Pharmaceutical patent litigation in 2026 is testing a practical question: how much commercial protection does a patent portfolio provide when a competing drug is ready to enter the mark et?
The answer depends on the scope of the claims, the strength of the patent specification, the competitor’s regulatory pathway, and whether the competitor can structure its label, formulation or method to avoid infringement.
Five cases are particularly important. The U.S. Supreme Court ruled for Hikma in the Vascepa skinny-label dispute. The Federal Circuit revived Teva’s $176.5 million patent case against Eli Lilly. Exelixis secured another favorable ruling involving three patents protecting CABOMETYX, a product that generated more than $2.1 billion in U.S. revenue in 2025. Novartis preserved UK protection for Entresto, which generated $7.75 billion in 2025. Jazz is defending its Xyrem patent portfolio against a proposed 505(b)(2) product from Tris.
| Case | Drug | Key 2026 development | Commercial exposure |
| Hikma v. Amarin | Vascepa | U.S. Supreme Court ruled for Hikma | Amarin 2025 revenue: $213.6M |
| Teva v. Eli Lilly | Ajovy / Emgality | Federal Circuit reversed invalidity ruling | Jury award: $176.5M |
| Exelixis v. MSN | CABOMETYX | Federal Circuit upheld 3 patents | U.S. revenue: $2.11B in 2025 |
| Novartis v. Accord | Entresto | UK court upheld patent + SPC | 2025 sales: $7.75B |
| Jazz v. Tris | Xyrem | NJ court allowed patent case to continue | 2025 sales: $146M |
- Hikma v. Amarin: The Supreme Court draws a line around skinny-label liability
Who is suing whom?
Amarin Pharma sued Hikma Pharmaceuticals over generic Vascepa, alleging that Hikma’s marketing and communications encouraged physicians to use the generic for a patented cardiovascular indication.
The dispute focused on when a generic manufacturer crosses the line from lawfully selling a drug with a carved-out indication to inducing infringement.
What did the Supreme Court decide?
Vascepa was initially approved for severe hypertriglyceridemia. Amarin later obtained approval for reducing cardiovascular risk in certain patients.
Hikma obtained FDA approval for its generic using a skinny label that excluded the patented cardiovascular indication.
Amarin argued that Hikma’s website and other communications nevertheless encouraged use for that patented indication.
In June 2026, the U.S. Supreme Court unanimously reversed the Federal Circuit and remanded the case.
The Court held that induced infringement requires affirmative conduct intended to encourage infringement. The possibility that physicians might use the generic for a patented indication was not sufficient.
The Court also explained the significance of the FDA’s AB rating. A generic is considered therapeutically equivalent to the brand under the conditions specified in the generic’s own label, including lawful indication carve-outs.
The commercial data
The litigation matters because Vascepa remains central to Amarin’s business.
- 2025 total revenue: $213.6M
- 2025 U.S. product revenue: $154.1M
- 2024 U.S. product revenue: $166.7M
- Q2 2026 U.S. product revenue: $32.2M
- Q2 2025 U.S. product revenue: $36.5M
- U.S. icosapent ethyl market share, Q2 2026: approximately 48%
- U.S. market share, Q2 2025: approximately 43%
Amarin attributed continued revenue pressure to generic competition and lower net pricing.
The case therefore establishes a specific boundary: a lawful skinny label does not become infringing merely because physicians may prescribe the generic for an excluded indication. Evidence of affirmative encouragement is critical.
- Teva v. Eli Lilly: Broad antibody claims face the enablement test
Who is suing whom?
Teva sued Eli Lilly over Emgality, Lilly’s anti-CGRP migraine drug, alleging infringement of patents associated with Teva’s Ajovy.
A jury found infringement and awarded Teva $176.5 million.
The district court later held the relevant patents invalid.
In April 2026, the Federal Circuit reversed the invalidity judgment and remanded the case.
The Federal Circuit did not simply reinstate a final $176.5 million judgment. The earlier jury findings and award remain relevant as the case continues.
What was the patent issue?
The patents cover methods of treating headaches using antibodies that inhibit CGRP.
Lilly argued that the claims covered a broad class of antibodies and that practicing them would require excessive experimentation.
The district court agreed.
The Federal Circuit disagreed with the district court’s enablement conclusion. It found that the evidence could support a jury finding that the claimed class of humanized anti-CGRP antibodies could perform the claimed function without the level of experimentation identified by the district court.
This places the case within a larger legal issue for biologics: how broad can an antibody claim be when the specification describes only a limited number of examples?
