US Patent 9,993,461: Sparsentan Patent Scope, Claims, Expiration, and Generic Entry Risk
US Patent 9,993,461 protects specified dosing regimens of sparsentan for glomerulosclerosis and IgA nephropathy, including focal segmental glomerulosclerosis (FSGS). The patent does not primarily claim sparsentan as a chemical entity, a tablet formulation, or a manufacturing process. Its commercial importance is as a method-of-use patent covering administration of 200 mg, 400 mg, or 800 mg per day.
The patent is associated with Travere Therapeutics’ Filspari, whose active ingredient is sparsentan. Filspari received FDA accelerated approval for adults with primary IgA nephropathy who are at risk of disease progression.[1] The patent’s principal commercial relevance is therefore to generic or alternative-product entry into the IgA nephropathy market.
What drug does US Patent 9,993,461 protect?
US Patent 9,993,461 covers treatment methods using sparsentan, an orally administered dual endothelin A receptor and angiotensin II type 1 receptor antagonist. The patent claims use of the compound identified in the patent as Formula I.
Based on the claimed indications and dose levels, Formula I corresponds to sparsentan, the active pharmaceutical ingredient in Filspari. The claims cover:
| Patent element |
Scope |
| Active ingredient |
Sparsentan, or a pharmaceutically acceptable salt |
| Indications |
Glomerulosclerosis and IgA nephropathy |
| Daily dose range |
200 mg/day to 800 mg/day |
| Express dose embodiments |
200 mg/day, 400 mg/day, and 800 mg/day |
| Dosage form |
Not expressly limited in the quoted claims |
| Route |
The quoted claims do not expressly specify a route |
| Patient population |
A subject in need of treatment |
| Claim type |
Method of treatment |
The claims are directed to administration of the compound, not to every use of sparsentan or every pharmaceutical product containing sparsentan.
What are the claims of US Patent 9,993,461?
Claim 1 is the broadest independent claim in the provided set. It requires:
- Treating glomerulosclerosis or IgA nephropathy;
- Administering an effective amount of Formula I or a pharmaceutically acceptable salt; and
- Administering from 200 mg/day through 800 mg/day.
Claim 2 narrows the dose to 200 mg/day, 400 mg/day, or 800 mg/day. Claims 3, 4, and 5 separately claim each of those doses.
Claim 6 narrows the disease to glomerulosclerosis. Claim 7 narrows it to IgA nephropathy. Claims 8 through 11 combine IgA nephropathy with the listed dose alternatives.
Claim dependency and practical coverage
| Claims |
Disease |
Dose |
| 1 |
Glomerulosclerosis or IgA nephropathy |
200-800 mg/day |
| 2 |
Glomerulosclerosis or IgA nephropathy |
200, 400, or 800 mg/day |
| 3 |
Glomerulosclerosis or IgA nephropathy |
200 mg/day |
| 4 |
Glomerulosclerosis or IgA nephropathy |
400 mg/day |
| 5 |
Glomerulosclerosis or IgA nephropathy |
800 mg/day |
| 6 |
Glomerulosclerosis |
200-800 mg/day |
| 7 |
IgA nephropathy |
200-800 mg/day |
| 8 |
IgA nephropathy |
200, 400, or 800 mg/day |
| 9 |
IgA nephropathy |
200 mg/day |
| 10 |
IgA nephropathy |
400 mg/day |
| 11 |
IgA nephropathy |
800 mg/day |
Claims 3 through 5 and 9 through 11 are important fallback positions. If a court limits or invalidates the broader dose-range claims, a narrower dose-specific claim could remain relevant to a product or clinical protocol using one of the stated doses.
What is the scope of the dose limitation?
The dose limitation is central to infringement analysis. A product or treatment protocol would generally need to administer sparsentan within the claimed range and for one of the claimed diseases.
The range in claim 1 is 200 mg/day to 800 mg/day, inclusive. The dependent claims identify 200 mg/day, 400 mg/day, and 800 mg/day. The claims do not, on their face, require that the daily dose be administered once daily, twice daily, or in a particular tablet strength.
Filspari’s approved labeling provides titration from 200 mg once daily to 400 mg once daily after 14 days, subject to tolerability and clinical circumstances.[1] That dosing pattern falls within the literal numerical scope of the patent’s principal claims.
A regimen below 200 mg/day or above 800 mg/day would fall outside claim 1’s express dose range. That does not eliminate all risk. Other patent claims, equivalents analysis, or separate patents could remain relevant. The quoted claims alone, however, are numerically focused on 200 through 800 mg per day.
What diseases are protected by the patent?
The patent expressly covers glomerulosclerosis and IgA nephropathy.
