Lymph-node metastasis from gastric adenocarcinoma in a patient bearing a germ line missense variant MSH2 c.1808A > T (Asp603Val) responds to the immune checkpoint inhibitor pembrolizumab.

We report the sensitivity of immune checkpoint inhibitors for tumors developing in a patient bearing the MSH2 c.1808A > T (Asp603Val) variant belonging to a pedigree of Lynch syndrome. This variant was previously thought to be of unknown significance, but we recently found that this missense mutation was likely pathogenic.