FTC Backs Antitrust Case Over Amgen’s Enbrel Patent Strategy

The Federal Trade Commission has filed an amicus brief in a private antitrust lawsuit accusing drug manufacturer Amgen of illegally acquiring exclusive rights to patent applications in order to prolong its market dominance over Enbrel, a widely used treatment for rheumatoid arthritis and other inflammatory conditions.

According to the agency, Amgen shaped patent applications it had acquired so that the resulting patents would cover Enbrel specifically, allowing the company to extend its period of market exclusivity well beyond what would normally be expected for the drug. The FTC argues that this conduct kept lower-cost biosimilar alternatives off the market, forcing patients and health systems to continue paying higher prices for a treatment that could otherwise have faced generic-style competition years earlier.

The brief does not initiate new litigation against Amgen but instead weighs in on an existing private antitrust case, offering the commission’s view on how competition law should apply to the acquisition and strategic use of patent rights in the biologics sector. The FTC has asked the court to consider the broader implications of allowing pharmaceutical companies to acquire and reshape patent applications in ways that extend exclusivity beyond the scope originally intended, framing the practice as a potential violation of antitrust principles rather than a routine exercise of intellectual property rights.

Enbrel has been one of Amgen’s top-selling products for years, generating billions of dollars in annual revenue as one of the few biologic treatments available for rheumatoid arthritis, psoriasis, and related autoimmune conditions before biosimilar versions became available in other markets. Biologic drugs, which are manufactured from living cells rather than chemical compounds, are generally more complex and expensive to develop than traditional small-molecule drugs, and the biosimilar versions meant to compete with them face a more rigorous and costly approval pathway than standard generic drugs.

That complexity has long given brand-name biologic manufacturers extended de facto exclusivity, even after initial patents expire, because rivals must invest heavily to prove their biosimilar products are equivalent. Patent thickets, a term used to describe overlapping and sequential patent filings around a single product, have become a common industry practice that critics say allows companies to indefinitely delay competition by continually filing new patents tied to minor formulation or delivery changes. Regulators and consumer advocates have argued this practice drives up costs for patients, insurers, and government health programs, particularly for high-cost specialty drugs used to treat chronic conditions.

The FTC has increasingly focused on pharmaceutical patent practices in recent years, arguing that some strategies used by drug makers cross the line from legitimate intellectual property protection into anticompetitive conduct designed purely to block rivals. The agency has previously challenged what it calls improperly listed patents in FDA databases and has scrutinized pay-for-delay settlements between brand-name and generic manufacturers. Biologic drugs, given their high price points and complex manufacturing requirements, have drawn particular attention from antitrust enforcers seeking to open pathways for biosimilar competition and reduce costs across the health care system.

The amicus brief represents one of several recent actions by the commission aimed at addressing what it describes as anticompetitive practices in health care and pharmaceutical markets. By weighing in on this case, the FTC signals its intent to continue scrutinizing how drug manufacturers use patent acquisitions and filings to manage market exclusivity, even when the underlying dispute originates as private litigation rather than a direct government enforcement action.

The case remains pending in court, and it is not yet clear how the judge will weigh the commission’s arguments alongside those of the parties directly involved in the litigation, according to the Federal Trade Commission’s announcement.