Amgen Lawsuits: Antitrust Verdict, Drug Pricing, and Patents

Amgen, one of the world’s largest biotechnology companies, is currently defending or resolving several major lawsuits, including a $406.8 million antitrust verdict won by Regeneron in May 2025, a constitutional challenge to Colorado’s cap on the price of Enbrel, a multibillion-dollar transfer-pricing fight with the IRS and a related shareholder class action, an FTC consent order tied to its Horizon Therapeutics acquisition, and continuing patent battles with biosimilar makers. Together, the Amgen lawsuits below sketch the company’s active legal exposure as of mid-2026.

The Regeneron Antitrust Verdict

On May 15, 2025, a federal jury in the U.S. District Court for the District of Delaware ordered Amgen to pay Regeneron Pharmaceuticals $406.8 million — $135.6 million in compensatory damages and $271.2 million in punitive damages.¹ The jury found Amgen liable on nine of ten counts, including violations of the Sherman Act, the Clayton Act, New York’s Donnelly Act, California’s Cartwright Act, and Delaware tort law. Amgen prevailed only on a count under California’s Unfair Practices Act.²

Regeneron filed the case in May 2022, alleging Amgen ran an anticompetitive scheme to push its cholesterol drug Praluent out of the market in favor of Amgen’s competing drug Repatha.³ Both drugs are PCSK9 inhibitors that lower cholesterol and reduce cardiovascular risk.

At the heart of the case were “cross-therapeutic bundled rebates.” According to Regeneron’s complaint, Amgen leveraged two unrelated blockbuster anti-inflammatory drugs, Enbrel and Otezla, which together made up a $12.8 billion market in 2020–2021, to pressure pharmacy benefit managers into giving Repatha exclusive or preferred formulary status. Amgen allegedly threatened to withhold rebates on Enbrel and Otezla unless PBMs excluded Praluent from coverage. Regeneron said it could not match the bundled offer because it lacked an equally diverse portfolio, and that Amgen also priced Repatha below cost, absorbing losses with revenue from its larger anti-inflammatory franchise. Praluent was excluded from coverage for 51% of prescriptions, its share at one major payor dropped more than 60% in six months, and U.S. net sales fell from $186 million in 2020 to $170 million in 2021. Regeneron said it was forced to eliminate its Praluent sales force and halt further research on the drug.⁴

Amgen denied the allegations throughout the litigation and argued in court filings that the suit was an attempt to interfere with PBM competition and that it had competed fairly on price.³ After the verdict, Amgen filed a renewed motion for judgment as a matter of law; Regeneron filed a motion for a permanent injunction. Both motions remain pending.

Colorado Drug-Pricing Challenge

Amgen is fighting Colorado’s Prescription Drug Affordability Board over its authority to cap the price of Enbrel, one of Amgen’s highest-revenue products. Colorado’s PDAB voted to set an “upper payment limit” on Enbrel after determining the drug was unaffordable, with the cap scheduled to take effect in 2027.⁵

Amgen filed its first lawsuit on March 22, 2024, in the U.S. District Court for the District of Colorado, arguing the state law creating the board is preempted by federal patent law under the Supremacy Clause, violates the Due Process Clause of the Fourteenth Amendment, and violates the Dormant Commerce Clause by regulating transactions outside Colorado.⁶

On March 28, 2025, Judge Nina Y. Wang ruled against Amgen on cross-motions for summary judgment, allowing the board to proceed.⁷ Amgen appealed to the U.S. Court of Appeals for the Federal Circuit in April 2025 and filed a second lawsuit in the same district court on October 30, 2025, raising overlapping constitutional claims against the board’s specific actions on Enbrel.⁶

On June 4, 2026, Chief Judge Daniel Domenico heard arguments on Amgen’s request for a temporary injunction to block the price cap but did not immediately rule, saying he would issue a written decision “soon.” Amgen argues that capping prices on drugs still under patent protection interferes with federal patent law. Colorado counters that the upper payment limit applies to what patients and insurers pay, and it is unclear whether the cap would actually reduce Amgen’s revenue given the complexity of the pharmaceutical supply chain.⁵

