Using serial analysis of plasma cell-free DNA (cfDNA)[74] isolated from three patients with FGFR2 fusion positive cholangiocarcinoma, receiving infigratinib, Goyal et al. [71] detected the emergence of resistance gatekeeper conferring mutations in FGFR2. Mutations at V564F, within the kinase domain developed in all three patients, suggesting this is common mechanism of resistance. Here, FGFR2 is linked to cholangiocarcinoma.