Immatics and Immunocore report early ASCO 2026 data

Immatics presented updated Phase 1 results for its PRAME-directed TCR T-cell therapy IMA203CD8 at the 2026 ASCO Annual Meeting. Gynecologic cancer data were delivered on May 30, 2026 in a Rapid Oral Abstract Session on gynecologic cancer (Abstract 5509). Synovial sarcoma data followed on May 31, 2026 in a Rapid Oral Abstract Session focused on sarcoma (Abstract 11516).

Across these presentations, Immatics reported that a one-time infusion of IMA203CD8 in an ongoing Phase 1 dose-escalation and dose-expansion study produced anti-tumor activity in multiple tumor types. The company described the tolerability profile of the therapy as manageable in this early-stage clinical setting.

IMA203CD8 is designed to target PRAME, an antigen that Immatics stated is expressed in more than 50 cancer types. On the basis of this broad expression profile, the company is positioning IMA203CD8 for investigation across a range of solid tumors. The gynecologic cancer and synovial sarcoma data presented at ASCO 2026 form part of this wider effort to evaluate PRAME-directed TCR T-cell therapy in diverse indications.

Immatics reported that the current Phase 1 trial uses a one-time infusion approach within a dose-escalation and dose-expansion framework. The data discussed at ASCO represent early-phase safety and activity findings that inform further clinical planning. Detailed numerical efficacy or safety results were not specified in the available descriptions but were summarized as demonstrating anti-tumor activity with manageable tolerability.

Immatics stated that it intends to expand clinical evaluation of IMA203CD8 into additional PRAME-positive solid tumor indications beyond those presented at ASCO. This strategy is based on the reported anti-tumor activity and the broad PRAME expression across cancers noted by the company. The expansion aims to better define the potential role of PRAME-directed TCR T-cell therapy in solid tumors.

The company also plans to present durability follow-up data at the recommended Phase 2 dose of IMA203CD8 in the second half of 2026. This forthcoming update is expected to provide additional insight into the persistence and longevity of responses observed after a one-time infusion. Immatics framed these current ASCO 2026 presentations as early-phase clinical updates outlining the next steps for development.

Separately at the 2026 ASCO Annual Meeting, Immunocore presented updated results from its Phase 1/2 trial of brenetafusp in heavily pretreated advanced melanoma. The data were shared in a poster presentation on May 31, 2026. The trial population consisted of patients with advanced melanoma who had received multiple prior treatments.

Immunocore characterized the updated brenetafusp results as demonstrating meaningful disease control in this heavily pretreated group. The company stated that the findings support continued evaluation of brenetafusp in advanced melanoma. As with the IMA203CD8 update, the brenetafusp presentation was an early-phase clinical report focused on emerging efficacy and safety signals and on defining future development steps.