The efficacy of selpercatinib in RET-mutated TC was investigated in a phase I–II study (LIBRETTO-001, ClinicalTrials.gov ID: NCT03157128), showing durable efficacy with mainly low-grade toxic effects in patients with MTC who previously received cabozantinib or vandetanib (n = 55), or were treatment naive (n = 88), and in patients harboring RET fusion-positive TC (n = 19) (53). This evidence concerns the gene RET and medullary thyroid gland carcinoma.