Eli Lilly and Company announced the opening of the LIBRETTO-531 clinical trial for selpercatinib, also known as LOXO-292, for treatment-naïve RET-mutant medullary thyroid cancer (MTC) patients. This is the second Phase 3 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.
"Approximately 60 percent of people with medullary thyroid cancer have an activating RET point mutation, yet the current therapeutic options are not ideal for many patients," said Lori Wirth, MD, medical director of the Center for Head and Neck Cancer, Massachusetts General Hospital Cancer Center. "This Phase 3 trial of selpercatinib in patients with advanced or metastatic RET-mutant MTC seeks to confirm a new standard of care that we hope will provide a more effective treatment option for this patient population."
LIBRETTO-531 is a randomized Phase 3 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.
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Selpercatinib, also known as LOXO-292, is 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. RET fusions and mutations occur across multiple tumor types with varying frequency. Selpercatinib was designed to inhibit native RET signaling as well as anticipated acquired resistance mechanisms.
Selpercatinib has received breakthrough designations in RET fusion-positive NSCLC, RET-mutant medullary thyroid cancer (MTC) and RET fusion-positive thyroid cancers.
Genomic alterations in RET kinase, which include fusions and activating point mutations, lead to overactive RET signaling and uncontrolled cell growth. RET fusions have been identified in approximately 2 percent of non-small cell lung cancer, 10-20 percent of papillary and other thyroid cancers and a subset of other cancers. Activating RET point mutations account for approximately 60 percent of MTC. RET fusion cancers and RET-mutant MTC are primarily dependent on this single activated kinase for their proliferation and survival. This dependency, often referred to as "oncogene addiction," renders such tumors highly susceptible to small molecule inhibitors targeting RET.