Five patients (26%), four with tumours harbouring CD74‐ROS1 fusions and one with a SLC34A2‐ROS1 fusion‐positive tumour showed emergence of acquired ROS1 resistance mutations (ROS1G2032R; ROS1F2004C/I) at PD, which were not present pre‐treatment. The gene discussed is SLC34A2; the disease is neoplasm.