Taysha Gene Therapies (TSHA) 10-Q11 May 232023 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2023	May 11, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Trading Symbol	TSHA
Entity Registrant Name	Taysha Gene Therapies, Inc.
Entity Central Index Key	0001806310
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity File Number	001-39536
Entity Tax Identification Number	84-3199512
Entity Address, Address Line One	3000 Pegasus Park Drive
Entity Address, Address Line Two	Ste 1430
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75247
City Area Code	214
Local Phone Number	612-0000
Entity Common Stock, Shares Outstanding		64,178,567
Title of 12(b) Security	Common stock, par value $0.00001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 63,425	$ 87,880
Prepaid expenses and other current assets	8,933	8,537
Total current assets	72,358	96,417
Restricted cash	2,637	2,637
Property, plant and equipment, net	14,642	14,963
Operating lease right-of-use assets	10,647	10,943
Other non-current assets	1,316	1,316
Total assets	101,600	126,276
Current liabilities
Accounts payable	9,002	10,946
Accrued expenses and other current liabilities	16,602	18,287
Deferred revenue	28,851	33,557
Total current liabilities	54,455	62,790
Term loan, net	38,161	37,967
Operating lease liability, net of current portion	19,928	20,440
Other non-current liabilities	4,004	4,130
Total liabilities	116,548	125,327
Commitments and contingencies - Note 11
Stockholders' (deficit) equity
Preferred stock, $0.00001 par value per share; 10,000,000 shares authorized and no shares issued and outstanding as of March 31, 2023 and December 31, 2022
Common stock, $0.00001 par value per share; 200,000,000 shares authorized and 63,473,349 and 63,207,507 issued and outstanding as of March 31, 2023 and December 31, 2022, respectively	1	1
Additional paid-in capital	404,114	402,389
Accumulated deficit	(419,063)	(401,441)
Total stockholders' (deficit) equity	(14,948)	949
Total liabilities and stockholders' (deficit) equity	$ 101,600	$ 126,276

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement Of Financial Position [Abstract]
Preferred stock, par value per share	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 0.00001	$ 0.00001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	63,473,349	63,207,507
Common stock, shares outstanding	63,473,349	63,207,507

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Revenue	$ 4,706
Operating expenses:
Research and development	12,514	$ 38,182
General and administrative	8,751	11,469
Total operating expenses	21,265	49,651
Loss from operations	(16,559)	(49,651)
Other income (expense):
Interest income	319	14
Interest expense	(1,374)	(672)
Other expense	(8)	(8)
Total other expense, net	(1,063)	(666)
Net loss	$ (17,622)	$ (50,317)
Net loss per common share, basic	$ (0.28)	$ (1.32)
Net loss per common share, diluted	$ (0.28)	$ (1.32)
Weighted average common shares outstanding, basic	63,260,905	38,174,717
Weighted average common shares outstanding, diluted	63,260,905	38,174,717

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Balance at Dec. 31, 2021	$ 95,383	$ 222		$ 331,032	$ (235,649)	$ 222
Balance, shares at Dec. 31, 2021			38,473,945
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2016-02 [Member]
Stock-based compensation	$ 5,453			5,453
Net loss	(50,317)				(50,317)
Balance at Mar. 31, 2022	50,741			336,485	(285,744)
Balance, shares at Mar. 31, 2022			38,473,945
Balance at Dec. 31, 2022	$ 949		$ 1	402,389	(401,441)
Balance, shares at Dec. 31, 2022	63,207,507		63,207,507
Stock-based compensation	$ 1,675			1,675
Issuance of common stock upon release of restricted stock units, net, shares			229,922
Issuance of common stock under ESPP	50			50
Issuance of common stock under ESPP, shares			35,920
Net loss	(17,622)				(17,622)
Balance at Mar. 31, 2023	$ (14,948)		$ 1	$ 404,114	$ (419,063)
Balance, shares at Mar. 31, 2023	63,473,349		63,473,349

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (17,622)	$ (50,317)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	331	260
Research and development license expense		1,250
Stock-based compensation	1,675	5,329
Non-cash lease expense	300	309
Other	128	194
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(400)	271
Accounts payable	359	2,544
Accrued expenses and other liabilities	(250)	(779)
Deferred revenue	(4,706)
Net cash used in operating activities	(20,185)	(40,939)
Cash flows from investing activities
Purchase of research and development license		(3,000)
Purchase of property, plant and equipment	(3,900)	(8,427)
Net cash used in investing activities	(3,900)	(11,427)
Cash flows from financing activities
Payment of shelf registration costs	(387)	(151)
Proceeds from common stock issuances under ESPP	50	277
Other	(33)	(233)
Net cash provided by financing activities	(370)	(107)
Net decrease in cash, cash equivalents and restricted cash	(24,455)	(52,473)
Cash, cash equivalents and restricted cash at the beginning of the period	90,517	151,740
Cash, cash equivalents and restricted cash at the end of the period	66,062	99,267
Cash and cash equivalents	63,425	96,630
Restricted cash	2,637	2,637
Supplemental disclosure of cash flow information:
Cash paid for interest	1,125	419
Supplemental disclosure of noncash investing and financing activities:
Property, plant and equipment in accounts payable and accrued expenses	$ 112	4,513
Right-of-use assets obtained in exchange for lease liabilities		18,634
Offering costs not yet paid		21
Purchase of research and development license not yet paid		$ 1,250

Organization and Description of

Organization and Description of Business Operations	3 Months Ended
Organization and Description of Business Operations	Mar. 31, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Description of Business Operations	Note 1—Organization and Descr iption of Business Operations Taysha Gene Therapies, Inc. (the “Company” or “Taysha”) was originally formed under the laws of the State of Texas on September 20, 2019 (“Inception”). Taysha converted to a Delaware corporation on February 13, 2020 , which had no impact to the Company’s par value or issued and authorized capital structure. Taysha is a patient-centric gene therapy company focused on developing and commercializing AAV-based gene therapies for the treatment of monogenic diseases of the central nervous system in both rare and large patient populations. Sales Agreement On October 5, 2021, the Company entered into a Sales Agreement (the “Sales Agreement”) with SVB Securities LLC (f/k/a SVB Leerink LLC) and Wells Fargo Securities, LLC (collectively, the “Sales Agents”), pursuant to which the Company may issue and sell, from time to time in its sole discretion, shares of its common stock having an aggregate offering price of up to $ 150.0 million through the Sales Agents. In March 2022, the Company amended the Sales Agreement to, among other things, include Goldman Sachs & Co. LLC as an additional Sales Agent. The Sales Agents may sell common stock by any method permitted by law deemed to be an “at-the-market offering” as defined in Rule 415(a)(4) of the Securities Act, including sales made directly on or through the Nasdaq Global Select Market or any other existing trade market for the common stock, in negotiated transactions at market prices prevailing at the time of sale or at prices related to prevailing market prices, or any other method permitted by law. The Sales Agents are entitled to receive 3.0 % of the gross sales price per share of common stock sold under the Sales Agreement. In April 2022, the Company sold 2,000,000 shares of common stock under the Sales Agreement and received $ 11.6 million in net proceeds. No other shares of common stock have been issued and sold pursuant to the Sales Agreement as of March 31, 2023. Liquidity and Going Concern The accompanying condensed consolidated financial statements are prepared in accordance with generally accepted accounting principles applicable to a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. Pursuant to ASC 205, Presentation of Financial Statements , the Company is required to and does evaluate at each annual and interim period whether there are conditions or events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. The Company concluded that there was insufficient funding available to allow the Company to fund its currently planned research and discovery programs for a period exceeding one year from the filing of those financial statements, and that those conditions raised substantial doubt about the Company’s ability to continue as a going concern. In October 2022, the Company entered into a securities purchase agreement (the “Securities Purchase Agreement”) and an option agreement (the “Option Agreement,” together with the Securities Purchase Agreement, the “Astellas Transactions”) with Audentes Therapeutics, Inc. (d/b/a Astellas Gene Therapy) (“Astellas”), pursuant to which the Company agreed to issue and sell 7,266,342 shares of its common stock for aggregate proceeds of $ 30.0 million and received a one-time payment in the amount of $ 20.0 million (the “Upfront Payment”), respectively, for total gross proceeds of $ 50.0 million. See Note 5 for additional information. Also in October 2022, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Goldman Sachs & Co. LLC (the "Underwriter”) to issue and sell 14,000,000 shares of common stock at a price to the public of $ 2.00 per share. The Underwriter exercised its option to purchase an additional 765,226 shares of the Company’s common stock at a price of $ 1.88 per share. The net proceeds from the offering were $ 27.7 million, after deducting underwriting discounts and other offering expenses. The Company has incurred operating losses since inception and expects to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of March 31, 2023, the Company had an accumulated deficit of $ 419.1 million. Losses are expected to continue as the Company continues to invest in its research and development activities. Future capital requirements will depend on many factors, including the timing and extent of spending on research and development and the market acceptance of the Company’s products. The Company will need to obtain additional financing in order to complete clinical studies and launch and commercialize any product candidates for which it receives regulatory approval. There can be no assurance that such financing will be available or will be on terms acceptable to the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2—Summary of Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP") as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X and are consistent in all material respects with those included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022, filed with the Securities and Exchange Commission ("SEC") on March 28, 2023 (the “2022 Annual Report”). In the opinion of management, the unaudited condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. The consolidated balance sheet as of December 31, 2022 is derived from audited financial statements, however, it does not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes in the Company’s 2022 Annual Report. Principles of Consolidation The accompanying interim condensed consolidated financial statements include the accounts of Taysha and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The most significant estimates and assumptions in the Company’s financial statements relate to the determination of the fair value of the common stock prior to the initial public offering (as an input into stock-based compensation), estimating manufacturing accruals and accrued or prepaid research and development expenses, the measurement of impairment of long-lived assets, and the allocation of consideration received in connection with the Astellas Transactions. These estimates and assumptions are based on current facts, historical experience and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources. Actual results may differ materially from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected. Significant Accounting Policies There have been no changes in the Company’s significant accounting policies as disclosed in Note 2 to the audited consolidated financial statements included in the 2022 Annual Report. Comprehensive Loss Comprehensive loss is equal to net loss as presented in the accompanying condensed consolidated statements of operations. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended, with guidance regarding the accounting for and disclosure of leases. This update requires lessees to recognize the liabilities related to all leases, including operating leases, with a term greater than 12 months on the balance sheets. This update also requires lessees and lessors to disclose key information about their leasing transactions. On December 31, 2022 , the Company adopted ASU 2016-02 using the modified retrospective approach and utilizing the effective date as its date of initial application. The Company has retrospectively changed its previously issued condensed consolidated financial statements as of March 31, 2022 as presented within the Company's March 31, 2022 Quarterly Report on Form 10-Q to reflect the adoption of ASC 842 on January 1, 2022. The condensed consolidated financial statements for the three months ended March 31, 2022 presented herein differ from the Company's condensed consolidated financial statements included in the Company's March 31, 2022 Quarterly Report on Form 10-Q as those condensed consolidated financial statements were prepared using the former accounting standard referred to as ASC Topic 840, Leases. The Company elected the following practical expedients, which must be elected as a package and applied consistently to all of its leases at the transition date (including those for which the entity is a lessee or a lessor): i) the Company did not reassess whether any expired or existing contracts are or contain leases; ii) the Company did not reassess the lease classification for any expired or existing leases (that is, all existing leases that were classified as operating leases in accordance with ASC 840 are classified as operating leases, and all existing leases that were classified as capital leases in accordance with ASC 840 are classified as finance leases); and iii) the Company did not reassess initial direct costs for any existing leases. For leases that existed prior to the date of initial application of ASC 842 (which were previously classified as operating leases), a lessee may elect to use either the total lease term measured at lease inception under ASC 840 or the remaining lease term as of the date of initial application of ASC 842 in determining the period for which to measure its incremental borrowing rate. In transition to ASC 842, the Company utilized the remaining lease term of its leases in determining the appropriate incremental borrowing rates. The adoption of this standard resulted in the recognition of operating lease right-of-use assets and operating lease liabilities of $ 18.4 million and $ 19.1 million, respectively, on the Company’s condensed consolidated balance sheet at adoption relating to its operating leases. The lease liabilities were determined based on the present value of the remaining minimum lease payments. Upon adoption of ASC 842, the Company also (i) derecognized the build-to-suit lease asset of $ 26.3 million previously presented in property, plant and equipment, (ii) derecognized the build-to-suit lease liability of $ 26.5 million, and (iii) eliminated $ 0.7 million of deferred rent liabilities and tenant improvement allowances as of January 1, 2022 as these liabilities are reflected in the operating lease right-of-use assets. In adopting ASU 2016-02, the Company recorded a total one-time adjustment of $ 0.2 million to the opening balance of accumulated deficit as of January 1, 2022 related to the de-recognition of the build-to-suit lease asset and related build-to-suit lease obligation. The adoption did not have a material impact on accumulated deficit and on the condensed consolidated statements of operations and cash flows. The following table summarizes the effect of the adoption of ASC 842 on the condensed consolidated statement of operation and statement of cash flows for the three months ended March 31, 2022 (in thousands): Pre ASC 842 Three Months Ended ASC 842 Adjustments After ASC 842 Three Months Ended Condensed Consolidated Statements of Operations Operating expenses: Research and development $ 37,799 $ 383 $ 38,182 Other income (expense): Interest expense ( 849 ) 177 ( 672 ) Condensed Consolidated Statements of Cash Flows Adjustments to reconcile net loss to net cash used in operating activities: Depreciation expense $ 257 $ 3 $ 260 Non-cash lease expense — 309 309 Changes in operating assets and liabilities: Accrued expenses and other current liabilities ( 538 ) ( 241 ) ( 779 ) Cash flows from financing activities Other ( 368 ) 135 ( 233 ) Supplemental disclosure of noncash investing and financing activities: Right-of-use assets obtained in exchange for lease liabilities — 18,634 18,634 In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), 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. This guidance is effective for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022, with early adoption permitted. The Company adopted this guidance on January 1, 2022 . There is no impact to the consolidated balance sheets as of December 31, 2022 because of the full valuation allowance position taken for deferred taxes.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
Balance Sheet Components	Mar. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Note 3—Balance Sheet Components Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, Prepaid research and development $ 4,710 $ 4,840 Prepaid clinical trial 2,568 2,119 Deferred offering costs 724 724 Prepaid insurance 373 388 Prepaid bonus 26 18 Other 532 448 Total prepaid expenses and other current assets $ 8,933 $ 8,537 Property, plant and equipment, net consisted of the following (in thousands): March 31, December 31, Leasehold improvements $ 2,091 $ 2,091 Laboratory equipment 2,868 2,868 Computer equipment 1,115 1,115 Furniture and fixtures 908 898 Construction in progress 9,633 9,633 16,615 16,605 Accumulated depreciation ( 1,973 ) ( 1,642 ) Property, plant and equipment, net $ 14,642 $ 14,963 In November 2022, the Company recognized a non-cash impairment charge of $ 36.4 million for the manufacturing facility asset group, of which $ 26.3 million relates to construction in progress and finance lease right-of-use assets. The impairment charge was estimated using a discounted cash flow model and recorded in the consolidated statements of operations for the year ended December 31, 2022. Property, plant and equipment, net includes $ 1.2 million and $ 1.3 million of assets capitalized as finance leases as of March 31, 2023 and December 31, 2022, respectively. Depreciation expense was $ 0.3 million and $ 0.3 million for the three months ended March 31, 2023 and 2022, respectively. Accrued expenses and other current liabilities consisted of the following (in thousands): March 31, December 31, Accrued research and development $ 6,451 $ 8,190 Accrued severance 3,027 1,463 Accrued clinical trial 2,462 1,473 Lease liabilities, current portion 1,752 1,521 Accrued compensation 1,242 2,519 Accrued professional and consulting fees 866 390 Accrued property, plant and equipment 112 2,081 Other 690 650 Total accrued expenses and other current liabilities $ 16,602 $ 18,287

