Such is the case for pembrolizumab for tumors with microsatellite instability (< 1% of cholangiocarcinomas) or high tumor mutational burden (TMB > 10 mutations/Mb) [53, 54], or TRK-inhibitors (larotrectinib or entrectinib) for tumors with NTRK rearrangements (< 5% of cholangiocarcinomas) [55, 56]. The gene discussed is NTRK1; the disease is cholangiocarcinoma.