In the present case, the loss of MSH2 and MSH6 expression led to the diagnosis of MSI-high status.5) The frequency of dMMR in pancreatic cancer is around 1%,6–9) and data on the pancreatic cancer cohort in KEYNOTE-158 disappointingly demonstrated an ORR of pembrolizumab <20% in this subgroup.2) On the other hand, Coston et al. reported an ORR of pembrolizumab of 75% (20% complete response in retrospective data).10). The gene discussed is MSH2; the disease is pancreatic neoplasm.