Alaunos Therapeutics (TCRT) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
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		215,525,411
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock
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, 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, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 100,056	$ 115,069
Receivables	5,006	4,665
Prepaid expenses and other current assets	7,648	10,855
Total current assets	112,710	130,589
Property and equipment, net	11,090	10,231
Right of use asset	4,357	4,650
Deposits	130	130
Other non-current assets	185	745
Total assets	128,472	146,345
Current liabilities:
Accounts payable	4,190	960
Accrued expenses	14,012	16,589
Lease liability - current portion	759	819
Total current liabilities	18,961	18,368
Lease liability - noncurrent portion	3,870	3,995
Total liabilities	22,831	22,363
Commitments and contingencies (Note 7)
Preferred stock, $0.001 par value, 30,000,000 shares authorized
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized; 215,257,674 and 214,591,906 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	215	215
Additional paid-in capital	891,081	887,868
Accumulated deficit	(785,655)	(764,101)
Total stockholders' equity	105,641	123,982
Total liabilities and stockholders' equity	$ 128,472	$ 146,345

BALANCE SHEETS (Parenthetical)

BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	30,000,000	30,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	215,257,674	214,591,906
Common stock, shares outstanding	215,257,674	214,591,906

STATEMENTS OF OPERATIONS

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses:
Research and development	$ 13,336	$ 12,706
General and administrative	8,227	5,954
Total operating expenses	21,563	18,660
Loss from operations	(21,563)	(18,660)
Other income, net	9	367
Net loss	$ (21,554)	$ (18,293)
Basic and diluted net loss per share	$ (0.10)	$ (0.09)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	213,954,665	199,814,768

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, 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
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)
Issuance of restricted common stock		$ 1	(1)
Issuance of restricted common stock (in shares)		555,900
Balance at Mar. 31, 2020	180,337	$ 214	882,541	(702,418)
Balance (in shares) at Mar. 31, 2020		214,286,337
Balance at Dec. 31, 2020	123,982	$ 215	887,868	(764,101)
Balance (in shares) at Dec. 31, 2020		214,591,906
Stock-based compensation	2,197		2,197
Exercise of employee stock options	$ 1,016		1,016
Exercise of employee stock options (in shares)	352,442	352,442
Restricted stock awards (in shares)		313,326
Net loss	$ (21,554)			(21,554)
Balance at Mar. 31, 2021	$ 105,641	$ 215	$ 891,081	$ (785,655)
Balance (in shares) at Mar. 31, 2021		215,257,674

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Adjustment to additional paid in capital stock issuance costs	$ 2.7
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, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (21,554)	$ (18,293)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	540	142
Stock-based compensation	2,197	1,940
(Increase) decrease in:
Receivables	(340)	2,548
Prepaid expenses and other current assets	3,207	2,585
Right of use asset	292	193
Other noncurrent assets	559	(556)
Increase (decrease) in:
Accounts payable	2,654	(510)
Accrued expenses	(2,684)	2,206
Lease liabilities	(184)	(161)
Net cash used in operating activities	(15,313)	(9,906)
Cash flows from investing activities:
Purchases of property and equipment	(717)	(513)
Net cash used in investing activities	(717)	(513)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,017	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	1,017	101,680
Net increase in cash and cash equivalents, and restricted cash	(15,013)	91,261
Cash and cash equivalents, and restricted cash, beginning of period	115,069	79,741
Cash and cash equivalents, and restricted cash, end of period	100,056	171,002
Supplementary disclosure of cash flow information:
Accounts included in accrued expenses and accounts payable related to property and equipment	$ 682	$ 2,303

