This study involves an investigational cellular therapy called Afamitresgene Autoleucel. The overall goal of this study is to find out how safe and effective this cellular therapy is in treating people that have been diagnosed with synovial sarcoma, malignant peripheral nerve sheath tumors (MPNST), neuroblastoma or osteosarcoma that has grown or returned after being treated.

The Synovial Sarcoma Registry and Biospecimen Repository was opened in June of 2023 with the goal of furthering research and improving outcomes for patients with synovial sarcoma. This study is open to anyone treated in the United States. You do NOT have to travel to Philadelphia to participate.