Amarin v. Hikma: settling the skinny label question 

When the U.S. Supreme Court agreed to hear Hikma Pharmaceuticals v. Amarin Pharma, it took on a dispute that, on the surface, looks narrow – a disagreement over how a generic drug was marketed after entering the market with a skinny label. In practice, the case touches on how long and how reliably companies can protect the value of additional indications developed after a drug’s first approval. 

At issue is whether a generic manufacturer can be found liable for patent infringement not by explicitly promoting an off-label use, but by marketing a skinny-label product in ways that may predictably lead physicians to prescribe it beyond its approved indication.  

The Amarin v. Hikma dispute 

Vascepa, the prescription form of icosapent ethyl developed by Amarin Pharma, was first approved by the U.S. Food and Drug Administration (FDA) in 2012 for patients with high triglyceride levels. Later clinical data supported an expanded use to reduce cardiovascular events, and Amarin secured a separate FDA approval for that indication in late 2019. Each approval was backed by patents tied to the respective use, meaning the period of exclusive rights for the later indication extended beyond the expiration of the original patent. 

When Hikma Pharmaceuticals sought to bring a generic version of icosapent ethyl to market, it filed an Abbreviated New Drug Application (ANDA) limiting its label to the now-off-patent indication for triglyceride lowering, the original indication Amarin had secured back in 2012. Because the later cardiovascular indication remained patented, Hikma’s product was approved with a narrower set of uses, a regulatory carve-out often referred to as a skinny label. Under U.S. law, generic manufacturers can enter the market for unprotected uses while avoiding patented ones, provided the label accurately reflects the FDA’s approval. 

Chemically, there is no difference between Hikma’s product and Amarin’s branded version. The distinction lies in what the FDA has authorized each company to promote, and that regulatory difference is what has brought the dispute into the courts. 

Indeed, Amarin’s complaint, filed after Hikma’s generic launched, centers not on the chemistry but on how Hikma described and marketed its product. In press releases and other materials, Hikma referred to its version as a generic equivalent to Vascepa and highlighted the overall size of the Vascepa market.  

Amarin argued that this framing, while stopping short of explicitly promoting unapproved uses, would lead physicians to prescribe the generic for the cardiovascular indication that Hikma’s label did not cover, and in doing so, would induce infringement of Amarin’s still-valid patents. A federal district court initially dismissed Amarin’s claims, but in 2024, the U.S. Court of Appeals for the Federal Circuit reversed, allowing Amarin’s induced infringement theory to proceed. On January 16, the Supreme Court agreed to review that decision. 

The Supreme Court case is explicitly framed around whether allegations like “generic version” language and references to public information, such as branded-drug sales, can be enough, on their own, to plead induced infringement when the patented use has been fully carved out of the generic label. That kind of phrasing is precisely what Amarin Pharma points to in its induced-infringement theory. 

What is a skinny label? 

In the U.S. drug approval system, most generic versions of an already-marketed medicine enter the market through an ANDA, which lets a generic applicant show that its product is bioequivalent to a branded drug without repeating costly clinical trials. This is what Hikma did. 

Under the regulatory framework established by the Hatch-Waxman Act, the FDA generally requires generics to have the same labeling as the reference drug. But when a branded product has multiple approved uses, some of which remain covered by valid patents, the law provides a way for a generic to seek approval for only some of those uses. A generic can file a statement saying that it is not seeking approval for patented uses, and it must then submit labeling that omits those uses. The resulting approval and label are narrower than the brand-name counterpart’s, a “skinny label.” 

Put simply, a skinny label lets a generic version be approved for non-patented indications while leaving out patented ones. On one hand, it creates an opportunity for generics to enter the market for indications not protected by patents, which tends to lead to lower prices and broader competition. On the other hand, by excluding patented uses from the generic label, it preserves the branded innovator’s exclusive rights for those indications until the relevant patents expire. 

A key nuance in this system is the difference between regulatory approval and actual practice use. Physicians in the U.S. may prescribe medicines for any medically appropriate purpose, even if that use is not on the FDA-approved label, known as off-label prescribing. But while doctors can legally prescribe off-label, manufacturers are not permitted to promote off-label uses of their products. This distinction is where the legal tension in Amarin v. Hikma lies.  

Amarin is arguing that “skinny label” compliance doesn’t automatically insulate a generic if its broader messaging effectively invites use in a patented indication. Hikma is arguing that if that’s enough to trigger liability, then the carve-out pathway becomes much riskier to use in practice. 

What’s at stake: innovation incentives vs generic access 

Hikma v. Amarin is a question about how two basic policy goals interact in the pharmaceutical system: encouraging investment in later clinical development and enabling timely, affordable generic competition. 

One line of concern, voiced by Amarin, is that when a patented follow-on use can be economically undermined by routine marketing around a skinny label, the real-world value of secondary patents is weakened, even if they remain valid on paper. Innovators logically rely on the promise of future revenue from expanded indication approvals to justify the cost and risk of investment in additional clinical trials. If the economic return from those follow-on efforts is made even more uncertain by skinny labeled drugs, that could influence strategic decisions about where to allocate R&D resources.  

Impacts could extend beyond drugs such as Vascepa. If innovators see that secondary patents offer limited practical protection, they may adjust their clinical pipelines, for example, placing a higher premium on new molecular entities, rather than pure indication expansion. Likewise, projects that focus on repurposing existing molecules for new clinical needs could reassess the return on investment under heightened legal risk.  

From the generic and competition side, skinny labels are meant to enable earlier market entry for unpatented uses, bringing price competition sooner. The thesis is that if routine, factually accurate statements, such as describing a product as a generic version of a branded drug or referencing the branded drug’s overall market, are enough to support induced-infringement claims, the skinny-label pathway becomes legally fragile in practice. Generic manufacturers may delay launches, avoid skinny labels altogether, or narrow how they communicate around approvals, with knock-on effects for competition and access. 

A study by researchers at the Solomon Center for Health Law and Policy at Yale Law School looked at earlier court decisions involving skinny labels and inducement claims and suggests that, after those rulings, generic manufacturers were less likely to launch products using skinny labels and prescribing patterns shifted accordingly. The authors argue that this reflects how legal uncertainty around inducement can shape real-world launch decisions and market behavior, even when the regulatory pathway itself remains available. 

The Supreme Court has not yet signaled how it views these competing economic rationales, but by agreeing to take the case, it does recognize that there is an unsettled question about where regulatory compliance ends. The decision, expected later this year, will provide clearer guidance on that boundary.