Eli Lilly and Company announced the opening of the LIBRETTO-431 clinical trial for selpercatinib, also known as LOXO-292, for treatment-naïve RET fusion-positive non-small cell lung cancer (NSCLC) patients. Enrolled trial participants will be randomised to receive either selpercatinib or platinum-based (carboplatin or cisplatin) and pemetrexed therapy with or without pembrolizumab as initial treatment of their advanced or metastatic RET fusion-positive NSCLC. "Given the remarkable results of the LIBRETTO-001 trial, I am excited to open this important phase 3 trial of selpercatinib, a highly selective and potent molecule that has previously demonstrated sustained responses with a well-tolerated safety profile," said professor Ben Solomon, principal investigator at the Peter MacCallum Cancer Centre in Melbourne Australia. "This trial endeavors to generate outcome data that place patients with RET fusions alongside those with EGFR mutations and ALK fusions, as driver-positive populations that should be treated with targeted therapies in the first-line setting, rather than chemoimmunotherapy." "This is an important milestone in the journey to further demonstrate the benefit of selpercatinib and the potential for people living with advanced or metastatic RET fusion-positive non-small cell lung cancer in the first-line setting against the current standard of care," said Anne White, president of Lilly Oncology. "Launching a trial of this size underscores the importance of now including RET fusions in the paradigm of genomic testing in lung cancer." LIBRETTO-431 is a randomised phase 3 clinical trial of patients with treatment-naïve RET fusion-positive NSCLC. The trial will enroll 400 patients with advanced or metastatic RET fusion-positive NSCLC who have received no prior systemic therapy for metastatic disease. Enrolled trial participants will be randomised 1:1 to receive either selpercatinib or platinum-based (carboplatin or cisplatin) and pemetrexed therapy with or without pembrolizumab as initial treatment of their advanced or metastatic RET fusion-positive NSCLC. RET fusions may be identified using local testing. This trial's primary endpoint is progression-free survival (PFS) and secondary endpoints include overall survival (OS), overall response rate (ORR), duration of response (DoR), and intracranial ORR. For patients randomised to the control arm, crossover is allowed at progression. 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 per cent of non-small cell lung cancer, 10-20 per cent of papillary and other thyroid cancers and a subset of other cancers. Activating RET point mutations account for approximately 60 per cent 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.