Regeneron Pharmaceuticals is currently involved in a cluster of major lawsuits on multiple fronts: a $407 million antitrust verdict it won against Amgen in May 2025, two active Department of Justice False Claims Act cases tied to its eye drug Eylea, patent infringement suits against six biosimilar developers, a securities class action, consolidated shareholder derivative litigation, and an employment discrimination case brought by a former director. The Regeneron lawsuits break down as follows.
The $407 Million Antitrust Win Against Amgen
On May 15, 2025, a federal jury in Delaware found that Amgen used anticompetitive bundling to shut Regeneron’s cholesterol drug Praluent out of the market in favor of Amgen’s competing PCSK9 inhibitor Repatha. The jury awarded Regeneron $135.6 million in compensatory damages and $271.2 million in punitive damages, roughly $407 million in total.1Regeneron Investor Relations. Regeneron Prevails Over Amgen in Antitrust PCSK9 Lawsuit
The evidence at trial showed Amgen offered pharmacy benefit managers bundled rebates that tied discounts on its high-demand drugs Enbrel and Otezla to the condition that PBMs choose Repatha as the exclusive PCSK9 product on their formularies. The jury found Amgen liable under the Sherman Act, the Clayton Act, New York’s Donnelly Act, California’s Cartwright Act, and Delaware tort law. Regeneron prevailed on every claim it brought except one under California’s Unfair Practices Act.2Haug Partners. Regeneron Pharmaceuticals, Inc. v. Amgen Inc.
The verdict is not final. On June 12, 2025, Amgen filed a renewed motion for judgment as a matter of law or, alternatively, a new trial. Regeneron filed its own motions seeking a permanent injunction, a constructive trust, and prejudgment interest. Those post-trial motions remain pending.2Haug Partners. Regeneron Pharmaceuticals, Inc. v. Amgen Inc. An Amgen spokesperson said the company was “disappointed” and looked forward to those proceedings.3Fierce Pharma. Amgen on Hook to Pay More Than $400M After Regeneron Triumphs in Cholesterol Drug Antitrust Suit
Two DOJ False Claims Act Cases Over Eylea
Regeneron is defending two separate federal fraud lawsuits in the District of Massachusetts, both centered on Eylea (aflibercept), and both brought under the False Claims Act. They involve different alleged schemes.
The Copay Foundation Kickback Case
The first lawsuit alleges Regeneron violated the Anti-Kickback Statute by paying tens of millions of dollars to the Chronic Disease Fund, a charitable foundation that covered Medicare patients’ copayments for Eylea. The DOJ contends these were not real charitable donations but a scheme to eliminate copay costs and induce prescribing. According to the government, Regeneron tracked foundation data to ensure its money went only to Eylea patients and calculated that its payments would produce more than a 400 percent return in Medicare revenue. The DOJ also alleges senior executives lied to company auditors in 2013 about receiving Eylea-specific data from the foundation.4U.S. Department of Justice. United States Files Suit Against Regeneron for Paying Kickbacks Through Co-Pay Foundation
Regeneron denies the donations influenced prescribing. A key battle in the case has been over causation. In September 2023, Chief Judge F. Dennis Saylor IV ruled the government must prove “but-for” causation, meaning it has to show physicians would not have prescribed Eylea without the copay assistance. The First Circuit affirmed that standard on February 18, 2025, rejecting the DOJ’s argument for a looser “causal link” test and joining the Sixth and Eighth Circuits, which deepened a split with the Third Circuit.5U.S. Court of Appeals for the First Circuit. United States v. Regeneron Pharmaceuticals, No. 23-2086
That ruling did not end the case. The First Circuit noted its holding applies only to claims under the 2010 amendment’s “per se” false claim pathway and does not block a “false certification” theory. In October 2025, the DOJ filed a summary judgment brief arguing every Medicare Part B claim for Eylea submitted between 2013 and 2014 carried an implied certification of Anti-Kickback Statute compliance.6Sheppard Mullin. Regeneron, the False Claims Act, and a New Era in Government Enforcement The case remains active.
The Eylea Price Reporting Case
The second DOJ suit, in which the government intervened on April 10, 2024, alleges Regeneron inflated Medicare reimbursement rates for Eylea by failing to report credit card processing fees it paid on behalf of physician-customers as “price concessions.” The original whistleblower complaint came from two former Regeneron employees, Julianne Nunnelly and Matthew Shanks.7FraudFighters. DOJ Files Second Qui Tam Lawsuit Against Regeneron Pharmaceuticals
According to the government, Regeneron paid credit card fees for distributors so physicians could buy Eylea by credit card without surcharges, and the physicians received cash-back rewards. The DOJ says Regeneron knew those payments qualified as price concessions but reported them internally as “bona fide service fees” to conceal them, resulting in hundreds of millions of dollars in inflated Medicare reimbursements. Eylea accounted for more than $25 billion in Medicare payments between 2012 and 2023. Under the False Claims Act, the government can pursue treble damages plus penalties.8U.S. Department of Justice. United States Files Complaint Against Regeneron Pharmaceuticals Alleging Fraudulent Drug Pricing
Eylea Biosimilar Patent Litigation
Regeneron has sued six biosimilar developers to block competing versions of Eylea, all consolidated in the Northern District of West Virginia. The cases center on U.S. Patent No. 11,084,865, which covers VEGF-trap formulations for intravitreal injection and expires on June 14, 2027.9U.S. Court of Appeals for the Federal Circuit. Regeneron Pharmaceuticals v. Mylan Pharmaceuticals, No. 2024-1965 The outcomes so far split three ways.