The IRS Tax Dispute and Related Shareholder Suit

Amgen faces a transfer-pricing dispute with the IRS over profits routed through a manufacturing subsidiary in Puerto Rico. The IRS alleges Amgen under-reported U.S. taxable income by nearly $24 billion for the 2010–2015 period. It first claimed $3.6 billion in back taxes for 2010–2012, then added a $5.1 billion claim for 2013–2015 plus $2 billion in penalties in April 2022, bringing potential liability to $10.7 billion.⁸ A trial in the U.S. Tax Court began in November 2024. Amgen maintains its tax position is correct and consistent with prior IRS audits. As of reporting in 2025, Amgen had set aside roughly $4.1 billion in reserves and argued that any additional tax could be partially offset by up to $3.1 billion in previously accrued repatriation taxes.⁹

The tax dispute produced a securities fraud class action. In 2023, shareholders filed suit in the U.S. District Court for the Southern District of New York alleging Amgen made false or misleading statements between July 2020 and April 2022 by failing to adequately disclose the IRS claims and its exposure to billions in back taxes and penalties.¹⁰ In September 2024, a judge declined to dismiss the case, finding the complaint raised a “strong inference” that Amgen’s delayed disclosure was “reckless under the circumstances.”⁹ The case (No. 23-cv-02138) is before Judge John P. Cronan. The lead plaintiff moved for class certification in December 2025, and as of mid-2026 the case remains in discovery.

An older securities class action, In re Amgen Inc. Securities Litigation, was resolved in 2016 when Amgen agreed to pay $95 million to settle claims it failed to disclose data on Aranesp. The class covered investors who bought Amgen securities between April 2004 and May 2007.¹¹ Amgen denied wrongdoing.¹²

The 2012 Off-Label Marketing Settlement

The largest resolved enforcement action against Amgen came in December 2012, when the company agreed to pay $762 million to settle criminal and civil charges brought by the U.S. Department of Justice. It was the largest criminal and civil False Claims Act settlement involving a biotech company at the time.¹³

Amgen pleaded guilty in the U.S. District Court for the Eastern District of New York to illegally introducing the misbranded drug Aranesp into interstate commerce. The company had promoted Aranesp at doses and for uses to treat cancer-related anemia that the FDA had rejected or never approved. Prosecutors said Amgen used “reactive marketing” to circumvent restrictions on off-label promotion. Criminal penalties totaled $150 million, including a $136 million fine and $14 million in forfeiture.¹³

On the civil side, Amgen paid $612 million to resolve False Claims Act allegations covering off-label promotion of Aranesp, Enbrel, and Neulasta, along with kickbacks to healthcare providers and false price reporting. The settlement resolved ten whistleblower lawsuits.¹⁴ Amgen also entered a five-year Corporate Integrity Agreement with the Department of Health and Human Services requiring board-level compliance oversight, independent reviews, and public disclosure of payments to doctors.¹³

In a related action, Amgen paid $24.9 million in April 2013 to settle False Claims Act allegations that it paid kickbacks to long-term care pharmacy providers, including Omnicare, PharMerica, and Kindred Healthcare, through performance-based rebates tied to volume thresholds for Aranesp. The rebates allegedly encouraged pharmacies to switch Medicare and Medicaid patients from competing drugs to Aranesp. Amgen did not admit liability.¹⁵

The FTC Consent Order on Horizon Therapeutics

In 2023, the Federal Trade Commission and attorneys general from six states challenged Amgen’s $27.8 billion acquisition of Horizon Therapeutics, arguing the deal would let Amgen leverage its blockbuster portfolio to entrench the monopoly positions of two Horizon products: Tepezza, used to treat thyroid eye disease, and Krystexxa, used to treat chronic refractory gout.¹⁶ The concern echoed the conduct later alleged in the Regeneron lawsuit: bundling rebates across the product line to steer PBMs and insurers toward Horizon’s drugs.

Amgen settled and closed the merger under a consent order finalized by a 3-0 FTC vote on December 14, 2023.¹⁷ The order, effective for 15 years, prohibits Amgen from bundling any product with Tepezza or Krystexxa, or from conditioning rebates on the sale or formulary positioning of those two drugs. Amgen is also barred from using rebates to disadvantage competitors of either product. Through 2032, Amgen must obtain prior FTC approval before acquiring any products, biosimilars, or companies involved in treatments for thyroid eye disease or chronic refractory gout. An appointed monitor oversees compliance, and Amgen must submit annual reports and turn over all payer contracts related to the two drugs.¹⁶

Patent and Biosimilar Litigation

Patent fights are a constant in Amgen’s docket, both as a holder of valuable biologic patents and as a defendant when other companies claim their inventions were used without permission.

