Last updated: August 7, 2026
Amarin Pharma Inc. v. Hikma Pharmaceuticals USA Inc., Case No. 2:16-cv-02525, concerned Hikma's abbreviated new drug application for generic icosapent ethyl, marketed as the generic equivalent of Amarin's Vascepa. The dispute centered on patents covering purified eicosapentaenoic acid, or EPA, and the use of icosapent ethyl to reduce cardiovascular risk in statin-treated patients.
The litigation ended with a major loss for Amarin. The asserted cardiovascular-risk-reduction claims were held invalid for obviousness, and the Federal Circuit affirmed. Hikma subsequently obtained FDA approval and launched generic icosapent ethyl with a label directed primarily to severe hypertriglyceridemia rather than Amarin's REDUCE-IT cardiovascular indication. The decision materially weakened Amarin's patent position and accelerated generic exposure for Vascepa.
What patents did Amarin assert against Hikma?
Amarin asserted patents relating to Vascepa's composition, manufacturing characteristics, and cardiovascular-risk-reduction method of use. The most commercially important patents were the following:
| Patent |
Principal subject matter |
Relevance in Hikma litigation |
| U.S. Patent No. 8,648,048 |
Highly purified EPA compositions |
Asserted in the original ANDA litigation |
| U.S. Patent No. 9,283,181 |
EPA compositions and formulations |
Asserted against Hikma |
| U.S. Patent No. 9,643,997 |
Cardiovascular-risk-reduction methods |
Central to the later patent dispute |
| U.S. Patent No. 9,700,087 |
Use of icosapent ethyl in statin-treated patients with elevated triglycerides |
Central method-of-use patent |
| U.S. Patent No. 10,568,861 |
Later-issued cardiovascular method claims |
Relevant to subsequent litigation and infringement theories |
The case became focused on the REDUCE-IT-related method claims. Those claims covered administration of icosapent ethyl to patients with elevated triglycerides who were receiving statin therapy and remained at risk of cardiovascular events. The claims were commercially significant because Amarin's expanded Vascepa indication was based on the REDUCE-IT cardiovascular-outcomes study.
The court treated the asserted claims as obvious in view of the prior art, including Amarin's earlier MARINE and ANCHOR clinical data, the known properties of EPA, and prior publications concerning cardiovascular risk and triglyceride reduction. Amarin Pharma, Inc. v. Hikma Pharmaceuticals USA Inc., 2020 WL 968879 (D. Del. Feb. 28, 2020).
What was the procedural history of the Amarin v. Hikma case?
Amarin filed suit after Hikma submitted an ANDA seeking FDA approval for generic icosapent ethyl capsules. The ANDA filing triggered patent litigation under the Hatch-Waxman Act.
The principal milestones were:
| Date |
Event |
| 2016 |
Amarin commenced patent litigation after Hikma's ANDA filing |
| 2016-2019 |
Claim-construction, discovery, expert analysis, and pretrial proceedings |
| February 2020 |
District court held the principal asserted claims invalid for obviousness |
| May 2020 |
FDA approved Hikma's generic icosapent ethyl product |
| 2020 |
Hikma launched generic icosapent ethyl for the non-cardiovascular indication |
| 2021 |
Federal Circuit affirmed the district court's invalidity ruling |
| 2021 onward |
Amarin pursued separate theories involving label language, promotional conduct, and later-issued patents |
The litigation did not produce an injunction blocking Hikma's commercial launch. Once the asserted patent claims were held invalid, Amarin could not use those claims to prevent approval or continued marketing of Hikma's product.
The Federal Circuit's affirmance left the core obviousness ruling intact. The appellate decision confirmed that the trial court had properly evaluated the asserted method claims against the prior art and had not imposed an improper requirement that the prior art expressly predict the full REDUCE-IT clinical outcome. Amarin Pharma, Inc. v. Hikma Pharmaceuticals USA Inc., Fed. Cir. decision affirming the district court's invalidity judgment.
Why did the court find Amarin's patents obvious?
The court's obviousness analysis turned on the combination of known scientific information available before the asserted patents' effective filing dates.