Business

Business	3 Months Ended
	Mar. 31, 2021
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, 2021, the Company had approximately $100.1 million of cash and cash equivalents and the Company’s accumulated deficit was approximately $785.7 million. Given its current development plans, the Company anticipates cash resources will be sufficient to fund operations into the second quarter of 2022. The Company’s ability to continue operations after its current cash resources are exhausted depends on its ability to obtain additional financing or to achieve profitable operations, as to which no assurances can be given. Cash requirements may vary materially from those now planned because of changes in the Company’s focus and direction of its research and development programs, competitive and technical advances, patent developments, regulatory changes or other developments. If adequate additional funds are not available when required, or if the Company is unsuccessful in entering into partnership agreements for further development of its product candidates, management may need to curtail its development efforts and planned operations to conserve cash. The Company’s amended and restated certificate of incorporation authorizes it to issue 250,000,000 shares of common stock. As of April 30, 202 1 . 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, 2020, 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 months ended March 31, 2021 are not necessarily indicative of the results to be expected for the full fiscal year 202 1 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 and other research and development expenses; • Collaboration agreements; • Fair value measurements of stock-based compensation; and • Income taxes. Impact of COVID-19 Pandemic With the ongoing COVID-19 COVID-19 COVID-19 COVID-19 COVID-19 COVID-19 COVID-19 Subsequent Events On May 6,2021, the Company announced its commitment to a plan to realign its research and development resources to wind down the clinical trials of its Controlled IL-12 program as part of the Company’s decision to allocate an increasing amount of its resources and capital to its Sleeping Beauty TCR program. See Note 12. Organizational Changes On February 25, 2021, the Company announced that Heidi Hagen, formerly Lead Independent Director, was appointed Interim Chief Executive Officer, replacing Dr. Laurence Cooper, MD., Ph.D. Ms. Hagen is remaining as a member of the Board of Directors. Dr. Cooper also stepped down from his seat on the Board of Directors and will be continuing with the Company in a scientific advisory consulting role to support the Company’s programs.

Financings

Financings	3 Months Ended
	Mar. 31, 2021
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. 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-Market In June 2019, the Company entered into an Open Market Sale Agreement, or sales agreement, with Jefferies LLC, as agent, or 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 SEC. During the three months ended March 31, 2020, the Company sold an aggregate of 2,814,673 shares of its common stock at an average price of $4.77 per share under the ATM program. The net proceeds from sales under the ATM program During the three months ended March 31, 2021, there were no sales under the Company’s ATM program.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
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 December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
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, 2021 and December 31, 2020 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 $ 79,775 $ 79,775 $ — $ — ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 75,990 $ 75,990 $ — $ — 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	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss per Share	5. Net Loss per Share Basic net loss per share is computed by dividing average Such potentially dilutive shares of common stock consisted of the following as of March 31, 2021 and 2020, respectively: March 31, 2021 2020 Stock options 10,738,378 6,676,879 Inducement stock options 463,333 1,030,000 Unvested restricted stock 1,074,606 1,495,536 Warrants 22,272,727 22,272,727 34,549,044 31,475,142