Harbour BioMed Patent Verdict

On June 14, 2026, a jury in the U.S. District Court for the District of Delaware found that Amgen and its subsidiary Teneobio willfully infringed patents owned by Harbour BioMed related to an antibody discovery platform. The trial, overseen by Judge Maryellen Noreika, ran from June 8 to June 14, 2026. The jury awarded the full requested amount of $20,203,704. Because the infringement was found willful, Harbour BioMed can petition the judge to treble the damages, potentially raising the award to roughly $60.6 million.¹⁸ No ruling on trebling had been reported as of mid-2026.

Enbrel Biosimilar Battles

Amgen has used its Enbrel patents to keep biosimilar competitors off the U.S. market until at least 2029. In litigation against Sandoz over the biosimilar Erelzi, a court found two key Amgen patents valid and infringed and issued a permanent injunction blocking Erelzi’s launch until April 2029. Samsung Bioepis’s biosimilar Eticovo, approved by the FDA in April 2019, is similarly blocked until 2029 under a separate permanent injunction.¹⁹ The Supreme Court declined in May 2021 to hear Novartis’s challenge to the Enbrel patents.²⁰

Sandoz tried a different tack in April 2025, filing an antitrust lawsuit against Amgen in the Eastern District of Virginia. The court dismissed it on February 17, 2026, ruling the antitrust claims should have been brought as compulsory counterclaims during the original 2016 patent litigation. Sandoz has appealed.¹⁹

Denosumab Biosimilar Settlements

Amgen reached confidential settlements in two patent cases over biosimilar versions of denosumab, sold as Prolia and Xgeva. In January 2025, a court found Amgen’s patents valid and infringed by Celltrion’s denosumab biosimilars, and the parties settled to permit Celltrion to launch as early as June 1, 2025.²¹ In a parallel case against Sandoz, a court similarly upheld the patents and the parties settled to allow Sandoz to launch its denosumab biosimilars on May 31, 2025.²²

Sandoz v. Amgen at the Supreme Court

An earlier case, Sandoz Inc. v. Amgen Inc., reached the Supreme Court in 2017. The Court ruled unanimously on June 12, 2017, that the Biologics Price Competition and Innovation Act’s “patent dance” disclosure requirement is not enforceable through a federal injunction, and that a biosimilar applicant may provide notice of commercial marketing before receiving FDA licensure rather than after.²³ The ruling gave biosimilar manufacturers more flexibility to reach the market without procedural delay from the original drug’s manufacturer.²⁴

1
Regeneron. Regeneron Prevails Over Amgen in Antitrust PCSK9 Lawsuit
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Big Molecule Watch. Regeneron Awarded $407 Million in Amgen Antitrust Suit
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Fierce Pharma. Amgen on Hook to Pay More Than $400M After Regeneron Triumphs in Cholesterol Drug Antitrust Suit
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Amgen. Amgen Announces Settlement of Securities Litigation
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Cancer Letter. Amgen Securities Litigation Settlement
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U.S. Department of Justice. Amgen Inc. Pleads Guilty to Federal Charge, Pays $762 Million to Resolve Criminal and Civil Allegations
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FBI. Amgen Inc. to Pay More Than $762 Million to Resolve Illegal Marketing Allegations
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U.S. Department of Justice. Amgen to Pay U.S. $24.9 Million to Resolve False Claims Act Allegations
16
FTC. Biopharmaceutical Giant Amgen to Settle FTC, State Challenges to Its Horizon Therapeutics Acquisition
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FTC. FTC Approves Final Order Settling Horizon Therapeutics Acquisition Challenge
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Harbour BioMed. Harbour BioMed Prevails in Patent Infringement Trial
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BiologicsHQ. Court Dismisses Sandoz’s Enbrel (Etanercept) Antitrust Lawsuit
20
BioPharma Dive. Novartis Challenge to Amgen’s Enbrel Patents Ends at Supreme Court’s Door
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Amgen. Amgen Update on Patent Litigation Related to Celltrion Denosumab Biosimilar Products
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Amgen. Amgen Update on Patent Litigation Related to Sandoz Denosumab Biosimilar Products
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Supreme Court of the United States. Sandoz Inc. v. Amgen Inc., 582 U.S. (2017)