Regeneron ($REGN) Fianlimab Trial Risks and Study Outlook Case

• $REGN investors filed a claim against Regeneron for overstating the likelihood that its Phase III fianlimab study would succeed and minimizing risks created by delayed trial events.

• After Regeneron disclosed that the study failed its primary endpoint, $REGN fell 9.8% on May 18, 2026.

• $REGN investors can join this case to be notified about potential recovery.

Case Details:

Between August 1, 2025 and May 15, 2026, Regeneron told investors its fianlimab and Libtayo combination could deliver meaningful benefits for advanced melanoma. Executives emphasized strong earlier-stage results, conservative trial assumptions, durable treatment responses, and confidence that the delayed study remained positioned for success.

However, during this period, investors allege the trial’s slow event rate increased the risk of failure rather than confirming strong treatment performance. Regeneron allegedly failed to disclose that its original statistical assumptions were flawed, the treatment was not clearly outperforming standard therapy, and the delayed events forced a late protocol change that increased uncertainty around the study.

Then, on April 29, 2026, the company revealed that the primary analysis would include additional patients with at least six months of follow-up.

$REGN fell 6.2%, closing at $686.36. Additional revelations followed on May 15, when Regeneron announced the study failed to show a statistically significant improvement in progression-free survival.

By May 18, shares had dropped to $629.68, representing a total decline of 14.0% over the correction period.

Based on these events, $REGN investors filed a claim against Regeneron, alleging the company:

• It overstated the study’s likelihood of success.

• It minimized risks from delayed trial events and the late protocol change.

• It caused investor losses when the study failed its primary endpoint.

Investors argue Regeneron misled the market about fianlimab’s clinical performance and trial risks, causing losses when the truth emerged.