Regeneron’s LAG-3 inhibitor fianlimab missed a key efficacy mark in a late-stage melanoma study, failing to beat Keytruda (pembrolizumab) by a statistically significant margin and adding to setbacks for the checkpoint class. The Phase 3 result underlines the difficulty of finding oncology combinations that improve outcomes beyond existing PD-1 therapy in unselected melanoma populations. In a separate move aimed at offsetting pipeline risk, Regeneron also announced a major partnership with Parabilis Medicines for Parabilis’ Helicon peptide platform. The deal includes $125 million up front and up to about $2.2 billion in potential milestones, with royalties tied to commercial outcomes, positioning Parabilis’ peptide-discovery approach as a new R&D engine for Regeneron. Taken together, the fianlimab disappointment and the Parabilis collaboration highlight a near-term pivot—away from a stalled LAG-3 strategy and toward next-generation target discovery—while the company still leans on immuno-oncology as a core growth bet.