RET and thyroid cancer: Similarly, the LIBRETTO-001 open-label, phase I/II, basket trial is underway, investigating the efficacy and safety of selpercatinib, a highly selective RET kinase inhibitor with CNS activity that has shown efficacy in RET fusion-positive lung and thyroid cancers, in a group of patients with RET fusion-positive advanced solid non-lung or thyroid tumors [78].