# Fianlimab + cemiplimab phase 3 (first-line melanoma)

Source: https://onco.cc/trials/fianlimab-phase3-melanoma/  
OnCo record `fianlimab-phase3-melanoma` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A second LAG-3 blocker failed to beat pembrolizumab alone, a warning that the Opdualag result is not automatically a class effect.

## Summary

Regeneron reported that the trial missed its primary PFS endpoint; the high-dose combination improved median PFS numerically by 5.1 months, but the difference was not statistically significant. Differences from RELATIVITY-047 include the comparator (pembrolizumab rather than nivolumab), the antibody, and dosing. The adjuvant fianlimab phase 3 continues.

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-07
- Tags: failure; lesson:class-effect-not-guaranteed
- Registry id: NCT05352672
- Phase: 3
- Setting: Untreated unresectable or metastatic melanoma: fianlimab + cemiplimab (two dose levels) vs pembrolizumab
- Sponsor: Regeneron
- Enrolled: 1546
- Result: Primary PFS endpoint not met; numerical +5.1 months median PFS at the high dose.
- Outcomes: Progression-free survival, fianlimab 1600 mg + cemiplimab vs pembrolizumab: Fianlimab 1600 mg + cemiplimab 11.5 months vs Pembrolizumab 6.4 months, HR 0.845; Progression-free survival, fianlimab 400 mg + cemiplimab vs pembrolizumab: Fianlimab 400 mg + cemiplimab 9.6 months vs Pembrolizumab 6.4 months, HR 0.931; Progression-free survival, cemiplimab monotherapy arm: Cemiplimab 6.3 months
- Replication: Second LAG-3 setback after RELATIVITY-098; the numerical PFS gain at the high dose did not reproduce the phase 1 signal, and RELATIVITY-047 remains the only positive randomised LAG-3 trial in melanoma.

## Sources

- ClinicalTrials.gov NCT05352672: https://clinicaltrials.gov/study/NCT05352672
- Regeneron update: https://investor.regeneron.com/news-releases/news-release-details/regeneron-provides-update-phase-3-trial-fianlimab-lag-3

## Connected records

- cancers: [Advanced melanoma (unresectable stage III and stage IV)](https://onco.cc/cancers/advanced-melanoma/), [Melanoma](https://onco.cc/cancers/melanoma/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- targets: [LAG-3](https://onco.cc/targets/lag3/), [PD-1](https://onco.cc/targets/pd1/)
- drugs: [Cemiplimab](https://onco.cc/drugs/cemiplimab/), [Fianlimab](https://onco.cc/drugs/fianlimab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- companies: [Regeneron](https://onco.cc/companies/regeneron/)
- trials: [RELATIVITY-047](https://onco.cc/trials/relativity-047/)
- pairings: [Caution: LAG-3 blockade outside active disease](https://onco.cc/pairings/lag3-adjuvant-caution/)
- ideas: [Extended-interval immunotherapy: give checkpoint inhibitors every 8-12 weeks once stable](https://onco.cc/ideas/idea-tr1-extended-interval-checkpoint-dosing/), [Give immunotherapy in the morning](https://onco.cc/ideas/idea-chronotherapy-immunotherapy/), [Microbiome transplant as a routine immunotherapy adjunct](https://onco.cc/ideas/idea-microbiome-io-fmt/), [Randomised trials of stopping immunotherapy after one year versus continuing](https://onco.cc/ideas/idea-tr1-immunotherapy-stop-trials/)

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