U.S. Patent 9,216,179: Scope, Claims, Expiration, and Lesinurad Patent Landscape
U.S. Patent No. 9,216,179 protects specific combination-treatment methods using lesinurad with allopurinol. The patent does not broadly cover lesinurad, allopurinol, or every combination therapy. Its claims require administration to a human and impose clinically defined serum-urate, safety, response, or tophus-related conditions. The patent was assigned to Ardea Biosciences, later acquired by AstraZeneca, and is associated with Zurampic (lesinurad), which the FDA approved in combination with a xanthine oxidase inhibitor for gout-related hyperuricemia.
The principal commercial risk is a method-of-use claim directed to lesinurad-allopurinol combination therapy. The principal validity and enforcement issues are the claim-result limitations, including the adverse-event threshold, serum urate thresholds, intraday change from baseline, and treatment of patients with tophi.
What drug does U.S. Patent 9,216,179 protect?
The claimed compound is lesinurad, chemically identified in the patent as:
2-(5-bromo-4-(4-cyclopropylnaphthalen-1-yl)-4H-1,2,4-triazol-3-ylthio)acetate
The patent also covers pharmaceutically acceptable salts of that compound. Lesinurad is a selective uric acid transporter 1 inhibitor, or URAT1 inhibitor. It reduces renal tubular reabsorption of uric acid and was developed for use with a xanthine oxidase inhibitor such as allopurinol.
Zurampic was approved by the FDA on December 22, 2015, for use with an xanthine oxidase inhibitor in adults with hyperuricemia associated with gout. The FDA-approved dose was 200 mg once daily with an xanthine oxidase inhibitor and hydration. Zurampic was not approved as monotherapy because of renal safety concerns and reduced clinical utility outside combination treatment (FDA, 2015).
What is the legal subject matter?
The patent is a method-of-treatment patent. It does not principally claim:
- The lesinurad molecule as a composition of matter;
- Allopurinol;
- A tablet formulation;
- A manufacturing process;
- A general method of inhibiting URAT1;
- Every use of lesinurad for gout.
Instead, it claims administration of lesinurad, or a pharmaceutically acceptable salt, together with allopurinol while achieving specified clinical outcomes.
What are the limitations of claim 1?
Claim 1 requires all of the following:
| Limitation |
Requirement |
| Patient |
A human |
| Active agent |
Lesinurad or a pharmaceutically acceptable salt |
| Second agent |
Allopurinol |
| Administration |
Co-administration |
| Therapeutic objective |
Reduced serum uric acid, treatment of hyperuricemia, or treatment of gout |
| Serum urate result |
Less than 6 mg/dL |
| Safety result |
An adverse event in less than 15% of humans |
The claim is narrower than a conventional combination-treatment claim because it includes both an efficacy condition and a safety condition.
A potentially infringing treatment would need to satisfy the claimed combination and the claimed outcome. Administration of lesinurad alone would not meet the claim. Administration with febuxostat rather than allopurinol would not literally satisfy the allopurinol limitation, although other patents or regulatory provisions could create separate risks.
The phrase "co-administration" generally requires administration of both agents in a treatment regimen. It does not necessarily require that the ingredients be in the same tablet. Separate tablets taken during the same treatment period may fall within the claim if the other limitations are satisfied.
What is the scope of claim 2?
Claim 2 covers co-administration of lesinurad and allopurinol that produces serum urate levels below 4 mg/dL.
| Claim 2 element |
Scope |
| Drug combination |
Lesinurad plus allopurinol |
| Patient |
Human |
| Disease context |
Hyperuricemia, gout, or reduced serum uric acid |
| Required outcome |
Serum urate below 4 mg/dL |
| Safety limitation |
None expressly stated |
Claim 2 does not include the less-than-15% adverse-event limitation found in claim 1. It also does not expressly require serum urate below 6 mg/dL because a level below 4 mg/dL necessarily satisfies a below-6 mg/dL threshold as a matter of arithmetic, although claim construction and prosecution history can affect how overlapping claims are interpreted.
