Regeneron’s two-drug regimen combining fianlimab and Libtayo did not significantly outperform pembrolizumab (Keytruda) in a late-stage melanoma trial, adding to pressure on LAG-3-targeted strategies. Analysts cited surprise in the failure, and the result erased substantial market value tied to expectations for the combination. The setback follows additional late-stage disappointments in the LAG-3 space, raising urgency around how Regeneron recalibrates its oncology portfolio and trial designs as it seeks future probability-weighted outcomes.