A phase I clinical trial (NCT00682227) was conducted to examine the safety, immunogenicity, and antitumor effect of a cancer vaccine targeting TTK protein kinase, lymphocyte antigen 6 family member K (LY6K), and insulin-like growth factor 2 mRNA binding protein 3 (IMP-3) against esophageal squamous cell carcinoma. The gene discussed is LY6K; the disease is esophageal squamous cell carcinoma.