Why did Regeneron's stock drop sharply before market open?

Regeneron's stock fell 11.8% premarket because its experimental fianlimab-cemiplimab combination failed to meet the primary endpoint—statistical significance in improving progression-free survival (PFS)—in a late-stage trial for advanced melanoma.

What was the main clinical outcome of Regeneron's late-stage melanoma trial?

The trial showed that the fianlimab-cemiplimab combination did not achieve statistical significance in improving progression-free survival (PFS), although it demonstrated a numeric improvement of 5.1 months in median PFS compared to Merck's Keytruda.

Regeneron drops after skin cancer treatment misses late-stage trial goal

May 18, 2026

Regeneron shares fell 11.8% after its experimental fianlimab-cemiplimab combination failed to meet statistical significance in a late-stage melanoma trial against Merck's Keytruda. Despite a numeric improvement in progression-free survival, the results disappointed investors regarding the drugmaker's pipeline progress.

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Regeneron drops after skin cancer treatment misses late-stage trial goal

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