Eli Lilly initiates LIBRETTO-531 phase III clinical trial for LOXO 292 to treat RET-mutant medullary thyroid cancer.

Eli Lilly announced the opening of the LIBRETTO-531 clinical trial [NCT04211337] for selpercatinib, also known as LOXO-292, for treatment-naïve RET-mutant medullary thyroid cancer (MTC) patients. This is the second Phase III trial to open for selpercatinib, a highly selective and potent, oral investigational new medicine in clinical development for the treatment of patients with cancers that harbor abnormalities in the rearranged during transfection (RET) kinase. Enrolled trial participants will be randomized to receive either selpercatinib or physician's choice of cabozantinib or vandetanib as initial treatment of their advanced or metastatic RET-mutant MTC. LIBRETTO-531 is a randomized Phase III clinical trial of patients with treatment-naïve RET-mutant MTC. The trial will enroll 400 patients with advanced or metastatic RET-mutant MTC who have received no prior systemic therapy for metastatic disease. Enrolled trial participants will be randomized 2:1 to receive either selpercatinib or physician's choice of cabozantinib or vandetanib as initial treatment of their advanced or metastatic RET-mutant MTC. RET mutations may be identified using local testing. This trial's efficacy endpoints are progression-free survival (PFS), treatment failure-free survival (TFFS), overall survival (OS), overall response rate (ORR), and duration of response (DoR). For patients randomized to the control arm, crossover is allowed at progression.