Commitments and Contingencies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands							12 Months Ended
	Oct. 20, 2023	Aug. 14, 2023	Mar. 17, 2023	May 28, 2019	Aug. 17, 2015	Jan. 13, 2015	Dec. 31, 2023	Dec. 31, 2022	Apr. 03, 2023	Oct. 22, 2019	Feb. 19, 2019	Oct. 05, 2018	Aug. 24, 2004
Accrued Payments
Research and development expense							$ 16,279	$ 25,018
Royalty amount							0	0
Maximum royalty amount												$ 100,000
Collaboration revenue							5	2,922
Unspecified monetary damages			$ 3,200
Loss contingency, name of plaintiff			KBI Biopharma
Litigation expense	$ 1,000
Md Anderson Warrant [Member]
Accrued Payments
Number of Warrants										222,222
Warrant exercise per share										$ 0.015
Warrant Expiry date										Dec. 31, 2026
MD Anderson Related to the 2015 R&D Agreement [Member]
Accrued Payments
Clinical expenses							100	0
MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Reimbursement of historical costs										$ 20,000
Clinical expenses							800	800
Aggregate potential benchmark payments										36,500
Payments due prior to the first marketing approval										$ 3,000
CRADA Agreement [Member]
Accrued Payments
Agreement termination date		Oct. 13, 2023
Contribution payable on per annum basis							1,000
Obligations due under contract											$ 5,000
Annual expense incurred							500	0
MD Anderson Agreement and Worldwide License [Member]
Accrued Payments
License agreement commencing date						Jan. 13, 2015
The University of Texas MD Anderson Cancer Center and The Texas A & M University System [Member]
Accrued Payments
Milestone maximum payment													$ 4,500
One time milestone payment								2,500
The University of Texas MD Anderson Cancer Center and The Texas A & M University System [Member] | Royalty [Member]
Accrued Payments
Payment under license agreement							1	2
License Agreement with the National Cancer Institute [Member]
Accrued Payments
License Expense							400	700
License Agreement with the National Cancer Institute [Member] | One Time Benchmark Payments [Member]
Accrued Payments
First benchmark payment				$ 100
Ziop License Agreement With The National Cancer Institute [Member]
Accrued Payments
Minimum royalties amount payable				300
Royalties amount payable thereafter				100
Aggregate minimum annual royalties paid				$ 1,500
Description Of First Benchmark Payable				The first benchmark payment of $0.1 million was paid during the year ended December 31, 2022 upon the initiation of the Company's TCR-T Library Phase 1/2 Trial, which was a qualifying Phase 1 clinical trial under the terms of the Patent License.
Description Of option To terminate Agreement				The NCI could terminate or modify the Patent License in the event of a material breach, including if the Company did not meet certain milestones by certain dates, or upon certain insolvency events that remain uncured following the date that is 90 days following written notice of such breach or insolvency event.
Agreement termination, notice period				60 days
Ziop License Agreement With The National Cancer Institute [Member] | Performance Based Payments [Member]
Accrued Payments
Aggregate Benchmark Payments Payable				$ 4,300
Ziop License Agreement With The National Cancer Institute [Member] | One Time Benchmark Payments [Member]
Accrued Payments
Potential Benchmark Payments Payable				12,000
Ziop License Agreement With The National Cancer Institute [Member] | Post Marketing Approval [Member] | Performance Based Payments [Member]
Accrued Payments
Aggregate Benchmark Payments Payable				3,000
Ziop License Agreement With The National Cancer Institute [Member] | Licensed Products [Member] | One Time Benchmark Payments [Member]
Accrued Payments
Maximum Sales Revenue On Which Benchmark Payments Payable				1,000,000
Minimum sales revenue on which benchmark payments payable				$ 250,000
Collaboration Agreement with Solasia Pharma K.K. [Member]
Accrued Payments
Collaboration revenue							0	2,900
Collaboration Agreement with Solasia Pharma K.K. [Member] | Royalty [Member]
Accrued Payments
Collaboration revenue							5
Intrexon Corporation [Member]
Accrued Payments
Annual License fee							$ 100	$ 100	$ 75			100
Expected additional milestones payable												52,500
Intrexon Corporation [Member] | T-Cell Receptor [Member]
Accrued Payments
Maximum royalty amount												$ 100,000
Portion of income payable to related party												20.00%
Minimum [Member] | MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development expense					$ 15,000
Maximum [Member] | MD Anderson License and the Research and Development Agreement [Member]
Accrued Payments
Research and development expense					$ 20,000