Regeneron Pharmaceuticals, Inc.: Regeneron Provides Update on Phase 3 Trial of Fianlimab (LAG-3 Inhibitor) Combination in First-Line Unresectable or Metastatic Melanoma

Regeneron Pharmaceuticals announced Phase 3 trial results for its LAG-3 inhibitor fianlimab combined with cemiplimab as a first-line treatment for unresectable or metastatic melanoma. The trial, involving 1,546 patients aged 12 or older, compared two dose levels of the combination to pembrolizumab monotherapy and cemiplimab monotherapy. The high-dose combination (1600 mg fianlimab + 350 mg cemiplimab) showed a median progression-free survival (PFS) of 11.5 months, a 5.1-month improvement over pembrolizumab’s 6.4 months, but failed to reach statistical significance (p=0.0627). The low-dose combination (400 mg fianlimab + 350 mg cemiplimab) achieved a median PFS of 9.6 months, with no significant difference from pembrolizumab. The study did not identify new safety concerns with the fianlimab combinations. Regeneron is concurrently running a Phase 3 head-to-head trial comparing the high-dose fianlimab combination to Opdualag (nivolumab + relatlimab-rmbw) for the same patient population. Detailed findings from the trial will be presented at an upcoming medical conference. The trial design included randomization into four groups: high-dose combination, low-dose combination, pembrolizumab monotherapy, and cemiplimab monotherapy. The low-dose group was compared to a subset of pembrolizumab patients (n=421). All treatments were administered every three weeks. Regeneron emphasized that fianlimab and cemiplimab’s potential uses remain investigational, with regulatory approval pending. The company’s proprietary technologies, including VelociSuite, were leveraged in developing these therapies. Further data from ongoing trials will determine the clinical path forward for the combination.