Alaunos Therapeutics (TCRT) 10-Q 8 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
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		216,145,826
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	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 91,725	$ 115,069
Receivables	1,510	4,665
Prepaid expenses and other current assets	3,319	10,855
Total current assets	96,554	130,589
Property and equipment, net	11,662	10,231
Right of use asset	5,179	4,650
Deposits	365	130
Other non-current assets	2	745
Total assets	113,762	146,345
Current liabilities:
Accounts payable	1,463	960
Current portion of long-term debt	12,037	0
Accrued expenses	13,963	16,589
Lease liability - current portion	710	819
Total current liabilities	28,173	18,368
Long-term debt	12,174	0
Lease liability - non-current portion	4,708	3,995
Total liabilities	45,055	22,363
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock, $0.001 par value; 350,000,000 shares authorized; 216,145,804 and 214,591,906 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	216	215
Additional paid-in capital	899,549	887,868
Accumulated deficit	(831,058)	(764,101)
Total stockholders' equity	68,707	123,982
Total liabilities and stockholders' equity	$ 113,762	$ 146,345

BALANCE SHEETS (Parenthetical)

BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares issued	216,145,804	214,591,906
Common stock, shares outstanding	216,145,804	214,591,906

STATEMENTS OF OPERATIONS

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Collaboration revenue	$ 398		$ 398
Operating expenses:
Research and development	14,521	$ 13,968	41,427	$ 38,725
General and administrative	8,173	6,353	25,469	18,862
Total operating expenses	22,694	20,321	66,896	57,587
Loss from operations	(22,296)	(20,321)	(66,498)	(57,587)
Other income (expense):
Interest income (expense), net	(444)	7	(444)	412
Other income (expense), net	7	(1)	(15)	(29)
Other income (expense), net	(437)	6	(459)	383
Net loss	$ (22,733)	$ (20,315)	$ (66,957)	$ (57,204)
Basic and diluted net loss per share	$ (0.11)	$ (0.10)	$ (0.31)	$ (0.27)
Weighted average common shares outstanding, basic and diluted	214,542,465	212,837,367	214,310,349	208,497,410

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	5,393		5,393
Exercise of employee stock options	43		43
Exercise of employee stock options (in shares)		22,916
Cancelled restricted common stock (in shares)		(141,230)
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	(57,204)			(57,204)
Balance at Sep. 30, 2020	144,918	$ 214	886,033	(741,329)
Balance (in shares) at Sep. 30, 2020		214,165,690
Balance at Jun. 30, 2020	163,414	$ 214	884,214	(721,014)
Balance (in shares) at Jun. 30, 2020		214,150,940
Stock-based compensation	1,792		1,792
Exercise of employee stock options	27		27
Exercise of employee stock options (in shares)		14,750
Net loss	(20,315)			(20,315)
Balance at Sep. 30, 2020	144,918	$ 214	886,033	(741,329)
Balance (in shares) at Sep. 30, 2020		214,165,690
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	9,857		9,857
Exercise of employee stock options	$ 1,037		1,037
Exercise of employee stock options (in shares)	363,109	363,109
Restricted stock awards		$ 1	(1)
Restricted stock awards (in shares)		1,601,224
Issuance of warrants	$ 788		788
Cancelled restricted common stock	0	$ 0
Cancelled restricted common stock (in shares)		(410,435)
Net loss	(66,957)			(66,957)
Balance at Sep. 30, 2021	68,707	$ 216	899,549	(831,058)
Balance (in shares) at Sep. 30, 2021		216,145,804
Balance at Jun. 30, 2021	88,281	$ 216	896,390	(808,325)
Balance (in shares) at Jun. 30, 2021		215,559,148
Stock-based compensation	2,371		2,371
Restricted stock awards	0		0
Restricted stock awards (in shares)		875,000
Issuance of warrants	788		788
Cancelled restricted common stock (in shares)		(288,344)
Net loss	(22,733)			(22,733)
Balance at Sep. 30, 2021	$ 68,707	$ 216	$ 899,549	$ (831,058)
Balance (in shares) at Sep. 30, 2021		216,145,804

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	9 Months Ended
	Sep. 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	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (66,957)	$ (57,204)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,892	708
Amortization of financing costs	148
Stock-based compensation	9,857	5,393
(Increase) decrease in:
Receivables	3,155	(2,098)
Prepaid expenses and other current assets	7,646	8,249
Right of use asset	(529)	(98)
Other noncurrent assets	508	(636)
Increase (decrease) in:
Accounts payable	503	1,713
Accrued expenses	(3,169)	3,828
Lease liabilities	604	168
Net cash used in operating activities	(46,342)	(39,977)
Cash flows from investing activities:
Purchases of property and equipment	(2,964)	(6,012)
Net cash used in investing activities	(2,964)	(6,012)
Cash flows from financing activities:
Proceeds from long-term debt borrowing	25,000
Debt issuance costs	(75)
Proceeds from exercise of stock options	1,037	43
Issuance of common stock in connection with a public offering, net	0	88,661
Issuance of common stock in connection with at the market offerings, net	0	13,015
Net cash provided by financing activities	25,962	101,719
Net increase (decrease) in cash and cash equivalents	(23,344)	55,730
Cash and cash equivalents, and restricted cash, beginning of period	115,069	79,741
Cash and cash equivalents, and restricted cash, end of period	91,725	135,471
Supplementary disclosure of cash flow information:
Cash paid for interest	136
Amounts included in accrued expenses and accounts payable related to property and equipment	348	$ 1,163
Issuance costs in accounts payable and accrued expenses	184
Supplementary disclosure of noncash investing and financing activities
Warrants issued in a term loan	$ 788

Business

Business	9 Months Ended
	Sep. 30, 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 is a clinical stage biopharmaceutical company focused on discovering, developing and commercializing next generation immuno-oncology platforms that leverage cell therapies to treat patients with cancers. The Company is developing technologies that utilize the immune system by employing innovative cell engineering to deliver safe and effective cell therapies for the treatment of multiple cancer types. Specifically, the Company is focused on developing T-cell receptor, or TCR, T cell therapies to target neoantigens in solid tumors, or TCR-T. A part of the Company's platform is referred to as “ Sleeping Beauty ” and is based on the non-viral genetic engineering of immune cells using a transposon/transposase system that is intended to stably engineer T cells outside of the body for subsequent infusion. The Company’s operations to date have consisted primarily of conducting research and development and raising capital to fund those efforts. In May 2021, the Company announced that it will be winding down our existing Controlled IL-12 clinical program for the treatment of recurrent glioblastoma multiforme. The Company will continue to seek a partner for this program and have also begun exploring potential synergies between this technology and our cell therapy programs. Costs incurred during the three and nine months ended September 30, 2021 under the program wind-down have not been material. 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 September 30, 2021, the Company had approximately $ 91.7  million of cash and cash equivalents. The Company’s accumulated deficit at September 30, 2021 was approximately $ 831.1  million. Given its current development plans and cash management efforts, the Company anticipates cash resources will be sufficient to fund operations into the second quarter of 2023. The Company’s ability to continue operations after its current cash resources are exhaust ed 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 amende d and restated certificate of incorporation authorizes it to issue 350,000,000 shares of common stock . As of October 29, 2021, there were 216,145,826 shares of common stock outstanding and an additional 33,778,465 shares of common stock reserved for issuance pursuant to outstanding stock options and warrants. Basis of Presentation The accompanying unaudited interim financial statements have been prepared in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. Certain information and note disclosures required by generally accepted accounting principles in the United States have been condensed or omitted pursuant to such rules and regulations. 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 presentation of the financial position of the Company and its results of operations and cash flows for the periods presented. 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 for the fiscal year ended December 31, 2020 filed with the SEC on March 1, 2021, or the Annual Report. The results disclosed in the statements of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the full fiscal year 2021. 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 pandemic, the Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its business and operations. The Company continues to evaluate the impact of the COVID-19 global pandemic on patients, healthcare providers and its employees, as well as its operations and the operations of its business partners and healthcare communities. In response to the COVID-19 pandemic, the Company has implemented policies at its locations to mitigate the risk of exposure to COVID-19 by its personnel. The extent to which the COVID-19 pandemic impacts the Company’s business, clinical development and regulatory efforts and the value of its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements, the result of vaccination efforts and the effectiveness of any other actions taken globally to contain and treat the disease. The global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the COVID-19 pandemic could have a material adverse effect on the Company’s business, financial condition, results of operations and growth prospects.