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2023
Leases [Abstract]
Leases	Note 4— Leases The Company leases certain office, laboratory, and manufacturing space. Dallas Lease On January 11, 2021, the Company entered into a lease agreement (the “Dallas Lease”) with Pegasus Park, LLC, a Delaware limited liability company (the “Dallas Landlord”), pursuant to which the Company will lease approximately 15,000 square feet of office space at 3000 Pegasus Park Drive, Dallas, Texas 75247 (the “Office Space”). The Dallas Lease commenced on May 27, 2021 , and has a term of approximately ten years . The Company has an option to extend the term of the Dallas Lease for one additional period of five years. The Company has a right of first refusal with respect to certain additional adjacent office space before the Dallas Landlord accepts any offer for such space. The Dallas Landlord has the right to terminate the Dallas Lease, or the Company’s right to possess the Office Space without terminating the Dallas Lease, upon specified events of default, including the Company’s failure to pay rent in a timely manner and upon the occurrence of certain events of insolvency with respect to the Company. Dallas Lease Expansion On December 14, 2021, the Company amended the Dallas Lease (the “Dallas Lease Amendment”) with the Dallas Landlord, pursuant to which the Company will lease approximately 18,000 square feet of office space adjacent to the Office Space at 3000 Pegasus Park Drive, Dallas, Texas 75247 (the “Expansion Premises”). The Dallas Lease Amendment commenced on July 1, 2022, and has a term of approximately ten years . The Company is obligated to pay operating costs and utilities applicable to the Expansion Premises. Total future minimum lease payments under the Dallas Lease Amendment over the initial 10 year term are approximately $ 6.0 million. The Company will be responsible for costs of constructing interior improvements within the Expansion Premises that exceed a $ 40.00 per rentable square foot construction allowance provided by the Dallas Landlord. The Company has a right of first refusal with respect to certain additional office space on the 15 th floor at 3000 Pegasus Park Drive, Dallas, Texas 75247 before the Dallas Landlord accepts any offer for such space. Durham Lease On December 17, 2020, the Company entered into a lease agreement (the “Durham Lease”) with Patriot Park Partners II, LLC, a Delaware limited liability company (the “Durham Landlord”), pursuant to which the Company agreed to lease approximately 187,500 square feet of a manufacturing facility located at 5 National Way, Durham, North Carolina (the “Facility”). The Durham Lease commenced on April 1, 2021 and is expected to have a term of approximately fifteen years and six months . The Company has two options to extend the term of the Durham Lease, each for a period of an additional five years . The Company was not required to provide a security deposit in connection with its entry into the Durham Lease. The Company will be responsible for constructing interior improvements within the Facility. The Company was required to place $ 2.6 million in an escrow account which will be released when the improvements are substantially complete. The escrow funds are recorded as restricted cash on the condensed consolidated balance sheet as of March 31, 2023. The Durham Landlord has the right to terminate the Durham Lease upon specified events of default, including the Company’s failure to pay rent in a timely manner and upon the occurrence of certain events of insolvency with respect to the Company. Summary of all lease costs recognized under ASC 842 The following table summarizes the lease costs recognized under ASC 842 and other information pertaining to the Company's operating leases for the three months ended March 31, 2023 and 2022 (in thousands): For the Three Months Ended March 31, 2023 2022 Operating lease cost $ 708 $ 535 Variable lease cost 243 194 Total lease cost $ 951 $ 729 Supplemental information related to the remaining lease term and discount rate are as follows: March 31, 2023 December 31, 2022 Weighted average remaining lease term (in years) - Finance leases 3.63 3.88 Weighted average remaining lease term (in years) - Operating leases 11.27 11.45 Weighted average discount rate - Finance leases 10.51 % 10.51 % Weighted average discount rate - Operating leases 7.74 % 7.72 % Supplemental cash flow information related to the Company's operating leases are as follows (in thousands): For the three months ended March 31, 2023 2022 Operating cash flows for operating leases $ 692 $ 363 As of March 31, 2023, future minimum commitments under ASC 842 under the Company's operating and finance leases were as follows (in thousands): Year Ending December 31, Operating Finance 2023 $ 2,255 $ 341 2024 2,918 454 2025 3,021 454 2026 2,485 399 2027 2,577 — Thereafter 19,721 — Total lease payments 32,977 1,648 Less: imputed interest ( 11,625 ) ( 311 ) Total lease liabilities $ 21,352 $ 1,337 Lease liabilities, current 1,424 328 Lease liabilities, non-current 19,928 1,009 Total lease liabilities $ 21,352 $ 1,337 In 2021, the Company signed a lease agreement pursuant to which the Company will lease equipment to generate its supply of electricity, which has not yet commenced for accounting purposes as of March 31, 2023. This lease agreement provides for total remaining lease payments of $ 3.5 million over the 10 -year lease term, which is not included in the maturity table above.