The question is especially important following the Supreme Court’s decision in Amgen v. Sanofi, which placed significant limits on broad antibody genus claims that are not adequately enabled.
The commercial data
The dispute covers two major migraine products:
- Emgality worldwide revenue: more than $870M in 2024
- Ajovy revenue: $673M in 2025
- Original jury award to Teva: $176.5M
The commercial value of the patent claims therefore extends well beyond the damages number.
For biologics companies, the patent specification must support the claimed technical scope. Broad claims can cover more competing antibodies, but broader scope also creates a larger enablement and written-description target for challengers.
- Exelixis v. MSN: CABOMETYX shows the value of layered patent protection
Who is suing whom?
Exelixis has been litigating against MSN Laboratories over proposed versions of CABOMETYX, which contains cabozantinib.
The litigation involves multiple patents covering different technical aspects of the drug.
What happened in 2026?
On August 31, 2026, the Federal Circuit affirmed the district court’s conclusion that three asserted patents were not invalid:
- U.S. Patent No. 11,091,439: crystalline cabozantinib malate
- U.S. Patent No. 11,091,440: pharmaceutical compositions
- U.S. Patent No. 11,098,015: methods of treatment
The Federal Circuit also dismissed MSN’s appeal concerning U.S. Patent No. 11,298,349 as moot.
The three upheld patents protect different technical layers:
active ingredient → crystal/salt form → pharmaceutical composition → therapeutic use
Exelixis’ patent position also includes earlier patents covering the cabozantinib composition, salt or polymorph, formulations and methods, as well as a separate low-impurity formulation patent that expires later.
The commercial data
CABOMETYX generated:
- 2025 U.S. net product revenue: $2.113B
- 2024 U.S. net product revenue: $1.798B
- 2025 growth: 18%
- H1 2026 revenue: approximately $1.123B
- H1 2026 growth: 9%
- 2025 global cabozantinib franchise revenue: approximately $2.9B
This is a growing product rather than a declining legacy franchise.
Exelixis said the Federal Circuit decision could support an earliest potential MSN launch date of January 15, 2030, subject to additional appeals, regulatory exclusivity and other patent issues.
The case demonstrates why pharmaceutical patent estates often extend beyond the original molecule patent. A generic challenger may defeat one patent and still face enforceable claims covering the salt, crystal form, formulation or therapeutic use.
- Novartis v. Accord: Entresto shows why patent protection is jurisdiction-specific
Who is suing whom?
Accord Healthcare challenged Novartis’ patent protection for Entresto, the heart-failure treatment containing sacubitril/valsartan.
The UK dispute focused on a European patent that had expired, while a Supplementary Protection Certificate (SPC) continued protection.
What did the UK court decide?
In August 2026, the UK High Court rejected Accord’s challenge.
Justice Richard Meade upheld the relevant patent and SPC and found that Accord’s proposed product would infringe.
The court rejected attacks involving plausibility, obviousness and SPC validity. Its conclusion was direct: “all the attacks on the patent fail.”
The SPC extends protection until 2028, despite expiry of the underlying European patent in 2023.
The commercial data
Entresto generated:
- 2025 global sales: $7.748B
- 2025 U.S. sales: $3.285B
- 2025 sales outside the U.S.: $4.463B
- Q2 2026 sales: $1.181B
- Q2 2025 sales: $2.357B
- Q2 year-on-year decline: approximately 50%
The decline in 2026 reflects increasing generic pressure, making the UK SPC particularly important.
The outcome also differs by jurisdiction. Novartis was unsuccessful in its U.S. effort to block generic competition in 2025, while the UK court upheld protection in 2026.
For a global drug, therefore, patent expiry is not a single worldwide event. The relevant date can differ by country because of patent validity, SPCs, national litigation and local regulatory requirements.
- Jazz v. Tris: Xyrem tests the interaction between patents and the regulatory pathway
Who is suing whom?
Jazz Pharmaceuticals sued Tris Pharma in New Jersey over Tris’ proposed competing version of Xyrem, a sodium oxybate treatment for narcolepsy.
Tris pursued FDA approval through a 505(b)(2) NDA, rather than an ANDA.
Its filing included Paragraph IV certifications against seven Orange Book-listed Xyrem patents.
Jazz filed two patent infringement suits against Tris in February 2026.
What happened in 2026?
In July 2026, a New Jersey federal judge refused to dismiss Jazz’s patent case.
The litigation includes patents covering methods of administering gamma-hydroxybutyrate.
