Commitments and Contingencies	6 Months Ended
Jun. 30, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and Contingencies License Agreements Exclusive License Agreement with Precigen On April 3, 2023, the Company entered into the Amended and Restated Exclusive License Agreement with Precigen, or the A&R License Agreement, which restated and amended the parties' previous license agreement in full. Under the A&R License Agreement, the Company still had exclusive, worldwide rights to research, develop and commercialize TCR products designed for neoantigens or driver mutations for the treatment of cancer and non-exclusive rights to use non-driver mutation TCRs. On October 4, 2024, pursuant to Section 10.2 of the License Agreement, the Company duly notified Precigen of its full termination of all rights under the License Agreement. The decision to terminate the A&R License Agreement was made after a thorough review of our strategic priorities and business objectives, including recognizing that the non-viral Sleeping Beauty gene transfer platform patent will expire in 2026. The Company continues to prosecute certain of the intellectual property underlying the TCRs targeting driver mutations such as KRAS, TP53 and EGFR, and the hunTR TCR discovery platform used in the discovery of our proprietary TCR library. The Company continues to explore strategic alternatives, including, but not limited to, an acquisition, merger, reverse merger, sale of assets, strategic partnerships, capital raises or other transactions. License Agreement and Research and Development Agreement —The University of Texas MD Anderson Cancer Center In 2015, the Company, together with Precigen, entered into a license agreement, or the MD Anderson License with MD Anderson (which Precigen subsequently assigned to PGEN). Pursuant to the MD Anderson License, the Company, together with Precigen, holds an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson including technologies relating to novel CAR T-cell therapies, non-viral gene transfer systems, genetic modification and/or propagation of immune cells and other cellular therapy approaches, Natural Killer, or NK Cells, and TCRs. In 2015, the Company, Precigen and MD Anderson entered into the 2015 R&D Agreement to formalize the scope and process for the transfer by MD Anderson, pursuant to the terms of the MD Anderson License, of certain existing research programs and related technology rights, as well as the terms and conditions for future collaborative research and development of new and ongoing research programs. As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the 2015 R&D Agreement. At various times, the Company amended the 2015 R&D Agreement to extend the term until December 31, 2026 and in 2019 entered into the 2019 R&D Agreement, pursuant to which the Company agreed to collaborate with respect to the TCR program. The Company did not incur clinical costs from MD Anderson related to the these agreements for the three and six months ended June 30, 2025. The 2019 R&D Agreement will terminate on December 31, 2026 and either party may terminate the 2019 R&D Agreement following written notice of a material breach. The 2019 R&D Agreement also contains customary provisions related to indemnification obligations, confidentiality and other matters. In connection with the execution of the 2019 R&D Agreement, on October 22, 2019, the Company issued MD Anderson a warrant to purchase 22,222 shares of the Company's common stock, which is referred to as the MD Anderson Warrant. The MD Anderson Warrant has an initial exercise price of $1.50 per share, expires on December 31, 2026, and vests upon the occurrence of certain clinical milestones. As of June 30, 2025, the milestones have not been met. Patent and Technology License Agreement—The University of Texas MD Anderson Cancer Center and the Texas A&M University System In August 2004, the Company entered into a patent and technology license agreement with MD Anderson and the Texas A&M University System, which the Company refers to, collectively, as the Licensors. Under this agreement, the Company was granted an exclusive, worldwide license to rights (including rights to U.S. and foreign patent and patent applications and related improvements and know-how) for the manufacture and commercialization of two classes of organic arsenicals (water- and lipid-based) for human and animal use. The class of water-based organic arsenicals includes darinaparsin. Under the terms of the agreement, the Company may be required to make payments to the Licensors upon achievement of certain milestones in varying amounts which, on a cumulative basis could total up to an additional $4.5 million. In addition, the Licensors are entitled to receive low single digit royalties on net sales from a licensed product and will also be entitled to receive a portion of any fees that the Company may receive from a possible sublicense under certain circumstances. During three and six months ended June 30, 2025 and 2024, the Company did not incur any milestone expenses or royalty expenses under this agreement. Collaboration Agreement with Solasia Pharma K.K. In 2011, the Company entered into a License and Collaboration Agreement with Solasia Pharma K. K., or Solasia, which was amended in 2014 to include an exclusive worldwide license and further amended in 2021 to revise certain payment schedule details, or, as so amended, the Solasia License and Collaboration Agreement. Pursuant to the Solasia License and Collaboration Agreement, the Company granted Solasia an exclusive license to develop and commercialize darinaparsin in both intravenous and oral forms and related organic arsenic molecules, in all indications for human use. As consideration for the license, the Company is eligible to receive from Solasia development- and sales-based milestones, a royalty on net sales of darinaparsin, once commercialized, and a percentage of any sublicense revenue generated by Solasia. During the six months ended June 30, 2025, the Company earned royalty revenue totaling $2 thousand under this agreement, all of which was earned during the three months ended March 31, 2025. During the three and six months ended June 30, 2024, the Company earned $4 thousand and $6 thousand, respectively, in royalty revenues on net sales under this agreement. Insurance Contract During the six months ended June 30, 2025 , the Company entered into an insurance arrangement whereby an insurance contract for certain risks which was previously paid in full began to be in force for a period of six years. Accordingly, the Company began amortizing the prepaid expense related to the contract. The Company has classified the prepaid contract between its current portion and long term-portion. As of June 30, 2025, $857 is included in prepaid expenses and other current assets and $997 is included in prepaid expense and other non-current assets in the accompanying condensed consolidated balance sheet. Director Resignation On April 15, 2025, Dr. Hofmeister resigned as a member of the Board of Directors of the Company with immediate effect. Dr. Hofmeister’s resignation was not the result of any disagreement on any matter relating to the Company’s operations, policies or practices.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

