
Lessee, Operating Lease, Liability, Maturity	As of June 30, 2020, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): 2020 (excluding the six months ended June 30, 2020) $ 540 2021 739 2022 213 2023 220 2024 226 Thereafter 514 Total lease payments 2,452 Less: Imputed interest and adjustments (461 ) Present value of lease payments $ 1,991

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 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 June 30, For the six months ended June 30, (in thousands) 2020 2019 2020 2019 Research and development $ 535 $ 297 $ 1,065 $ 729 General and administrative 1,126 1,502 2,536 2,526 Stock-based compensation expense $ 1,661 $ 1,799 $ 3,601 $ 3,255
Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model	For the three months ended June 30, 2020 and 2019, the fair value of stock options was estimated on the date of grant using a Black- option valuation model with the following assumptions: For the three months ended June 30, 2020 2019 Risk-free interest rate 0.43 - 0.60 % 1.89 - 2.42 % Expected life in years 6 - 6.25 5.75 - 6.25 Expected volatility 73.10 - 73.90 % 72.68 - 78.85 % Expected dividend yield 0 % 0 %
Stock Option Activity under Stock Option Plan	Stock option activity under the Company’s stock option plans for the six months ended June 30, 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 1,049,000 4.01 Exercised (8,166 ) 1.87 Cancelled (322,200 ) 3.49 Outstanding, June 30, 2020 6,561,513 $ 3.96 7.90 $ 2,900 Options exercisable, June 30, 2020 3,453,006 $ 3.83 6.68 $ 1,700 Options exercisable, December 31, 2019 2,765,357 $ 4.39 6.70 $ 3,603 Options available for future grant 6,032,404
Summary of Unvested Restricted Stock	A summary of the status of unvested restricted stock for the six months ended June 30, 2020 is as follows: Number of Shares Weighted-Average Non-vested, 939,636 $ 2.93 Granted 555,900 4.21 Vested — — Cancelled 141,230 3.15 Non-vested, 1,354,306 $ 3.43

Business - Additional Informati

Business - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 153,521	$ 79,741
Accumulated deficit	$ 721,014	$ 684,125

Financings - Additional Informa

Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 10, 2020	Feb. 05, 2020	Jun. 30, 2019	Jun. 30, 2020
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
Sale of stock consideration received on transaction				$ 13,000
Underwriting offering cost				$ 400
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
Open Market Sale Agreement [Member] | At The Market Offering [Member]
Class of Stock [Line Items]
Sale of stock consideration received on transaction			$ 100,000

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 74,438	$ 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	$ 74,438	$ 68,031

Potential Dilutive Shares Exclu

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	31,051,879	26,071,564
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	6,561,513	5,077,591
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	863,333	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	1,354,306	1,554,579

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

Jun. 30, 2020

Jun. 30, 2019

Jun. 30, 2020

Jun. 30, 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

$ 12,051

$ 9,998

$ 24,757

$ 19,474

Cash balance

153,521

153,521

$ 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

$ 5,000

Quarterly payments under contract

1,300

1,300

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

Expected Cash Payment Payable

1,500

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

1,500

600

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

14,100

14,100

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

Accrued Payments

Prepaid Royalties

300

300

Intrexon Corporation

Accrued Payments

Licensing fee

$ 115,000

Research and development expense

1,900

Milestone payment receivable

$ 5,000

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

$ 800

800

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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating lease cost	$ 236	$ 182	$ 471	$ 360
Total lease cost	$ 236	$ 182	$ 471	$ 360
Weighted-average remaining lease term (years)	4 years 4 months 9 days	2 years 4 months 24 days	4 years 4 months 9 days	2 years 4 months 24 days
Weighted-average discount rate	8.00%	8.00%	8.00%	8.00%

Operating lease liabilities (De

Operating lease liabilities (Detail) $ in Thousands	Jun. 30, 2020USD ($)
2020 (excluding the six months ended June 30, 2020)	$ 540
2021	739
2022	213
2023	220
2024	226
Thereafter	514
Total lease payments	2,452
Less: Imputed interest and adjustments	(461)
Present value of lease payments	$ 1,991

