Subsequent Events	6 Months Ended
Jun. 30, 2026
Subsequent Events [Abstract]
Subsequent Events	Note U – Subsequent Events Securities Purchase Agreement On July 13, 2026, the Company entered into a Securities Purchase Agreement for a private placement with certain institutional and other accredited investors. The closing of the Private Placement occurred on July 15, 2026, subject to the satisfaction of customary closing conditions. Under the terms of the Purchase Agreement, the Company has agreed to issue and sell (i) 23,035,227 shares of the Company’s common stock, (ii) accompanying Series A purchase warrants to purchase 21,144,277 shares of common stock at an exercise price of $4.02 per share and (iii) accompanying Series B purchase warrants to purchase 33,797,214 shares of common stock at an exercise price of $5.03 per share. The combined effective purchase price per share, or per pre-funded warrant less its exercise price, together with the accompanying Series A Warrant and Series B Warrant, was $3.69. The aggregate gross proceeds received were approximately $85.0 million, before deducting Private Placement expenses, with up to an additional $255.0 million in gross proceeds upon exercise of the Series A Warrants and Series B Warrants, assuming the exercise in full of such warrants. The pre-funded warrants have an exercise price of $0.01 per share, are exercisable immediately, do not expire until exercised in full, and contain customary beneficial ownership limitation provisions. The pre-funded warrants are equity-classified. See Note C for their treatment in the computation of basic net income (loss) per share. The Series A Warrants are exercisable immediately and expire upon the earlier of (i) the fifth anniversary of the closing date of the Private Placement and (ii) the date that is 30 days following the day on which the Company publicly discloses, by press release or Current Report on Form 8-K, that at least 60 patients have been dosed in the Phase 3 clinical trial of BOT/BAL for the neoadjuvant treatment of colon cancer (the “ROBBIN” trial). The Series B Warrants are exercisable immediately and expire upon the earliest of (i) the fifth anniversary of the closing date of the Private Placement, (ii) the date that is 30 days following the day on which the Company publicly discloses, by press release or Current Report on Form 8-K, pathologic response data for at least 50 patients dosed with BOT plus BAL in the ROBBIN trial and (iii) unless the holder shall at such time have exercised in full the Series A Warrant held by such holder, 12:01 a.m. (New York City time) on the date immediately following the expiration date of the Series A Warrants. Exercise of the Series A Warrants and Series B Warrants is at the discretion of the holders. No assurance can be given that any such warrants will be exercised or that the Company will receive any additional proceeds from them. The Series A Warrants and Series B Warrants are equity-classified. BATTMAN Discontinuation and the Initiation of the ROBBIN Trial In connection with its strategic prioritization of neoadjuvant BOT/BAL in MSS colon cancer, the Company discontinued its planned future financial contribution to BATTMAN, the Phase 3 study sponsored by the Canadian Cancer Trials Group (CCTG) evaluating BOT/BAL in refractory MSS/pMMR metastatic colorectal cancer. Agenus was one of the study's funding sources and supplied BOT/BAL, while CCTG served as the study sponsor and conducted the trial. Following Agenus's funding decision, CCTG formally terminated the study. The decision reflected financing and development priorities and was not driven by enrollment performance, efficacy or safety findings, or an interim analysis. The Company will continue to support BOT/BAL treatment for patients previously enrolled in BATTMAN where medically appropriate and permitted under applicable requirements. The Company has established physician-led compassionate access pathways in Canada, Australia and New Zealand, which will remain open to new physician requests through December 31, 2026. In addition, the Company announced a planned registrational Phase 3 trial (ROBBIN) of neoadjuvant BOT/BAL for high-risk Stage II and Stage III MSS colon cancer.

Subsequent Events

6 Months Ended

Jun. 30, 2026

Note U – Subsequent Events

Securities Purchase Agreement

On July 13, 2026, the Company entered into a Securities Purchase Agreement for a private placement with certain institutional and other accredited investors. The closing of the Private Placement occurred on July 15, 2026, subject to the satisfaction of customary closing conditions.

Under the terms of the Purchase Agreement, the Company has agreed to issue and sell (i) 23,035,227 shares of the Company’s common stock, (ii) accompanying Series A purchase warrants to purchase 21,144,277 shares of common stock at an exercise price of $4.02 per share and (iii) accompanying Series B purchase warrants to purchase 33,797,214 shares of common stock at an exercise price of $5.03 per share. The combined effective purchase price per share, or per pre-funded warrant less its exercise price, together with the accompanying Series A Warrant and Series B Warrant, was $3.69. The aggregate gross proceeds received were approximately $85.0 million, before deducting Private Placement expenses, with up to an additional $255.0 million in gross proceeds upon exercise of the Series A Warrants and Series B Warrants, assuming the exercise in full of such warrants.

The pre-funded warrants have an exercise price of $0.01 per share, are exercisable immediately, do not expire until exercised in full, and contain customary beneficial ownership limitation provisions. The pre-funded warrants are equity-classified. See Note C for their treatment in the computation of basic net income (loss) per share.

The Series A Warrants are exercisable immediately and expire upon the earlier of (i) the fifth anniversary of the closing date of the Private Placement and (ii) the date that is 30 days following the day on which the Company publicly discloses, by press release or Current Report on Form 8-K, that at least 60 patients have been dosed in the Phase 3 clinical trial of BOT/BAL for the neoadjuvant treatment of colon cancer (the “ROBBIN” trial).

The Series B Warrants are exercisable immediately and expire upon the earliest of (i) the fifth anniversary of the closing date of the Private Placement, (ii) the date that is 30 days following the day on which the Company publicly discloses, by press release or Current Report on Form 8-K, pathologic response data for at least 50 patients dosed with BOT plus BAL in the ROBBIN trial and (iii) unless the holder shall at such time have exercised in full the Series A Warrant held by such holder, 12:01 a.m. (New York City time) on the date immediately following the expiration date of the Series A Warrants.

Exercise of the Series A Warrants and Series B Warrants is at the discretion of the holders. No assurance can be given that any such warrants will be exercised or that the Company will receive any additional proceeds from them. The Series A Warrants and Series B Warrants are equity-classified.

BATTMAN Discontinuation and the Initiation of the ROBBIN Trial

In connection with its strategic prioritization of neoadjuvant BOT/BAL in MSS colon cancer, the Company discontinued its planned future financial contribution to BATTMAN, the Phase 3 study sponsored by the Canadian Cancer Trials Group (CCTG) evaluating BOT/BAL in refractory MSS/pMMR metastatic colorectal cancer. Agenus was one of the study's funding sources and supplied BOT/BAL, while CCTG served as the study sponsor and conducted the trial. Following Agenus's funding decision, CCTG formally terminated the study. The decision reflected financing and development priorities and was not driven by enrollment performance, efficacy or safety findings, or an interim analysis.

The Company will continue to support BOT/BAL treatment for patients previously enrolled in BATTMAN where medically appropriate and permitted under applicable requirements. The Company has established physician-led compassionate access pathways in Canada, Australia and New Zealand, which will remain open to new physician requests through December 31, 2026.

In addition, the Company announced a planned registrational Phase 3 trial (ROBBIN) of neoadjuvant BOT/BAL for high-risk Stage II and Stage III MSS colon cancer.