Financings

Financings	9 Months Ended
	Sep. 30, 2021
Text Block [Abstract]
Financings	2. Financings August 2021 Term Loan On August 6, 2021, the Company entered into a Loan and Security Agreement with Silicon Valley Bank and affiliates of Silicon Valley Bank (collectively, “SVB”) (the “Term Loan Agreement”). The Term Loan Agreement provides for an initial term loan of $ 25.0 million funded at the closing, with an additional tranche of $ 25.0 million available if certain funding and clinical milestones are met by August 31, 2022. Please refer to Note 4, Debt , for further discussion of the Company's Term Loan Agreement with SVB. February 2020 Public Offering On February 5, 2020, the Company entered into an underwriting agreement with Jefferies LLC, or Jeffries, 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 (File No. 333-232283) previously filed with the SEC, and a prospectus supplement thereunder. The underwriters purchased the 27,826,086 shares on February 5, 2020. The net proceeds from the offering were approximately $ 84.8 million after deducting underwriting discounts and offering expenses paid by the Company. 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 (ATM) Facility In June 2019, the Company entered into an Open Market Sale Agreement, or Sales Agreement, with 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 nine months ended September 30, 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 Sales Agreement. The net proceeds from sales were approximately $ 13.0 million after deducting underwriting discounts. During the nine months ended September 30, 2021, there were no sales under the Sales Agreement.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 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 , which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. T he Company adopted this standard effective January 1, 2021, with no material impact upon adoption .

Debt

Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt	4. Debt The carrying values of our debt obligation were as follows: September 30, 2021 Term Loan Agreement $ 25,078 Unamortized discount on Term Loan Agreement ( 867 ) Total debt 24,211 Less: current portion of long-term debt ( 12,037 ) Long-term debt $ 12,174 On August 6, 2021, the Company entered into a $ 50.0 million Term Loan Agreement with SVB, with an initial borrowing of $ 25.0 million ("Term A Tranche"). Loans under the Term Loan Agreement are secured by a first lien of substantially all the assets of the Company, other than the Company's intellectual property. Proceeds from intellectual property are available as security for amounts borrowed. The Term Loan Agreement requires the Company to meet certain funding and clinical milestones in order to either: (i) extend the maturity date of the initial loan ("Equity Milestone") or (ii) to utilize the Term Loan Agreement's remaining $ 25.0 million available borrowing capacity (“Term B Tranche”). Principal repayments for the Term A Tranche will start on April 1, 2022, with a maturity date of March 1, 2023; however, if an Equity Milestone is achieved on or before March 31, 2022, principal repayments for the Term A Tranche will start on September 1, 2022, with a maturity date of August 1, 2025 . Upon achievement of certain funding and clinical milestones associated with the Term B Tranche on or before August 31, 2022, the Company may borrow the remaining $ 25.0 million available under the Term Loan Agreement with principal repayments for the Term Loan Agreement starting on September 1, 2023 and a maturity date of August 1, 2025. Outstanding loans bear interest, payable monthly, at the greater of (a) 7.75 % and (b) the current published U.S. prime rate, plus a margin of 4.5 %. As of September 30, 2021, interest on outstanding loans was 7.75 %. In addition to the payment of the outstanding principal plus accrued interest due, the Company will also owe SVB 5.75 % of the original principal amounts borrowed as a final payment ("Final Payment"). The Final Payment will be accreted over the term of the loan using the effective interest method. The Company may, at its option, make up to two prepayments, each prepayment consisting of no less than $ 5,000,000 of any outstanding borrowings under the Term Loan Agreement, plus accrued and unpaid interest, subject to a prepayment premium. In addition to any outstanding principal plus accrued interest selected for prepayment, the Company would also prepay a pro-rata portion of the prepayment premium and the Final Payment associated with the principal amount being repaid. The Company cannot re-borrow any amounts previously paid. Should the Company fail to achieve the Equity Milestone on or before December 31, 2021, cash and cash equivalents equal to 50 % of the then outstanding principal plus associated Final Payment must be deposited into an account pledged to SVB as additional cash collateral. The Term Loan Agreement restricts the Company, apart from conducting its operations in the normal course of business and certain other permitted exceptions, from entering into mergers or acquisitions, incurring additional indebtedness, paying dividends, delisting its stock from the Nasdaq stock exchange or disposing of assets or making changes to its business operations without the consent of SVB. The Term Loan Agreement also contains standard conditions, as well as insolvency and delisting of the Company’s common stock from Nasdaq, as deemed events of default. Should the debt become mandatorily repayable upon an event of default, a default interest rate of 3 % above otherwise applicable rates would be due on any balances outstanding. In connection with the Term Loan Agreement, the Company also issued warrants to SVB providing for the purchase of a total of 432,844 shares of its common stock at an exercise price of $ 2.22 per share. The warrants are exercisable in whole or in part any time prior to August 6, 2031, and were recorded at their relative fair value amount of $ 0.8 million in additional paid-in capital upon issuance (with an offsetting reduction to the carrying value of outstanding debt). Should the Company achieve the Term B Milestone and borrow the remaining $ 25.0 million available under the Term Loan Agreement, an additional 432,842 warrants will be issued and recorded at that time to SVB with similar terms to the initial issuance described above. The Term Loan Agreement issuance costs were approximately $ 1.0 million and primarily related to the warrants issued to SVB, which will be amortized into interest expense over the period to March 1, 2023 . Interest expense, including the amortization of issuance costs, was $ 0.4 million for the third quarter of 2021. The fair value of the Term Loan Agreement as of September 30, 2021 approximates its face value due to proximity to the transaction.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	5. 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 September 30, 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 $ 84,891 $ 84,891 $ — $ — ($ 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	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	6. 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, inducement stock options, unvested restricted stock and warrants, 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 consisted of the following as of September 30, 2021 and 2020, respectively: September 30, 2021 2020 Stock options 11,072,894 6,572,191 Inducement stock options 97,500 863,333 Unvested restricted stock 1,510,655 1,289,389 Warrants 22,705,571 22,272,727 35,386,620 30,997,640