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	6. Related Party Transactions Collaborations with Precigen/ PGEN During the year ended December 31, 2018, the Company and PGEN Therapeutics, Inc. or PGEN, a wholly owned subsidiary of Precigen Inc., or Precigen, which was formerly known as Intrexon Corporation, entered into an Exclusive License Agreement (Note 7). Collaboration with PGEN and MD Anderson 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 C T-cell non-viral During the three months ended March 31, 2021 and year ending December 31, 2020, the Company did not make any payments to MD Anderson, and the total aggregate payments made in connection with this agreement have been Collaboration with Vineti Inc. On July 9, 2020, the Company entered into a master service agreement and statement of work with Vineti, Inc., or Vineti. Pursuant to the agreements, Vineti is developing a software platform to coordinate and orchestrate the order, cell collection and manufacturing process for the Company’s TCR-T co-founder Joint Venture with TriArm Therapeutics/Eden Biocell 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 Sleeping Beauty- CAR-T therapies as set forth in a separate license agreement. Eden BioCell is a joint venture in the People’s Republic of China (including Macau and Hong Kong), Taiwan and Korea. The Company licensed to Eden BioCell the rights in Greater China for its third-generation Sleeping Beauty-generated CAR-T therapies targeting the CD19 antigen. Eden BioCell is owned equally by the Company and TriArm and the parties share decision-making authority. Venture, which is an investor in TriArm. Mr. Huang also serves as a member of Eden BioCell’s Board of Directors. For the three months ended March 31, 2021 and 2020, Eden Biocell incurred a net loss and the Company continues to have no commitment to fund its operations.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies License Agreements Exclusive License Agreement with PGEN Therapeutics On October 5, 2018, the Company entered into an exclusive license agreement, or the License Agreement, with PGEN. 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 In consideration of the licenses and other rights granted by PGEN, the Company pays PGEN an annual license fee of $0.1 million. The Company did not have any annual license expenses for the three months ended March 31, 2021 and 2020. 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 PGEN will pay the Company royalties ranging from low-single mid-single . During the three months ended March 31, 2021 there were $0.1 million of expenses for services performed by PGEN and no expenses incurred during the three months ended March 31, 2020. As of March 31, 2021 and December 31, 2020, the Company had $0.1 million, respectively, in accrued expenses related to services for amounts due to PGEN. 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 to February 2021 and was formerly a tenured professor of pediatrics at MD Anderson and is now currently a visiting scientist under that institution’s policies. 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 three months ended March 31, 2021 and 2020, 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 $5.1 million, which is included in prepaid expenses and other current assets on the Company’s balance sheet at March 31, 2021. On October 22, 2019, the Company entered into the 2019 Research and Development Agreement, or the 2019 Agreement, with 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 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. No costs have been incurred under this agreement as of March 31, 2021. 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 10 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 , six-months, On January 8, 2020, the Company entered into an amendment to the Patent License which expanded the TCR library to include additional TCRs reactive to mutated KRAS and TP53. 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. During the three months ended March 31, 2021, the Company recognized $0.3 million related to royalty payments under this agreement. On September 28, 2020, the Company entered into a second amendment to the patent license agreement which expanded the TCR library to include additional TCRs. 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, which has not been met at March 31, 2021. 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. 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. During the three-month periods ended March 31, 2021, and 2020, the Company expensed million related to the patent services under this agreement. Additionally, the Company recorded 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 million of expense for both three-month periods ended March 31, 2021 and 2020. 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. No amounts were accrued or paid during the three months ended March 31, 2021 and 2020. 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. No amounts were accrued or received during the three months ended March 31, 2021 and 2020.

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases, Operating [Abstract]
Leases	8. Leases In June 2012, the Company entered into a master lease for the Company’s corporate office headquarters in Boston, Massachusetts, which for office space in Houston, Texas, 210 square feet and were required to make rental payments at an average monthly rate of approximately On January 30, 2018, the Company entered into a lease agreement, or the First Houston Lease, for office space in Houston, Texas at MD Anderson through April 2021. On March 12, 2019, the Company entered into a lease agreement, or the Second Houston Lease, for additional office s Under the terms of the Second Houston Lease, the Company leases from MD Anderson, approximately per month throughout the term. All future rent expense incurred in Houston, will be deducted from the Company’s prepayments to MD Anderson. Effective December 15, 2020, the Company leased an additional square feet from MD Anderson. The Company is initially required to make rental payments of approximately thousand per month through April 2028, subject to an annual base rent increase of approximately throughout the term beginning in April 2023. Future rent expense incurred in Houston, will be deducted from the Company’s prepayments to MD Anderson. The components of lease expense were as follows: (in thousands) Three Months Ended Operating lease cost $ 381 Total lease cost $ 381 Weighted-average remaining lease term (years) 6.21 Weighted-average discount rate 8.00 % Effective June 1, 2020, the Company entered into a noncancelable lease for a period of less than a year with monthly payments of approximately $10 thousand that is not subject to right of use asset recognition under ASC 842. Effective September 1, 2020, the Company added additional space to the noncancelable lease for a period of less than a year with monthly payments now totaling approximately $15 thousand. The Company recorded approximately $0.1 million in rent expense under this short-term lease during the three months ended March 31, 2021 . As of March 31, 2021, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): 2021 (excluding the three months ended March 31, 2021) $ 879 202 2 800 202 3 820 202 4 844 202 5 869 Thereafter 1,519 Total lease payments 5,731 Less: Imputed interest and adjustments (1,231 ) Present value of lease payments $ 4,500