The prior-art record included:
- Evidence that EPA was a known omega-3 fatty acid with potential cardiovascular and triglyceride-related effects.
- Amarin's MARINE study, which showed that icosapent ethyl reduced triglyceride levels in patients with severe hypertriglyceridemia.
- Amarin's ANCHOR study, which examined patients with persistent high triglycerides despite statin therapy.
- Published medical literature linking elevated triglycerides and residual cardiovascular risk.
- The known use of statins in patients with cardiovascular risk.
- A reasonable expectation that purified EPA could be evaluated in statin-treated patients with elevated triglycerides.
The court did not require the prior art to prove that icosapent ethyl would reduce cardiovascular events with the same degree of certainty later shown by REDUCE-IT. For an obviousness analysis, the relevant question was whether a skilled person would have had a reason to pursue the claimed treatment and a reasonable expectation of success.
Amarin argued that REDUCE-IT produced unexpected clinical benefits. The court rejected that position because the asserted claims were broad and because the prior art supplied substantial motivation to investigate EPA in the claimed patient population. The appellate court affirmed the district court's treatment of the objective indicia and unexpected-results evidence.
What was the Orange Book and FDA status of Vascepa?
Vascepa is the brand name for icosapent ethyl, an ethyl ester of EPA. The FDA first approved Vascepa for severe hypertriglyceridemia. In December 2019, the FDA approved an expanded indication to reduce the risk of cardiovascular events in certain statin-treated adults with elevated triglycerides and established cardiovascular disease or diabetes plus additional risk factors. FDA, Vascepa prescribing information.
The two indications had different patent and generic-entry implications:
| Indication |
Commercial significance |
Generic-label issue |
| Severe hypertriglyceridemia |
Original Vascepa market |
Generally available to ANDA applicants |
| Cardiovascular-risk reduction |
Higher-value REDUCE-IT market |
Protected through method-of-use patents and labeling restrictions |
Hikma's FDA-approved product was positioned with a label that omitted the cardiovascular-risk-reduction indication. This type of partial indication strategy is commonly called a "skinny label" or "carve-out label." The purpose is to avoid directly seeking approval for a patented method of use while obtaining approval for an unpatented indication.
The FDA approved Hikma's 1-gram icosapent ethyl capsules in May 2020. FDA, Drugs@FDA: Hikma icosapent ethyl capsules, NDA/ANDA approval records.
Did Hikma file a Paragraph IV certification?
Yes. Hikma's ANDA included Paragraph IV certifications challenging Amarin's listed patents. A Paragraph IV certification states that a listed patent is invalid, unenforceable, or would not be infringed by the proposed generic product.
Amarin's lawsuit triggered the Hatch-Waxman litigation framework. The filing imposed a statutory approval stay while the litigation proceeded, subject to the statutory limits applicable to the case. The core legal issues were:
- Whether Hikma's proposed product would infringe the asserted claims.
- Whether the asserted claims were valid.
- Whether Amarin could obtain an injunction preventing FDA approval or commercial launch.
- Whether Hikma's carved-out label nevertheless created induced-infringement exposure.
The district court's invalidity ruling removed the principal obstacle to approval. The Federal Circuit's affirmance eliminated the remaining appellate basis for blocking Hikma based on those claims.
What patent litigation affected generic entry for Vascepa?
The litigation created two distinct generic-entry questions.
ANDA patent litigation
The first question was whether Hikma could obtain FDA approval despite Amarin's listed patents. The answer became yes after the asserted patents were held invalid.
Post-approval induced infringement
The second question was whether Hikma could be liable for inducing infringement of cardiovascular method claims despite omitting the cardiovascular indication from its FDA label.
Amarin argued that Hikma's public statements, product materials, website content, and commercial activities encouraged use of generic icosapent ethyl for cardiovascular-risk reduction. That theory required proof that Hikma actively encouraged infringement and that the encouragement caused physicians or patients to practice the patented method.
