Skinny labelling after Hikma v Amarin: active inducement in the US Supreme Court

On 4 June 2026, the US Supreme Court handed down its judgment in Hikma Pharmaceuticals v Amarin Pharma, finding that Amarin Pharma (Amarin) had not plausibly shown that Hikma was actively encouraging infringing use of its generic product in light of its skinny label, and granting Hikma Pharmaceuticals’ (Hikma) motion to dismiss the case.

The facts 

Amarin developed and markets Vascepa®, the active ingredient in which is icosapent ethyl, approved by the FDA in 2012 for the treatment of severe hypertriglyceridaemia (the SH indication). In 2019, a second indication was approved for reducing cardiovascular risk in patients with hypertriglyceridaemia who were already taking statins (the CV indication). Amarin obtained two method-of-use patents for the CV indication.

In 2016, Hikma developed a generic icosapent ethyl product and submitted an ANDA for approval with a paragraph IV certification, asserting that the patents protecting Amarin’s SH indication were invalid. This was subsequently found to be the case by the District Court, which held the patents invalid. Hikma then amended its FDA authorisation application with a “section viii statement” under §355(j)(2)(A)(viii) for a skinny label, carving out the patented CV indication. Its generic was approved in 2020 and was assigned an AB rating, meaning it was therapeutically equivalent to Vascepa®.

Amarin filed suit in the District of Delaware, alleging that Hikma was actively inducing infringement of the CV indication patents based on (i) the label itself; (ii) the patient information leaflet; and (iii) Hikma’s website and press releases. Hikma applied for a motion to dismiss the case, which was originally granted by the District Court, but the decision was reversed by the Federal Circuit on appeal, which held that it was at least plausible that a physician could read the relevant statements as instructions or encouragement to infringe the method-of-use patents.

Hikma appealed to the Supreme Court. The central question was whether Amarin had plausibly alleged that Hikma actively encouraged infringing use, not merely whether doctors could plausibly read the alleged statements as instructions to infringe.

“Active steps” 

In the US, to determine whether there has been infringement by active inducement, there are three requirements under §271(b): 

1. direct infringement by a third party;
2. knowledge that the induced acts constitute patent infringement; and
3. active steps to encourage direct infringement;

The issue of what constitutes “active steps” was key in this case, as it must involve purposeful, culpable expression and conduct, rather than passive actions that bring about off-label use. In assessing each of the factors asserted by Amarin the Court found that:

1. the information relating to the clinical study in the label was an FDA requirement. Hikma was required to have an identical label under 21 U.S.C. §355(j)(2)(A)(v).
2. the fact that the patient information leaflet included a warning about side effects for people with cardiovascular disease and a disclaimer that medicines are prescribed for other purposes was not sufficient to show inducement.
3. Hikma’s website and press release, which described the drug as a “generic equivalent”, stated that the therapeutic category was “hypertriglyceridemia”, referred to the total sales figures for all indications when showing the market value, and highlighted the “AB” rating, were not enough to stimulate infringement. Affirmative statements or actions are required, not merely an omission that the generic was limited to the SH indication. Moreover, Hikma’s website actively clarified that the generic was indicated for fewer than all the approved indications of Vascepa®.

Discussion

The US Supreme Court has set a high bar for originators seeking to show “active steps” to induce infringement. The judgment itself acknowledges that, in practice, generic manufacturers “know” and “perhaps even expect” that their products will be put to infringing use. This is particularly the case when all States actively encourage switching to the cheaper generic product. Mere knowledge is not enough, however.

It is interesting to note that the Court acknowledges that the inducement need not be “express”, as was argued by Hikma, but that active steps can be achieved through implicit encouragement. It will be interesting to see what circumstances will result in implicit inducement in light of the high bar set by the Court.

Although not strictly a case on skinny labelling, this judgment is aligned with the UPC in how it treats the label itself as evidence of infringement. In Regeneron and Sanofi v Amgen (UPC_CFI_505/2024), which related to the use of PCSK9 inhibitors to lower Lp(a) levels in a defined patient group, the Düsseldorf Local Division held that the information in section 5.1 of the SmPC was not sufficient to prove infringement of the second medical use patent. The key question is whether the infringer knew, or reasonably ought to have known, that it infringed. Sanofi argued that the label, which reported clinical trial data that “Repatha reduced unbound…Lp(a)” by around 25%, was sufficient to prove infringement despite Repatha not being approved to lower Lp(a) levels. The Local Division rejected this argument, holding that the label itself was insufficient to prove infringement.

It appears that in both the US and Europe, originators will need to adduce much more affirmative evidence of off-label use in cases involving skinny labels and second medical use patents. The label itself is not enough, nor are omissions by the generic manufacturer. More active steps are required, although what evidence will be sufficient is still an open question in both jurisdictions.