RET and medullary thyroid gland carcinoma: A multicenter, randomized, open-label, phase III trial comparing selpercatinib to physicians’ choice of cabozantinib or vandetanib (standard of care) in patients with progressive, advanced, kinase inhibitor naïve, RET-mutant MTC (LIBRETTO-531) is ongoing and recruiting patients (ClinicalTrials.gov Identifier: NCT04211337).