Immats N.V. announced a clinical data update for the IMA203 monotherapy covering the completed Phase 1a dose escalation part of the trial and initial data from the first 5 patients in the ongoing Phase 1b dose expansion cohort A (monotherapy). In the Phase 1 trial with ACTengine(R) IMA203, Immatics is treating recurrent and/or refractory solid cancer patients utilizing TCR-T cells directed against an HLA-A02-presented peptide derived from PRAME, which is frequently expressed across several solid cancer indications. Overall, IMA203 continues to be well tolerated and achieved confirmed objective responses across multiple solid cancers such as cutaneous melanoma, ovarian cancer, head and neck cancer, uveal melanoma, and synovial sarcoma.

Encouraging early signs of improved durability were seen with a 50% (6/12) confirmed objective response rate, when patients were infused at the target dose or above with more than 1 billion TCR-T cells. Key clinical findings from IMA203 TCR-T monotherapy The data obtained during the Phase 1a and Phase 1b cohort A trial provide clinical validation of PRAME as a highly promising T cell target for solid cancers. Confirmed clinical responses were observed at high and low PRAME-expression levels above threshold, indicating IMA203's potential to provide clinical benefit for all PRAME biomarker-positive cancer patients.

The predicted high PRAME prevalence across key indications has so far been supported by prevalence rates obtained during the clinical screening of patients.