On May 15, 2026 Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) reported results from the Phase 3 trial evaluating two dose levels of fianlimab (LAG-3 inhibitor) in combination with cemiplimab (PD-1 inhibitor) as a first-line treatment for patients with unresectable locally advanced or metastatic melanoma. The trial did not reach statistical significance for the primary endpoint of improvement in progression-free survival (PFS) compared to pembrolizumab (PD-1 inhibitor) monotherapy. No new safety signals were identified with the fianlimab combination.

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High-Dose
Combination
(n=508) Low-Dose
Combination
(n=422) Pembrolizumab
Monotherapy
(n=462) Cemiplimab
Monotherapy*
(n=154)
Primary endpoint:
median PFS, months
(95% Confidence
Interval [CI])

11.5 (6.3, 16.8)

9.6 (6.2, 13.9)

6.4 (4.4, 11.1)

6.3 (4.0, 17.2)

Hazard Ratio (95%
CI)
Relative to
Pembrolizumab

0.845 (0.709,
1.008) 0.931 (0.773,
1.122)#
p-Value p=0.0627 p=0.4661#
*Cemiplimab was used to define contribution of components and was not used in the statistical comparison
# Low dose combination compared against subset of concurrently randomized patients on pembrolizumab (n=421)

Detailed results from the trial will be presented at an upcoming medical meeting.

A Phase 3 head-to-head trial, also in first-line unresectable or metastatic melanoma, evaluating the high-dose fianlimab combination versus Opdualag (nivolumab and relatlimab-rmbw) is ongoing.

The potential uses of fianlimab and cemiplimab described above are investigational, and safety and efficacy of this combination have not been evaluated by any regulatory authority.

About the Phase 3 Trial
This randomized, double-blind Phase 3 trial is investigating the combination of fianlimab and cemiplimab versus pembrolizumab in patients 12 years of age or older with unresectable locally advanced or metastatic melanoma who have not received a previous systemic treatment for advanced disease. The trial enrolled 1,546 patients who were randomized to receive either: 1600 mg fianlimab and 350 mg cemiplimab (high-dose combination) every 3 weeks; 400 mg fianlimab and 350 mg cemiplimab (low-dose combination) every 3 weeks; placebo and 200 mg pembrolizumab every 3 weeks; or placebo and 350 mg cemiplimab every 3 weeks.

(Press release, Regeneron, MAY 15, 2026, View Source [SID1234665777])