Astellas Agreements

Astellas Agreements	3 Months Ended
Astellas Agreements	Mar. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Astellas Agreements	Note 7—Research, Collaboration and License Agreements UT Southwestern Agreement On November 19, 2019, the Company entered into a research, collaboration and license agreement (“UT Southwestern Agreement”) with the Board of Regents of the University of Texas System on behalf of The University of Texas Southwestern Medical Center (“UT Southwestern”). Under the UT Southwestern Agreement, UT Southwestern is primarily responsible for preclinical development activities with respect to licensed products for use in certain specified indications (up to investigational new drug application-enabling studies), and the Company is responsible for all subsequent clinical development and commercialization activities with respect to the licensed products. UT Southwestern will conduct such preclinical activities for a two-year period under mutually agreed upon sponsored research agreements that were entered into beginning in April 2020. During the initial research phase, the Company has the right to expand the scope of specified indications under the UT Southwestern Agreement. In connection with the UT Southwestern Agreement, the Company obtained an exclusive, worldwide, royalty-free license under certain patent rights of UT Southwestern and a non-exclusive, worldwide, royalty-free license under certain know-how of UT Southwestern, in each case to make, have made, use, sell, offer for sale and import licensed products for use in certain specified indications. Additionally, the Company obtained a non-exclusive, worldwide, royalty-free license under certain patents and know-how of UT Southwestern for use in all human uses, with a right of first refusal to obtain an exclusive license under certain of such patent rights and an option to negotiate an exclusive license under other of such patent rights. The Company is required to use commercially reasonable efforts to develop, obtain regulatory approval for, and commercialize at least one licensed product. On April 2, 2020, the Company amended the UT Southwestern Agreement to include the addition of another licensed product and certain indications, and a right of first refusal to the Company over certain patient dosing patents. No additional consideration was transferred in connection with this amendment. In March 2022, the Company and UT Southwestern mutually agreed to revise the payment schedules and current performance expectations of the current sponsored research agreements under the UT Southwestern Agreement and defer payments by fifteen months. The UT Southwestern Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last valid claim of a licensed patent in such country for such licensed product. After the initial research term, the Company may terminate the agreement, on an indication-by-indication and licensed product-by-licensed product basis, at any time upon specified written notice to UT Southwestern. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. In November 2019, as partial consideration for the license rights granted under the UT Southwestern Agreement, the Company issued 2,179,000 shares of its common stock, or 20 % of its then outstanding fully-diluted common stock, to UT Southwestern. The Company does not have any future milestone or royalty obligations to UT Southwestern under the UT Southwestern Agreement other than costs related to maintenance of patents. Queen’s Agreement On February 21, 2020, the Company entered into a license agreement with Queen’s (the “Queen’s Agreement”) to obtain the exclusive perpetual, royalty-bearing license, with the right to sublicense through multiple tiers, under certain patent rights and know-how of Queen’s, including certain improvements to such patent rights and know-how, to develop products in any field which use one or more valid claims of the patents licensed under the Queen’s Agreement (the “Licensed Patents”), or the technology, information and intellectual property related to the patents licensed under the Queen’s Agreement (together with the Licensed Patents, the “Licensed Products”), and to make, have made, use, sell, offer for sale, import and export Licensed Products and otherwise exploit such patents and know-how for use in certain specified indications. In exchange for the rights granted to the Company, the Company made a cash payment of $ 3.0 million in April 2020 which was recorded within research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license does not have an alternative future use. The Company is obligated to make aggregate cash payments of up to $ 10.0 million upon the completion of a combination of regulatory milestones and up to $ 10.0 million upon the completion of a combination of commercial milestones. In further consideration of the rights granted, beginning with the Company’s first commercial sale of the Licensed Products, the Company will also pay an annual earned royalty in the low single digits on net sales of Licensed Products, subject to certain customary reductions, and a percentage of non-royalty sublicensing revenue ranging in the low double digits. Royalties are payable, on a Licensed Products-by-Licensed Products and a country-by-country basis, until expiration of the last valid claim of a Licensed Patent covering such Licensed Products in such country and the expiration of any regulatory exclusivity for such Licensed Products in such country. No additional milestone payments were made in connection with the Queen’s Agreement during the three months ended March 31, 2023. Abeona CLN1 Agreements In August 2020, the Company entered into license and inventory purchase agreements (collectively, the “Abeona Agreements”) with Abeona Therapeutics Inc. (“Abeona”) for worldwide exclusive rights to certain intellectual property rights and know-how relating to the research, development and manufacture of ABO-202, an AAV-based gene therapy for CLN1 disease (also known as infantile Batten disease). Under the terms of the Abeona Agreements, the Company made initial cash payments to Abeona of $ 3.0 million for the license fee and $ 4.0 million for purchase of clinical materials and reimbursement for previously incurred development costs in October 2020. In exchange for the license rights, the Company recorded an aggregate of $ 7.0 million within research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license or acquired inventory do not have an alternative future use. The Company is obligated to make up to $ 26.0 million in regulatory-related milestones and up to $ 30.0 million in sales-related milestones per licensed CLN1 product. The Company will also pay an annual earned royalty in the high single digits on net sales of any licensed CLN1 products. The license agreement with Abeona (the “Abeona License Agreement”) expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the Abeona License Agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the Abeona License Agreement for convenience upon specified prior written notice to Abeona. In December 2021, a regulatory milestone was triggered in connection with this agreement and therefore the Company recorded $ 3.0 million within research and development expenses in the consolidated statements of operations for the year ended December 31, 2021. The milestone fee was paid in January 2022 and classified as an investing cash outflow in the condensed consolidated statements of cash flows for the three months ended March 31, 2022. No additional milestone payments were triggered in connection with this agreement during the three months ended March 31, 2023. Abeona Rett Agreement On October 29, 2020, the Company entered into a license agreement (the “Abeona Rett Agreement”) with Abeona pursuant to which the Company obtained an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses under certain patents, know-how and materials originally developed by the University of North Carolina at Chapel Hill, the University of Edinburgh and Abeona to research, develop, manufacture, have manufactured, use, and commercialize licensed products for gene therapy and the use of related transgenes for Rett syndrome. Subject to certain obligations of Abeona, the Company is required to use commercially reasonable efforts to develop at least one licensed product and commercialize at least one licensed product in the United States. In connection with the Abeona Rett Agreement, the Company paid Abeona a one-time upfront license fee of $ 3.0 million which was recorded in research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license does not have an alternative future use. The Company is obligated to pay Abeona up to $ 26.5 million in regulatory-related milestones and up to $ 30.0 million in sales-related milestones per licensed Rett product and high single-digit royalties on net sales of licensed Rett products. Royalties are payable on a licensed product-by-licensed product and country-by-country basis until the latest of the expiration or revocation or complete rejection of the last licensed patent covering such licensed product in the country where the licensed product is sold, the loss of market exclusivity in such country where the product is sold, or, if no licensed product exists in such country and no market exclusivity exists in such country, ten years from first commercial sale of such licensed product in such country. The Abeona Rett Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the agreement for convenience upon specified prior written notice to Abeona. In March 2022, the Company’s clinical trial application ("CTA") filing for TSHA-102 for the treatment of Rett Syndrome was approved by Health Canada and therefore triggered a regulatory milestone payment in connection with this agreement. The Company recorded $ 1.0 million within research and development expenses in the condensed consolidated statements of operations for the three months ended March 31, 2022. The $ 1.0 million regulatory milestone fee was paid in July 2022. No additional milestone payments were made in connection with this agreement during the three months ended March 31, 2023. Acquisition of Worldwide Rights for TSHA-120 for the treatment of GAN In March 2021, the Company acquired the exclusive worldwide rights to a clinical-stage AAV9 gene therapy program, now known as TSHA-120, for the treatment of Giant Axonal Neuropathy (“GAN”). TSHA-120 is an intrathecally dosed AAV9 gene therapy currently being evaluated in a clinical trial for the treatment of GAN. The trial is being conducted by the National Institutes of Health (“NIH”) in close collaboration with a leading patient advocacy group focused on finding treatments and cures for GAN. TSHA-120 has received rare pediatric disease and orphan drug designations from the U.S. Food and Drug Administration for the treatment of GAN. The worldwide rights were acquired through a license agreement, effective March 29, 2021, between Hannah’s Hope Fund for Giant Axonal Neuropathy, Inc. (“HHF”) and the Company (the “GAN Agreement”). Under the terms of the GAN Agreement, in exchange for granting the Company the exclusive worldwide rights to TSHA-120, HHF received an upfront payment of $ 5.5 million and will be eligible to receive clinical, regulatory and commercial milestones totaling up to $ 19.3 million, as well as a low, single-digit royalty on net sales upon commercialization of the product. No additional milestone payments were made in connection with the GAN Agreement during the three months ended March 31, 2023. License Agreement for CLN7 In March 2022, the Company entered into a license agreement with UT Southwestern (the “CLN7 Agreement”) pursuant to which the Company obtained an exclusive worldwide, royalty-bearing license with right to grant sublicenses to develop, manufacture, use, and commercialize licensed products for gene therapy for CLN7, a form of Batten Disease. In connection with the CLN7 Agreement, the Company paid a one-time upfront license fee of $ 0.3 million. The Company recorded the upfront license fee in research and development expense in the condensed consolidated statements of operations since the acquired license does not have an alternative future use. The Company is obligated to pay UT Southwestern up to $ 7.7 million in regulatory-related milestones and up to $ 7.5 million in sales-related milestones, as well as a low, single-digit royalty on net sales upon commercialization of the product. No additional milestone payments were made in connection with this agreement during the three months ended March 31, 2023.
Astellas
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Astellas Agreements	Note 5—Astellas Agreements On October 21, 2022 (the “Effective Date”), the Company entered into the Option Agreement with Astellas, pursuant to which the Company granted to Astellas an exclusive option to obtain an exclusive, worldwide, royalty and milestone-bearing right and license (A) to research, develop, make, have made, use, sell, offer for sale, have sold, import, export and otherwise exploit, or, collectively, exploit, the product known, as of the Effective Date, as TSHA-120 (the “120 GAN Product”), and any backup products with respect thereto for use in the treatment of GAN or any other gene therapy product for use in the treatment of GAN that is controlled by Taysha or any of its affiliates or with respect to which the Company or any of its affiliates controls intellectual property rights covering the exploitation thereof, or a GAN Product, and (B) under any intellectual property rights controlled by Taysha or any of its affiliates with respect to such exploitation (the “GAN Option”). Subject to certain extensions, the GAN Option is exercisable from the Effective Date through a specified period of time following Astellas’ receipt of (i) the formal minutes from the Type B end-of-Phase 2 meeting between Taysha and the FDA in response to the Company’s meeting request sent to the FDA on September 19, 2022 for the 120 GAN Product (the “Type B end-of-Phase 2 Meeting”), (ii) all written feedback from the FDA with respect to the Type B end-of-Phase 2 Meeting, and (iii) all briefing documents sent by Taysha to the FDA with respect to the Type B end-of-Phase 2 Meeting. Under the Option Agreement, the Company also granted to Astellas an exclusive option to obtain an exclusive, worldwide, royalty and milestone-bearing right and license (A) to exploit any Rett Product (as defined below), and (B) under any intellectual property rights controlled by Taysha or any of its affiliates with respect to such exploitation (the “Rett Option,” and together with the GAN Option, each, an “Option”). Subject to certain extensions, the Rett Option is exercisable from the Effective Date through a specified period of time following Astellas’ receipt of (i) certain clinical data from the female pediatric trial and (ii) certain specified data with respect to TSHA-102, such period, the Rett Option Period, related to (i) the product known, as of the Effective Date, as TSHA-102 and any backup products with respect thereto for use in the treatment of Rett syndrome, and (ii) any other gene therapy product for use in the treatment of Rett syndrome that is controlled by Taysha or any of its affiliates or with respect to which the Company or any of its affiliates controls intellectual property rights covering the exploitation thereof (a “Rett Product”). The parties have agreed that, if Astellas exercises an Option, the parties will, for a specified period, negotiate a license agreement in good faith on the terms and conditions outlined in the Option Agreement, including payments by Astellas of a to be determined upfront payment, certain to be determined milestone payments, and certain to be determined royalties on net sales of GAN Products and/or Rett Products, as applicable. During the Rett Option Period, the Company has agreed to (A) not solicit or encourage any inquiries, offers or proposals for, or that could reasonably be expected to lead to, a Change of Control (as defined in the Option Agreement), or (B) otherwise initiate a process for a potential Change of Control, in each case, without first notifying Astellas and offering Astellas the opportunity to submit an offer or proposal to the Company for a transaction that would result in a Change of Control. If Astellas fails or declines to submit any such offer within a specified period after the receipt of such notice, the Company will have the ability to solicit third party bids for a Change of Control transaction. If Astellas delivers an offer to the Company for a transaction that would result in a Change of Control, the Company and Astellas will attempt to negotiate in good faith the potential terms and conditions for such potential transaction that would result in a Change of Control for a specified period, which period may be shortened or extended by mutual agreement. As partial consideration for the rights granted to Astellas under the Option Agreement, Astellas paid the Company the Upfront Payment, which is $ 20.0 million. Astellas or any of its affiliates shall have the right, in its or their discretion and upon written notice to the Company, to offset the amount of the Upfront Payment (in whole or in part, until the full amount of the Upfront Payment has been offset) against (a) any payment(s) owed to Taysha or any of its affiliates (or to any third party on behalf of the Company) under or in connection with any license agreement entered into with respect to any GAN Product or Rett Product, including, any upfront payment, milestone payment or royalties owed to Taysha or any of its affiliates (or to any third party on behalf of the Company) under or in connection with any such license agreement or (b) any amount owed to Taysha or any of its affiliates in connection with a Change of Control transaction with Astellas or any of its affiliates. As further consideration for the rights granted to Astellas under the Option Agreement, the Company and Astellas also entered into the Securities Purchase Agreement. Securities Purchase Agreement On October 21, 2022, the Company entered into the Securities Purchase Agreement with Astellas, pursuant to which the Company agreed to issue and sell to Astellas in a private placement (the “Private Placement”), an aggregate of 7,266,342 shares (the “Private Placement Shares”), of its common stock, for aggregate gross proceeds of $ 30.0 million. The Private Placement closed on October 24, 2022. Pursuant to the Securities Purchase Agreement, in connection with the Private Placement, Astellas has the right to designate one individual to attend all meetings of the Board in a non-voting observer capacity. The Company also granted Astellas certain registration rights with respect to the Private Placement Shares. Accounting Treatment In October 2022, upon closing of the Private Placement and transferring the 7,266,342 shares to Astellas, the Company recorded the issuance of shares at fair value. Fair value of the shares transferred to Astellas was calculated in accordance with ASC 820, Fair Value Measurement by analyzing the Company's stock price for a short period of time prior to and after the transaction date as traded on the NASDAQ. The NASDAQ trading data is considered an active market and a Level 1 measurement under ASC 820. The fair value was determined to be approximately $ 13.95 million or $ 1.92 per share. The $ 16.1 million difference between the $ 30.0 million paid by Astellas and the fair market value of shares issued was allocated to the transaction price of the Option Agreement. The Company determined that the Option Agreement falls within the scope of ASC 606, Revenue from Contracts with Customers as the development of TSHA-102 for the treatment of Rett Syndrome and TSHA-120 for the treatment of GAN are considered ordinary activities for the Company. In accordance with ASC 606, the Company evaluated the Option Agreement and identified three separate performance obligations: (1) option to obtain licensing right to GAN, (2) option to obtain licensing right to Rett and (3) performance of research and development activities in the Rett development plan. The transaction price is determined to be $ 36.1 million which is comprised of the $ 20.0 million Upfront Payment and the $ 16.1 million allocated from the Private Placement. To determine the standalone selling price ("SSP") of the Rett and GAN options, which the Company concluded to be material rights, the Company utilized the probability-weighted expected return (PWERM) method. The PWERM method contemplates the probability and timing of an option exercise. At contract inception, the Company estimated that the probability of exercise was 50 % for each of the GAN and Rett options. The SSP of the Rett research and development activities was estimated using an expected cost plus margin approach. The standalone selling prices of the material rights and Rett research and development activities were then used to proportionately allocate the $ 36.1 million transaction price to the three performance obligations. The $ 36.1 million transaction price was recorded as deferred revenue on the condensed consolidated balance sheet at the inception of the Astellas Transactions. The following table summarizes the allocation of the transaction price to the three performance obligations at contract inception: Transaction Price Allocation Option to obtain license for Rett $ 5,485 Option to obtain license for GAN 2,317 Rett research and development activities 28,257 Total $ 36,059 Revenue allocated to the material rights will be recognized at a point in time when each option period expires or when a decision is made by Astellas to exercise or not exercise each option. Revenue from the Rett research and development activities will be recognized as activities are performed using an input method, according to the costs incurred as related to the total costs expected to be incurred to satisfy the performance obligation. The transfer of control occurs over this time period and is a reliable measure of progress towards satisfying the performance obligation. Research and development services related to this performance obligation are expected to be completed by the first quarter of 2024. During the three months ended March 31, 2023, there were no significant changes to the total estimated costs to be incurred to satisfy the performance obligation associated with the Rett research and development activities. The Company recognized revenue of $ 4.7 million from Rett research and development activities for the three months ended March 31, 2023. The Company had $ 28.9 million of deferred revenue on the condensed consolidated balance sheet as of March 31, 2023. The Company will recognize revenues for these performance obligations as they are satisfied, which for the Rett research and development activities is expected to occur over a period of approximat ely 0.8 years.

