XAGE1B and synovial sarcoma: NY-ESO-1 and XAGE-1B are one of the CTAs, which are a large family of tumor-associated antigens only in germ cells of the testis and placenta (12, 13), and in various malignant tumors, such as melanoma (14), squamous cell carcinoma (15), non-small cell lung cancer (16), gastric cancer (17), hepatocellular carcinoma (18), breast cancer (19), ovarian cancer (20), bladder cancer (21), prostate cancer (22), multiple myeloma (23), synovial sarcoma (24), and Ewing’s sarcoma (25).