From a commercial perspective, claim 2 may be important for patients receiving intensive urate-lowering therapy. Generic or follow-on products could face a claim risk if their labeling instructs use of lesinurad with allopurinol in patients expected to reach serum urate below 4 mg/dL.
What is the scope of claim 3?
Claim 3 requires:
- Lesinurad or a pharmaceutically acceptable salt;
- Allopurinol;
- Administration to a human;
- Serum urate below 6 mg/dL; and
- An intraday serum-urate change from baseline of more than 50%.
The intraday-change limitation is technically significant. It requires a comparison between a baseline serum urate measurement and a measurement taken within the same day or defined intraday period. The patent’s specification and prosecution history would be important in determining:
- How baseline is measured;
- Whether baseline means pretreatment serum urate;
- The timing of the second measurement;
- Whether the change is calculated as an absolute or percentage change;
- Whether the claim requires each treated patient to meet the threshold or permits a study-population result.
A potential accused product would not be evaluated solely by its label. Clinical trial data, pharmacodynamic studies, investigator instructions, and medical-use materials could be relevant to whether the claimed result is induced or expected.
What is the scope of claim 4?
Claim 4 applies to gout patients characterized by large accumulated deposits of uric acid, commonly called tophi.
The claim requires:
- Lesinurad or a pharmaceutically acceptable salt;
- Allopurinol;
- Treatment of a human;
- Serum urate below 6 mg/dL; and
- Gout characterized by tophi.
Claim 4 does not expressly include the less-than-15% adverse-event requirement or the greater-than-50% intraday-change requirement. It is directed to a clinically severe gout population. Tophi are generally associated with longstanding, inadequately controlled hyperuricemia and may occur in joints, soft tissue, or other locations.
This limitation narrows the claim to patients with a specific disease presentation. A label that only identifies ordinary gout without directing treatment of patients with tophi may present a weaker induced-infringement case than a label that expressly identifies chronic tophaceous gout.
How strong is the patent estate for lesinurad?
The lesinurad estate has several distinct layers:
| Protection category |
Relevance to lesinurad |
| Composition of matter |
Protects the lesinurad molecule and potentially salts |
| Combination method |
Protects lesinurad with allopurinol |
| Clinical-outcome claims |
Protects specified serum urate and safety results |
| Patient-population claims |
Protects treatment of patients with tophi |
| Formulation protection |
May protect dosage forms, salts, or pharmaceutical compositions depending on separate family members |
| Regulatory exclusivity |
Protects the approved product for a limited period independent of patent term |
U.S. Patent 9,216,179 is most important as a combination and clinical-use patent. It does not replace the composition-of-matter patent. A generic applicant seeking to market lesinurad would need to assess both the molecule-level patents and the method patents.
A separate patent commonly associated with the lesinurad compound and compositions is U.S. Patent No. 8,980,856. The relationship between that patent and U.S. Patent 9,216,179 illustrates the layered structure of the estate: one patent can protect the active compound while another protects a particular clinical regimen.
When does U.S. Patent 9,216,179 expire?
The patent’s ordinary term is tied to its earliest effective U.S. nonprovisional or international filing date, subject to patent-term adjustment, terminal disclaimers, and any applicable pediatric extension.
Public patent databases identify July 27, 2029, as the expected expiration date associated with the principal early lesinurad patent family, including U.S. Patent 9,216,179. The exact enforceable expiration date should be taken from the USPTO patent record because patent-term adjustment can modify the nominal 20-year term (U.S. Patent and Trademark Office, n.d.).
| Event |
Date or status |
| Earliest family priority |
July 27, 2009, for the principal lesinurad family |
| U.S. Patent 9,216,179 issuance |
December 22, 2015 |
| Expected patent expiration |
Approximately July 27, 2029, subject to PTA or disclaimer |
| FDA approval of Zurampic |
December 22, 2015 |
| FDA small-molecule exclusivity |
Expired in December 2018 |
| Product status |
Zurampic U.S. marketing was discontinued and the NDA was later withdrawn at the sponsor’s request |
Patent expiration does not depend on whether the branded product remains commercially marketed. A withdrawn or discontinued product can remain covered by unexpired patents.
