Antitrust Battle Over Enbrel Biosimilars Could Reshape Biologic Competition

Sandoz, the generics division of novartis (NVS), has escalated its fight against Amgen (AMGN) by filing an antitrust lawsuit alleging the biotech giant has unlawfully blocked competition for its $3.3 billion arthritis drug Enbrel®. The April 14, 2025, case—filed in the U.S. District Court for the Eastern District of Virginia—targets Amgen’s use of patents to delay the U.S. market entry of Sandoz’s biosimilar etanercept, Erelzi®, which received FDA approval in 2016. The lawsuit claims Amgen’s tactics violate federal antitrust laws, threatening to upend long-standing strategies in the biosimilar arena and reshape investor calculations for both companies.

The Legal Standoff: Patents vs. Competition

At the heart of the dispute is Amgen’s alleged abuse of its patent portfolio to maintain dominance over Enbrel®, a decades-old biologic used to treat autoimmune conditions like rheumatoid arthritis. Sandoz argues that Amgen has acquired and asserted patents for minor improvements—such as drug delivery systems or formulations—to extend exclusivity far beyond the original 12-year exclusivity period granted for biologics under the Biologics Price Competition and Innovation Act (BPCIA).

“This isn’t about valid patents,” said Sandoz in its filing, “but about leveraging legal loopholes to stifle competition and deny patients affordable alternatives.” The lawsuit seeks an immediate injunction to allow Erelzi’s launch and treble damages under the Sherman Act, a provision that could amplify penalties if Amgen is found guilty of antitrust violations.

Market Implications: Cost Savings vs. Revenue Risk

Enbrel® generated $3.3 billion in U.S. sales in 2024, a figure that could drop sharply if Erelzi enters the market. Biosimilars typically reduce prices by 30–50%, and Sandoz estimates that delayed access to Erelzi has deprived 7.5 million Americans of potential cost savings. For investors, the stakes are twofold:
1. Amgen’s Revenue Pressure: A loss could accelerate biosimilar competition, trimming Enbrel’s sales and impacting Amgen’s bottom line. The drug accounted for 15% of Amgen’s 2024 revenue, with biosimilar erosion already expected in coming years.
2. Sandoz’s Growth Opportunity: Novartis’s generics division has struggled with declining revenue, making Erelzi’s delayed launch a critical missed opportunity. A win could unlock billions in biosimilar sales and bolster Novartis’s pipeline.

The case also highlights broader industry tensions. Unlike small-molecule generics, biologics face complex patent thickets that often delay competition by years. Sandoz’s focus on antitrust law—a departure from typical patent litigation—suggests a strategic shift to challenge systemic barriers.

Precedent and Policy: A Landmark Case?

The lawsuit could set a critical precedent for how courts interpret antitrust law in pharmaceuticals. If Sandoz prevails, it might embolden other biosimilar manufacturers to challenge perceived patent abuses, accelerating competition for high-revenue biologics like Humira (which faces its own patent battles). Conversely, an Amgen victory could cement the industry’s reliance on secondary patents to extend exclusivity, prolonging high prices.

For investors, the outcome may also influence valuation metrics. Amgen’s stock (AMGN) has historically traded at a premium for its pipeline, but biosimilar threats could pressure multiples if revenue declines outpace expectations. Meanwhile, Novartis’s generics division has lagged peers like Teva (TEVA), making Sandoz’s success here a key catalyst for NVS’s shares.

Conclusion: A Crossroads for Biosimilar Competition

The Sandoz-Amgen lawsuit transcends a single drug’s lifecycle, reflecting a broader clash between innovation incentives and market access. With Enbrel’s U.S. exclusivity set to expire in 2029, the case could redefine how patents are used—and abused—in the biologics space.

Investors should monitor regulatory rulings and patent expiration timelines closely. If Sandoz succeeds, Amgen’s stock (AMGN) faces near-term volatility, while biosimilar players like NVS may see long-term upside. Conversely, a ruling in Amgen’s favor could delay biosimilar competition but risks intensifying antitrust scrutiny across the sector. Either way, this case underscores the high financial and ethical stakes in a market where billions hinge on the fine print of patent law.

As the courtroom battle unfolds, one thing is clear: the outcome will echo far beyond Enbrel’s shelves, shaping how the biopharma industry balances profit and patient access for years to come.