REGN 1-WEEK DEADLINE ALERT: Regeneron Pharmaceuticals, Inc. Investors Alerted to September 14, 2026 Lead Plaintiff Deadline in Class Action Lawsuit

Investors in Regeneron Pharmaceuticals (NASDAQ: REGN) are alerted to a securities class action lawsuit filed following revelations about a Phase 3 clinical trial for a melanoma therapy. The news of the trial's failure caused a significant drop in Regeneron's stock price, resulting in an $11 billion market cap wipeout and triggering the lawsuit. The suit seeks to represent investors who purchased Regeneron common stock between August 1, 2025, and May 15, 2026. The litigation focuses on Regeneron's statements regarding its Phase 3 trial of Fianlimab in combination with Libtayo for metastatic or locally advanced melanoma. The complaint alleges that Regeneron made misleading statements and failed to disclose that the trial's preliminary statistical assumptions were flawed, the active treatment arm showed no meaningful differentiation from standard therapies, and achieving the primary endpoint was unlikely. Regeneron assured investors of the trial's success, even as event rates slowed. The truth began to emerge on April 29, 2026, when Regeneron announced a change to the trial protocol, altering the primary analysis of progression-free survival. An analyst questioned if this was due to an insufficient underlying PFS benefit. On May 12, 2026, Regeneron admitted the protocol change was made nearly six months prior in response to slow event rates and had been submitted to regulatory authorities. On May 15, 2026, Regeneron reported that the trial did not reach statistical significance for its primary endpoint of improvement in progression-free survival.