Companies Blocked by Injunction
The district court granted preliminary injunctions against Samsung Bioepis, Formycon AG, and Celltrion in mid-2024, keeping their Eylea biosimilars off the U.S. market. The Federal Circuit affirmed the injunctions against Samsung Bioepis and Formycon on January 29, 2025, rejecting challenges to personal jurisdiction, patent validity, and irreparable harm.9U.S. Court of Appeals for the Federal Circuit. Regeneron Pharmaceuticals v. Mylan Pharmaceuticals, No. 2024-1965 It affirmed the Celltrion injunction on March 5, 2025.10U.S. Court of Appeals for the Federal Circuit. Regeneron Pharmaceuticals v. Mylan Pharmaceuticals, No. 2024-2058 The Patent Trial and Appeal Board denied inter partes review petitions from all three companies in June 2025.11Pearce IP. Update on Challenges to Regeneron’s US Aflibercept Patents
Amgen’s Pavblu Launched Anyway
Regeneron did not get a preliminary injunction against Amgen’s Eylea biosimilar Pavblu (aflibercept-ayyh). The district court found a substantial question of noninfringement because Pavblu eliminates the separate buffer component claimed in the ‘865 patent, and the Federal Circuit affirmed on March 14, 2025.12U.S. Court of Appeals for the Federal Circuit. Regeneron Pharmaceuticals v. Amgen, No. 2024-2351 Amgen launched Pavblu on November 15, 2024, becoming the first Eylea biosimilar on the U.S. market. Regeneron still has 31 other patents asserted against Pavblu in the ongoing district court case.13Loeb & Loeb. The Landscape of Regeneron’s Eylea Litigation Update
Settlements With Biocon and Sandoz
Two disputes have been resolved through negotiated launch dates. On April 15, 2025, Regeneron and Biocon Biologics settled to allow Biocon’s interchangeable biosimilar Yesafili (aflibercept-jbvf) to enter the U.S. market in the second half of 2026, or earlier under certain conditions.14Biocon Biologics. Biocon Biologics Secures Market Entry Date for Yesafili On September 9, 2025, the court dismissed all claims between Regeneron and Sandoz following a settlement letting Sandoz launch Enzeevu (aflibercept-abzv) in the fourth quarter of 2026.15Big Molecule Watch. Sandoz and Regeneron Settle Aflibercept BPCIA Case
Securities Class Action
Investors sued Regeneron after the DOJ’s April 2024 pricing complaint and later Eylea revenue shortfalls. The class action, Radtke v. Regeneron Pharmaceuticals, Inc., was filed in January 2025 in the Southern District of New York.16Labaton Keller Sucharow. Radtke v. Regeneron Pharmaceuticals, Inc. It covers the class period from November 2, 2023, through October 30, 2024, and alleges Regeneron misled investors by failing to disclose that credit card fee payments should have been reported as price concessions, which inflated Eylea’s reported sales and its Average Sales Price to Medicare.
Two events allegedly moved the stock: the April 2024 DOJ complaint, after which shares fell about 3.4 percent over two days, and the October 31, 2024 third-quarter earnings, when Eylea HD missed analyst estimates and the company acknowledged a lower net selling price, sending shares down roughly 9.2 percent.17Glancy Prongay & Murray. Regeneron Pharmaceuticals, Inc. Securities Fraud Class Action Labaton Keller Sucharow and Motley Rice were appointed co-lead counsel in July 2025.16Labaton Keller Sucharow. Radtke v. Regeneron Pharmaceuticals, Inc. The case sits before Judge Mary Kay Vyskocil, and as of June 2026 no ruling on a motion to dismiss has been recorded.18PACER Monitor. Radtke v. Regeneron Pharmaceuticals, Inc.
Consolidated Shareholder Derivative Suits
The securities case produced parallel derivative litigation on behalf of Regeneron against current and former directors and officers, including CEO Leonard S. Schleifer and Chief Scientific Officer George D. Yancopoulos. The suits, consolidated as In re Regeneron Pharmaceuticals, Inc. Derivative Litigation, allege breaches of fiduciary duty tied to the same Eylea conduct at issue in the DOJ pricing case.19PACER Monitor. In re Regeneron Pharmaceuticals, Inc. Derivative Litigation
In March 2026, the court denied motions to remand to state court and consolidated several actions under the lead case. The derivative proceedings are stayed until the motion to dismiss in the securities class action is resolved with finality or a defendant files an answer.19PACER Monitor. In re Regeneron Pharmaceuticals, Inc. Derivative Litigation
Employment Discrimination Case
Former Regeneron employee Joanne Kim sued the company and her former manager, Ashutosh Katiyar, in July 2024 in the Southern District of New York. Kim, formerly Director of Customer Insights and Analytics on the Eylea brand, alleged she was fired four days after asking for schedule flexibility to care for her disabled child. Regeneron said the termination reflected a role elimination during a reorganization; Kim alleged the company then hired consultants to do her work.20Justia. Kim v. Regeneron Pharmaceuticals, Inc.
On March 25, 2026, Judge Loretta A. Preska partially granted and partially denied Regeneron’s motion to dismiss. Claims allowed to proceed include FMLA interference, ADA disability discrimination on an “associational discrimination” theory tied to Kim’s role as caregiver, ADA retaliation, and discrimination and retaliation claims under New York City’s Human Rights Law. The court dismissed Kim’s Title VII claims and her claim under the Earned Safe and Sick Time Act. The court held that an employer’s alleged fear that an employee will be “inattentive at work” because of a family member’s disability can support an ADA associational discrimination claim.20Justia. Kim v. Regeneron Pharmaceuticals, Inc.