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation The Company recognized stock-based compensation expense on all employee and non-employee For the three months ended March 31, (in thousands) 2021 2020 Research and development $ 733 $ 530 General and administrative 1,464 1,410 Stock-based compensation expense $ 2,197 $ 1,940 The Company granted an aggregate of 4,314,438 stock options during the three months ended March 31, 2021 with a weighted-average grant date fair value of $2.43 per share. 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. On March 4, 2021, the Company extended the contractual life of 216,700 fully vested stock options held by a former Company, in conformity with prior practice. These extensions resulted in additional stock during For the three months ended March 31, 2021 and 2020, 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, 2021 2020 Risk-free interest rate 0.09 - 1.05% 0.36 - 0.39% Expected life in years 5.50 - 5.75 - Expected volatility 72.92 - 73.59 - Expected dividend yield 0% 0% At March 31, 2021, there were 463,333 stock options that had been issued outside the 2012 Equity Incentive Plan, or the 2012 Plan and the 2020 Equity Incentive Plan, or the 2020 Plan. These options are excluded from the schedule below. Stock option activity under the Company’s stock option plans for the three months ended March 31, 2021 is as follows: (in thousands, except share and per share data) Number of Weighted- Weighted- Aggregate Outstanding, December 31, 2020 6,840,719 $ 3.81 Granted 4,314,438 3.79 Exercised (352,442 ) 2.89 Cancelled (84,337 ) 3.53 Outstanding, March 31, 2021 10,718,378 $ 3.83 13.40 $ 4,926 Options exercisable, March 31, 2021 3,562,744 $ 4.23 6.68 $ 2,176 Options exercisable, December 31, 2020 3,596,315 $ 4.17 6.90 $ 598 Options available for future grant 1,267,888 At March 31, 2021, total unrecognized compensation costs related to unvested stock options outstanding amounted to $16.0 million. The cost is expected to be recognized over a weighted-average period of 1.85 years. A summary of the status of unvested restricted stock for the three months ended March 31, 2021 is as follows: Number of Shares Weighted-Average Grant Date Fair Value Unvested, December 31, 202 0 786,280 $ 3.08 Granted 313,326 4.31 Vested — — Cancelled — — Unvested, March 31, 2021 1,099,606 $ 3.43 At March 31, 2021, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $2.6 million. The cost is expected to be recognized over a weighted-average period of 1.57 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 2012 Plan. The 2020 Plan had As a result, as of March 31, 2021, P

Warrants

Warrants	3 Months Ended
	Mar. 31, 2021
Warrants Disclosure [Abstract]
Warrant	10. 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 stock, or the 2018 warrants, 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, or (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 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. Proceeds from the warrant exercise, after deducting placement agent fees and other related expenses of $1.1 million were approximately $52.5 million. The Company issued participating investors new warrants to purchase up to 17,803,031 additional shares of common stock, or the 2019 warrants, as an inducement for the warrant holders to exercise their 2018 warrants. The 2019 warrants will expire on the fifth anniversary of the initial exercise date and have an exercise price of $7.00. The 2019 warrants were valued using a Black-Scholes valuation model and resulted in a $60.8 million non-cash On October 22, 2019, the Company entered into the 2019 Agreement with MD Anderson. Refer to Note 7 Commitments and Contingencies . The Company will recognize expense on the warrant in the same manner as if the Company paid cash for services to be rendered. The Company has not recognized any expense related to the warrant as of March 31, 2021, as no work towards any of the specified clinical milestones has begun.

