LY6K and metastatic neoplasm: Previously, a cancer vaccine comprising three HLA-A*24:02-restricted peptides derived from three antigens, i.e., lymphocyte antigen-6 complex locus (LY6k, also known as upregulated lung cancer 10; URLC10), TTK protein kinase, and insulin-like growth factor-II mRNA binding protein-3 (IMP3, also known as KH domain-containing protein overexpressed in cancer 1; KOC1), was found to prolong survival and induce antigen-specific cytotoxic T lymphocytes (CTLs) in patients with ESCC with locally advanced, recurrent, or/and metastatic tumors who failed to respond to the standard therapy [9].