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	7. 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 8). Collaboration with PGEN and MD Anderson On January 13, 2015, the Company, together with Precigen, entered into a License with the MD Anderson Cancer Center, or MD Anderson, (which Precigen subsequently assigned to PGEN). Pursuant to the MD Anderson License, the Company, together with PGEN, hold an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson, including technologies relating to novel CAR T-cell therapies, non-viral gene transfer systems, genetic modification and/or propagation of immune cells and other cellular therapy approaches, Natural Killer, or NK Cells, and TCRs, arising from the laboratory of Laurence Cooper, M.D., Ph.D., who served as the Company’s Chief Executive Officer from May 2015 to February 2021 and was formerly a tenured professor of pediatrics at MD Anderson. In partial consideration for entering into the MD Anderson License, the Company issued MD Anderson an aggregate of 11,722,163 shares of common stock for which the Company incurred a $ 67.3 million charge recorded in 2015. During the nine months ended September 30, 2021 and 2020, the Company did not make any payments to MD Anderson. The total aggregate payments made in connection with this agreement have been $ 41.9  million since inception. The net balance of cash resources on hand at MD Anderson available to offset expenses and future costs was zero at September 30, 2021 as the outstanding balance has been fully utilized. At September 30, 2021 and December 31, 2020, the Company had accounts receivable due from MD Anderson of $ 1.1 million and $ 4.7 million, respectively. Additionally, the Company recorded approximately $ 2.1 million and $ 1.4 million of accrued expenses due to MD Anderson for research and other activities at September 30, 2021 and December 31, 2020, respectively. 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 clinical programs. Heidi Hagen, who previously served as a member of our Board of Directors and served as Interim Chief Executive Officer of the Company from February 2021 through August 2021 , is a co-founder and former officer, of Vineti. During the three and nine months ended September 30, 2021, the Company recorded expenses of approximately $ 0.1 million and $ 0.4 million for services performed by Vineti, respectively. 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 commercialization of certain Sleeping Beauty- generated 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, or collectively, Greater China. 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. TriArm has contributed $ 10.0 million to Eden BioCell. TriArm also manages all clinical development in the territory pursuant to a Master Services Agreement between TriArm and Eden BioCell. James Huang, who became a director of the Company in July 2020, Chairman of the Board of Directors in January 2021 and Executive Chairman in February 2021, was the founder and serves as managing partner of Panacea Venture, which is an investor in TriArm. Mr. Huang also serves as a member of Eden BioCell’s Board of Directors. For the three and nine months ended September 30, 2021 and 2020, Eden Biocell incurred a net loss and the Company continues to have no commitment to fund its operations. In September 2021, TriArm and Ziopharm mutually agreed to dissolve the joint venture.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	. 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 ® gene switch, or RTS ® , for the treatment of cancer, referred to as IL-12 Products, (ii) CAR products directed to (A) CD19 for the treatment of cancer, referred to as CD19 Products, and (B) a second target for the treatment of cancer, subject to the rights of Ares Trading to pursue such target under the Ares Trading Agreement, and (iii) T-cell receptor, or TCR, products designed for neoantigens for the treatment of cancer. PGEN has also granted the Company an exclusive, worldwide, royalty-bearing, sub-licensable license for certain patents relating to the Sleeping Beauty technology to research, develop and commercialize TCR products for both neoantigens and shared antigens for the treatment of cancer, referred to as TCR Products. 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 Products, CD19 Products and TCR Products. 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 no t have any annual license payments for the three and nine months ended September 30, 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 digits to high-single digits on the net sales derived from the sales of any approved IL-12 Products and CAR Products. The Company will also pay PGEN royalties ranging from low-single digit to mid-single digit on the net sales derived from the sales of any approved TCR Products, up to a maximum royalty amount of $ 100.0 million in the aggregate. The Company will also pay PGEN 20 % of any sublicensing income received by the Company relating to the licensed products. PGEN will pay the Company royalties ranging from low-single digits to mid-single digits on the net sales derived from the sale of PGEN’s CAR products, up to $ 50.0 million. During the three and nine months ended September 30, 2021, there were zero and $ 0.1 million, respectively, of expenses for services performed by PGEN. During the three and nine months ended September 30, 2020, there were no expenses for services performed by PGEN. As of September 30, 2021, the Company did not have any outstanding liabilities related to services performed by PGEN. As of December 31, 2020, the Company had $ 0.1 million 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 therapies, non-viral gene transfer systems, genetic modification and/or propagation of immune cells and other cellular therapy approaches, Natural Killer, or NK Cells, and TCRs, arising from the laboratory of Laurence Cooper, M.D., Ph.D., who was the Company’s Chief Executive Officer from May 2015 to February 2021 and was formerly a tenured professor of pediatrics at MD Anderson. On February 25, 2021, the Company announced that Dr. Cooper was stepping down from his role as Chief Executive Officer and as a member of the Board of Directors, but will be remaining with the Company in a scientific advisory consulting role to support the Company's operations. 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 cure period, MD Anderson will have the right to convert the MD Anderson License into a non-exclusive license if Ziopharm and PGEN are not using commercially reasonable efforts to commercialize the licensed intellectual property on a case-by-case basis. After five years from the date of the MD Anderson License and subject to a 180-day cure period, MD Anderson had the right to terminate the MD Anderson License with respect to specific technology(ies) funded by the government or subject to a third-party contract if the Company and PGEN did not meet the diligence requirements in such funding agreement or contract, as applicable. MD Anderson may also terminate the agreement with written notice upon material breach by us and PGEN, if such breach has not been cured within 60 days of receiving such notice. In addition, the MD Anderson License will terminate upon the occurrence of certain insolvency events for both the Company and PGEN and may be terminated by the mutual written agreement of the Company, PGEN, and MD Anderson. On August 17, 2015, the Company, Precigen and MD Anderson entered into the Research and Development, or the 2015 Agreement, to formalize the scope and process for the transfer by MD Anderson, pursuant to the terms of the MD Anderson License, of certain existing research programs and related technology rights, as well as the terms and conditions for future collaborative research and development of new and ongoing research programs. Pursuant to the 2015 Agreement, the Company, Precigen and MD Anderson formed a joint steering committee to oversee and manage the new and ongoing research programs. Under the License Agreement with PGEN, the Company and PGEN agreed that PGEN would no longer participate on the joint steering committee after the date of the License Agreement. As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $ 15.0 million and no greater than $ 20.0 million per year. On October 22, 2019, the Company entered into an amendment to the Research and Development Agreement extending its term until December 31, 2026. During the three and nine months ended September 30, 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 was zero at September 30, 2021 as the outstanding balance has been fully utilized. At September 30, 2021 and December 31, 2020, the Company had accounts receivable due from MD Anderson of $ 1.1 million and $ 4.7 million, respectively. Additionally, the Company recorded approximately $ 2.1 million and $ 1.4 million of accrued expenses due to MD Anderson for research and other activities at September 30, 2021 and December 31, 2020, respectively. 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 immunotherapy program, which uses non-viral gene transfer to stably express and clinically evaluate neoantigen-specific TCRs in T cells. Under the 2019 Agreement, the parties will, among other things, collaborate on programs to expand the Company’s TCR library and conduct clinical trials. 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 gene transfer technologies under the Agreement, including the Company’s Sleeping Beauty technology. The Company has granted MD Anderson an exclusive license for such intellectual property outside the field of oncology and to develop and commercialize autologous TCR products manufactured using viral gene transfer technologies, and a non-exclusive license for allogeneic TCR products manufactured using viral-based technologies. 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 or paid under this agreement as of September 30, 2021. In connection with the execution of the 2019 Agreement, the Company issued MD Anderson warrants to purchase 3,333,333 shares of common stock. Refer to Note 11 – Warrants for further details. 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 therapy products engineered by transposon-mediated gene transfer to express TCRs reactive to mutated KRAS, TP53 and EGFR. In addition, pursuant to the Patent License, the Company holds an exclusive, worldwide license to certain intellectual property for manufacturing technologies to develop and commercialize autologous, peripheral blood T-cell therapy products engineered by non-viral gene transfer to express TCRs, as well as a non-exclusive, worldwide license to certain additional manufacturing technologies. 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, and the twelve-month anniversary of the effective date of the agreement of the Patent License. The $ 1.5 million was paid as of December 31, 2020. 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 . This payment of $ 0.1 million was expensed during the first quarter of 2021. 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. On April 16, 2021, the Company entered into a third amendment to the patent license agreement which modified the terms governing termination, modification and surrender of rights under the license. On May 4, 2021, the Company entered into a fourth amendment to the patent license agreement which expanded the TCR library to include additional TCRs. On August 13, 2021, the Company entered into a fifth amendment to the patent licensing agreement which expanded the TCR library to include an additional TCR. 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 September 30, 2021. In addition, the Company is required to pay the NCI one-time benchmark payments following aggregate net sales of licensed products at certain net sales up to $ 1.0 billion. The aggregate potential amount of these benchmark payments is $ 12.0 million. The Company must also pay the NCI royalties on net sales of products covered by the Patent License at rates in the low to mid-single digits depending upon the technology included in a licensed product. To the extent the Company enters into a sublicensing agreement relating to a licensed product, the Company is required to pay the NCI a percentage of all consideration received from a sublicensee, which percentage will decrease based on the stage of development of the licensed product at the time of the sublicense. 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. During the three and nine month periods ended September 30, 2021, the Company expensed $ 0.3 million and $ 0.5 million related to patent prosecution services under this agreement. The Company did no t incur expenses related to patent services during the three and nine month periods ended September 30, 2020. Additionally, the Company recorded $ 0.3 million in accrued expenses as of September 30, 2021 related to patent prosecution services. 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 transposon/transposase system to express TCRs for the treatment of solid tumors. The principal goal of the CRADA is to develop and evaluate ACT for patients with advanced cancers using autologous peripheral blood lymphocytes, or PBL, genetically modified using the non-viral Sleeping Beauty system to express TCRs that recognize neoantigens expressed within a patient’s cancer. Research conducted under the CRADA will be at the direction of Steven A. Rosenberg, M.D., Ph.D., Chief of the Surgery Branch at the NCI, in collaboration with the Company. In February 2019, the Company extended the CRADA with the NCI for two years, committing an additional $ 5.0 million to this program. The Company recorded $ 1.3 million of expense for both nine month periods ended September 30, 2021 and 2020, and for the three month period ended September 30, 2021 and 2020, the Company recorded expense of zero and $ 0.6 million, respectively. 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) for the manufacture and commercialization of two classes of organic arsenicals (water- and lipid-based) for human and animal use. The class of water-based organic arsenicals includes darinaparsin. 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 possi ble sublicense under certain circumstances. During the three and nine months ended September 30, 2021 the Company accrued $ 80,000 of fees under the terms of the license agreement. No amounts were accrued or paid during the three or nine months ended September 30, 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. During the three and nine months ended September 30, 2021, the Company recorded $ 0.4 million of collaboration revenue under the collaboration agreement with Solasia in accordance with variable consideration guidance within ASC Topic 606, Revenue from Contracts with Customers . No amounts were recorded or received during the three or nine months ended September 30, 2020. Collaboration with KBI On July 9, 2020, the Company entered into a master service agreement and statement of work with KBI Biopharma, a contract manufacturing organization serving the biotechnology industry, including cell therapy. Pursuant to the agreements, KBI will provide cGMP cell therapy manufacturing and testing for the Company’s library TCR-T cell clinical program. Collaboration with Aldevron On March 3, 2019, the Company entered into a master services agreement with Aldevron, a plasmid DNA manufacturer. On June 25, 2020, Aldevron announced an agreement for Aldevron to produce DNA plasmids under their neoGMP® service to be utilized in the manufacture of the Company’s TCR-T cell therapies for treatment of solid tumors.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases, Operating [Abstract]
Leases	9. Leases In June 2012, the Company entered into a master lease for the Company’s corporate office headquarters in Boston, Massachusetts, which was originally set to expire in August 2016 , but renewed through August 31, 2021 . As of September 30, 2021 and December 31, 2020, a total security depos it of $ 0.1 millio n is included in deposits on the Company’s balance sheet. On April 22, 2021, the Company extended its lease for a 9,800 square foot portion of its office space in Boston. The renewal for its office space was originally set to expire on August 31, 2021 , but has now been extended through August 2026. Under the terms of the renewal, the Company is required to make rental payments of approximately $ 26,000 per month. On January 30, 2018, the Company entered into a lease agreement for office space in Houston, Texas, at MD Anderson. Under the terms of the Houston lease agreement, the Company leased approximately 210 square feet and were required to make rental payments at an average monthly rate of approximately $ 1,000 . This lease was terminated effective March 31, 2020. On March 12, 2019, the Company entered into a lease agreement, or the First Houston Lease, for office and lab space in Houston, Texas at MD Anderson through April 2021. Under the terms of the First Houston Lease agreement, the Company leased approximately 1,038 square feet and was required to make rental payments at an average monthly rate of approximately $ 2,000 through April 2021. On October 15, 2019, the Company entered into a lease agreement, or the Second Houston Lease, for additional office space in Houston through February 2027. Under the terms of the Second Houston Lease, the Company leases from MD Anderson, approximately 8,443 square feet and is initially required to make rental payments of approximately $ 17,000 per month through February 2027, subject to an annual base rent increase of approximately 3.0 % throughout the term. Effective April 13, 2020, the Company leased an additional 5,584 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $ 12,000 per month through February 2027, subject to an annual base rent increase of approximately 3.0 % throughout the term. Effective December 15, 2020, the Company leased an additional 35,482 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $ 37,000 per month through April 2028, subject to an annual base rent increase of approximately 3.0 % throughout the term beginning in April 2023. The components of lease expense were as follows: Three Months Ended For the Nine Months Ended (in thousands) 2021 2020 2021 2020 Operating lease cost $ 352 $ 267 $ 1,113 $ 768 Total lease cost $ 352 $ 267 $ 1,113 $ 768 Weighted-average remaining lease term (years) 5.71 4.99 5.71 4.99 Weighted-average discount rate 8.00 % 8.00 % 8.00 % 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 $ 10,000 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 $ 15,000 . Rent expense was zero and $ 5,000 during the three and nine months ended September 30, 2021, respectively. As of September 30, 2021, this lease has been terminated and the Company has no further obligation. As of September 30, 2021, the future minimum lease payments of the Company’s operating lease obligations for the years ended December 31, were as follows (in thousands): 2021 (excluding the nine months ended September 30, 2021) $ 273 2022 1,102 2023 1,132 2024 1,166 2025 1,201 Thereafter 1,873 Total lease payments 6,747 Less: Imputed interest and adjustments ( 1,329 ) Present value of lease payments $ 5,418