Joint Venture

Joint Venture	3 Months Ended
	Mar. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture	11. Joint Venture On December 18, 2018, the Company entered into a Framework Agreement with TriArm pursuant to which the parties agreed to launch 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 7 m s a 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. For the three months ended March 31, 2021 and 2020, Eden BioCell incurred a net loss and the Company continues to have no commitment to fund its operations.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events The Company has evaluated subsequent events from the balance sheet date through the date on which these financial statements were issued. Except as disclosed below, the Company did not have any material subsequent events that impacted its financial statements or disclosures. On May 6, 2021, the Company announced its commitment to a plan to realign its research and development resources to wind down the clinical trials of its Controlled IL-12 program as part of the Company’s decision to allocate an increasing amount of its resources and capital to its Sleeping Beauty TCR program. Pursuant to this plan, the Company will eliminate approximately of its existing workforce on a staggered basis over the remainder of 2021. Affected employees will be offered separation benefits, including severance payments and, in some cases, retention bonuses, along with temporary healthcare coverage assistance. Additionally, the Company is evaluating its facilities and vendor relationships utilized in the Controlled IL-12 program and the associated contractual obligations to determine the appropriate course of action and any associated charges to wind down the ongoing clinical trials. The Company estimates the severance and termination-related costs to be approximately $0.8 million and will record these charges in the second quarter of 2021. On April 5, 2021, the Company entered into a formal separation agreement with Dr. Laurence Cooper, which resulted in the termination of Dr. Cooper’s employment as the Company’s Chief Executive Officer, effective April 9, 2021. As consideration under the separation agreement, Dr. Cooper is to receive certain severance benefits including severance pay, a restricted stock grant in lieu of Dr. Cooper’s 2020 discretionary bonus, COBRA coverage and reimbursement of legal fees. Dr. Cooper is also continuing with the Company in a scientific advisory consultant capacity to support the Company’s programs. During the three months ended March 31, 2021, the Company recorded a charge of approximately million related to his separation. Additional charges related to his separation and continuing consulting costs will be incurred in subsequent quarters.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
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, 2021 and December 31, 2020 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 $ 79,775 $ 79,775 $ — $ — ($ in thousands) Fair Value Measurements at Reporting Date Using Description Balance as of Quoted Prices in Significant Other Significant Assets: Cash equivalents $ 75,990 $ 75,990 $ — $ —

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share	Such potentially dilutive shares of common stock consisted of the following as of March 31, 2021 and 2020, respectively: March 31, 2021 2020 Stock options 10,738,378 6,676,879 Inducement stock options 463,333 1,030,000 Unvested restricted stock 1,074,606 1,495,536 Warrants 22,272,727 22,272,727 34,549,044 31,475,142

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases, Operating [Abstract]
Components of Lease Expense	The components of lease expense were as follows: (in thousands) Three Months Ended Operating lease cost $ 381 Total lease cost $ 381 Weighted-average remaining lease term (years) 6.21 Weighted-average discount rate 8.00 %
Lessee, Operating Lease, Liability, Maturity	As of March 31, 2021, the maturities of the Company’s operating lease liabilities for the years ended December 31, were as follows (in thousands): 2021 (excluding the three months ended March 31, 2021) $ 879 202 2 800 202 3 820 202 4 844 202 5 869 Thereafter 1,519 Total lease payments 5,731 Less: Imputed interest and adjustments (1,231 ) Present value of lease payments $ 4,500

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
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) 2021 2020 Research and development $ 733 $ 530 General and administrative 1,464 1,410 Stock-based compensation expense $ 2,197 $ 1,940
Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model	For the three months ended March 31, 2021 and 2020, 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, 2021 2020 Risk-free interest rate 0.09 - 1.05% 0.36 - 0.39% Expected life in years 5.50 - 5.75 - Expected volatility 72.92 - 73.59 - Expected dividend yield 0% 0%
Stock Option Activity under Stock Option Plan	Stock option activity under the Company’s stock option plans for the three months ended March 31, 2021 is as follows: (in thousands, except share and per share data) Number of Weighted- Weighted- Aggregate Outstanding, December 31, 2020 6,840,719 $ 3.81 Granted 4,314,438 3.79 Exercised (352,442 ) 2.89 Cancelled (84,337 ) 3.53 Outstanding, March 31, 2021 10,718,378 $ 3.83 13.40 $ 4,926 Options exercisable, March 31, 2021 3,562,744 $ 4.23 6.68 $ 2,176 Options exercisable, December 31, 2020 3,596,315 $ 4.17 6.90 $ 598 Options available for future grant 1,267,888
Summary of Unvested Restricted Stock	A summary of the status of unvested restricted stock for the three months ended March 31, 2021 is as follows: Number of Shares Weighted-Average Grant Date Fair Value Unvested, December 31, 202 0 786,280 $ 3.08 Granted 313,326 4.31 Vested — — Cancelled — — Unvested, March 31, 2021 1,099,606 $ 3.43

Business - Additional Informati

Business - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 100,056	$ 115,069
Accumulated deficit	$ 785,655	$ 764,101
Common Stock, Shares Authorized	250,000,000	250,000,000
Common Stock, Shares, Outstanding	215,257,674	214,591,906
Common Stock [Member]
Common Stock, Shares Authorized	250,000,000
Common Stock, Shares, Outstanding	215,525,411
Common stock reserved for future issuance	33,965,938