A carved-out label reduces direct label-based infringement risk, but it does not eliminate all potential induced-infringement exposure. Promotional statements and other affirmative conduct can become important if they recommend the patented use. The Federal Circuit's induced-infringement jurisprudence requires more than the mere sale of a drug with substantial off-label uses. The plaintiff must identify affirmative acts and intent to encourage the infringing use. GlaxoSmithKline LLC v. Teva Pharmaceuticals USA, Inc., 7 F.4th 1320 (Fed. Cir. 2021).
The Amarin-Hikma dispute therefore had commercial importance beyond the validity judgment. It tested the limits of skinny-label strategies for drugs with a high-value patented indication and a separate unpatented indication.
How did the decision affect Amarin's patent estate?
The decision weakened the portion of Amarin's patent estate that protected the REDUCE-IT cardiovascular indication.
Composition and formulation patents
Composition patents covering highly purified EPA can protect the product itself, but they are vulnerable if the claimed composition is anticipated or obvious over earlier purified EPA disclosures. Their practical value depends on claim scope, purity thresholds, formulation limitations, and expiration dates.
Method-of-use patents
Method claims can provide the strongest protection for a new clinical indication when the active ingredient is already known. They also face a significant obviousness risk when:
- The disease or risk factor is already linked to the active ingredient.
- The patient population is defined using conventional clinical criteria.
- The dosage is within a known range.
- The prior art contains clinical studies involving the same or overlapping population.
- The claimed benefit is an expected result of pursuing the prior-art treatment.
Amarin's cardiovascular method claims were commercially valuable but legally vulnerable because the court found that the prior art supplied a reason to test EPA in the claimed population.
Later-issued patents
Later-issued continuation and divisional patents could create additional litigation risk if they contained materially different claim limitations, such as dosing schedules, patient-selection criteria, or specific clinical endpoints. They could not, however, revive claims already held invalid merely by restating the same inventive concept in substantially similar form.
Which companies challenged Vascepa's exclusivity?
Hikma was the most consequential generic challenger in the reported case. Other generic manufacturers, including Dr. Reddy's Laboratories, also entered the icosapent ethyl market after FDA approval and patent developments.
| Company |
Product |
Market role |
| Amarin Pharma |
Vascepa |
Brand product and original sponsor |
| Hikma Pharmaceuticals USA |
Icosapent ethyl capsules |
Major generic challenger and early commercial entrant |
| Dr. Reddy's Laboratories |
Icosapent ethyl capsules |
Subsequent generic competition |
| Other ANDA sponsors |
Icosapent ethyl |
Potential additional price pressure |
The market had no biosimilar issue because Vascepa is a small-molecule drug, not a biologic. The relevant competitive threat was conventional ANDA substitution and generic price competition.
What was the revenue exposure from the Hikma launch?
Vascepa's value depended heavily on its cardiovascular-risk-reduction indication. Before generic entry, Amarin had positioned Vascepa as a large cardiovascular-outcomes product rather than a niche triglyceride-lowering medicine.
The invalidity judgment and Hikma launch created three forms of revenue exposure:
- Loss of exclusivity for the severe-hypertriglyceridemia market.
- Prescription substitution pressure from generic icosapent ethyl.
- Uncertainty over whether the carved-out generic would capture prescriptions written for cardiovascular-risk reduction through off-label use.
The commercial impact depended on substitution rules, payer coverage, physician prescribing, label communications, and the outcome of induced-infringement disputes. The patent ruling also reduced Amarin's negotiating leverage in licensing and settlement discussions because the central method claims could no longer support a credible injunction.
How strong was Amarin's patent estate after the decision?
Amarin's estate was mixed.
| Estate component |
Strength after Hikma decision |
Business implication |
| Purified EPA composition claims |
Moderate, depending on claim scope and prior art |
Potential manufacturing and composition barrier |
| REDUCE-IT method claims |
Weak after invalidity judgment |
Limited ability to block generic cardiovascular use |
| Formulation claims |
Case-specific |
Could protect dosage form or stability features if narrowly drafted |
| Later continuation claims |
Variable |
May create residual litigation risk |
| Trade secrets and manufacturing know-how |
Potentially meaningful |
Could raise quality, scale-up, and supply barriers |
| Regulatory exclusivity |
Limited compared with patent protection |
Did not replace invalidated patent claims |
The principal lesson is that clinical novelty does not automatically establish patentable novelty. A later clinical trial may demonstrate an important benefit, but patent claims directed to administering a known compound to a medically predictable population can still be obvious.