License Agreements

Exclusive License Agreement with Precigen

On April 3, 2023, the Company entered into the Amended and Restated Exclusive License Agreement with Precigen, or the A&R License Agreement, which restated and amended the parties' previous license agreement in full. Under the A&R License Agreement, the Company still had exclusive, worldwide rights to research, develop and commercialize TCR products designed for neoantigens or driver mutations for the treatment of cancer and non-exclusive rights to use non-driver mutation TCRs. On October 4, 2024, pursuant to Section 10.2 of the License Agreement, the Company duly notified Precigen of its full termination of all rights under the License Agreement.

The decision to terminate the A&R License Agreement was made after a thorough review of our strategic priorities and business objectives, including recognizing that the non-viral Sleeping Beauty gene transfer platform patent will expire in 2026. The Company continues to prosecute certain of the intellectual property underlying the TCRs targeting driver mutations such as KRAS, TP53 and EGFR, and the hunTR TCR discovery platform used in the discovery of our proprietary TCR library. The Company continues to explore strategic alternatives, including, but not limited to, an acquisition, merger, reverse merger, sale of assets, strategic partnerships, capital raises or other transactions.

License Agreement and Research and Development Agreement —The University of Texas MD Anderson Cancer Center

In 2015, the Company, together with Precigen, entered into a license agreement, or the MD Anderson License with MD Anderson (which Precigen subsequently assigned to PGEN). Pursuant to the MD Anderson License, the Company, together with Precigen, holds an exclusive, worldwide license to certain technologies owned and licensed by MD Anderson including technologies relating to novel CAR T-cell therapies, non-viral gene transfer systems, genetic modification and/or propagation of immune cells and other cellular therapy approaches, Natural Killer, or NK Cells, and TCRs.

In 2015, the Company, Precigen and MD Anderson entered into the 2015 R&D Agreement to formalize the scope and process for the transfer by MD Anderson, pursuant to the terms of the MD Anderson License, of certain existing research programs and related technology rights, as well as the terms and conditions for future collaborative research and development of new and ongoing research programs.