Loan with Silicon Valley Bank

Loan with Silicon Valley Bank	3 Months Ended
Loan with Silicon Valley Bank	Mar. 31, 2023
Debt Disclosure [Abstract]
Loan with Silicon Valley Bank	Note 6—Loan with Silicon Valley Bank On August 12, 2021 (the “Closing Date”), the Company entered into a Loan and Security Agreement (the “Term Loan Agreement”), by and among the Company, the lenders party thereto from time to time (the “Lenders”) and Silicon Valley Bank, as administrative agent and collateral agent for the Lenders (“Agent”). The Term Loan Agreement provides for (i) on the Closing Date, $ 40.0 million aggregate principal amount of term loans available through December 31, 2021 , (ii) from January 1, 2022 until September 30, 2022 , an additional $ 20.0 million term loan facility available at the Company’s option upon having three distinct and active clinical stage programs, determined at the discretion of the Agent, at the time of draw, (iii) from October 1, 2022 until March 31, 2023 , an additional $ 20.0 million term loan facility available at the Company’s option upon having three distinct and active clinical stage programs, determined at the discretion of the Agent, at the time of draw and (iv) from April 1, 2023 until December 31, 2023 , an additional $ 20.0 million term loan facility available upon approval by the Agent and the Lenders (collectively, the “Term Loans”). The Company drew $ 30.0 million in term loans on the Closing Date and $ 10.0 million in term loans in December 2021. The Company did no t draw on the two additional $ 20.0 million tranches prior to expiration on September 30, 2022 and March 31, 2023 . The interest rate applicable to the Term Loans is the greater of (a) the WSJ Prime Rate plus 3.75 % or (b) 7.00 % per annum. The Term Loans are interest only from the Closing Date through August 31, 2024, after which the Company is required to pay equal monthly installments of principal through August 1, 2026 , the maturity date. The Term Loans may be prepaid in full through August 12, 2023 with payment of a 1.00 % prepayment premium, after which they may be prepaid in full with no prepayment premium. An additional final payment of 7.5 % of the amount of Terms Loans advanced by the Lenders (“Exit Fee”) will be due upon prepayment or repayment of the Term Loans in full. The Exit Fee of $ 3.0 million was recorded as debt discount and has also been fully accrued within non-current liabilities as of March 31, 2023. The debt discount is being accreted using the effective interest method over the term of the Term Loans within interest expense in the condensed consolidated statements of operations. The obligations under the Term Loan Agreement are secured by a perfected security interest in all of the Company’s assets except for intellectual property and certain other customarily excluded property pursuant to the terms of the Term Loan Agreement. There are no financial covenants and no warrants associated with the Term Loan Agreement. The Term Loan Agreement contains various covenants that limit the Company’s ability to engage in specified types of transactions without the consent of the Lenders which include, among others, incurring or assuming certain debt; merging, consolidating or acquiring all or substantially all of the capital stock or property of another entity; changing the nature of the Company’s business; changing the Company’s organizational structure or type; licensing, transferring or disposing of certain assets; granting certain types of liens on the Company’s assets; making certain investments; and paying cash dividends. The Term Loan Agreement also contains customary representations and warranties, and also includes customary events of default, including payment default, breach of covenants, change of control, and material adverse effects. The Company was in compliance with all covenants under the Term Loan Agreement as of March 31, 2023. Upon the occurrence of an event of default, a default interest rate of an additional 5 % per annum may be applied to the outstanding loan balances, and the Lenders may declare all outstanding obligations immediately due and payable and exercise all of its rights and remedies as set forth in the Term Loan Agreement and under applicable law. During the three months ended March 31, 2023, the Company recognized interest expense related to the Term Loan of $ 1.3 million. Future principal debt payments on the loan payable as of March 31, 2023 are as follows (in thousands): Year Ending December 31, 2023 $ — 2024 6,667 2025 20,000 2026 13,333 Total principal payments 40,000 Unamortized debt discount ( 1,839 ) Term Loan, net $ 38,161 On March 10, 2023, Silicon Valley Bank, based in Santa Clara, California, was closed by the California Department of Financial Protection and Innovation, which appointed the Federal Deposit Insurance Corporation (“FDIC”) as receiver. On March 27, 2023, First Citizens Bank purchased the remaining assets, deposits and loans of Silicon Valley Bank.

Research, Collaboration and Lic

Research, Collaboration and License Agreements	3 Months Ended
Research, Collaboration and License Agreements	Mar. 31, 2023
Research Collaboration And License Agreements [Abstract]
Research, Collaboration and License Agreements	Note 7—Research, Collaboration and License Agreements UT Southwestern Agreement On November 19, 2019, the Company entered into a research, collaboration and license agreement (“UT Southwestern Agreement”) with the Board of Regents of the University of Texas System on behalf of The University of Texas Southwestern Medical Center (“UT Southwestern”). Under the UT Southwestern Agreement, UT Southwestern is primarily responsible for preclinical development activities with respect to licensed products for use in certain specified indications (up to investigational new drug application-enabling studies), and the Company is responsible for all subsequent clinical development and commercialization activities with respect to the licensed products. UT Southwestern will conduct such preclinical activities for a two-year period under mutually agreed upon sponsored research agreements that were entered into beginning in April 2020. During the initial research phase, the Company has the right to expand the scope of specified indications under the UT Southwestern Agreement. In connection with the UT Southwestern Agreement, the Company obtained an exclusive, worldwide, royalty-free license under certain patent rights of UT Southwestern and a non-exclusive, worldwide, royalty-free license under certain know-how of UT Southwestern, in each case to make, have made, use, sell, offer for sale and import licensed products for use in certain specified indications. Additionally, the Company obtained a non-exclusive, worldwide, royalty-free license under certain patents and know-how of UT Southwestern for use in all human uses, with a right of first refusal to obtain an exclusive license under certain of such patent rights and an option to negotiate an exclusive license under other of such patent rights. The Company is required to use commercially reasonable efforts to develop, obtain regulatory approval for, and commercialize at least one licensed product. On April 2, 2020, the Company amended the UT Southwestern Agreement to include the addition of another licensed product and certain indications, and a right of first refusal to the Company over certain patient dosing patents. No additional consideration was transferred in connection with this amendment. In March 2022, the Company and UT Southwestern mutually agreed to revise the payment schedules and current performance expectations of the current sponsored research agreements under the UT Southwestern Agreement and defer payments by fifteen months. The UT Southwestern Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last valid claim of a licensed patent in such country for such licensed product. After the initial research term, the Company may terminate the agreement, on an indication-by-indication and licensed product-by-licensed product basis, at any time upon specified written notice to UT Southwestern. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. In November 2019, as partial consideration for the license rights granted under the UT Southwestern Agreement, the Company issued 2,179,000 shares of its common stock, or 20 % of its then outstanding fully-diluted common stock, to UT Southwestern. The Company does not have any future milestone or royalty obligations to UT Southwestern under the UT Southwestern Agreement other than costs related to maintenance of patents. Queen’s Agreement On February 21, 2020, the Company entered into a license agreement with Queen’s (the “Queen’s Agreement”) to obtain the exclusive perpetual, royalty-bearing license, with the right to sublicense through multiple tiers, under certain patent rights and know-how of Queen’s, including certain improvements to such patent rights and know-how, to develop products in any field which use one or more valid claims of the patents licensed under the Queen’s Agreement (the “Licensed Patents”), or the technology, information and intellectual property related to the patents licensed under the Queen’s Agreement (together with the Licensed Patents, the “Licensed Products”), and to make, have made, use, sell, offer for sale, import and export Licensed Products and otherwise exploit such patents and know-how for use in certain specified indications. In exchange for the rights granted to the Company, the Company made a cash payment of $ 3.0 million in April 2020 which was recorded within research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license does not have an alternative future use. The Company is obligated to make aggregate cash payments of up to $ 10.0 million upon the completion of a combination of regulatory milestones and up to $ 10.0 million upon the completion of a combination of commercial milestones. In further consideration of the rights granted, beginning with the Company’s first commercial sale of the Licensed Products, the Company will also pay an annual earned royalty in the low single digits on net sales of Licensed Products, subject to certain customary reductions, and a percentage of non-royalty sublicensing revenue ranging in the low double digits. Royalties are payable, on a Licensed Products-by-Licensed Products and a country-by-country basis, until expiration of the last valid claim of a Licensed Patent covering such Licensed Products in such country and the expiration of any regulatory exclusivity for such Licensed Products in such country. No additional milestone payments were made in connection with the Queen’s Agreement during the three months ended March 31, 2023. Abeona CLN1 Agreements In August 2020, the Company entered into license and inventory purchase agreements (collectively, the “Abeona Agreements”) with Abeona Therapeutics Inc. (“Abeona”) for worldwide exclusive rights to certain intellectual property rights and know-how relating to the research, development and manufacture of ABO-202, an AAV-based gene therapy for CLN1 disease (also known as infantile Batten disease). Under the terms of the Abeona Agreements, the Company made initial cash payments to Abeona of $ 3.0 million for the license fee and $ 4.0 million for purchase of clinical materials and reimbursement for previously incurred development costs in October 2020. In exchange for the license rights, the Company recorded an aggregate of $ 7.0 million within research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license or acquired inventory do not have an alternative future use. The Company is obligated to make up to $ 26.0 million in regulatory-related milestones and up to $ 30.0 million in sales-related milestones per licensed CLN1 product. The Company will also pay an annual earned royalty in the high single digits on net sales of any licensed CLN1 products. The license agreement with Abeona (the “Abeona License Agreement”) expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the Abeona License Agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the Abeona License Agreement for convenience upon specified prior written notice to Abeona. In December 2021, a regulatory milestone was triggered in connection with this agreement and therefore the Company recorded $ 3.0 million within research and development expenses in the consolidated statements of operations for the year ended December 31, 2021. The milestone fee was paid in January 2022 and classified as an investing cash outflow in the condensed consolidated statements of cash flows for the three months ended March 31, 2022. No additional milestone payments were triggered in connection with this agreement during the three months ended March 31, 2023. Abeona Rett Agreement On October 29, 2020, the Company entered into a license agreement (the “Abeona Rett Agreement”) with Abeona pursuant to which the Company obtained an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses under certain patents, know-how and materials originally developed by the University of North Carolina at Chapel Hill, the University of Edinburgh and Abeona to research, develop, manufacture, have manufactured, use, and commercialize licensed products for gene therapy and the use of related transgenes for Rett syndrome. Subject to certain obligations of Abeona, the Company is required to use commercially reasonable efforts to develop at least one licensed product and commercialize at least one licensed product in the United States. In connection with the Abeona Rett Agreement, the Company paid Abeona a one-time upfront license fee of $ 3.0 million which was recorded in research and development expenses in the consolidated statements of operations for the year ended December 31, 2020 since the acquired license does not have an alternative future use. The Company is obligated to pay Abeona up to $ 26.5 million in regulatory-related milestones and up to $ 30.0 million in sales-related milestones per licensed Rett product and high single-digit royalties on net sales of licensed Rett products. Royalties are payable on a licensed product-by-licensed product and country-by-country basis until the latest of the expiration or revocation or complete rejection of the last licensed patent covering such licensed product in the country where the licensed product is sold, the loss of market exclusivity in such country where the product is sold, or, if no licensed product exists in such country and no market exclusivity exists in such country, ten years from first commercial sale of such licensed product in such country. The Abeona Rett Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the agreement for convenience upon specified prior written notice to Abeona. In March 2022, the Company’s clinical trial application ("CTA") filing for TSHA-102 for the treatment of Rett Syndrome was approved by Health Canada and therefore triggered a regulatory milestone payment in connection with this agreement. The Company recorded $ 1.0 million within research and development expenses in the condensed consolidated statements of operations for the three months ended March 31, 2022. The $ 1.0 million regulatory milestone fee was paid in July 2022. No additional milestone payments were made in connection with this agreement during the three months ended March 31, 2023. Acquisition of Worldwide Rights for TSHA-120 for the treatment of GAN In March 2021, the Company acquired the exclusive worldwide rights to a clinical-stage AAV9 gene therapy program, now known as TSHA-120, for the treatment of Giant Axonal Neuropathy (“GAN”). TSHA-120 is an intrathecally dosed AAV9 gene therapy currently being evaluated in a clinical trial for the treatment of GAN. The trial is being conducted by the National Institutes of Health (“NIH”) in close collaboration with a leading patient advocacy group focused on finding treatments and cures for GAN. TSHA-120 has received rare pediatric disease and orphan drug designations from the U.S. Food and Drug Administration for the treatment of GAN. The worldwide rights were acquired through a license agreement, effective March 29, 2021, between Hannah’s Hope Fund for Giant Axonal Neuropathy, Inc. (“HHF”) and the Company (the “GAN Agreement”). Under the terms of the GAN Agreement, in exchange for granting the Company the exclusive worldwide rights to TSHA-120, HHF received an upfront payment of $ 5.5 million and will be eligible to receive clinical, regulatory and commercial milestones totaling up to $ 19.3 million, as well as a low, single-digit royalty on net sales upon commercialization of the product. No additional milestone payments were made in connection with the GAN Agreement during the three months ended March 31, 2023. License Agreement for CLN7 In March 2022, the Company entered into a license agreement with UT Southwestern (the “CLN7 Agreement”) pursuant to which the Company obtained an exclusive worldwide, royalty-bearing license with right to grant sublicenses to develop, manufacture, use, and commercialize licensed products for gene therapy for CLN7, a form of Batten Disease. In connection with the CLN7 Agreement, the Company paid a one-time upfront license fee of $ 0.3 million. The Company recorded the upfront license fee in research and development expense in the condensed consolidated statements of operations since the acquired license does not have an alternative future use. The Company is obligated to pay UT Southwestern up to $ 7.7 million in regulatory-related milestones and up to $ 7.5 million in sales-related milestones, as well as a low, single-digit royalty on net sales upon commercialization of the product. No additional milestone payments were made in connection with this agreement during the three months ended March 31, 2023.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
Stock-Based Compensation	Mar. 31, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 8—Stock-Based Compensation On July 1, 2020, the Company’s board of directors approved the 2020 Equity Incentive Plan (“Existing Plan”) which permits the granting of incentive stock options, non-statutory stock options, stock appreciation rights, RSAs, RSUs and other stock-based awards to employees, directors, officers and consultants. As of September 16, 2020, the approval date of the New Plan (as defined below), no additional awards will be granted under the Existing Plan. The terms of the Existing Plan will continue to govern the terms of outstanding equity awards that were granted prior to approval of the New Plan. On September 16, 2020, the Company’s stockholders approved the 2020 Stock Incentive Plan (“New Plan”), which became effective upon the execution of the underwriting agreement in connection with the IPO. The number of shares of common stock reserved for issuance under the New Plan automatically increases on January 1 of each year, for a period of ten years , from January 1, 2021 continuing through January 1, 2030 , by 5 % of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. On January 1, 2023, the Company’s board of directors increased the number of shares of common stock reserved for issuance under the New Plan by 3,160,375 shares. Furthermore, on September 16, 2020, the Company’s stockholders approved the Employee Stock Purchase Plan (“ESPP”), which became effective upon the execution of the underwriting agreement in connection with the IPO. The maximum number of shares of common stock that may be issued under the ESPP will not exceed 362,000 shares of common stock, plus the number of shares of common stock that are automatically added on January 1st of each year for a period of up to ten years , commencing on the first January 1 following the IPO and ending on (and including) January 1, 2030 , in an amount equal to the lesser of (i) one percent ( 1.0 %) of the total number of shares of capital stock outstanding on December 31st of the preceding calendar year, and (ii) 724,000 shares of common stock. No shares were added to the ESPP in 2021. On January 1, 2022 and 2023, the Company’s board of directors increased the number of shares of common stock reserved for issuance under the ESPP by 384,739 and 632,075 respectively. The Company has issued 108,993 shares of common stock under the ESPP as of March 31, 2023. The number of shares available for grant under the Company's incentive plans were as follows: Existing New Plan Plan Total Available for grant - December 31, 2022 — 1,067,682 1,067,682 Plan adjustments and amendments ( 667,828 ) 3,828,203 3,160,375 Grants — ( 1,597,604 ) ( 1,597,604 ) Forfeitures 667,828 1,936,143 2,603,971 Available for grant - March 31, 2023 — 5,234,424 5,234,424 Stock Options For the three months ended March 31, 2023, 1,043,371 shares of common stock under the New Plan were awarded with a weighted-average grant date fair value per sh are of $ 0.85 . The stoc k options vest over four years and have a ten-year contractual term. The following weighted-average assumptions were used to estimate the fair value of time-based vesting stock options that were granted during the three months ended March 31, 2023 and 2022: Three Months Ended March 31, 2023 2022 Risk-free interest rate 3.46 % 1.91 % Expected dividend yield — — Expected term (in years) 6.1 6.1 Expected volatility 81 % 76 % The following table summarizes time-based vesting stock option activity, during the three months ended March 31, 2023: Weighted Weighted Average Aggregate Average Remaining Intrinsic Stock Exercise Contractual Value Options Price Life (in years) (in thousands) Outstanding at December 31, 2022 6,158,078 $ 11.84 8.9 $ 62 Options granted 1,043,371 1.18 — — Options cancelled or forfeited ( 1,765,389 ) 11.50 — — Options expired ( 123,198 ) 24.00 — — Outstanding at March 31, 2023 5,312,862 $ 9.58 8.2 $ — Options exercisable at March 31, 2023 1,401,840 $ 22.18 4.6 $ — The aggregate intrinsic value in the above table is calculated as the difference between the fair value of the Company’s common stock at the respective reporting date and the exercise price of the stock options. As of March 31, 2023, the total unrecognized compensation related to unvested stock option awards granted was $ 12.6 million, which the Company expects to recognize over a weighted-average period of approximately 2.6 y ears. No stock options were exercised during the period. Performance and Market-based Stock Options In February 2023, the Company issued 140,468 stock options to employees under the New Plan that contain a combination of performance and market-based vesting conditions, subject to continued employment through each anniversary and achievement of the market and performance conditions. The grant date fair value of the stock options that contain performance and market-based vesting conditions was not material. As of March 31, 2023, 116,690 of the performance and market-based options were outstanding, and no options vested during the period. Restricted Stock Units In February 2023, the Company issued 81,236 RSUs to employees under the New Plan. T he RSUs are subject to a service-based vesting condition. The service-based RSUs vest in equal annual installments over a four-year period. The Company at any time may accelerate the vesting of the RSUs. Such shares are not accounted for as out standing until they vest. As of March 31, 2023, the total unrecognized compensation related to unvested RSUs granted was $ 3.3 million which is expected to be amortized on a straight-line basis over a weighted-average period of approximately 1.3 years. The Company's default tax withholding method for RSUs is the sell-to-cover method, in which shares with a market value equivalent to the tax withholding obligation are sold on behalf of the holder of the RSUs upon vesting and settlement to cover the tax withholding liability and the cash proceeds from such sales are remitted by the Company to taxing authorities. In March 2023, the Company issued 251,296 RSUs to RA Session II, the former President and Chief Executive officer of the Company in connection with his resignation from the Company and Board of Directors. The RSUs vested immediately. The Company’s RSU activity for the three months ended March 31, 2023 was as follows: Weighted Average Grant Date Number Fair Value of Shares per Share Nonvested at December 31, 2022 1,257,844 $ 6.52 Restricted units granted 332,532 1.06 Vested ( 251,296 ) 1.02 Cancelled or forfeited ( 658,343 ) 5.18 Nonvested at March 31, 2023 680,737 $ 7.18 Performance and Market-based Restricted Stock Units In February 2023, the Company issued 81,233 RSUs to employees under the New Plan that contain a combination of performance and market-based vesting conditions, subject to continued employment through each anniversary and achievement of market and performance conditions. The grant date fair value of the RSUs that contain performance and market-based vesting conditions was not material. As of March 31, 2023, 69,344 of the performance and market-based RSUs were outstanding and no RSUs vested during the period. Restricted Stock Awards RA Session II, the Company’s former President and Chief Executive Officer, was awarded 769,058 RSAs under the Existing Plan on July 1, 2020, which are expected to vest over a three-year term, subject to continuous employment. The fair value of these RSAs at the grant date of July 1, 2020 was $ 5.28 per share. On March 2, 2023, Mr. Session resigned from the Board of Directors, therefore cancelling any unvested tranches. The Company’s RSA activity for the three months ended March 31, 2023 was as follows: Weighted Average Grant Date Number Fair Value of Shares per Share Nonvested at December 31, 2022 85,494 $ 5.28 Restricted stock granted — — Vested ( 64,120 ) 5.28 Cancelled or forfeited ( 21,374 ) 5.28 Nonvested at March 31, 2023 — $ — Employee Stock Purchase Plan In February 2022, the Company’s board of directors authorized the first offering under the ESPP. Under the ESPP, eligible employees may purchase shares of Taysha common stock through payroll deductions at a price equal to 85 % of the lower of the fair market values of the stock as of the beginning or the end of six-month offering periods. An employee’s payroll deductions under the ESPP are limited to 15 % of the employee’s compensation and employees may not purchase more than 1,800 of shares of Taysha common stock during any offering period. During the three months ended March 31, 2023 and 2022, stock-based compensation expense related to the ESPP was not material. The following table summarizes the total stock-based compensation expense for the stock options, ESPP, RSAs and RSUs recorded in the condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022 (in thousands): For the Three Months Ended March 31, 2023 2022 Research and development expense $ ( 263 ) $ 2,577 General and administrative expense 1,938 2,752 Total $ 1,675 $ 5,329

