Immatics Reports 56% Response Rate in Phase 1b Melanoma Cell Therapy Trial

Immatics has reported promising results from its ongoing Phase 1b trial of the IMA203 PRAME cell therapy for heavily pretreated metastatic melanoma, showing a confirmed objective response rate (ORR) of 56% and a median progression-free survival (PFS) of over 6 months, which is double the expected PFS for patients previously treated with checkpoint inhibitors. The therapy demonstrated durable responses with a median duration of response of 12.1 months and a median overall survival of 15.9 months. Subgroup analysis revealed a 50% ORR for cutaneous melanoma patients and a 67% ORR for uveal melanoma patients, including those refractory to tebentafusp. Safety data indicated manageable side effects, mainly mild cytokine release syndrome and cytopenias related to lymphodepletion. These positive Phase 1b data support the ongoing Phase 3 SUPRAME trial evaluating IMA203 in unresectable or metastatic cutaneous melanoma patients who have received prior checkpoint inhibitor therapy. Experts at ASCO highlighted this as among the most exciting advances in cell therapy for refractory melanoma, marking significant momentum in the field following the FDA approval of lifileucel earlier in 2024.