Regeneron’s melanoma immunotherapy program stumbled in a late-stage test: the company said a fianlimab plus Libtayo regimen failed to improve outcomes versus Keytruda in a phase 3 setting, adding to recent LAG-3 setbacks. The result triggered investor concern about the efficacy window for this checkpoint strategy in the tumor types tested. In a separate but fast-following move, Regeneron also announced a deal with Parabilis Medicines to develop drugs against five undisclosed targets using Parabilis’ Helicon peptide platform. The partnership includes $125 million up front and up to about $2.2 billion in milestone payments, plus royalties. Together, the two announcements underscore how checkpoint and platform bets are being recalibrated after clinical readouts: Regeneron is attempting to manage portfolio risk by pairing pipeline setbacks with new modality and target expansion. Market impact is likely to hinge on how the company communicates next steps for LAG-3 assets and how quickly the Helicon platform deal can yield development candidates with clear translational rationale.