Net Loss Per Common Share

Net Loss Per Common Share	3 Months Ended
Net Loss Per Common Share	Mar. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Common Share	Note 9—Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. Since the Company had a net loss in all periods presented, basic and diluted net loss per common share are the same. The following table represents the calculation of basic and diluted net loss per common share (in thousands, except share and per share data): For the Three Months Ended March 31, 2023 2022 Net loss $ ( 17,622 ) $ ( 50,317 ) Weighted-average shares of common stock outstanding used to compute net loss per common share, basic and diluted 63,260,905 38,174,717 Net loss per common share, basic and diluted $ ( 0.28 ) $ ( 1.32 ) The following common stock equivalents outstanding as of March 31, 2023 and 2022 were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti‑dilutive: March 31, March 31, Unvested RSUs 750,081 1,886,765 Unvested RSAs — 277,855 Stock options 5,429,552 5,437,837 Total 6,179,633 7,602,457

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Note 10—Income Taxes Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. There is no provision for income taxes because the Company has incurred operating losses and capitalized certain items for income tax purposes since its inception and maintains a full valuation allowance against its net deferred tax assets. The reported amount of income tax expense for the period differs from the amount that would result from applying the federal statutory tax rate to net loss before taxes primarily because of the change in valuation allowance. As of March 31, 2023, there were no material changes to either the nature or the amounts of the uncertain tax positions previously determined for the year ended December 31, 2022.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2023
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 11—Commitments and Contingencies Litigation The Company is not a party to any material legal proceedings and is not aware of any pending or threatened claims. From time to time, the Company may be subject to various legal proceedings and claims that arise in the ordinary course of its business activities. Commitments In the normal course of business, the Company enters into contracts that contain a variety of indemnifications with its employees, licensors, suppliers and service providers. The Company’s maximum exposure under these arrangements is unknown at March 31, 2023. The Company does not anticipate recognizing any significant losses relating to these arrangements.

Strategic Reprioritization

Strategic Reprioritization	3 Months Ended
Strategic Reprioritization	Mar. 31, 2023
Restructuring And Related Activities [Abstract]
Strategic Reprioritization	Note 12 – Strategic Reprioritization In March 2022, the Company implemented changes to the Company’s organizational structure as well as a broader operational cost reduction plan to enable the Company to focus on specific clinical-stage programs for GAN and Rett syndrome. Substantially all other research and development activities have been paused to increase operational efficiency. In connection with prioritization of programs, the Company reduced headcount by approximately 35 % across all functions in March 2022. In accordance with ASC 420, Exit and Disposal Activities, the Company recorded one-time severance and termination-related costs of $ 2.6 million in the condensed consolidated statements of operations for the three months ended March 31, 2022, primarily within research and development expenses. In December 2022 and throughout the first quarter of 2023, the Company further reduced headcount and recorded additional one-time severance and termination related costs of $ 2.7 million within research and development and general and administrative expenses. The Company expects payment of these costs to be complete by March 31, 2024. The amount of accrued severance recorded as of March 31, 2023 is as follows (amounts in thousands): As of March 31, 2023 Accrued severance balance as of December 31, 2022 $ 1,463 Severance recorded 2,691 Severance paid ( 1,127 ) Accrued severance balance as of March 31, 2023 $ 3,027

Retirement Plan

Retirement Plan	3 Months Ended
Retirement Plan	Mar. 31, 2023
Compensation And Retirement Disclosure [Abstract]
Retirement Plan	Note 13 – Retirement Plan In July 2021, the Company adopted a 401(k) retirement savings plan that provides retirement benefits to all full-time employees. Eligible employees may contribute a percentage of their annual compensation, subject to Internal Revenue Service limitations. The Company contributed $ 0.1 million and $ 0.4 million to the 401(k) retirement savings plan for the three months ended March 31, 2023 and 2022, respectively.

