Key Takeaways:
Regeneron Pharmaceuticals Inc. faces a securities class action after its Phase III melanoma trial failed, wiping out about $7 billion in market value over two trading sessions.
"Shareholders were misled about the viability of the Fianlimab-Libtayo study, which had fundamentally flawed statistical assumptions from the outset," Thomas J. McKenna, a partner at Gainey McKenna & Egleston, said in a statement announcing the lawsuit.
The class period runs from Aug. 1, 2025 to May 15, 2026. On April 29, Regeneron disclosed during its first-quarter earnings call that it had expanded the number of patients eligible for progression-free survival analysis in the study, sending shares down 6.2% to $686.36 from $731.77 the prior day. Two weeks later, the company announced the trial "did not reach statistical significance for the primary endpoint of improvement in progression-free survival," triggering a second decline of 9.8% to $629.68.
The combined selloff erased roughly 16% of Regeneron's value from its April 28 close. The complaint alleges that Regeneron's preliminary statistical assumptions were fundamentally flawed, that the active treatment arm was failing to achieve meaningful clinical differentiation over standard therapies, and that the trial would ultimately fail to reach statistical significance even without overperformance of the control arm.
Regeneron was testing Fianlimab, a human monoclonal antibody targeting the LAG-3 immune checkpoint receptor on T-cells, in combination with Libtayo as a first-line treatment for advanced melanoma. The study began enrollment in mid-2022. Multiple law firms — including Robbins LLP, Gainey McKenna & Egleston, and Levi & Korsinsky — have filed or announced investigations into potential securities law violations.
The lawsuit seeks to recover losses for investors who purchased Regeneron securities during the class period. The lead plaintiff deadline is Sept. 14. The case was filed in the U.S. District Court for the Southern District of New York.
The failed trial removes a key pipeline candidate for Regeneron, which has relied heavily on its blockbuster eye drug Eylea for revenue. Investors will watch for any updates on the company's remaining late-stage pipeline assets and whether the litigation leads to settlement costs or governance changes.
This article is for informational purposes only and does not constitute investment advice.
