Association of genetic variations within the PD-L2 immune checkpoint gene with outcome in stage II and III colon cancer.

626Background: Immune checkpoints can either inhibit or stimulate T-cell responses and therefore play a key role in maintaining an equilibrium between self tolerance and autoimmunity. Targeting immune checkpoint molecules can result in increased antitumor immunity by stimulation of the immune system. We hypothesize, that variations in genes encoding for both inhibitory or stimulatory immune checkpoint proteins may predict outcome in stage II and III colon cancer patients. Methods: The impact of 6 functional single nucleotide polymorphisms (SNPs) within the PD1, PD-L1, PD-L2, TIM3, OX40 and CD27 genes on time to recurrence was evaluated in 201 patients with stage II and III colon cancer. Genomic DNA was extracted from formalin-fixed paraffin embedded tissue and the SNPs were analyzed by PCR-based direct sequencing. Results: Baseline characteristics were as follows: female/male ratio = 42.8% / 57.2%; median age = 70y (19-91); median follow-up = 43months. The PD-L2 rs16923189 SNP showed significant associati...