URLC10 CTL induction was highly prevalent (93.3%) and strong (grade +++) after S-588410 was administered a median 5 (range 3–14) times, in contrast to previous reports of low URLC10 CTL induction, requiring at least eight vaccine doses, in patients with advanced head and neck squamous cell carcinoma [14], advanced/recurrent non-small cell lung cancer [16] and advanced gastric cancer [17]. Here, LY6K is linked to head and neck squamous cell carcinoma.