CTLA4 and cholangiocarcinoma: et al. also reported that the presence of MSI-H non-CRC tumors (endometrial, ampullary or cholangiocarcinoma, small bowel, and stomach) predicts an impressive response rate in patients and that somatic mutation loads were associated with prolonged progression-free survival.25 Prediction of benefit from immunotherapy by mutational loads was also demonstrated in melanomas treated with ipilimumab or tremelimumab, antibodies against cytotoxic T-lymphocyte antigen 4 (CTLA-4), and in non-small cell lung cancers treated with pembrolizumab [22, 24].