Subsequent Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Note 14– Subsequent Events In April 2023, the Company entered into a securities purchase agreement, or the SSI Securities Purchase Agreement, with two affiliates of SSI Strategy Holdings LLC, or SSI, named therein, or the SSI Investors, pursuant to which the Company agreed to issue and sell to the SSI Investors in a private placement, or the SSI Private Placement, 705,218 shares of its common stock, or the SSI Shares, and warrants, or the SSI Warrants, to purchase an aggregate of 525,000 shares of the Company's common stock, or the Warrant Shares. SSI provides certain consulting services to the Company. Each SSI Warrant has an exercise price of $ 0.7090 per Warrant Share, which was the closing price of the Company's common stock on the Nasdaq Global Market on April 4, 2023. The SSI Warrants issued in the SSI Private Placement provide that the holder of the SSI Warrants will not have the right to exercise any portion of its SSI Warrants until the achievement of certain clinical and regulatory milestones related to the Company's clinical programs. The SSI Private Placement closed on April 5, 2023. Gross proceeds of the SSI Private Placement were $ 500,000 . The shares of common stock issued by the Company pursuant to the SSI Securities Purchase Agreement were not initially registered under the Securities Act. The Company relied on the exemption from the registration requirements of the Securities Act under Section 4(a)(2) thereof.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP") as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X and are consistent in all material respects with those included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022, filed with the Securities and Exchange Commission ("SEC") on March 28, 2023 (the “2022 Annual Report”). In the opinion of management, the unaudited condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. The consolidated balance sheet as of December 31, 2022 is derived from audited financial statements, however, it does not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes in the Company’s 2022 Annual Report.
Principles of Consolidation	Principles of Consolidation The accompanying interim condensed consolidated financial statements include the accounts of Taysha and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The most significant estimates and assumptions in the Company’s financial statements relate to the determination of the fair value of the common stock prior to the initial public offering (as an input into stock-based compensation), estimating manufacturing accruals and accrued or prepaid research and development expenses, the measurement of impairment of long-lived assets, and the allocation of consideration received in connection with the Astellas Transactions. These estimates and assumptions are based on current facts, historical experience and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources. Actual results may differ materially from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is equal to net loss as presented in the accompanying condensed consolidated statements of operations.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended, with guidance regarding the accounting for and disclosure of leases. This update requires lessees to recognize the liabilities related to all leases, including operating leases, with a term greater than 12 months on the balance sheets. This update also requires lessees and lessors to disclose key information about their leasing transactions. On December 31, 2022 , the Company adopted ASU 2016-02 using the modified retrospective approach and utilizing the effective date as its date of initial application. The Company has retrospectively changed its previously issued condensed consolidated financial statements as of March 31, 2022 as presented within the Company's March 31, 2022 Quarterly Report on Form 10-Q to reflect the adoption of ASC 842 on January 1, 2022. The condensed consolidated financial statements for the three months ended March 31, 2022 presented herein differ from the Company's condensed consolidated financial statements included in the Company's March 31, 2022 Quarterly Report on Form 10-Q as those condensed consolidated financial statements were prepared using the former accounting standard referred to as ASC Topic 840, Leases. The Company elected the following practical expedients, which must be elected as a package and applied consistently to all of its leases at the transition date (including those for which the entity is a lessee or a lessor): i) the Company did not reassess whether any expired or existing contracts are or contain leases; ii) the Company did not reassess the lease classification for any expired or existing leases (that is, all existing leases that were classified as operating leases in accordance with ASC 840 are classified as operating leases, and all existing leases that were classified as capital leases in accordance with ASC 840 are classified as finance leases); and iii) the Company did not reassess initial direct costs for any existing leases. For leases that existed prior to the date of initial application of ASC 842 (which were previously classified as operating leases), a lessee may elect to use either the total lease term measured at lease inception under ASC 840 or the remaining lease term as of the date of initial application of ASC 842 in determining the period for which to measure its incremental borrowing rate. In transition to ASC 842, the Company utilized the remaining lease term of its leases in determining the appropriate incremental borrowing rates. The adoption of this standard resulted in the recognition of operating lease right-of-use assets and operating lease liabilities of $ 18.4 million and $ 19.1 million, respectively, on the Company’s condensed consolidated balance sheet at adoption relating to its operating leases. The lease liabilities were determined based on the present value of the remaining minimum lease payments. Upon adoption of ASC 842, the Company also (i) derecognized the build-to-suit lease asset of $ 26.3 million previously presented in property, plant and equipment, (ii) derecognized the build-to-suit lease liability of $ 26.5 million, and (iii) eliminated $ 0.7 million of deferred rent liabilities and tenant improvement allowances as of January 1, 2022 as these liabilities are reflected in the operating lease right-of-use assets. In adopting ASU 2016-02, the Company recorded a total one-time adjustment of $ 0.2 million to the opening balance of accumulated deficit as of January 1, 2022 related to the de-recognition of the build-to-suit lease asset and related build-to-suit lease obligation. The adoption did not have a material impact on accumulated deficit and on the condensed consolidated statements of operations and cash flows. The following table summarizes the effect of the adoption of ASC 842 on the condensed consolidated statement of operation and statement of cash flows for the three months ended March 31, 2022 (in thousands): Pre ASC 842 Three Months Ended ASC 842 Adjustments After ASC 842 Three Months Ended Condensed Consolidated Statements of Operations Operating expenses: Research and development $ 37,799 $ 383 $ 38,182 Other income (expense): Interest expense ( 849 ) 177 ( 672 ) Condensed Consolidated Statements of Cash Flows Adjustments to reconcile net loss to net cash used in operating activities: Depreciation expense $ 257 $ 3 $ 260 Non-cash lease expense — 309 309 Changes in operating assets and liabilities: Accrued expenses and other current liabilities ( 538 ) ( 241 ) ( 779 ) Cash flows from financing activities Other ( 368 ) 135 ( 233 ) Supplemental disclosure of noncash investing and financing activities: Right-of-use assets obtained in exchange for lease liabilities — 18,634 18,634 In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), 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. This guidance is effective for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022, with early adoption permitted. The Company adopted this guidance on January 1, 2022 . There is no impact to the consolidated balance sheets as of December 31, 2022 because of the full valuation allowance position taken for deferred taxes.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2023
Accounting Policies [Abstract]
Summary of Effect of the Adoption of ASC 842 on Statement of Operation and Cash Flows	The following table summarizes the effect of the adoption of ASC 842 on the condensed consolidated statement of operation and statement of cash flows for the three months ended March 31, 2022 (in thousands): Pre ASC 842 Three Months Ended ASC 842 Adjustments After ASC 842 Three Months Ended Condensed Consolidated Statements of Operations Operating expenses: Research and development $ 37,799 $ 383 $ 38,182 Other income (expense): Interest expense ( 849 ) 177 ( 672 ) Condensed Consolidated Statements of Cash Flows Adjustments to reconcile net loss to net cash used in operating activities: Depreciation expense $ 257 $ 3 $ 260 Non-cash lease expense — 309 309 Changes in operating assets and liabilities: Accrued expenses and other current liabilities ( 538 ) ( 241 ) ( 779 ) Cash flows from financing activities Other ( 368 ) 135 ( 233 ) Supplemental disclosure of noncash investing and financing activities: Right-of-use assets obtained in exchange for lease liabilities — 18,634 18,634

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
Balance Sheet Components (Tables)	Mar. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, Prepaid research and development $ 4,710 $ 4,840 Prepaid clinical trial 2,568 2,119 Deferred offering costs 724 724 Prepaid insurance 373 388 Prepaid bonus 26 18 Other 532 448 Total prepaid expenses and other current assets $ 8,933 $ 8,537
Schedule of Property Plant and Equipment Net	Property, plant and equipment, net consisted of the following (in thousands): March 31, December 31, Leasehold improvements $ 2,091 $ 2,091 Laboratory equipment 2,868 2,868 Computer equipment 1,115 1,115 Furniture and fixtures 908 898 Construction in progress 9,633 9,633 16,615 16,605 Accumulated depreciation ( 1,973 ) ( 1,642 ) Property, plant and equipment, net $ 14,642 $ 14,963
Schedule of Accrued Expense and Other Current Labilities	Accrued expenses and other current liabilities consisted of the following (in thousands): March 31, December 31, Accrued research and development $ 6,451 $ 8,190 Accrued severance 3,027 1,463 Accrued clinical trial 2,462 1,473 Lease liabilities, current portion 1,752 1,521 Accrued compensation 1,242 2,519 Accrued professional and consulting fees 866 390 Accrued property, plant and equipment 112 2,081 Other 690 650 Total accrued expenses and other current liabilities $ 16,602 $ 18,287

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2023
Leases [Abstract]
Schedule of Lease Cost	The following table summarizes the lease costs recognized under ASC 842 and other information pertaining to the Company's operating leases for the three months ended March 31, 2023 and 2022 (in thousands): For the Three Months Ended March 31, 2023 2022 Operating lease cost $ 708 $ 535 Variable lease cost 243 194 Total lease cost $ 951 $ 729
Schedule of Supplemental Information Related to Remaining Lease Term and Discount Rate	Supplemental information related to the remaining lease term and discount rate are as follows: March 31, 2023 December 31, 2022 Weighted average remaining lease term (in years) - Finance leases 3.63 3.88 Weighted average remaining lease term (in years) - Operating leases 11.27 11.45 Weighted average discount rate - Finance leases 10.51 % 10.51 % Weighted average discount rate - Operating leases 7.74 % 7.72 %
Schedule of Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to the Company's operating leases are as follows (in thousands): For the three months ended March 31, 2023 2022 Operating cash flows for operating leases $ 692 $ 363
Schedule of Future Minimum Commitments Under Company's Operating and Finance Leases	As of March 31, 2023, future minimum commitments under ASC 842 under the Company's operating and finance leases were as follows (in thousands): Year Ending December 31, Operating Finance 2023 $ 2,255 $ 341 2024 2,918 454 2025 3,021 454 2026 2,485 399 2027 2,577 — Thereafter 19,721 — Total lease payments 32,977 1,648 Less: imputed interest ( 11,625 ) ( 311 ) Total lease liabilities $ 21,352 $ 1,337 Lease liabilities, current 1,424 328 Lease liabilities, non-current 19,928 1,009 Total lease liabilities $ 21,352 $ 1,337

Astellas Agreements (Tables)

Astellas Agreements (Tables)	3 Months Ended
Astellas Agreements (Tables)	Mar. 31, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Allocation for Transaction Price to the Three Performance Obligations	The following table summarizes the allocation of the transaction price to the three performance obligations at contract inception: Transaction Price Allocation Option to obtain license for Rett $ 5,485 Option to obtain license for GAN 2,317 Rett research and development activities 28,257 Total $ 36,059

Loan with Silicon Valley Bank (

Loan with Silicon Valley Bank (Tables)	3 Months Ended
Loan with Silicon Valley Bank (Tables)	Mar. 31, 2023
Debt Disclosure [Abstract]
Schedule of Future Principal Debt Payments on Loan Payable	Future principal debt payments on the loan payable as of March 31, 2023 are as follows (in thousands): Year Ending December 31, 2023 $ — 2024 6,667 2025 20,000 2026 13,333 Total principal payments 40,000 Unamortized debt discount ( 1,839 ) Term Loan, net $ 38,161

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
Stock-Based Compensation (Tables)	Mar. 31, 2023
Schedule of Share Based Compensation Available for Grant under Incentive Plans	The number of shares available for grant under the Company's incentive plans were as follows: Existing New Plan Plan Total Available for grant - December 31, 2022 — 1,067,682 1,067,682 Plan adjustments and amendments ( 667,828 ) 3,828,203 3,160,375 Grants — ( 1,597,604 ) ( 1,597,604 ) Forfeitures 667,828 1,936,143 2,603,971 Available for grant - March 31, 2023 — 5,234,424 5,234,424
Schedule of Restricted Stock Units Activity	The Company’s RSU activity for the three months ended March 31, 2023 was as follows: Weighted Average Grant Date Number Fair Value of Shares per Share Nonvested at December 31, 2022 1,257,844 $ 6.52 Restricted units granted 332,532 1.06 Vested ( 251,296 ) 1.02 Cancelled or forfeited ( 658,343 ) 5.18 Nonvested at March 31, 2023 680,737 $ 7.18
Schedule of Restricted Stock Awards Activity	The Company’s RSA activity for the three months ended March 31, 2023 was as follows: Weighted Average Grant Date Number Fair Value of Shares per Share Nonvested at December 31, 2022 85,494 $ 5.28 Restricted stock granted — — Vested ( 64,120 ) 5.28 Cancelled or forfeited ( 21,374 ) 5.28 Nonvested at March 31, 2023 — $ —
Schedule of Total Stock-Based Compensation Expense for Stock Options, ESPP, RSAs and RSUs	The following table summarizes the total stock-based compensation expense for the stock options, ESPP, RSAs and RSUs recorded in the condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022 (in thousands): For the Three Months Ended March 31, 2023 2022 Research and development expense $ ( 263 ) $ 2,577 General and administrative expense 1,938 2,752 Total $ 1,675 $ 5,329
Stock Options
Schedule of Assumptions Used to Estimate Fair Value of Stock Options and Cancelled Options	The following weighted-average assumptions were used to estimate the fair value of time-based vesting stock options that were granted during the three months ended March 31, 2023 and 2022: Three Months Ended March 31, 2023 2022 Risk-free interest rate 3.46 % 1.91 % Expected dividend yield — — Expected term (in years) 6.1 6.1 Expected volatility 81 % 76 %
Schedule of Stock Option Activity	The following table summarizes time-based vesting stock option activity, during the three months ended March 31, 2023: Weighted Weighted Average Aggregate Average Remaining Intrinsic Stock Exercise Contractual Value Options Price Life (in years) (in thousands) Outstanding at December 31, 2022 6,158,078 $ 11.84 8.9 $ 62 Options granted 1,043,371 1.18 — — Options cancelled or forfeited ( 1,765,389 ) 11.50 — — Options expired ( 123,198 ) 24.00 — — Outstanding at March 31, 2023 5,312,862 $ 9.58 8.2 $ — Options exercisable at March 31, 2023 1,401,840 $ 22.18 4.6 $ —