Financings - Additional Informa

Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 10, 2020	Feb. 05, 2020	Mar. 31, 2021	Mar. 31, 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			0	2,814,673
Sale of stock consideration received on transaction				$ 13,000
par value per share				$ 4.77
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] | 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, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 79,775	$ 75,990
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	$ 79,775	$ 75,990

Potential Dilutive Shares Exclu

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	34,549,044	31,475,142
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	22,272,727
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	10,738,378	6,676,879
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	463,333	1,030,000
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,074,606	1,495,536

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2015
Related Party Transaction [Line Items]
Research and development expense	$ 13,336,000	$ 12,706,000
MD Anderson License and the Research and Development Agreement [Member]
Related Party Transaction [Line Items]
Cash resources on hand	5,100,000
License Agreement | M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)				11,722,163
Research and development expense				$ 67,300,000
Cooperative Research and Development Agreement | M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Research and development service agreement aggregate payments	41,900,000		$ 41,900,000
Vineti Inc [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Expenses From Transactions With Related Party	200,000
Eden Biocell [Member]
Related Party Transaction [Line Items]
Payments to Fund Long-term Loans to Related Parties	10,000,000
Additional Loans Committed	$ 25,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	May 28, 2019	Jan. 13, 2015	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2017	Nov. 28, 2020	Oct. 22, 2019	Feb. 19, 2019	Oct. 05, 2018	Aug. 24, 2004
Accrued Payments
Research and development expense			$ 13,336,000	$ 12,706,000
Cash balance			$ 100,056,000		$ 115,069,000
Agreement commencement date						2015-05
Expected Cash Payment Payable							$ 1,500,000
Minimum Royalties Amount Payable							$ 100,000
MD Anderson Warrant [Member]
Accrued Payments
Number of Warrants			3,333,333
MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development service agreement aggregate quarterly payments			$ 15,000,000
Reimbursement of historical costs								$ 20,000,000
Aggregate potential benchmark payments								36,500,000
Accrued Payments								$ 3,000,000
Development costs incurred			0
CRADA Agreement [Member]
Accrued Payments
Obligations due under contract									$ 5,000,000
Quarterly payments under contract				600,000
CAR Products [Member]
Accrued Payments
Amount of royalties receivable										$ 50,000,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Accrued Payments
Milestone maximum payment											$ 4,500,000
License Agreement with the National Cancer Institute [Member]
Accrued Payments
Minimum Royalties Amount Payable			300,000
Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Expected Cash Payment Payable	$ 1,500,000
Expected cash payment payable per installments	500,000
Minimum Royalties Amount Payable	$ 300,000
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, which has not been met at March 31, 2021.
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 the Patent License					1,500,000
Annual Licensing fee paid			0	0
Ziop License Agreement With The National Cancer Institute [Member] | Performance Based Payments Member [Member]
Accrued Payments
Aggregate Benchmark Payments Payable	$ 4,300,000
Ziop License Agreement With The National Cancer Institute [Member] | One Time Benchmark Payments [Member]
Accrued Payments
Potential Benchmark Payments Payable	12,000,000
Ziop License Agreement With The National Cancer Institute [Member] | Post Marketing Approval [Member] | Performance Based Payments Member [Member]
Accrued Payments
Aggregate Benchmark Payments Payable	3,000,000
Ziop 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	$ 1,000,000,000
Patent And Technology License Agreement [Member] | The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Accrued Payments
Accrued payments			0		0
Collaboration Agreement With Solasia Pharma KK [Member]
Accrued Payments
Accrued payments or receipts			0		$ 0
License Agreement With PGEN Therapeutics [Member] | License [Member]
Accrued Payments
Cost of Goods and Services Sold			100,000	0
Prepaid Expenses and Other Current Assets | MD Anderson License
Accrued Payments
Cash balance			5,100,000
Prepaid Expenses and Other Current Assets | Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Prepaid Royalties			300,000
Intrexon Corporation
Accrued Payments
Annual Licensing fee										100,000
Expected additional milestones payable										52,500,000
Expected Cash Payment Payable			100,000
Intrexon Corporation | T-cell receptor
Accrued Payments
Maximum royalty amount										$ 100,000,000
Portion of income payable to related party										20.00%
Minimum | License Agreement with the National Cancer Institute [Member]
Accrued Payments
Royalty fee			$ 100,000	$ 100,000
Maximum [Member] | MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development expense		$ 20,000,000

