While on-target resistance mutations in the FGFR2 kinase domain (N649H/K, V564F, E656A, L617V, K641R and K659M) have been detected in circulating tumour DNA in the context of FGFR2 translocations in cholangiocarcinoma patients who have received infigratinib [32,33], such mutations have yet to be identified in cancers with FGFR3 molecular alterations. The gene discussed is FGFR2; the disease is cholangiocarcinoma.