Libretto-531: A Phase III Study of Selpercatinib in Multikinase Inhibitor-Naïve <i>RET</i> -Mutant Medullary Thyroid Cancer
Lori J. Wirth, Marcia S. Brose, Rossella Elisei, Jaume Capdevila, Ana O. Hoff, Mimi I. Hu, Makoto Tahara, Bruce Robinson, Ming Gao, Meng Xia, Patricia Maeda, Eric J. Sherman
Abstract
Selpercatinib is a first-in-class, highly selective and potent, central nervous system-active RET kinase inhibitor. In the phase I/II trial, selpercatinib demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pre-treated and treatment-naive patients with RET-mutant medullary thyroid cancer (MTC). LIBRETTO-531 (NCT04211337) is a multicenter, open-label, randomized, controlled, phase III trial comparing selpercatinib to cabozantinib or vandetanib in patients with advanced/metastatic RET-mutant MTC. The primary objective is to compare progression-free survival (per RECIST 1.1) by blinded independent central review of patients with progressive, advanced, multikinase inhibitor-naive, RET-mutant MTC treated with selpercatinib versus cabozantinib or vandetanib. Key secondary objectives are to compare other efficacy outcomes (per RECIST 1.1) and tolerability of selpercatinib versus cabozantinib or vandetanib.