Lease expense (Detail)

Lease expense (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Operating lease cost	$ 381
Total lease cost	$ 381
Weighted-average remaining lease term (years)	6 years 2 months 15 days
Weighted-average discount rate	8.00%

Operating lease liabilities (De

Operating lease liabilities (Detail) $ in Thousands	Mar. 31, 2021USD ($)
2021 (excluding the three months ended March 31, 2021)	$ 879
2022	800
2023	820
2024	844
2025	869
Thereafter	1,519
Total lease payments	5,731
Less: Imputed interest and adjustments	(1,231)
Present value of lease payments	$ 4,500

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	Dec. 15, 2020USD ($)ft²	Sep. 01, 2020USD ($)	Jun. 01, 2020USD ($)	Apr. 13, 2020USD ($)	Oct. 15, 2019USD ($)ft²	Mar. 12, 2019USD ($)ft²	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	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	35,482				8,443
Operating Lease Area | ft²									210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021	$ 37			$ 12	$ 17				$ 1
Annual Base Rent	3.00%			3.00%	3.00%
Lessee Operating Lease Monthly Rental Payment		$ 15
Operating lease rental expenses							$ 100

Stock-Based Compensation Expens

Stock-Based Compensation Expense Included in Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,197	$ 1,940
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	733	530
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,464	$ 1,410

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Mar. 04, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Jun. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued		10,718,378		6,840,719
Stock options, granted		4,314,438	896,000
Options available for future grant		1,267,888
Weighted-average grant date fair value		$ 2.43	$ 2.64
Number of options vested	216,700
Adiitional stock compensation expenses		$ 82,000
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding		$ 16,000,000
Expected recognition period		1 year 10 months 6 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		$ 2,600,000
Expected recognition period		1 year 6 months 25 days
Outside 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued		463,333
2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant		1,287,888
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
	Mar. 31, 2021	Mar. 31, 2020
Risk-free interest rate, Minimum	0.09%	0.36%
Risk-free interest rate, Maximum	1.05%	0.39%
Expected volatility, Minimum	72.92%	73.59%
Expected volatility, Maximum	74.20%	74.18%
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	5 years 6 months	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		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Number of Shares
Beginning Balance	6,840,719
Granted	4,314,438	896,000
Exercised	(352,442)
Cancelled	(84,337)
Ending Balance	10,718,378		6,840,719
Options exercisable, at end of period	3,562,744		3,596,315
Options available for future grant	1,267,888
Weighted Average Exercise Price
Beginning Balance	$ 3.81
Granted	3.79
Exercised	2.89
Cancelled	3.53
Ending Balance	3.83		$ 3.81
Options exercisable, at end of period	$ 4.23		$ 4.17
Weighted Average Contractual Term (Years)
Outstanding, at end of period	13 years 4 months 24 days
Options exercisable, at end of period	6 years 8 months 4 days		6 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 4,926
Options exercisable, at end of period	$ 2,176		$ 598

Summary of Non-Vested Restricte

Summary of Non-Vested Restricted Stock (Detail) - Unvested Restricted Common Stock	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Number of Shares
Beginning Balance | shares	786,280
Granted | shares	313,326
Ending Balance | shares	1,099,606
Weighted Average Grant Date Fair Value
Beginning Balance | $ / shares	$ 3.08
Granted | $ / shares	4.31
Ending Balance | $ / shares	$ 3.43

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 12, 2019	Mar. 31, 2021	Mar. 31, 2020
Fair Value Assumptions Expected volatility Rate Maximum		74.20%	74.18%
Fair Value Assumptions Risk Free Interest Rate Maximum		1.05%	0.39%
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, 2021	Dec. 31, 2020	Jan. 03, 2019
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued		215,257,674	214,591,906
Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments		$ 0
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

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021
Subsequent Event [Line Items]
Severance costs	$ 800	$ 600
Controlled IL12 Program [Member] | Workforce Reduction Plan [Member]
Subsequent Event [Line Items]
Percentage of number of workforce eliminated		15.00%