ACTengine® IMA203 Combined With mRNA-4203

This study is testing a combination of two cutting-edge cancer treatments: ACTengine® IMA203, an engineered T-cell therapy that targets a protein called PRAME on cancer cells, plus an mRNA cancer vaccine (mRNA-4203), in people with advanced melanoma (skin cancer) or synovial sarcoma (a soft tissue cancer). **You may be eligible if...** - You have been diagnosed with unresectable or metastatic cutaneous melanoma or synovial sarcoma confirmed by biopsy - You have a specific genetic marker called HLA-A*02:01 (found through a blood test) - Your cancer has progressed despite at least one prior PD-1 immunotherapy (for melanoma) or you have received (or declined) standard chemotherapy (for synovial sarcoma) - You are in reasonably good physical condition (ECOG 0–1) with a life expectancy of more than 5 months - You have measurable disease on scans **You may NOT be eligible if...** - You do not have the HLA-A*02:01 genetic marker - You have active brain metastases that are untreated or unstable - Your organs are not functioning well enough for the treatment - You have active autoimmune conditions Talk to your doctor to see if this trial is right for you.