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	Jun. 01, 2020USD ($)	Mar. 12, 2019USD ($)ft²	Sep. 30, 2020	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Oct. 15, 2019USD ($)ft²	Jan. 30, 2018USD ($)ft²
Land Subject to Ground Leases | ft²		1,038
Operating Lease Monthly Rental Payment | $	$ 10	$ 2
Boston, MA
Security Deposit | $				$ 100	$ 100
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	$ 1
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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,661	$ 1,799	$ 3,601	$ 3,255
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	535	297	1,065	729
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,126	$ 1,502	$ 2,536	$ 2,526

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Jun. 30, 2020	May 26, 2020	Jan. 06, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 29, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	6,561,513			6,561,513		6,561,513			5,842,879
Stock options, granted				153,000	199,422	1,049,000	1,695,755
Options available for future grant	6,032,404			6,032,404		6,032,404
Weighted-average grant date fair value				$ 1.99	$ 3.13	$ 2.55	$ 1.80
Number of shares issued for accrued annual performance bonus			446,428
Number of options vested	31,220	448,130
Adiitional stock compensation expenses				$ 154,000		$ 154,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested		45,277
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding	$ 7,700,000			7,700,000		$ 7,700,000
Expected recognition period						1 year 9 months 21 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	$ 3,100,000			$ 3,100,000		$ 3,100,000
Expected recognition period						1 year 6 months 21 days
Number of shares vested						0
Outside 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued	863,333			863,333		863,333
2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for new issue								21,000,000
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant								0
2003 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant								0

Fair Value of Stock Options Ass

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Detail)	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Risk-free interest rate, Minimum	0.43%	1.89%
Risk-free interest rate, Maximum	0.60%	2.42%
Expected volatility, Minimum	73.10%	72.68%
Expected volatility, Maximum	73.90%	78.85%
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	5 years 9 months

Stock Option Activity Under Sto

Stock Option Activity Under Stock Option Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Number of Shares
Beginning Balance			5,842,879
Granted	153,000	199,422	1,049,000	1,695,755
Exercised			(8,166)
Cancelled			(322,200)
Ending Balance	6,561,513		6,561,513		5,842,879
Options exercisable, at end of period	3,453,006		3,453,006		2,765,357
Options available for future grant	6,032,404		6,032,404
Weighted Average Exercise Price
Beginning Balance			$ 3.21
Granted			4.01
Exercised			1.87
Cancelled			3.49
Ending Balance	$ 3.96		3.96		$ 3.21
Options exercisable, at end of period	$ 3.83		$ 3.83		$ 4.39
Weighted Average Contractual Term (Years)
Outstanding, at end of period			7 years 10 months 24 days
Options exercisable, at end of period			6 years 8 months 4 days		6 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 2,900		$ 2,900
Options exercisable, at end of period	$ 1,700		$ 1,700		$ 3,603

Summary of Non-Vested Restricte

Summary of Non-Vested Restricted Stock (Detail) - Unvested Restricted Common Stock	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Number of Shares
Beginning Balance | shares	939,636
Granted | shares	555,900
Vested | shares	0
Cancelled | shares	141,230
Ending Balance | shares	1,354,306
Weighted Average Grant Date Fair Value
Beginning Balance | $ / shares	$ 2.93
Granted | $ / shares	4.21
Vested | $ / shares	0
Cancelled | $ / shares	3.15
Ending Balance | $ / shares	$ 3.43

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 12, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020
Fair Value Assumptions Expected volatility Rate Maximum		73.90%	78.85%
Fair Value Assumptions Risk Free Interest Rate Maximum		0.60%	2.42%
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		3,333,333
Warrant Exercise Per share		$ 0.001		$ 0.001
fair value of adjustment of warrants				$ 14,500
Warrant Expiry date		Dec. 31, 2026		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		18,939,394
Warrant Exercise Per share	$ 3.01	$ 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	Jun. 30, 2020	Dec. 31, 2019	Jan. 03, 2019
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued		214,292,170	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