What generic launch scenarios existed after the judgment?
The most likely launch scenario was a generic product with an indication carve-out:
- FDA approval for severe hypertriglyceridemia.
- Exclusion of the cardiovascular-risk-reduction indication.
- Commercial distribution at a discount to Vascepa.
- Physician and payer-driven off-label use.
- Continued litigation over promotional conduct or later-issued claims.
A second scenario involved broader practical substitution despite the narrower label. Pharmacies and payers could substitute the generic for prescriptions written for icosapent ethyl, although the legal and reimbursement treatment of cardiovascular-risk-reduction prescriptions could vary.
A third scenario involved additional generic entrants. Each new ANDA approval would increase price pressure and reduce Amarin's ability to preserve premium pricing through brand differentiation alone.
Key Takeaways
- The litigation concerned Hikma's ANDA for generic icosapent ethyl, the active ingredient in Vascepa.
- Amarin's principal cardiovascular method claims were held invalid for obviousness.
- The Federal Circuit affirmed the core invalidity judgment.
- Hikma received FDA approval in May 2020 and launched with an indication carve-out.
- The case reduced Amarin's ability to block generic entry based on REDUCE-IT method patents.
- A skinny label reduced, but did not eliminate, potential induced-infringement theories based on promotional conduct.
- Vascepa faced conventional generic risk, not biosimilar risk.
- The decision weakened Amarin's licensing leverage and exposed cardiovascular-indication revenue to off-label generic substitution.
FAQs About Amarin v. Hikma and Vascepa Generic Entry
Did Hikma invalidate all Vascepa patents?
No. The judgment addressed the asserted claims in the litigation. It did not automatically invalidate every patent covering Vascepa, every continuation patent, or every manufacturing and formulation claim.
Can a generic sell icosapent ethyl for cardiovascular-risk reduction?
A generic with a carved-out label may not be approved for the patented indication, but physicians can prescribe FDA-approved drugs off label. Commercial conduct that affirmatively encourages the patented use can create separate induced-infringement issues.
Was Vascepa protected by biologic exclusivity?
No. Icosapent ethyl is a small-molecule drug. Its principal exclusivity mechanisms were patents, FDA regulatory exclusivity, and brand-market positioning.
What made Amarin's cardiovascular patents vulnerable?
The court found that the prior art provided a reason to study purified EPA in statin-treated patients with elevated triglycerides and supplied a reasonable expectation of success. The later REDUCE-IT results did not overcome that obviousness showing.
Did the Hikma case establish a rule for all skinny-label products?
No. The outcome depended on the specific patent claims, prior art, label language, and evidence of promotional conduct. Skinny-label risk remains fact-specific under the Hatch-Waxman Act and induced-infringement law.
References
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Amarin Pharma, Inc. v. Hikma Pharmaceuticals USA Inc., 2020 WL 968879 (D. Del. Feb. 28, 2020).
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Amarin Pharma, Inc. v. Hikma Pharmaceuticals USA Inc., Federal Circuit decision affirming district-court judgment, 2021.
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Food and Drug Administration. (2019). Vascepa prescribing information. U.S. Department of Health and Human Services.
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Food and Drug Administration. (2020). Drugs@FDA: Icosapent ethyl capsules, Hikma Pharmaceuticals USA Inc. U.S. Department of Health and Human Services.
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GlaxoSmithKline LLC v. Teva Pharmaceuticals USA, Inc., 7 F.4th 1320 (Fed. Cir. 2021).
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U.S. Patent No. 8,648,048. Purified EPA compositions.
-
U.S. Patent No. 9,283,181. EPA compositions and formulations.
-
U.S. Patent No. 9,643,997. Cardiovascular-risk-reduction methods.
-
U.S. Patent No. 9,700,087. Icosapent ethyl cardiovascular-risk-reduction methods.
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U.S. Patent No. 10,568,861. Cardiovascular-risk-reduction methods.