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Text Block [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation The Company recognized stock-based compensation expense on all employee and non-employee awards as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2021 2020 2021 2020 Research and development 535 522 2,115 1,587 General and administrative 1,836 1,270 7,742 3,806 Stock-based compensation expense $ 2,371 $ 1,792 $ 9,857 $ 5,393 The Company granted an aggregate of 2,755,000 and 7,150,438 stock options during the three and nine months ended September 30, 2021, with a weighted-average grant date fair value of $ 1.08 and $ 1.91 per share, respectively. The Company granted an aggregate of 203,178 and 1,252,178 stock options during the three and nine months ended September 30, 2020, with a weighted-average grant date fair value of $ 1.96 and $ 2.45 per share, respectively. On March 4, 2021, the Company extended the contractual life of 216,700 fully vested stock options held by a former director of the Company. On April 5, 2021, the Company extended the contractual life of 751,371 stock options and accelerated the vesting of 226,889 shares of restricted stock held by a former officer of the Company. On April 29, 2021, the Company extended the contractual life of 10,417 vested and 167,023 unvested stock options and accelerated the vesting of 4,137 shares of restricted stock held by a former director. On May 17, 2021, the Company extended the contractual life of 347,267 vested stock options held by a former officer of the Company. These extensions resulted in additional stock compensation expense of approximately $ 2.0 million during the nine months ended September 30, 2021. For the three and nine months ended September 30, 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 September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 0.89 - 0.96 % 0.36 - 0.39 % 0.50 - 1.15 % 0.36 - 1.68 % Expected life in years 6.00 - 6.25 5.75 - 6.25 5.50 - 6.25 5.75 - 6.25 Expected volatility 72.53 - 72.84 % 73.59 - 74.18 % 72.53 - 74.80 % 71.11 - 74.18 % Expected dividend yield — % — % — % — % At September 30, 2021, there were 97,500 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 nine months ended September 30, 2021 is as follows: (in thousands, except share and per share data) Number Weighted- Weighted- Aggregate Outstanding, December 31, 2020 6,840,719 $ 3.81 Granted 7,150,438 2.97 Exercised ( 363,109 ) 2.86 Cancelled ( 2,555,154 ) 3.54 Outstanding, September 30, 2021 11,072,894 $ 3.36 8.32 $ 473 Options exercisable, September 30, 2021 5,743,820 $ 4.08 7.24 $ — Options exercisable, December 31, 2020 3,596,315 $ 4.17 6.90 $ 598 Options available for future grant 2,224,159 At September 30, 2021, total unrecognized compensation costs related to unvested stock options outstanding amounted to $ 8.0 million. The cost is expected to be recognized over a weighted-average period of 2.03 years. A summary of the status of unvested restricted stock for the nine months ended September 30, 2021 is as follows: Number of Shares Weighted-Average Unvested, December 31, 2020 786,280 $ 3.08 Granted 1,601,224 2.60 Vested ( 466,436 ) 3.68 Cancelled ( 410,413 ) 3.46 Unvested, September 30, 2021 1,510,655 $ 2.28 At September 30, 2021, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $ 2.4 million. The cost is expected to be recognized over a weighted-average period of 2.19 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 21 million shares authorized, 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 shares authorized in our certificate of incorporation. As a result, as of September 30, 2021, there are 2,224,159 shares available to grant from the 2020 Plan. Additionally, 2,625,000 stock options with an exercise price of $ 1.64 were granted on August 30, 2021 to the Company's Chief Executive Officer, as part of his compensation package. These options are subject to a vesting schedule. No ne of these options have vested and do not currently impact the shares available to grant from the 2020 Plan. No additional awards can be granted from the 2012 Plan or the Company's 2003 Stock Option Plan.