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	3 Months Ended
Net Loss Per Common Share (Tables)	Mar. 31, 2023
Earnings Per Share [Abstract]
Schedule of Calculation of Basic and Diluted Net Loss Per Common Share	The following table represents the calculation of basic and diluted net loss per common share (in thousands, except share and per share data): For the Three Months Ended March 31, 2023 2022 Net loss $ ( 17,622 ) $ ( 50,317 ) Weighted-average shares of common stock outstanding used to compute net loss per common share, basic and diluted 63,260,905 38,174,717 Net loss per common share, basic and diluted $ ( 0.28 ) $ ( 1.32 )
Schedule of Common Stock Equivalents Outstanding Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following common stock equivalents outstanding as of March 31, 2023 and 2022 were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti‑dilutive: March 31, March 31, Unvested RSUs 750,081 1,886,765 Unvested RSAs — 277,855 Stock options 5,429,552 5,437,837 Total 6,179,633 7,602,457

Strategic Reprioritization (Tab

Strategic Reprioritization (Tables)	3 Months Ended
Strategic Reprioritization (Tables)	Mar. 31, 2023
Restructuring And Related Activities [Abstract]
Summary of Accrued Severance Activity Recorded	The Company expects payment of these costs to be complete by March 31, 2024. The amount of accrued severance recorded as of March 31, 2023 is as follows (amounts in thousands): As of March 31, 2023 Accrued severance balance as of December 31, 2022 $ 1,463 Severance recorded 2,691 Severance paid ( 1,127 ) Accrued severance balance as of March 31, 2023 $ 3,027

Organization and Description _2

Organization and Description of Business Operations - Additional Information (Details) - USD ($)			1 Months Ended		3 Months Ended
	Oct. 21, 2022	Oct. 05, 2021	Oct. 31, 2022	Apr. 30, 2022	Mar. 31, 2023	Dec. 31, 2022
Organization and Description of Business Operations [Line Items]
Date of incorporation					Feb. 13, 2020
Common stock, shares issued					63,473,349	63,207,507
Common stock, par value per share					$ 0.00001	$ 0.00001
Accumulated deficit					$ (419,063,000)	$ (401,441,000)
Astellas
Organization and Description of Business Operations [Line Items]
Upfront payment	$ 20,000,000		$ 20,000,000
Gross proceeds including upfront payments			50,000,000
Sales Agreement
Organization and Description of Business Operations [Line Items]
Common stock shares issued and sold					0
Number of shares issued				2,000,000
Net proceeds from issuance of common stock				$ 11,600,000
Sales Agreement \| Sales Agents
Organization and Description of Business Operations [Line Items]
Percentage of gross sales price per share of common stock		3%
Sales Agreement \| Sales Agents \| Maximum
Organization and Description of Business Operations [Line Items]
Aggregate offering price from sale of common stock		$ 150,000,000
Securities Purchase Agreement \| Private Placement \| Astellas
Organization and Description of Business Operations [Line Items]
Net proceeds from issuance of common stock			$ 30,000,000
Common stock, shares issued	7,266,342		7,266,342
Underwriting Agreement
Organization and Description of Business Operations [Line Items]
Net proceeds from issuance of common stock			$ 27,700,000
Common stock, shares issued			14,000,000
Common stock, par value per share			$ 2
Option to purchase additional number of shares			765,226
Underwriter agreed to purchase share price of per share			$ 1.88

Significant Accounting Policies

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Significant Accounting Policies [Line Items]
Operating Lease, Right-of-Use Asset	$ 10,647	$ 10,943
Operating Lease, Liability	21,352
Derecognized build to suite lease asset	26,300
Derecognized build to suit lease liablility	26,500
Deferred rent liabiilities and tenant improvement allowances	700
Accumulated Deficit	$ 200
ASU 2016-02
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Dec. 31, 2022
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Operating Lease, Right-of-Use Asset	$ 18,400
Operating Lease, Liability	$ 19,100
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	false
ASU 2019-12
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2022
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true

Significant Accounting Polici_2

Significant Accounting Policies - Summary of Effect of the Adoption of ASC 842 on Statement of Operation and Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating expenses:
Research and development	$ 12,514	$ 38,182
Other income (expense):
Interest expense	(1,374)	(672)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	331	260
Non-cash lease expense	300	309
Changes in operating assets and liabilities:
Accrued expenses and other current liabilities		(779)
Cash flows from financing activities
Other	$ (33)	(233)
Supplemental disclosure of noncash investing and financing activities:
Right-of-use assets obtained in exchange for lease liabilities		$ 18,634
Accounting Standards Update [Extensible Enumeration]		Accounting Standards Update 2016-02 [Member]
Previously ASC 842
Operating expenses:
Research and development		$ 37,799
Other income (expense):
Interest expense		(849)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense		257
Changes in operating assets and liabilities:
Accrued expenses and other current liabilities		(538)
Cash flows from financing activities
Other		(368)
ASC 842 Adjustments
Operating expenses:
Research and development		383
Other income (expense):
Interest expense		177
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense		3
Non-cash lease expense		309
Changes in operating assets and liabilities:
Accrued expenses and other current liabilities		(241)
Cash flows from financing activities
Other		135
Supplemental disclosure of noncash investing and financing activities:
Right-of-use assets obtained in exchange for lease liabilities		$ 18,634

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Prepaid research and development	$ 4,710	$ 4,840
Prepaid clinical trial	2,568	2,119
Deferred offering costs	724	724
Prepaid insurance	373	388
Prepaid bonus	26	18
Other	532	448
Total prepaid expenses and other current assets	$ 8,933	$ 8,537

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Property, Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 16,615	$ 16,605
Accumulated depreciation	(1,973)	(1,642)
Property, plant and equipment, net	14,642	14,963
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	2,091	2,091
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	2,868	2,868
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,115	1,115
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	908	898
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 9,633	$ 9,633

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Depreciation expense		$ 331	$ 260
Non-cash impairment charge	$ 36,400
Impairment charges to construction in process and finance lease right of use assets	$ 26,300
Property, plant and equipment, net		14,642		$ 14,963
Assets Capitalized As Finance Leases
Property Plant And Equipment [Line Items]
Property, plant and equipment, net		$ 1,200		$ 1,300

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Accrued research and development	$ 6,451	$ 8,190
Accrued severance	3,027	1,463
Accrued clinical trial	2,462	1,473
Lease liabilities, current portion	1,752	1,521
Accrued compensation	1,242	2,519
Accrued professional and consulting fees	866	390
Accrued property, plant and equipment	112	2,081
Other	690	650
Total accrued expenses and other current liabilities	$ 16,602	$ 18,287

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands				3 Months Ended
Leases - Additional Information (Details) $ in Thousands	Dec. 14, 2021 USD ($) ft²	Jan. 11, 2021 ft²	Dec. 17, 2020 ft²	Mar. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Future minimum remianing lease payments \| $				$ 32,977
Durham Lease
Lessee, Lease, Description [Line Items]
Number of operating lease landlord square feet manufacturing facility \| ft²			187,500
Operating lease commencement date			Apr. 01, 2021
Operating lease term of contract			15 years 6 months
Lease, option to extend description				Company has two options to extend the term of the Durham Lease, each for a period of an additional five years.
Operating lease extend term of contract			5 years
Amount required to place in escrow account \| $				$ 2,600
On Site Generation Lease
Lessee, Lease, Description [Line Items]
Operating lease term of contract				10 years
Future minimum remianing lease payments \| $				$ 3,500
Pegasus Park L L C \| Dallas Lease
Lessee, Lease, Description [Line Items]
Number of operating lease landlord square feet manufacturing facility \| ft²		15,000
Operating lease commencement date		May 27, 2021
Operating lease term of contract		10 years
Lease, option to extend description		Company has an option to extend the term of the Dallas Lease for one additional period of five years.
Pegasus Park L L C \| Dallas Lease Amendment
Lessee, Lease, Description [Line Items]
Number of operating lease landlord square feet manufacturing facility \| ft²	18,000
Operating lease term of contract	10 years
Future minimum remianing lease payments \| $	$ 6,000
Pegasus Park L L C \| Dallas Lease Amendment \| Minimum
Lessee, Lease, Description [Line Items]
Maximum construction allowance provided by landlord per rentable square foot \| ft²	40

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Lease, Cost [Abstract]
Operating lease cost	$ 708	$ 535
Variable lease cost	243	194
Total lease cost	$ 951	$ 729

Leases - Supplemental Informati

Leases - Supplemental Information Related to Remaining Lease Term and Discount Rate (Details)	Mar. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted average remaining lease term (in years) - Finance leases	3 years 7 months 17 days	3 years 10 months 17 days
Weighted average remaining lease term (in years) - Operating leases	11 years 3 months 7 days	11 years 5 months 12 days
Weighted average discount rate - Finance leases	10.51%	10.51%
Weighted average discount rate - Operating leases	7.74%	7.72%

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash Flow, Operating Activities, Lessee [Abstract]
Operating cash flows for operating leases	$ 692	$ 363

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Commitments Under Company's Operating and Finance Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Operating Lease
2023	$ 2,255
2024	2,918
2025	3,021
2026	2,485
2027	2,577
Thereafter	19,721
Total lease payments	32,977
Less: imputed interest	(11,625)
Total lease liabilities	21,352
Operating lease liabilities, current	$ 1,424
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities And Other Liabilities
Operating lease liabilities, non-current	$ 19,928	$ 20,440
Total lease liabilities	21,352
Finance Lease
2023	341
2024	454
2025	454
2026	399
Total lease payments	1,648
Less: imputed interest	(311)
Total lease liabilities	1,337
Finance lease liabilities, current	$ 328
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities And Other Liabilities
Finance, lease liabilities, non-current	$ 1,009
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities Noncurrent
Total lease liabilities	$ 1,337
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Liabilities

Astellas Agreements - Additiona

Astellas Agreements - Additional Information (Details) - USD ($)		1 Months Ended		3 Months Ended
	Oct. 21, 2022	Oct. 31, 2022	Mar. 31, 2021	Mar. 31, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued				63,473,349	63,207,507
Probability of option exercise		50%
Deferred revenue				$ 28,900,000
Revenues				4,706,000
TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment			$ 5,500,000
Astellas
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 20,000,000	$ 20,000,000
Transaction price		36,100,000		36,059
Deferred revenue		$ 36,100,000
Astellas \| Securities Purchase Agreement \| Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued	7,266,342	7,266,342
Aggregate gross proceeds	$ 30,000,000
Fair value of shares transferred, Value		$ 13,950,000
Share price		$ 1.92
Transaction price		$ 16,100,000
Difference of market value paid		$ 30,000,000
Astellas \| TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment				20,000,000
Transaction price				36,100,000
Astellas \| TSHA-120 \| Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price				$ 16,100,000

Astellas Agreements - Additio_2

Astellas Agreements - Additional Information 1 (Details)	Mar. 31, 2023
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months 18 days

Astellas Agreements - Summary o

Astellas Agreements - Summary of Allocation for Transaction Price to the Three Performance Obligations (Details) - Astellas - USD ($)	1 Months Ended	3 Months Ended
	Oct. 31, 2022	Mar. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction Price Allocation	$ 36,100,000	$ 36,059
Option to obtain license for Rett
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction Price Allocation		5,485
Option to obtain license for GAN
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction Price Allocation		2,317
Rett research and development activities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction Price Allocation		$ 28,257

Loan with Silicon Valley Bank -

Loan with Silicon Valley Bank - Additional Information (Details)		3 Months Ended
	Aug. 12, 2021 USD ($) Program	Mar. 31, 2023 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Debt instrument, maturity date	Aug. 01, 2026
Percentage of interest rate	7%
Percentage of prepayment of facility	7.50%
Warrants associated with loan facility	$ 0
Exit fee recorded as debt discount		$ 3,000,000
Percentage of annual default interest rate	5%
Interest expense related to term loan		1,300,000
Prime Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.75%
Term Loan
Debt Instrument [Line Items]
Current borrowing capacity	$ 30,000,000		$ 10,000,000
Through December 31, 2021 \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 40,000,000
Debt instrument, maturity date	Dec. 31, 2021
January 1, 2022 until September 30, 2022 \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 20,000,000	$ 20,000,000
Debt instrument, maturity start date	Jan. 01, 2022
Debt instrument, maturity end date	Sep. 30, 2022	Sep. 30, 2022
Number of distinct and active clinical stage \| Program	3
Proceeds from term loan		$ 0
January 1, 2022 until March 31, 2023 \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 20,000,000
Debt instrument, maturity end date		Mar. 31, 2023
Proceeds from term loan		$ 0
October 1, 2022 until March 31, 2023 \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 20,000,000
Debt instrument, maturity start date	Oct. 01, 2022
Debt instrument, maturity end date	Mar. 31, 2023
Number of distinct and active clinical stage \| Program	3
April 1, 2023 until December 31, 2023 \| Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 20,000,000
Debt instrument, maturity start date	Apr. 01, 2023
Debt instrument, maturity end date	Dec. 31, 2023
Through August 13, 2023
Debt Instrument [Line Items]
Percentage of prepayment premium	1%

