Immatics Updates Phase 1b Data on IMA203 TCR-T for Melanoma, Previews SUPRAME Phase 3 Trial

Immatics N.V. (NASDAQ: IMTX), a clinical-stage biopharmaceutical company specializing in T cell-redirecting cancer immunotherapies, has shared updated Phase 1b clinical data on its ACTengine® IMA203 TCR-T therapy targeting PRAME in melanoma patients. Additionally, details were provided about the upcoming SUPRAME Phase 3 trial which aims to evaluate IMA203 in patients with metastatic melanoma.

The most recent data from the ongoing Phase 1b trial will be presented by Dr. Martin Wermke on October 11, 2024, at the Society for Melanoma Research Congress. The presentation will include additional patient cases, with the slides accessible on the Company’s website.

Dr. Martin Wermke, who is the Coordinating Investigator of the ACTengine® IMA203 TCR-T trial, noted the significant tumor shrinkage and durable responses observed, coupled with meaningful progression-free survival (PFS) and overall survival (OS) outcomes in patients who had no other treatment options. He emphasized the therapeutic potential of IMA203 and highlighted the rationale for expediting its late-stage clinical development.

Dr. Cedrik Britten, Chief Medical Officer of Immatics, expressed enthusiasm about the clinical data, emphasizing the durability and long-term efficacy of ACTengine® IMA203. He pointed out that in a subgroup of 12 out of 26 patients, more than 50% reduction in tumor lesions was observed, with a median PFS of 13.4 months. Britten also mentioned the positive discussions with the FDA, leading to a pivotal trial design that uses progression-free survival as the primary endpoint for full approval.

In the Phase 1b trial, 28 heavily pretreated metastatic melanoma patients were treated with IMA203 at the recommended Phase 2 dose. The patient population included those with a median of 2 lines of prior systemic treatments. The results showed a favorable tolerability profile for IMA203, with no treatment-related Grade 5 adverse events. Common adverse events included cytopenias and mild to moderate cytokine release syndrome.

The anti-tumor activity observed was significant, with durable objective responses in melanoma patients at the recommended Phase 2 dose. The data indicated a substantial improvement in progression-free survival and overall survival from Phase 1a to Phase 1b. Additionally, about half of the patients in Phase 1b experienced a deep response with more than 50% tumor reduction, which correlated with extended PFS.

Translational data showed that IMA203 T cells rapidly engrafted in all patients and persisted for over two years. There were clear associations between T cell dose, biological data, and clinical outcomes, indicating consistency in treatment responses.

Immatics completed a meeting with the U.S. FDA on September 24, 2024, to confirm the recommended Phase 2 dose and discuss the trial design for the SUPRAME Phase 3 trial. This trial will target 360 HLA-A*02:01-positive patients with second-line or later metastatic melanoma who have received prior treatment with a checkpoint inhibitor. The primary endpoint will be median progression-free survival.

The SUPRAME Phase 3 trial is scheduled to begin in December 2024, with patient enrollment expected to conclude by 2026. Immatics aims to submit a Biologics License Application in early 2027. The trial will be conducted globally, with sites in the United States and Europe.

Immatics has also highlighted its manufacturing capabilities, ensuring that ACTengine® IMA203 products are produced within seven days, followed by a quality control release testing. The company has built a new R&D and GMP manufacturing facility, expected to start operations in early 2025.

ACTengine® IMA203 is Immatics’ leading TCR-based autologous cell therapy targeting PRAME, a protein commonly expressed in many solid tumors. The therapy is currently being evaluated in a Phase 1 trial and is set for a Phase 3 trial planned to commence in December 2024. Immatics aims to use its expertise in target discovery and T cell receptor development to combat cancer effectively.