Tra‐1‐60: A new serum marker in patients with germ‐cell tumors

TRA‐1‐60 is a monoclonal antibody (MAb) that recognizes a mucin‐like antigenic determinant expressed on the surface of embryonal carcinoma (EC) progenitor cells. In order to determine whether this antigen is released into the serum of patients with a non‐seminomatous germ‐cell tumor (NSGCT), we developed a sensitive 2‐step immunoenzymometric assay. Of 42 EC‐positive NSGCT patients tested, 32 (76%) were found to release TRA‐1‐60‐reactive antigen into their serum, in contrast to 1 positive finding in 10 EC‐negative NSGCT patients. The marker was found in 67% (10/15) of the EC‐positive patients who were negative for both AFP and HCG. Sera from seminoma patients did not contain elevated levels of the TRA‐1‐60 antigen. Therefore, we propose that the TRA‐1‐60 antigen is a useful additional serum marker for following the progress of NSGCT(EC⁺) patients.