Hagens Berman says it is investigating Regeneron melanoma trial disclosures

By Atlas Watchline Staff · Legal · August 18, 2026

The firm said it is pursuing a securities class action over Regeneron Pharmaceuticals’ disclosures about a Phase 3 melanoma trial and the study’s missed endpoint.

Hagens Berman Sobol Shapiro said it is investigating a securities class action against Regeneron Pharmaceuticals over disclosures tied to a Phase 3 melanoma trial of fianlimab in combination with Libtayo.

The item, published Aug. 18, 2026, says the case centers on alleged misleading statements and omissions about the study’s progress and prospects. It identifies the trial as one for first-line treatment of metastatic or locally advanced melanoma and says the primary endpoint was progression-free survival, or PFS.

The release says the matter concerns investors because it alleges Regeneron gave an upbeat picture of the combination therapy while the study was struggling to show enough separation from standard treatments. The filing period named in the release runs from Aug. 1, 2025, through May 15, 2026, and the lead plaintiff deadline is Sept. 14, 2026.

According to the release, Regeneron first disclosed on April 29, 2026, that it had decided to alter the trial protocol so the primary PFS analysis would consider all enrolled patients with at least six months of follow-up. It says the company later said on May 12, 2026, that the change was made because of slow event rates and had been submitted to global regulatory authorities in the November-December timeframe.

The release says Regeneron then reported on May 15, 2026, that the trial did not reach statistical significance on the primary endpoint of improvement in PFS. It says that disclosure drove the shares sharply lower and erased about $11 billion in market value.

The allegations in the release are still allegations. Hagens Berman says it is examining whether Regeneron altered the protocol without telling investors in time, which the firm says could have misled the market.

Hagens Berman partner Reed Kathrein was quoted in the release as saying the firm is focused on whether the company changed the protocol without timely disclosure in order to mislead investors. The release also invites investors with substantial losses and people with non-public information to contact the firm and references the SEC whistleblower program.

What happens next is tied to the court process and the Sept. 14, 2026, deadline cited in the release for investors seeking to lead the case.

Sources

• PR Newswire release text

Editorial note: This article was prepared with AI assistance and includes source attribution for reader review.

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