Clinical Trial of Safety, Tolerability and Antitumor Activity of Genetically Engineered T Cells in Combination With Anti-Cancer Agents in Relapsed and Refractory Synovial Sarcoma Expressing New York Esophageal Antigen-1 (NY-ESO-1) and/or LAGE-1a

Adoptive T-cell therapy is a therapeutic approach that aims to generate an anti-tumor T-cell immune response by infusing a cancer subjects own T-cells obtained by leukapheresis, engineered and expanded in-vitro to express a tumor specific T-cell receptor. NY-ESO-1 and LAGE-1a antigens are tumor-associated proteins that have been found in several tumor types, including synovial sarcoma. This is an open-label study to evaluate the safety and efficacy of GSK3377794 (genetically engineered NY-ESO-1 Specific \[c259\] T Cells), in combination with anticancer agents including pembrolizumab in subjects with NY-ESO-1 and/or LAGE-1a positive relapsed and refractory synovial sarcoma. The study will consist of a target expression screening to determine if subjects are human leukocyte antigen (HLA)-A\*02:01, HLA-A\*02:05 and/or HLA-A\*02:06 positive and if their tumors express NY-ESO-1 and/or LAGE-1a, followed by a leukapheresis screening phase of up to 42 days prior to leukapheresis. Eligible subjects will enter a leukapheresis phase followed by lymphodepletion phase with cyclophosphamide and fludarabine. During the treatment phase, subjects will be administered GSK3377794 on Day 1 followed by pembrolizumab infusion once every 3 weeks from Day 22 (or Week 7) for up to 2 years. There will be a long-term follow-up phase from the end of treatment phase and for up to 15 years from the date of GSK3377794 administration.