Pembrolizumab shows promise for rare microsatellite-high intrahepatic cholangiocarcinoma

A 65-year-old man with unresectable, microsatellite-high intrahepatic cholangiocarcinoma experienced significant tumor shrinkage after receiving pembrolizumab, following a failed combination therapy. The comprehensive cancer genomic profiling identified an mlh1 pathogenic mutation, suggesting the microsatellite instability was somatic rather than inherited. Remarkably, the response was maintained for over 30 months, indicating pembrolizumab’s potential effectiveness in treating this rare cancer type. This case highlights the importance of genomic profiling in identifying suitable treatments for difficult malignancies.