Well‐tolerated treatment with no adverse events above grade 2Achieved over 85% regression in synovial sarcoma following three injections of LV305Sustained robust NY‐ESO‐1‐specific CD4+ and CD8 T‐cell response observed for over 2.5 yearsLV305‐triggered long‐lasting antitumour effector‐memory T‐cell responses. Here, CD8A is linked to synovial sarcoma.