Warrants

Warrants	9 Months Ended
	Sep. 30, 2021
Warrants Disclosure [Abstract]
Warrant	11. 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 . As such, the Company has concluded the warrants meet the scope exception for determining whether the instruments require accounting as derivatives and should be classified in stockholders’ equity. 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 charge to the Company’s statement of operations in 2019. On October 22, 2019, the Company entered into the 2019 Agreement with MD Anderson. Refer to Note 8 – Commitments and Contingencies for further details. 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. The Company has not recognized any expense related to the warrant as of September 30, 2021, as no work towards any of the specified clinical milestones has begun. On August 6, 2021, the Company entered into a Loan and Security Agreement with Silicon Valley Bank and affiliates, collectively, SVB. Refer to Note 4 - Debt . In connection with the Loan and Security Agreement, the Company issued SVB warrants to purchase 432,844 shares of common stock with an exercise price of $ 2.22 per share. The warrants have a ten year life and are fully vested upon issuance. The fair value of the warrants was estim ated at $ 0.8 million using a Black-Scholes model with the following assumptions: expected volatility of 79 %, risk free interest rate of 1.31 %, expected life of ten year s and no dividends.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2021
Restructuring and Related Activities [Abstract]
Restructuring	. Restructuring On September 27, 2021, in order to lower its existing cost structure in connection with the realignment of its business strategy, the Company announced a strategic reduction in force and notified approximately 60 full-time employees of its intention to terminate their services on or, in most cases, before November 30, 2021. Certain of the notified employees had employment agreements that provided for enhanced severance benefits. The severance benefits, apart from certain continuing company-paid health care benefits for up to twelve months, will be paid during the fourth quarter of 2021. T he Company expensed the following costs associated with these future termination benefit payments resulting from the strategic reduction in force: September 30, 2021 Research and Development $ 2,248 General and Administrative 1,289 Total Severance Expense $ 3,537 Amounts remaining to be expensed after September 30, 2021, for a limited number of employees continuing to render service through November 30, 2021, are di minimis. At September 30, 2021, the accrued liability balance associated with the strategic reduction in force announced in the third quarter of 2021 is $ 3.5 million and is expected to be paid in the fourth quarter of 2021.