As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the 2015 R&D Agreement. At various times, the Company amended the 2015 R&D Agreement to extend

the term until December 31, 2026 and in 2019 entered into the 2019 R&D Agreement, pursuant to which the Company agreed to collaborate with respect to the TCR program. The Company did not incur clinical costs from MD Anderson related to the these agreements for the three and six months ended June 30, 2025.

The 2019 R&D Agreement will terminate on December 31, 2026 and either party may terminate the 2019 R&D Agreement following written notice of a material breach. The 2019 R&D Agreement also contains customary provisions related to indemnification obligations, confidentiality and other matters.

In connection with the execution of the 2019 R&D Agreement, on October 22, 2019, the Company issued MD Anderson a warrant to purchase 22,222 shares of the Company's common stock, which is referred to as the MD Anderson Warrant. The MD Anderson Warrant has an initial exercise price of $1.50 per share, expires on December 31, 2026, and vests upon the occurrence of certain clinical milestones. As of June 30, 2025, the milestones have not been met.

Patent and Technology License Agreement—The University of Texas MD Anderson Cancer Center and the Texas A&M University System

In August 2004, the Company entered into a patent and technology license agreement with MD Anderson and the Texas A&M University System, which the Company refers to, collectively, as the Licensors. Under this agreement, the Company was granted an exclusive, worldwide license to rights (including rights to U.S. and foreign patent and patent applications and related improvements and know-how) for the manufacture and commercialization of two classes of organic arsenicals (water- and lipid-based) for human and animal use. The class of water-based organic arsenicals includes darinaparsin.

Under the terms of the agreement, the Company may be required to make payments to the Licensors upon achievement of certain milestones in varying amounts which, on a cumulative basis could total up to an additional $4.5 million. In addition, the Licensors are entitled to receive low single digit royalties on net sales from a licensed product and will also be entitled to receive a portion of any fees that the Company may receive from a possible sublicense under certain circumstances. During three and six months ended June 30, 2025 and 2024, the Company did not incur any milestone expenses or royalty expenses under this agreement.

Collaboration Agreement with Solasia Pharma K.K.

In 2011, the Company entered into a License and Collaboration Agreement with Solasia Pharma K. K., or Solasia, which was amended in 2014 to include an exclusive worldwide license and further amended in 2021 to revise certain payment schedule details, or, as so amended, the Solasia License and Collaboration Agreement. Pursuant to the Solasia License and Collaboration Agreement, the Company granted Solasia an exclusive license to develop and commercialize darinaparsin in both intravenous and oral forms and related organic arsenic molecules, in all indications for human use.

As consideration for the license, the Company is eligible to receive from Solasia development- and sales-based milestones, a royalty on net sales of darinaparsin, once commercialized, and a percentage of any sublicense revenue generated by Solasia.

During the six months ended June 30, 2025, the Company earned royalty revenue totaling $2 thousand under this agreement, all of which was earned during the three months ended March 31, 2025. During the three and six months ended June 30, 2024, the Company earned $4 thousand and $6 thousand, respectively, in royalty revenues on net sales under this agreement.

Insurance Contract

During the six months ended June 30, 2025 , the Company entered into an insurance arrangement whereby an insurance contract for certain risks which was previously paid in full began to be in force for a period of six years. Accordingly, the Company began amortizing the prepaid expense related to the contract. The Company has classified the prepaid contract between its current portion and long term-portion. As of June 30, 2025, $857 is included in prepaid expenses and other current assets and $997 is included in prepaid expense and other non-current assets in the accompanying condensed consolidated balance sheet.

Director Resignation

On April 15, 2025, Dr. Hofmeister resigned as a member of the Board of Directors of the Company with immediate effect. Dr. Hofmeister’s resignation was not the result of any disagreement on any matter relating to the Company’s operations, policies or practices.