LY6K and esophageal squamous cell carcinoma: Therefore, we had performed a phase I clinical cancer vaccination trials with a combination of multiple peptides that were derived from TTK, LY6K, and IMP3 for the HLA-A*2402 (+) patients with advanced ESCC who had been refractory to standard ESCC therapy, and the evidence in the phase I trial encouraged us to further develop this therapy as a phase II trial [6].