RET and thyroid gland carcinoma: In the phase 1/2 LIBRETTO-001 trial, selpercatinib exhibited durable efficacy with mostly low-grade adverse effects in patients with RET-altered thyroid cancer, including RET-mutant medullary thyroid cancer and RET fusion-positive thyroid cancer.511 The response rate and PFS were drastically high in all groups of patients, regardless of previous vandetanib or cabozantinib treatment.