Immatics provides update on Phase 1b trial of ACTengine in melanoma

Immatics N.V. announced updated Phase 1b clinical data on ACTengine IMA203 TCR-T targeting PRAME in melanoma patients and provided an update on SUPRAME, the upcoming Phase 3 trial to evaluate IMA203 in metastatic melanoma patients. As of August 23, 28 heavily pretreated patients with metastatic melanoma were treated at the recommended Phase 2 dose with IMA203 during the Phase 1b dose expansion part of the clinical trial. IMA203 monotherapy has maintained a favorable tolerability profile with no treatment-related Grade 5 adverse events in the safety population. The full IMA203 monotherapy tolerability profile is also generally consistent with that observed in the Phase 1b melanoma subset. All patients in dose expansion were treated with an updated version of IMA203. The data demonstrates a significant positive shift in median PFS and median OS between melanoma patients treated during Phase 1a and patients treated in Phase 1b. In addition, approximately half of all patients in the Phase 1b trial have a deep response. IMA203 T cells rapidly engrafted in all patients after a single dose and show a persistence of more than two years. Three associations/correlations were observed demonstrating high consistency of dose exposure, biological data and clinical outcome in all patients treated with IMA203 for which samples were available. On September 24, Immatics completed a Type D meeting with the FDA to confirm RP2D and the CMC package as well as discuss the trial design for the planned registration-enabling Phase 3 randomized-controlled clinical trial for IMA203. Written post-meeting minutes from the FDA have been received. The primary endpoint for full approval will be median PFS. A pre-specified interim analysis is planned for early 2026. The SUPRAME Phase 3 trial is planned to run globally with sites in the U.S. and Europe with the initial goal of seeking BLA approval in the U.S. The Phase 3 trial is on track to commence in December 2024. The company aims to submit a BLA in early 2027 for full approval.