Joint Venture

Joint Venture	9 Months Ended
	Sep. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Joint Venture	13. 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- generated CAR-T therapies as set forth in a separate license agreement (see Note 7). 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 -generated CAR-T therapies targeting the CD19 antigen for the territory of China (including Macau and Hong Kong), Taiwan and Korea. Eden BioCell will be responsible for certain milestone and royalty payments related to the Company’s license agreements with MD Anderson and PGEN (see Note 8). TriArm entered into a master services agreement with Eden BioCell and contributed $ 10.0 million of cash on the closing date. TriArm and the Company each received a 50 % equity interest in the joint venture in exchange for their contributions to Eden BioCell. 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. In March 2021 and as announced by the Company in April 2021, Eden BioCell, the Company’s Joint Venture in Taiwan with TriArm Therapeutics, began treating patients in a clinical trial with the Company’s investigational CD19 RPM CAR-T cell therapy, under the IND cleared by the Taiwan FDA in December. Two patients have now been treated in this trial. The lead investigator at National Taiwan University in Taipei, has reported no serious adverse safety events in either of these patients. Laboratory results continue to support, as previously published, that non-viral Sleeping Beauty gene transfer is effective in genetically modifying autologous T-cells. Patients were infused two days after gene transfer, thus shortening the turnaround time and demonstrating an advantage over viral methods. Based on laboratory data from the first two patients generated between March and May 2021, the TriArm/Eden team concluded, in concert with the investigator and the team at Ziopharm, that further process development work is required. In September 2021, TriArm and Ziopharm mutually agreed to dissolve the joint venture. For the three and nine months ended September 30, 2021 and 2020, Eden BioCell incurred a net loss. The Company continues to have no commitment to fund its operations.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events The Company has evaluated subsequent events from the balance sheet date through the date on which these financial statements were issued. The Company did not have any material subsequent events that impacted its financial statements or disclosures.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 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 , which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in ASC 740 and also clarifies and amends existing guidance to improve consistent application. T he Company adopted this standard effective January 1, 2021, with no material impact upon adoption .

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Debt	The carrying values of our debt obligation were as follows: September 30, 2021 Term Loan Agreement $ 25,078 Unamortized discount on Term Loan Agreement ( 867 ) Total debt 24,211 Less: current portion of long-term debt ( 12,037 ) Long-term debt $ 12,174

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 $ 84,891 $ 84,891 $ — $ — ($ 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)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share	The Company’s potentially dilutive shares, which include outstanding common stock options, inducement stock options, unvested restricted stock and warrants, 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 consisted of the following as of September 30, 2021 and 2020, respectively: September 30, 2021 2020 Stock options 11,072,894 6,572,191 Inducement stock options 97,500 863,333 Unvested restricted stock 1,510,655 1,289,389 Warrants 22,705,571 22,272,727 35,386,620 30,997,640

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases, Operating [Abstract]
Components of Lease Expense	The components of lease expense were as follows: Three Months Ended For the Nine Months Ended (in thousands) 2021 2020 2021 2020 Operating lease cost $ 352 $ 267 $ 1,113 $ 768 Total lease cost $ 352 $ 267 $ 1,113 $ 768 Weighted-average remaining lease term (years) 5.71 4.99 5.71 4.99 Weighted-average discount rate 8.00 % 8.00 % 8.00 % 8.00 %
Lessee, Operating Lease, Liability, Maturity	As of September 30, 2021, the future minimum lease payments of the Company’s operating lease obligations for the years ended December 31, were as follows (in thousands): 2021 (excluding the nine months ended September 30, 2021) $ 273 2022 1,102 2023 1,132 2024 1,166 2025 1,201 Thereafter 1,873 Total lease payments 6,747 Less: Imputed interest and adjustments ( 1,329 ) Present value of lease payments $ 5,418

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 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 awards as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2021 2020 2021 2020 Research and development 535 522 2,115 1,587 General and administrative 1,836 1,270 7,742 3,806 Stock-based compensation expense $ 2,371 $ 1,792 $ 9,857 $ 5,393
Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model	For the three and nine months ended September 30, 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 September 30, For the Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 0.89 - 0.96 % 0.36 - 0.39 % 0.50 - 1.15 % 0.36 - 1.68 % Expected life in years 6.00 - 6.25 5.75 - 6.25 5.50 - 6.25 5.75 - 6.25 Expected volatility 72.53 - 72.84 % 73.59 - 74.18 % 72.53 - 74.80 % 71.11 - 74.18 % Expected dividend yield — % — % — % — %
Stock Option Activity under Stock Option Plan	Stock option activity under the Company’s stock option plans for the nine months ended September 30, 2021 is as follows: (in thousands, except share and per share data) Number Weighted- Weighted- Aggregate Outstanding, December 31, 2020 6,840,719 $ 3.81 Granted 7,150,438 2.97 Exercised ( 363,109 ) 2.86 Cancelled ( 2,555,154 ) 3.54 Outstanding, September 30, 2021 11,072,894 $ 3.36 8.32 $ 473 Options exercisable, September 30, 2021 5,743,820 $ 4.08 7.24 $ — Options exercisable, December 31, 2020 3,596,315 $ 4.17 6.90 $ 598 Options available for future grant 2,224,159
Summary of Unvested Restricted Stock	A summary of the status of unvested restricted stock for the nine months ended September 30, 2021 is as follows: Number of Shares Weighted-Average Unvested, December 31, 2020 786,280 $ 3.08 Granted 1,601,224 2.60 Vested ( 466,436 ) 3.68 Cancelled ( 410,413 ) 3.46 Unvested, September 30, 2021 1,510,655 $ 2.28

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2021
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Costs	he Company expensed the following costs associated with these future termination benefit payments resulting from the strategic reduction in force: September 30, 2021 Research and Development $ 2,248 General and Administrative 1,289 Total Severance Expense $ 3,537

Business - Additional Informati

Business - Additional Information (Details) - USD ($) $ in Thousands	Oct. 29, 2021	Sep. 30, 2021	Dec. 31, 2020
Cash and cash equivalents		$ 91,725	$ 115,069
Accumulated deficit		$ 831,058	$ 764,101
Common stock, shares authorized		350,000,000	350,000,000
Common stock, shares outstanding		216,145,804	214,591,906
Common Stock [Member]
Common stock, shares authorized		350,000,000
Common stock, shares outstanding	216,145,826
Common stock reserved for future issuance	33,778,465

Financings - Additional Informa

Financings - Additional Information (Details) - USD ($)	Mar. 10, 2020	Feb. 05, 2020	Jun. 30, 2019	Sep. 30, 2021	Sep. 30, 2020	Aug. 06, 2021
Class of Stock [Line Items]
Sale of stock consideration received on transaction				$ 0	$ 88,661,000
Issuance of common stock in connection with at the market offering, net					$ 13,015,000
Term Loan [Member]
Class of Stock [Line Items]
Description of payment terms				Agreement with principal repayments for the Term Loan Agreement starting on September 1, 2023 and a maturity date of August 1, 2025.
Initial term loan						$ 25,000,000
Additonal tranche facility						$ 25,000,000
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					$ 13,000,000
par value per share					$ 4.77
At The Market Offering [Member] | Maximum [Member]
Class of Stock [Line Items]
Issuance of common stock in connection with at the market offering, net			$ 100,000,000
Underwriting Agreement [Member]
Class of Stock [Line Items]
Stock issued during period		27,826,086
Issuance & sale of common stock in public offering price per share		$ 3.25
Sale of stock consideration received on transaction		$ 84,800,000
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	$ 3,900,000

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt	$ 24,211
Less: current portion of long-term debt	(12,037)	$ 0
Long-term Debt, Excluding Current Maturities, Total	12,174	$ 0
Silicon Valley Bank Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	25,078
Unamortized discount on Term Loan Agreement	$ (867)

