SueWallSt Reminds Shareholders of a Lead Plaintiff Deadline of September 14, 2026 in Regeneron Pharmaceuticals, Inc. Lawsuit - REGN

Regeneron's clinical-trial risk disclosures are under scrutiny after allegations that the Company minimized Phase III Fianlimab-Libtayo statistical and protocol risks, including potential impact of FDA Otptimus-related amendments on progression-free survival analysis.

NEW YORK, July 23, 2026 /PRNewswire/ -- SueWallSt alerts investors in Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) that a securities class action has been filed on behalf of shareholders who purchased REGN securities between August 1, 2025 and May 15, 2026. Submit your information now.

REGN shares allegedly declined $102.09 per share, or 13.95%, from the Class Period high of $731.77 on April 28, 2026 to $629.68 after disclosures concerning the Phase III Fianlimab-Libtayo Study. IMPORTANT DATE: September 14, 2026 is the deadline for investors seeking appointment as lead plaintiff.

Regulatory Compliance Risk Allegedly Became Investor Loss

The complaint challenges whether Regeneron adequately disclosed the clinical, statistical, and regulatory risks surrounding its Phase III Fianlimab-Libtayo Study. The case alleges that public statements minimized the risk that slowing event accrual reflected flaws in preliminary statistical assumptions, rather than durable efficacy in the active treatment arms.

As alleged, Regeneron's study design also had to account for FDA Optimus requirements concerning dose contribution. The lawsuit contends that the Company's statements did not sufficiently disclose that the active treatment arm was allegedly failing to show meaningful differentiation over standard therapies.

Disclosure Gaps Alleged in the Phase III Study

The action claims investors were not adequately informed that:

• The prolonged slowdown in progression-free survival event accrual allegedly increased the risk of clinical failure.
• The study's statistical assumptions and design left it more vulnerable to missing its primary endpoint.
• The active treatment arm allegedly lacked meaningful clinical differentiation over pembrolizumab and other standard therapies.
• A protocol amendment expanded the PFS analysis population to include all patients with at least 6 months of follow-up.
• The study ultimately did not reach statistical significance for its primary endpoint of improved PFS.

Alleged SEC Disclosure Adequacy Issues

The complaint alleges that Regeneron's public disclosures mischaracterized the actual risk of failure facing the study and minimized risks to the study's odds of achieving its primary endpoint and overall statistical validity. On April 29, 2026, Regeneron disclosed that the protocol had been changed to expand the eligible patient group for PFS analysis.

On May 15, 2026, after market close, Regeneron announced that the Phase 3 Trial of Fianlimab did not reach statistical significance for the primary endpoint of improvement in PFS. The lawsuit alleges these disclosures corrected earlier alleged misstatements and caused investors to suffer losses.

"Generic risk factor language cannot substitute for disclosing specific, known problems that are already affecting a company's operations. Here, investors should review whether the alleged protocol, statistical, and FDA Optimus-related protocol amendment risks were adequately disclosed before REGN shares declined." -- Joseph E. Levi, Esq.

Find out if you might qualify to recover losses

WHY SUEWALLST: SueWallSt is powered by Levi & Korsinsky LLP. Levi & Korsinsky LLP has established itself as a nationally-recognized securities litigation firm that has secured hundreds of millions of dollars for aggrieved shareholders and built a track record of winning high-stakes cases. The firm has extensive expertise representing investors in complex securities litigation and a team of over 70 employees to serve our clients. For seven years in a row, Levi & Korsinsky has ranked in ISS Securities Class Action Services' Top 50 Report as one of the top securities litigation firms in the United States.

Frequently Asked Questions About the REGN Lawsuit

Q: What is the REGN class action lawsuit about? A: A securities class action has been filed against Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) alleging materially false and misleading statements between August 1, 2025 and May 15, 2026. Shares fell approximately 13.95% after the Company disclosed a protocol amendment and later announced that the Phase 3 Fianlimab trial did not reach statistical significance for the primary endpoint of improvement in progression-free survival. Investors who purchased shares during the Class Period and suffered losses may be eligible to seek compensation.

Q: What specific misstatements does the REGN lawsuit allege? A: The complaint alleges Regeneron made materially false or misleading statements regarding the Phase III Fianlimab-Libtayo Study, including statements that allegedly characterized slowing event accrual as a potentially favorable sign while minimizing statistical validity and clinical-failure risks. When the protocol amendment and failed primary endpoint were disclosed, the stock price declined sharply.

Q: What court was the REGN class action filed in? A: The case was filed in the United States District Court for the Southern District of New York and is governed by the Private Securities Litigation Reform Act of 1995.

Q: What is a lead plaintiff and why does it matter? A: A lead plaintiff is the investor appointed by the court to represent the entire class. Lead plaintiffs are typically investors with the largest documented losses. Being appointed does not increase individual recovery but gives direct oversight of how the case is run.

Q: What documents do I need to submit my information? A: Brokerage statements or trade confirmations showing purchase dates, share quantities, prices paid, and any subsequent sale dates and prices.

Q: What if I already sold my REGN shares, can I still recover losses? A: Yes. Eligibility is based on when you purchased, not whether you still hold the shares. Investors who bought during the Class Period and sold at a loss may still be eligible to participate.

Q: Do I need to go to court or give testimony? A: No. The overwhelming majority of class members never appear in court or give depositions. If there is a settlement or recovery, eligible class members generally submit a claim form to seek their portion.

Q: What does it cost me to participate? A: There is no upfront cost to contact the firm. Securities class actions are generally handled on a pure contingency basis. No upfront fees, no retainer, and no out-of-pocket costs. Any attorneys' fees and expenses awarded to class counsel are subject to court approval.

CONTACT:

Levi & Korsinsky, LLP

Joseph E. Levi, Esq.

33 Whitehall Street, 27th Floor

New York, NY 10004

[email protected]

Tel: (888) SueWallSt

Fax: (212) 363-7171

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SOURCE SueWallSt.com