Selpercatinib has been approved for adult patients with metastatic RET fusion–positive NSCLC and adult and pediatric patients ≥ 12 years of age with advanced or metastatic RET-mutant MTC or metastatic RET fusion–positive thyroid cancer who require systemic therapy and who are radioactive iodine refractory. Here, RET is linked to medullary thyroid gland carcinoma.