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Aug. 06, 2021	Aug. 06, 2021	Sep. 30, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Line of credit facility, interest rate		4.50%
Proceeds from Issuance of Warrants			$ 788,000	$ 788,000
Interest expense amortized date				Mar. 1, 2023
Interest expense			400,000
Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity under the credit facility	$ 25,000,000	$ 25,000,000
Initial borrowing	25,000,000	$ 25,000,000
Description of payment terms				Agreement with principal repayments for the Term Loan Agreement starting on September 1, 2023 and a maturity date of August 1, 2025.
Interest rate				7.75%
Percentage of final payment due		5.75%
Line of credit facility, interest rate		7.75%
Silicon Valley Bank Loan [Member]
Debt Instrument [Line Items]
Debt remaining borrowing capacity	25,000,000	$ 25,000,000
Debt Instrument, maturity date				Aug. 1, 2025
Debt instrument description of variable rate basis				Outstanding loans bear interest, payable monthly, at the greater of (a) 7.75% and (b) the current published U.S. prime rate, plus a margin of 4.5%. As of September 30,
Debt instrument, periodic payment	$ 5,000,000
Cash and cash equivalents portion to be pledged	50.00%
Additional rate of interest on default	3.00%
Number of warrants issued	432,844	432,844
Warrant exercise per share	$ 2.22	$ 2.22
Proceeds from Issuance of Warrants	$ 800,000
Additional number warrants issued	432,842	432,842
Silicon Valley Bank Loan [Member] | Term A Tranche [Member]
Debt Instrument [Line Items]
Description of payment terms				the Term A Tranche will start on April 1, 2022, with a maturity date of March 1, 2023; however, if an Equity Milestone is achieved on or before March 31, 2022, principal repayments for the Term A Tranche will start on September 1, 2022, with a maturity date of August 1, 2025.
Silicon Valley Bank Loan [Member] | Term B Tranche [Member]
Debt Instrument [Line Items]
Debt remaining borrowing capacity	$ 25,000,000	$ 25,000,000
Silicon Valley Bank Loan [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity under the credit facility	50,000,000	50,000,000
Silicon Valley Bank Loan [Member] | Term Loan [Member] | Term A Tranche [Member]
Debt Instrument [Line Items]
Initial borrowing	$ 25,000,000	$ 25,000,000
Silicon Valley Bank Loan [Member] | Warrants
Debt Instrument [Line Items]
Issuance costs			$ 1,000,000	$ 1,000,000

Debt - Schedule of Debt Maturit

Debt - Schedule of Debt Maturity (Parenthetical) (Details) $ in Millions	Aug. 06, 2021USD ($)
Silicon Valley Bank Loan [Member]
Debt Instrument [Line Items]
Debt remaining borrowing capacity	$ 25

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 84,891	$ 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	$ 84,891	$ 75,990

Potential Dilutive Shares Exclu

Potential Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	35,386,620	30,997,640
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	22,705,571	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	11,072,894	6,572,191
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	97,500	863,333
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,510,655	1,289,389

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2015	Dec. 31, 2020
Related Party Transaction [Line Items]
Research and development expense	$ 14,521	$ 13,968	$ 41,427	$ 38,725
Accrued expenses	13,963		13,963			$ 16,589
M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Due from Related Parties, Current	1,100		1,100			4,700
Accrued expenses	2,100		2,100			$ 1,400
MD Anderson License and the Research and Development Agreement [Member]
Related Party Transaction [Line Items]
Cash resources on hand	0		0
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
Cooperative Research and Development Agreement | M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Research and development service agreement aggregate payments			41,900
Vineti Inc [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Related Party Transaction Expenses From Transactions With Related Party Advisory Fees	$ 100		400
Eden Biocell [Member]
Related Party Transaction [Line Items]
Payments to Fund Long-term Loans to Related Parties			$ 10,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	May 28, 2019	Jan. 13, 2015	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2017	Nov. 28, 2020	Oct. 22, 2019	Feb. 19, 2019	May 10, 2018	Aug. 24, 2004
Accrued Payments
Research and development expense			$ 14,521,000		$ 13,968,000	$ 41,427,000	$ 38,725,000
Cash balance			91,725,000			91,725,000		$ 115,069,000
Agreement commencement date									2015-05
Expected Cash Payment Payable										$ 1,500,000
Minimum Royalties Amount Payable										$ 100,000
Annual Licensing fee paid			0
Receivables			1,510,000			$ 1,510,000		4,665,000
Restricted stock awards			$ 0
MD Anderson Warrant [Member]
Accrued Payments
Number of Warrants			3,333,333			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
Development costs paid						0
CRADA Agreement [Member]
Accrued Payments
Obligations due under contract												$ 5,000,000
Quarterly payments under contract			$ 0		600,000	1,300,000	1,300,000
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
MD Anderson License
Accrued Payments
Receivables			1,100,000			1,100,000		4,700,000
Accrued expenses			2,100,000			2,100,000		1,400,000
License Agreement with the National Cancer Institute [Member]
Accrued Payments
Minimum Royalties Amount Payable			300,000			300,000
payments under the Patent License				$ 100,000
License Agreement with the National Cancer Institute [Member] | One Time Benchmark Payments [Member]
Accrued Payments
Accrued payments or receipts			100,000			100,000
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 September 30, 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	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			80,000			80,000
Accrued payments					0		0
Collaboration Agreement With Solasia Pharma KK [Member]
Accrued Payments
Accrued payments or receipts			400,000		0	400,000	0
License Agreement With PGEN Therapeutics [Member] | License [Member]
Accrued Payments
Cost of Goods and Services Sold			0		0	100,000	0
Prepaid Expenses and Other Current Assets | MD Anderson License
Accrued Payments
Cash balance			0			0
Intrexon Corporation
Accrued Payments
Annual License Fees													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			$ 300,000		$ 0		$ 0
Minimum | Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Royalty fee						$ 500,000
Maximum [Member] | MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development expense		$ 20,000,000

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating lease cost	$ 352	$ 267	$ 1,113	$ 768
Total lease cost	$ 352	$ 267	$ 1,113	$ 768
Operating Lease, Weighted Average Remaining Lease Term	5 years 8 months 15 days	4 years 11 months 26 days	5 years 8 months 15 days	4 years 11 months 26 days
Weighted-average discount rate	8.00%	8.00%	8.00%	8.00%

Leases - Operating Lease Liabil

Leases - Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2021USD ($)
2021 (excluding the six months ended June 30, 2021)	$ 273
2022	1,102
2023	1,132
2024	1,166
2025	1,201
Thereafter	1,873
Total lease payments	6,747
Less: Imputed interest and adjustments	(1,329)
Present value of lease payments	$ 5,418

Leases - Additional Information

Leases - Additional Information (Details)	Apr. 22, 2021USD ($)ft²	Dec. 15, 2020USD ($)ft²	Jun. 01, 2020USD ($)	Apr. 13, 2020USD ($)ft²	Oct. 15, 2019USD ($)ft²	Mar. 12, 2019USD ($)ft²	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Jan. 30, 2018USD ($)ft²
Land Subject to Ground Leases | ft²	9,800					1,038
Operating Lease Monthly Rental Payment			$ 10,000			$ 2,000
Operating lease rental expenses							$ 0	$ 5,000
Lease obligation							5,418,000	5,418,000
Boston, MA
Security Deposit							100,000	$ 100,000	$ 100,000
Sublease term amendment	Aug. 31, 2021							Aug. 31, 2021
Operating lease expiration month and year								2016-08
Lessee Operating Lease Monthly Rental Payment	$ 26,000
Houston, TX
Land Subject to Ground Leases | ft²		35,482			8,443
Operating Lease Area | ft²				5,584						210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021		$ 37,000		$ 12,000	$ 17,000					$ 1,000
Annual Base Rent		3.00%		3.00%	3.00%
Lessee Operating Lease Monthly Rental Payment			$ 15,000
Lease obligation							$ 0	$ 0

