Hagens Berman says investors can seek lead plaintiff role in Regeneron securities suit
The complaint centers on a Phase 3 melanoma trial of fianlimab plus Libtayo and alleges Regeneron made misleading disclosures before the study failed to meet its main goal.
Hagens Berman says a securities class action has been filed against Regeneron Pharmaceuticals over disclosures tied to a Phase 3 melanoma trial of fianlimab plus Libtayo. The firm said the case concerns investors who bought or otherwise acquired Regeneron common stock between Aug. 1, 2025, and May 15, 2026.
The complaint, described in a PR Newswire release dated Aug. 10, 2026, alleges Regeneron and its management made false or misleading statements and omitted information about the trial’s prospects. The release says the study’s main goal was progression-free survival, or PFS, a measure of how long patients live without their cancer worsening.
The release says the company had described the combination as a “potential blockbuster,” and that news of the failed trial sent Regeneron shares sharply lower. The source says the move erased an estimated $11 billion in market value.
According to the release, the complaint alleges preliminary statistical assumptions were flawed, the active treatment arm was not meaningfully outperforming standard therapies, and success on the primary endpoint was unlikely. Those are allegations in the lawsuit, not findings by a court.
The release says Regeneron first disclosed on Apr. 29, 2026, that it had changed the protocol so the primary PFS analysis would include all enrolled patients with at least six months of follow-up. It says the company later explained on May 12, 2026, that the change was due to “slow event rates” and had been submitted to global regulatory authorities in November and December.
Regeneron then said on May 15, 2026, that the trial did not reach statistical significance for the primary PFS endpoint. The class period listed in the release ends that same day. Hagens Berman said the lead plaintiff deadline is Sept. 14, 2026.
Hagens Berman partner Reed Kathrein said the firm is investigating whether Regeneron altered the protocol without timely telling investors and whether defendants knew the combination’s blockbuster potential was not real, according to the release.
The next step is a lead plaintiff process for investors who say they were affected during the class period. The release also includes a whistleblower callout referring readers to the SEC Whistleblower program.
Sources
Editorial note: This article was prepared with AI assistance and includes source attribution for reader review.
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