Tris argued that changes to its proposed application could exclude uses covered by Jazz’s patents.
The dispute therefore turns partly on the relationship between the proposed regulatory label and the patent claims.
The commercial data
Jazz reported Xyrem net product sales of:
- 2023: $569.7M
- 2024: $233.8M
- 2025: $146.0M
- 2023–2025 decline: approximately 74%
The decline does not represent generic erosion alone. Jazz has also shifted patients toward Xywav, which generated approximately $1.66B in 2025 sales.
The remaining Xyrem patents nevertheless have commercial value because Jazz is protecting the revenue that remains while transitioning patients to Xywav.
What these five cases show about pharmaceutical patent strategy
The five disputes involve different technologies and legal issues, but the data points to several specific trends.
- Patent claims must match the competitor’s approved product
In Hikma v. Amarin, the generic manufacturer used a skinny label that excluded the patented cardiovascular indication. The Supreme Court held that downstream physician use alone did not establish inducement without affirmative encouragement.
- Claim breadth must be supported by the specification
In Teva v. Lilly, the Federal Circuit reversed an enablement-based invalidity ruling involving broad anti-CGRP antibody claims.
The case demonstrates the commercial trade-off: narrow claims may be easier to support but easier to design around; broad claims cover more potential products but face greater validity scrutiny.
- Multiple patents can create multiple barriers to entry
CABOMETYX has patents directed to the active ingredient, crystalline form, pharmaceutical composition and therapeutic use.
The August 2026 Federal Circuit decision left three of those patents intact.
- Patent protection differs by market
Entresto illustrates the difference between a European patent expiry, an SPC in the UK and litigation outcomes in the U.S.
For global products, IP teams need a country-specific view of validity, expiry, SPC protection, infringement and regulatory approval.
- FDA strategy can directly affect patent risk
Vascepa and Xyrem show why the competitor’s label, indication and regulatory pathway need to be analyzed alongside the patent claims.
The central question is no longer simply:
“Do we have a patent?”
It is:
“What exactly will the competitor seek approval to sell, which claims cover that product or use, and can the competitor structure its label, formulation or method to avoid those claims?”
That is increasingly where pharmaceutical patent disputes are decided.
The 2026 cases show that the strongest lifecycle strategy combines compound patents, formulation and crystal-form claims, method-of-treatment claims, regulatory exclusivity, SPCs, litigation and licensing strategy.
For IP teams, the relevant analysis is therefore the complete competitive pathway: patent scope + validity + regulatory label + formulation + jurisdiction + expected market-entry date.
That is the framework increasingly determining how long a pharmaceutical product can retain meaningful market protection.
Sources:
- https://www.supremecourt.gov/opinions/25pdf/24-889_5i36.pdf
- https://www.supremecourt.gov/docket/docketfiles/html/public/24-889.html
- https://www.cafc.uscourts.gov/04-16-2026-24-1094-teva-pharmaceuticals-international-gmbh-v-eli-lilly-and-company-opinion-24-1094/
- https://www.reuters.com/legal/litigation/us-appeals-court-revives-teva-lawsuit-against-eli-lilly-over-migraine-drug-2026-04-16/
- https://www.cafc.uscourts.gov/opinions-orders/25-1236.OPINION.8-31-2026_2747765.pdf
- https://ir.exelixis.com/news-releases/news-release-details/exelixis-announces-update-patent-litigation-trial-appeal-msn
- https://www.sec.gov/Archives/edgar/data/939767/000093976726000019/exel2025q42025exhibit991.htm
- https://www.sec.gov/Archives/edgar/data/939767/000093976726000098/exel-20260703.htm
- https://www.reuters.com/legal/litigation/novartis-defeats-uk-court-bid-invalidate-blockbuster-drug-entresto-patent-2026-08-13/
- https://cms.law/en/int/legal-updates/plausibility-without-data-lessons-from-accord-v-novartis-2026-ewhc-2127-pat
- https://www.law360.com/articles/2498764/jazz-patent-suit-over-xyrem-survives-dismissal-in-nj
- https://investor.jazzpharma.com/static-files/37b267e2-f998-4c75-8cd5-ca06debc6a79
- https://www.sec.gov/Archives/edgar/data/897448/000119312526085818/amrn-20251231.htm
- https://www.sec.gov/Archives/edgar/data/897448/000119312526323841/amrn-ex99_1.htm
- https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-reference-listed-drugs
- https://patentcenter.uspto.gov/
