Spearhead 1 Study in Subjects With Advanced Synovial Sarcoma or Myxoid/Round Cell Liposarcoma

Key Inclusion Criteria * Age ≥16 (10 years at selected sites) and \<=75 years * Diagnosis of advanced synovial sarcoma (Cohort 1, Cohort 2 and Cohort 3) or myxoid liposarcoma / myxoid round cell liposarcoma (Cohort 1 only) confirmed by cytogenetics. * Previously received either an anthracycline or ifosfamide containing regimen. * Measurable disease according to RECIST v1.1 prior to lymphodepletion * HLA-A\*02:01, HLA-A\*02:02, HLA-A\*02:03 or HLA-A\*02:06 positive * Tumor shows MAGE-A4 expression confirmed by central laboratory. North America Only (United States and Canada): Tumor (either an archival specimen or a fresh biopsy) shows MAGE-A4 expression of ≥1+ staining in ≥10% of the cells by immunohistochemistry. * ECOG Performance Status of 0 or1. For subjects aged ≥10 to ≥16 years old: Lansky Score ≥60%. • Left ventricular ejection fraction (LVEF) ≥50%. Note: other protocol defined Inclusion criteria may apply Key Exclusion Criteria: * HLA-A\*02:05 in either allele * Received or plans to receive the following therapy/treatment prior to leukapheresis or lymphodepleting chemotherapy: Cytotoxic chemotherapy, Tyrosine kinase inhibitor (TKI) (e.g. pazopanib), Immune therapy (including monoclonal antibody therapy, checkpoint inhibitors,), Anti-cancer Vaccine, Gene therapy using an integrating vector (subjects who have received a gene therapy using a lentiviral vector may be eligible for the study), Corticosteroids or any other immunosuppressive therapy, Investigational trea…