Stock-Based Compensation Expens

Stock-Based Compensation Expense Included in Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,371	$ 1,792	$ 9,857	$ 5,393
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	535	522	2,115	1,587
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,836	$ 1,270	$ 7,742	$ 3,806

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	Apr. 29, 2021	Apr. 05, 2021	Mar. 04, 2021	Aug. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	May 17, 2021	Dec. 31, 2020	Jun. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued		751,371			11,072,894		11,072,894		347,267	6,840,719
Stock options, granted					2,755,000	203,178	7,150,438	1,252,178
Unrecognized compensation costs related to unvested restricted stock outstanding					$ 2,400		$ 2,400
Expected recognition period							2 years 2 months 8 days
Options available for future grant					2,224,159		2,224,159
Exercise price of stock options							$ 2.86
Weighted-average grant date fair value					$ 1.08	$ 1.96	$ 1.91	$ 2.45
Number of options vested	10,417		216,700
Adiitional stock compensation expenses							$ 2,000
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, granted				2,625,000
Exercise price of stock options				$ 1.64
Unvested Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to unvested restricted stock outstanding					$ 8,000,000		$ 8,000,000
Expected recognition period							2 years 10 days
Number of Unvested Stock options	167,023
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Accelerated Vesting Share	4,137	226,889
Outside 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options issued					97,500		97,500
2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant					2,224,159		2,224,159
Shares available for new issue											21,000,000
Number of Unvested Stock options				0
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, granted				0
2003 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, granted				0

Fair Value of Stock Options Ass

Fair Value of Stock Options Assumptions Using Black-Scholes Option Valuation Model (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Risk-free interest rate, Minimum	0.89%	0.36%	0.50%	0.36%
Risk-free interest rate, Maximum	0.96%	0.39%	1.15%	1.68%
Expected volatility, Minimum	72.53%	73.59%	72.53%	71.11%
Expected volatility, Maximum	72.84%	74.18%	74.80%	74.18%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Maximum [Member]
Expected life in years	6 years 3 months	6 years 3 months	6 years 3 months	6 years 3 months
Minimum [Member]
Expected life in years	6 years	5 years 9 months	5 years 6 months	5 years 9 months

Stock Option Activity Under Sto

Stock Option Activity Under Stock Option Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Number of Shares
Beginning Balance			6,840,719
Granted	2,755,000	203,178	7,150,438	1,252,178
Exercised			(363,109)
Cancelled			(2,555,154)
Ending Balance	11,072,894		11,072,894		6,840,719
Options exercisable, at end of period	5,743,820		5,743,820		3,596,315
Options available for future grant	2,224,159		2,224,159
Weighted Average Exercise Price
Beginning Balance			$ 3.81
Granted			2.97
Exercised			2.86
Cancelled			3.54
Ending Balance	$ 3.36		3.36		$ 3.81
Options exercisable, at end of period	$ 4.08		$ 4.08		$ 4.17
Weighted Average Contractual Term (Years)
Outstanding, at end of period			8 years 3 months 25 days
Options exercisable, at end of period			7 years 2 months 26 days		6 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding, at end of period	$ 473		$ 473
Options exercisable, at end of period	$ 0		$ 0		$ 598

Summary of Non-Vested Restricte

Summary of Non-Vested Restricted Stock (Details) - Non Vested Restricted Stock Member	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of Shares
Beginning Balance | shares	786,280
Granted | shares	1,601,224
Vested | shares	(466,436)
Cancelled | shares	(410,413)
Ending Balance | shares	1,510,655
Weighted Average Grant Date Fair Value
Beginning Balance | $ / shares	$ 3.08
Granted | $ / shares	2.60
Vested | $ / shares	3.68
Cancelled | $ / shares	3.46
Ending Balance | $ / shares	$ 2.28

Warrants - Additional Informati

Warrants - Additional Information (Details) - USD ($)	Aug. 06, 2021	Sep. 12, 2019	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Fair Value Assumptions Expected volatility Rate Maximum			72.84%	74.18%		74.80%	74.18%
Fair Value Assumptions Risk Free Interest Rate Maximum			0.96%	0.39%		1.15%	1.68%
Fair Value Assumptions Expected Dividend Rate			0.00%	0.00%		0.00%	0.00%
Net Proceeds from Underwriting							$ 13,015,000
Proceeds from private placement		$ 52,500,000
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						$ 14,500,000
Warrant Expiry date			Dec. 31, 2026			Dec. 31, 2026
SVB Warrants [Member]
Common stock	$ 432,844
Exercise price	2.22
Warrants fully vested upon issuance	10 years
Black-Scholes Model [Member] | SVB Warrants [Member]
Fair value of adjustment of warrants	$ 800,000
Fair Value Assumptions Expected Term1	10 years
Expected volatility	79.00%
Risk-free interest rate	1.31%
Dividends	$ 0
Securities Purchase Agreement [Member]
Net Proceeds from Underwriting						$ 47,100,000
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						$ 18,400,000
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		$ 1,100,000
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						$ 60,800,000

Restructuring - Additional Info

Restructuring - Additional Information (Details) $ in Millions	Sep. 27, 2021Employee	Sep. 30, 2021USD ($)
Restructuring Cost and Reserve [Line Items]
Postemployment Benefits, Period Expense | $		$ 3.5
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring , expected number of positions eliminated | Employee	60

Restructuring - Schedule of res

Restructuring - Schedule of restructuring costs (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Restructuring Cost and Reserve [Line Items]
Total Severance Expense	$ 3,537
Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Total Severance Expense	2,248
General and Administrative [Member]
Restructuring Cost and Reserve [Line Items]
Total Severance Expense	$ 1,289

Joint Venture - Additional Info

Joint Venture - Additional Information (Details) - USD ($) $ in Thousands	Jul. 05, 2019	Sep. 30, 2021	Dec. 31, 2020	Jan. 03, 2019
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares issued		216,145,804	214,591,906
Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity method investments		$ 0
TriArm [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity interest in affilated entity	50.00%
TriArm [Member] | License Agreement Terms [Member] | Eden Bio Cell [Member]
Subsidiary or Equity Method Investee [Line Items]
Milestone payment made	$ 10,000
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] | TriArm [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 (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Aug. 06, 2021
Subsequent Event [Line Items]
Severance costs	$ 3,537
Term Loan [Member]
Subsequent Event [Line Items]
Initial borrowing		$ 25,000
Additonal tranche facility		$ 25,000
Interest rate	7.75%
Description of payment terms	Agreement with principal repayments for the Term Loan Agreement starting on September 1, 2023 and a maturity date of August 1, 2025.