Loan with Silicon Valley Bank_2

Loan with Silicon Valley Bank - Schedule of Future Principal Debt Payments on Loan Payable (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Debt Disclosure [Abstract]
2024	$ 6,667
2025	20,000
2026	13,333
Total principal payments	40,000
Unamortized debt discount	(1,839)
Term Loan, net	$ 38,161

Research, Collaboration and L_2

Research, Collaboration and License Agreements - Additional Information (Details)

1 Months Ended

3 Months Ended

12 Months Ended

Jul. 31, 2022 USD ($)

Mar. 31, 2022 USD ($)

Mar. 31, 2021 USD ($)

Oct. 31, 2020 USD ($)

Aug. 31, 2020 USD ($)

Apr. 30, 2020 USD ($) Product

Mar. 31, 2023 USD ($) shares

Mar. 31, 2022 USD ($)

Dec. 31, 2021 USD ($)

Dec. 31, 2020 USD ($)

Dec. 31, 2022 shares

Oct. 29, 2020 USD ($)

Feb. 21, 2020 USD ($)

Nov. 30, 2019 shares

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Common stock, shares issued | shares

63,473,349

63,207,507

Research and development

$ 12,514,000

$ 38,182,000

TSHA-120

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Additional milestone payments

Upfront payment

$ 5,500,000

Clinical, regulatory and commercial milestones to be received

$ 19,300,000

License Agreement for CLN7

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Additional milestone payments

Payment of one-time upfront license fee

$ 300,000

License agreement regulatory related milestones maximum amount payable

7,700,000

License agreement sales-related milestones maximum amount payable

$ 7,500,000

UT Southwestern Agreement

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Preclinical activities period under sponsored research agreements

2 years

Minimum licensed product to develop obtain regulatory approval for and commercialize | Product

Common stock, shares issued | shares

2,179,000

Percentage of fully diluted common stock shares outstanding

20%

Queens Agreement

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Additional milestone payments

Queens Agreement | Research and Development Expense

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Cash payment to acquire license agreement

$ 3,000,000

Queens Agreement | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement regulatory milestones payment

$ 10,000,000

License agreement commercial milestones payment

$ 10,000,000

Abeona CLN1 Agreements

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License fee payment

$ 3,000,000

Purchase of clinical materials and reimbursement incurred development costs

$ 4,000,000

Research and development

$ 3,000,000

$ 7,000,000

Abeona CLN1 Agreements | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License and inventory purchase agreement regulatory related milestones payment

26,000,000

License and inventory purchase agreement sales related milestones payment

$ 30,000,000

Abeona | Rett research and development activities

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Additional milestone payments

Research and development

$ 1,000,000

Payment of one-time upfront license fee

$ 3,000,000

Regulatory milestone fee paid

$ 1,000,000

Abeona | Maximum | Rett research and development activities

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Regulatory related milestones obligation payable

$ 26,500,000

Sale-related milestones per licensed product and royalties on net sales of licensed products payable

$ 30,000,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)			1 Months Ended		3 Months Ended
	Sep. 16, 2020	Jul. 01, 2020	Feb. 28, 2023	Feb. 28, 2022	Mar. 31, 2023	Mar. 31, 2022	Jan. 01, 2023	Dec. 31, 2022	Jan. 01, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of common stock price purchased through payroll deductions				85%
Percentage of payroll deductions of employee's compensation during offering period				15%
Maximum number of shares employees may purchase during offering period				1,800
Stock-based compensation expense					$ 1,675,000	$ 5,329,000
Employee Stock Purchase Plan (ESPP)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	724,000						632,075		384,739
Share-based payment award, expiration period	10 years
Share-based payment award, expiration date	Jan. 01, 2030
Percentage of automatic increase every year in common stock shares reserved for future issuance	1%
Share-based payment award, terms of award issuance					the number of shares of common stock that are automatically added on January 1st of each year for a period of up to ten years, commencing on the first January 1 following the IPO and ending on (and including) January 1, 2030, in an amount equal to the lesser of (i) one percent (1.0%) of the total number of shares of capital stock outstanding on December 31st of the preceding calendar year, and (ii) 724,000 shares of common stock.
Number of shares of common stock issued under ESPP	0				108,993
Employee Stock Purchase Plan (ESPP) \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance	362,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, compensation cost not yet recognized, weighted-average period of recognition					1 year 3 months 18 days
Share-based payment award, RSU/RSA granted					332,532
Outstsanding performance and market-based RSU's					680,737			1,257,844
Share-based payment award, unvested RSU/RSA granted, compensation cost not yet recognized					$ 3,300,000
Share-based payment award, RSU/RSA granted, weighted average grant date fair value					$ 1.06
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, options granted					1,043,371
Share-based payment award, options granted, exercise price per share					$ 1.18
Share-based payment award, options, compensation cost not yet recognized					$ 12,600,000
Share-based payment award, compensation cost not yet recognized, weighted-average period of recognition					2 years 7 months 6 days
Stock options were exercised during the period					$ 0
Outstanding performance and market-based options					5,312,862			6,158,078
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstsanding performance and market-based RSU's								85,494
Share-based payment award, RSU/RSA granted, weighted average grant date fair value		$ 5.28
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock issued under ESPP					35,920
2020 Equity Incentive Plan \| Restricted Stock Awards \| RA Session II
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, RSU/RSA granted		769,058			251,296
Award requisite service vesting period		3 years
New Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance							3,160,375
Share-based payment award, expiration period	10 years
Share-based payment award, commencement date	Jan. 01, 2021
Share-based payment award, expiration date	Jan. 01, 2030
Percentage of automatic increase every year in common stock shares reserved for future issuance	5%
Share-based payment award, terms of award issuance					The number of shares of common stock reserved for issuance under the New Plan automatically increases on January 1 of each year, for a period of ten years, from January 1, 2021 continuing through January 1, 2030, by 5% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors.
New Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
Share-based payment award, RSU/RSA granted			81,236
New Plan \| Performance and Market-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, RSU/RSA granted			81,233
Outstsanding performance and market-based RSU's					69,344
New Plan \| Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, expiration period					10 years
Share-based payment award, options granted					1,043,371
Award vesting period					4 years
Share-based payment award, options, weighted-average grant date fair value					$ 0.85
New Plan \| Performance and Market-based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, options granted			140,468
Outstanding performance and market-based options					116,690
Performance and Market-based Stock Options vested during period					0

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Share Based Compensation Available for Grant under Incentive Plans (Details)	3 Months Ended
	Mar. 31, 2023 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Available for grant beginning of period	1,067,682
Plan adjustments and amendments	3,160,375
Grants	(1,597,604)
Forfeitures	2,603,971
Available for grant ending of period	5,234,424
Existing Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan adjustments and amendments	(667,828)
Forfeitures	667,828
New Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Available for grant beginning of period	1,067,682
Plan adjustments and amendments	3,828,203
Grants	(1,597,604)
Forfeitures	1,936,143
Available for grant ending of period	5,234,424

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Assumptions Used to Estimate Fair Value Time Based Vesting of Stock Options (Details) - Stock Options	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	3.46%	1.91%
Expected term in years	6 years 1 month 6 days	6 years 1 month 6 days
Expected volatility	81%	76%

Stock-Based Compensation - Sc_3

Stock-Based Compensation - Schedule of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding. Stock Options, Beginning Balance	6,158,078
Options granted, Stock Options	1,043,371
Options cancelled or forfeited, Stock Options	(1,765,389)
Options expired, Stock Options	(123,198)
Outstanding. Stock Options, Ending Balance	5,312,862
Options exercisable at March 31, 2023, Stock Options	1,401,840
Options granted, Weighted Average Exercise Price	$ 1.18
Options cancelled or forfeited, Weighted Average Exercise Price	11.50
Options expired, Weighted Average Exercise Price	24
Outstanding, Weighted Average Exercise Price, Ending balance	9.58	$ 11.84
Options exercisable at March 31, 2023, Weighted Average Exercise Price	$ 22.18
Outstanding, Weighted Average Remaining Contractual Life	8 years 2 months 12 days	8 years 10 months 24 days
Options exercisable at March 31, 2023, Weighted Average Remaining Contractual Life	4 years 7 months 6 days
Outstanding, Aggregate Intrinsic Value, Beginning Balance	$ 62

Stock-Based Compensation - Sc_4

Stock-Based Compensation - Schedule of Restricted Stock Units Activity (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Nonvested, Number of Shares, Beginning Balance \| shares	1,257,844
Restricted units/stock granted, Number of Shares \| shares	332,532
Vested, Number of Shares \| shares	(251,296)
Cancelled or forfeited, Number of Shares \| shares	(658,343)
Nonvested, Number of Shares, Ending Balance \| shares	680,737
Nonvested, Weighted Average Grant Date Fair Value per Share, Beginning Balance \| $ / shares	$ 6.52
Restricted units/stock granted, Weighted Average Grant Date Fair Value per Share \| $ / shares	1.06
Vested, Weighted Average Grant Date Fair Value per Share \| $ / shares	1.02
Cancelled or forfeited, Weighted Average Grant Date Fair Value per Share \| $ / shares	5.18
Nonvested, Weighted Average Grant Date Fair Value per Share, Ending Balance \| $ / shares	$ 7.18

Stock-Based Compensation - Sc_5

Stock-Based Compensation - Schedule of Restricted Stock Awards Activity (Details) - Restricted Stock Awards - $ / shares		3 Months Ended
	Jul. 01, 2020	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Nonvested, Number of Shares, Beginning Balance		85,494
Vested, Number of Shares		(64,120)
Cancelled or forfeited, Number of Shares		(21,374)
Nonvested, Weighted Average Grant Date Fair Value per Share, Beginning Balance		$ 5.28
Restricted units/stock granted, Weighted Average Grant Date Fair Value per Share	$ 5.28
Vested, Weighted Average Grant Date Fair Value per Share		5.28
Cancelled or forfeited, Weighted Average Grant Date Fair Value per Share		$ 5.28

Stock-Based Compensation - Sc_6

Stock-Based Compensation - Schedule of Total Stock-Based Compensation Expense for Stock Options, ESPP, RSAs and RSUs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,675	$ 5,329
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	(263)	2,577
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,938	$ 2,752

Net Loss Per Common Share - Sch

Net Loss Per Common Share - Schedule of Calculation of Basic and Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Net loss	$ (17,622)	$ (50,317)
Weighted average common shares outstanding, basic	63,260,905	38,174,717
Weighted average common shares outstanding, diluted	63,260,905	38,174,717
Net loss per common share, basic	$ (0.28)	$ (1.32)
Net loss per common share, diluted	$ (0.28)	$ (1.32)

Net Loss Per Common Share - S_2

Net Loss Per Common Share - Schedule of Common Stock Equivalents Outstanding Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	6,179,633	7,602,457
Unvested RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	750,081	1,886,765
Unvested RSAs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share		277,855
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	5,429,552	5,437,837

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended
Income Taxes - Additional Information (Details)	Mar. 31, 2023 USD ($)
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 0

Strategic Reprioritization - Ad

Strategic Reprioritization - Additional Information (Details) - Exit and Disposal Activities - USD ($) $ in Millions	3 Months Ended	4 Months Ended
	Mar. 31, 2022	Mar. 31, 2023
Restructuring Cost And Reserve [Line Items]
Percentage of headcount reduced	35%
Severance and termination-related costs	$ 2.6	$ 2.7

Strategic Reprioritization - Su

Strategic Reprioritization - Summary of Accrued Severance Activity Recorded (Details) - Employee Severance $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued severance balance as of December 31, 2022	$ 1,463
Severance recorded	2,691
Severance paid	(1,127)
Accrued severance balance as of March 31, 2023	$ 3,027

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Contribution to retirement savings plan	$ 0.1	$ 0.4

Subsequent - Events - Additiona

Subsequent - Events - Additional Information (Details) - USD ($)	1 Months Ended
	Apr. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Common stock, shares issued		63,473,349	63,207,507
SSI Strategy Holdings LLC \| Private Placement \| Securities Purchase Agreement \| Subsequent Event
Subsequent Event [Line Items]
Common stock, shares issued	705,218
Warrants issued	525,000
Exercise price of warrants	$ 0.7090
Aggregate gross proceeds	$ 500,000