AFP and esophageal squamous cell carcinoma: The most studied TAAs are oncofetal antigens and cancer/testis antigens, including alpha fetoprotein (AFP), glypican-3 (GPC-3), New York esophageal squamous cell carcinoma-1, synovial sarcoma X-2, melanoma antigen gene-A, and human telomerase-reverse transcriptase, which can elicit a defensive immune response in the host.