What is the Orange Book status of lesinurad?
Zurampic was listed in the FDA Orange Book during its commercial life. The product’s approved labeling covered use with a xanthine oxidase inhibitor for hyperuricemia associated with gout. The Orange Book patent framework is relevant to an abbreviated new drug application, or ANDA, that relies on the Zurampic approval.
The key regulatory distinction is between:
- A currently marketed reference product;
- A discontinued product;
- A withdrawn application; and
- An unexpired patent historically listed for the product.
FDA withdrawal of the Zurampic NDA does not itself cancel or invalidate U.S. Patent 9,216,179. It can, however, complicate the commercial pathway for a generic applicant because the availability of a reference-listed drug, ANDA eligibility, and the effect of withdrawal depend on the specific FDA regulatory record and statutory pathway (FDA, n.d.-a; FDA, n.d.-b).
Are there Paragraph IV challenges to U.S. Patent 9,216,179?
A Paragraph IV certification would assert that a listed patent is invalid, unenforceable, or not infringed. For a lesinurad ANDA, the relevant patents could include:
- The composition-of-matter patent;
- U.S. Patent 9,216,179;
- Other listed patents covering formulations, salts, dosing, or methods of treatment.
The patent text alone does not establish a Paragraph IV filing, settlement, or district-court judgment. A complete litigation conclusion requires review of FDA patent-listing records, ANDA notices, federal district-court dockets, and any settlements filed under the Medicare Modernization Act reporting regime.
The claim structure creates several possible Paragraph IV positions:
Noninfringement positions
An applicant could argue that:
- Its product is not lesinurad or does not contain the claimed salt;
- Its labeling does not direct co-administration with allopurinol;
- Its labeling does not direct treatment of patients with tophi;
- Its label does not require or predict serum urate below 4 mg/dL;
- The claimed adverse-event or intraday-response limitation is not met.
Invalidity positions
Potential validity arguments could focus on:
- Anticipation or obviousness based on earlier lesinurad-allopurinol studies;
- Written-description support for the quantitative clinical outcomes;
- Enablement across the full scope of the claims;
- Indefiniteness of "adverse event" and the less-than-15% threshold;
- Ambiguity regarding baseline and intraday serum urate measurements;
- Whether the result limitations distinguish the claimed regimen over prior art.
The quantitative limitations may provide meaningful differentiation from broader combination-therapy prior art, but they can also create vulnerability if the specification does not adequately define the testing conditions or support the full claimed range.
What formulation patents protect lesinurad?
U.S. Patent 9,216,179 is not primarily a formulation patent. Its claims do not require:
- A particular tablet composition;
- A specific excipient;
- A fixed dissolution profile;
- A particular particle-size distribution;
- A particular manufacturing process;
- A fixed dose of lesinurad or allopurinol.
A separate formulation patent could create additional barriers if it covers the commercial tablet, salt form, stability profile, or manufacturing process. Those rights should be analyzed independently from the method claims in U.S. Patent 9,216,179.
The absence of a formulation limitation in the asserted claims can benefit a patent owner because infringement is not restricted to one physical dosage form. It can also benefit a challenger because an alternative formulation does not avoid the claims if the claimed drugs are co-administered and the clinical limitations are met.
Which companies competed with or challenged lesinurad?
Lesinurad competed primarily with established urate-lowering therapies rather than with a directly identical branded product.
| Therapy |
Mechanism |
Commercial relevance |
| Allopurinol |
Xanthine oxidase inhibitor |
Standard first-line therapy and the required partner in the asserted claims |
| Febuxostat |
Xanthine oxidase inhibitor |
Alternative oral urate-lowering therapy |
| Probenecid |
Uricosuric agent |
Older uricosuric competitor |
| Pegloticase |
Recombinant uricase |
Intravenous therapy for refractory chronic gout |
| Lesinurad |
URAT1 inhibitor |
Combination therapy with a xanthine oxidase inhibitor |
AstraZeneca acquired Ardea Biosciences in 2012. AstraZeneca commercialized lesinurad in the United States as Zurampic and also pursued combination products with allopurinol. The commercial program was affected by limited market adoption, renal monitoring requirements, boxed-warning concerns, and competition from established therapies. The U.S. product was later withdrawn from the market at the sponsor’s request.
