Furthermore, the functional in vitro assay revealed that MLH1 V384D and MLH1 R217C mutations had 50–60% MMR efficiency than wild-type MLH1. Although having high tumor mutational burden does not always associate with improved survival and clinical trials should be conducted to evaluate the survival benefit, these findings suggest that there is a decent percentage of MMR-deficient EMPD, which has an impaired MMR machinery, in EMPD and this subset of patients might achieve a durable response by anti-PD-1 immunotherapy. This evidence concerns the gene MLH1 and neoplasm.