Subsequent Events	6 Months Ended
Jun. 30, 2025
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events Merger Agreement with XOMA On August 4, 2025, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with XOMA Royalty Corporation, a Nevada corporation (“XOMA”), XRA 4 Corp., a Delaware corporation and a wholly-owned subsidiary of XOMA (“Merger Sub”). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock, by XOMA through a cash tender offer (the “Offer”) by Merger Sub, for a price per share of the common stock of (A) $1.95 in cash (the “Cash Amount”), subject to applicable tax withholding and without interest; plus (B) one non-tradeable contingent value right (a “CVR”) (such amount being the “CVR Amount” and the Cash Amount plus the CVR Amount, collectively being the “Offer Price”) and (ii) the merger of Merger Sub with and into the Company (the “Merger”) with the Company surviving the Merger, as a wholly owned subsidiary of XOMA. If the Merger Agreement is terminated by the Company under specified circumstances, the Company will be required to pay XOMA a termination fee of approximately $2.5 million. If XOMA terminates the Merger Agreement due to a failure to satisfy the Minimum Cash Condition, the Company will be required to pay to XOMA an expense reimbursement fee up to a maximum amount of approximately $1.0 million. Boston Sublease On July 31, 2025, the Company entered into a Sublease Agreement with Stellaromics, Inc. (“Subtenant”) with respect to a portion of the Boston Lease (the “Sublease”), to commence on the later to occur of (i) the date consent from landlord is obtained and delivered to Subtenant, (ii) November 1, 2025 and (iii) two weeks after the date the Company, as sublandlord, delivers possession of the subleased premises to Subtenant in the requisite condition. The term of the Sublease is expected to extend for three years and two months following commencement, subject to any earlier termination of the Boston Lease or the Sublease or exercise of a 24-month extension option by Subtenant. License Agreement with Takeda On August 1, 2025, in connection with and substantially concurrently with the signing of the Merger Agreement, the Company delivered a written notice to Takeda that the Company was terminating the Takeda License (such termination, the “Termination”), pursuant to which Takeda had granted the Company, among other things, an exclusive license of certain intellectual property to develop and commercialize HIL-214 (formerly TAK-214) worldwide (excluding Japan) in exchange for upfront consideration as well as future cash milestones and royalties on net sales. The Termination will be effective six months after delivery of the notice by the Company, unless the Company and Takeda agree to an earlier termination date. No material early termination penalties will be incurred by the Company in connection with such termination.

Subsequent Events

6 Months Ended

Jun. 30, 2025

12. Subsequent Events

Merger Agreement with XOMA

On August 4, 2025, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with XOMA Royalty Corporation, a Nevada corporation (“XOMA”), XRA 4 Corp., a Delaware corporation and a wholly-owned subsidiary of XOMA (“Merger Sub”). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock, by XOMA through a cash tender offer (the “Offer”) by Merger Sub, for a price per share of the common stock of (A) $1.95 in cash (the “Cash Amount”), subject to applicable tax withholding

and without interest; plus (B) one non-tradeable contingent value right (a “CVR”) (such amount being the “CVR Amount” and the Cash Amount plus the CVR Amount, collectively being the “Offer Price”) and (ii) the merger of Merger Sub with and into the Company (the “Merger”) with the Company surviving the Merger, as a wholly owned subsidiary of XOMA. If the Merger Agreement is terminated by the Company under specified circumstances, the Company will be required to pay XOMA a termination fee of approximately $2.5 million. If XOMA terminates the Merger Agreement due to a failure to satisfy the Minimum Cash Condition, the Company will be required to pay to XOMA an expense reimbursement fee up to a maximum amount of approximately $1.0 million.

Boston Sublease

On July 31, 2025, the Company entered into a Sublease Agreement with Stellaromics, Inc. (“Subtenant”) with respect to a portion of the Boston Lease (the “Sublease”), to commence on the later to occur of (i) the date consent from landlord is obtained and delivered to Subtenant, (ii) November 1, 2025 and (iii) two weeks after the date the Company, as sublandlord, delivers possession of the subleased premises to Subtenant in the requisite condition. The term of the Sublease is expected to extend for three years and two months following commencement, subject to any earlier termination of the Boston Lease or the Sublease or exercise of a 24-month extension option by Subtenant.

License Agreement with Takeda

On August 1, 2025, in connection with and substantially concurrently with the signing of the Merger Agreement, the Company delivered a written notice to Takeda that the Company was terminating the Takeda License (such termination, the “Termination”), pursuant to which Takeda had granted the Company, among other things, an exclusive license of certain intellectual property to develop and commercialize HIL-214 (formerly TAK-214) worldwide (excluding Japan) in exchange for upfront consideration as well as future cash milestones and royalties on net sales. The Termination will be effective six months after delivery of the notice by the Company, unless the Company and Takeda agree to an earlier termination date. No material early termination penalties will be incurred by the Company in connection with such termination.