What generic launch scenarios exist?
The main launch scenarios are:
| Scenario |
Patent and regulatory effect |
| No Paragraph IV challenge |
Entry generally waits until relevant patents expire or another pathway becomes available |
| Paragraph IV with no litigation |
Applicant may proceed after the statutory notice period, subject to FDA approval and other patents |
| Paragraph IV followed by litigation |
FDA approval may be delayed by the Hatch-Waxman stay, generally up to 30 months |
| Skinny-label strategy |
Applicant removes patented methods from labeling, but risk remains if the remaining label induces the claimed use |
| Reference-product withdrawal |
Regulatory eligibility may become more complex and may require reliance on FDA’s withdrawal rules |
| Composition patent expiration but method patent remains |
Commercial entry may remain exposed to method patents |
| Method patent expiration |
Entry may still be blocked by separate composition, formulation, or process patents |
Because claim 1 through claim 4 require allopurinol co-administration and clinical outcomes, a carefully drafted label could attempt to omit specific patented patient populations or outcomes. That strategy would not eliminate risk if the approved labeling, promotional materials, or prescribing instructions still encourage the claimed combination and use.
Key Takeaways
- U.S. Patent 9,216,179 is a lesinurad-allopurinol method-of-treatment patent.
- Its claims require treatment of humans, not merely possession or manufacture of lesinurad.
- Claim 1 requires serum urate below 6 mg/dL and adverse events in less than 15% of humans.
- Claim 2 requires serum urate below 4 mg/dL.
- Claim 3 requires serum urate below 6 mg/dL and an intraday change from baseline of more than 50%.
- Claim 4 covers patients with gout characterized by tophi and requires serum urate below 6 mg/dL.
- The patent does not broadly cover all lesinurad products, formulations, or uses.
- The expected expiration is approximately July 27, 2029, subject to patent-term adjustment and other USPTO-record details.
- The patent should be analyzed together with composition-of-matter, formulation, salt, manufacturing, and other lesinurad family patents.
- The principal legal vulnerabilities concern clinical-result definitions, enablement, written description, indefiniteness, and the prior-art status of lesinurad-allopurinol treatment.
- Product withdrawal does not invalidate the patent or automatically eliminate patent-based generic-entry risk.
Frequently Asked Questions
Does U.S. Patent 9,216,179 cover lesinurad monotherapy?
No. The asserted claims require co-administration of lesinurad with allopurinol.
Does the patent cover lesinurad used with febuxostat?
Not literally under the supplied claims. Each claim specifies allopurinol. A separate patent or regulatory theory could apply to a different combination.
Does a lesinurad generic avoid infringement by using a different tablet formulation?
Not necessarily. The claims are directed to co-administration and clinical outcomes, not to a specific tablet formulation.
Is treatment of tophaceous gout expressly protected?
Yes. Claim 4 expressly covers a human with gout characterized by large accumulated deposits of uric acid, or tophi.
Can a generic launch before 2029 if Zurampic is no longer marketed?
Potentially, but product withdrawal does not by itself eliminate unexpired patent rights. The applicant would need to address the applicable Orange Book, ANDA, reference-product, patent-certification, and litigation rules.
References
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Ardea Biosciences, Inc. (2015). U.S. Patent No. 9,216,179: Methods of treating hyperuricemia. U.S. Patent and Trademark Office.
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Ardea Biosciences, Inc. (2014). U.S. Patent No. 8,980,856: Compounds and compositions for the treatment of hyperuricemia. U.S. Patent and Trademark Office.
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U.S. Food and Drug Administration. (2015). FDA approves Zurampic to treat excess uric acid associated with gout. https://www.fda.gov/
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U.S. Food and Drug Administration. (n.d.-a). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
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U.S. Food and Drug Administration. (n.d.-b). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
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U.S. Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation resources. https://www.uspto.gov/ ━