IgA nephropathy
IgA nephropathy is the strongest commercial application because FDA approved Filspari for adults with primary IgA nephropathy at risk of disease progression.[1] The IgA nephropathy claims include the broad range in claim 7 and the specific dose claims in claims 8 through 11.
The FDA approval was granted under the accelerated-approval pathway based on reduction in proteinuria, a surrogate endpoint reasonably likely to predict clinical benefit. Continued approval depends on verification of clinical benefit in a confirmatory trial.[1]
Glomerulosclerosis and FSGS
“Glomerulosclerosis” is broader terminology than FSGS. FSGS is a pattern of kidney injury characterized by scarring in portions of some glomeruli. The claim language provided does not limit glomerulosclerosis to primary FSGS, genetic FSGS, secondary FSGS, or a particular histopathologic subtype.
That breadth creates possible claim-construction issues. A court could examine the specification, prosecution history, and technical meaning of “glomerulosclerosis” to determine whether the term covers all forms of glomerular scarring or a narrower clinical population.
The patent should not be treated as a claim to every FSGS treatment unless the asserted claim is construed to cover the relevant FSGS population and the accused regimen satisfies the remaining elements.
When does US Patent 9,993,461 expire?
The patent issued on June 12, 2018. Its term is governed by the patent-term rules applicable to the underlying application and any terminal disclaimer or patent-term adjustment. Public patent records identify the patent as a continuation or related member of the sparsentan development family, with a nominal term extending into the early 2030s.[2]
For commercial diligence, the controlling date is the patent expiration date displayed in the FDA Orange Book and the USPTO patent record, rather than the issue date. A patent-term adjustment, patent-term extension, terminal disclaimer, or pediatric extension can change the effective date.
Filspari also benefits from regulatory exclusivity separate from patent protection. FDA granted orphan-drug designation for IgA nephropathy, and orphan-drug exclusivity generally lasts seven years from approval for the approved indication.[1] The 2023 IgA nephropathy approval therefore creates a regulatory barrier that is distinct from US Patent 9,993,461.
What is the Orange Book status of US Patent 9,993,461?
US Patent 9,993,461 is listed in connection with Filspari in FDA’s Orange Book patent information for the product.[3] Its listing identifies the patent as relevant to an approved method of use rather than as a conventional composition-of-matter patent.
An Orange Book method-of-use listing can require a generic applicant to address the patent through one of the following pathways:
- Paragraph III certification, accepting that approval will be delayed until patent expiry;
- Paragraph IV certification, asserting that the patent is invalid, unenforceable, or will not be infringed;
- A section viii statement, carving out the patented method from the proposed labeling, if the remaining label supports approval.
The practical availability of a section viii carve-out depends on whether the proposed generic label can omit the patented indication or dosing information without creating an impermissible overlap with the approved use.
What Paragraph IV challenges and litigation affect the patent?
A Paragraph IV certification can trigger litigation under the Hatch-Waxman Act if the patent owner or NDA holder files suit within the statutory period after receiving notice.[4] The filing of a Paragraph IV certification does not itself invalidate the patent or authorize immediate commercial launch.
The commercially important litigation questions would include:
- Whether a generic applicant certifies against US Patent 9,993,461;
- Whether Travere files an infringement action;
- Whether the case concerns claim construction, written description, enablement, obviousness, or anticipation;
- Whether the parties enter a settlement;
- Whether the generic label includes or carves out IgA nephropathy and the covered doses.
The quoted claims create several potential validity issues. Dose-range claims can face obviousness challenges where the prior art discloses the compound, the disease, and overlapping doses. The patent owner would likely rely on clinical efficacy, dose-response evidence, unexpected results, or the lack of a reasonable expectation of success.
The claims also raise written-description and enablement questions if the specification does not adequately support the full range of diseases, doses, salts, and patient populations. The claim language covers both glomerulosclerosis and IgA nephropathy, but the strength of that breadth depends on the disclosure and prosecution record.
No settlement terms should be inferred from the patent’s existence or Orange Book listing. A settlement would require a separate public agreement, court filing, or regulatory record.
How strong is the patent estate for sparsentan?
US Patent 9,993,461 is valuable but narrower than a composition-of-matter patent. Its strength depends on the interaction of four factors:
| Factor |
Assessment |
| Chemical-entity protection |
Not the principal function of this patent |
| Indication protection |
Strongest for the expressly claimed IgA nephropathy and glomerulosclerosis uses |
| Dose protection |
Specific coverage from 200 mg/day through 800 mg/day |
| Generic design-around potential |
Meaningful if a competing label omits the patented indication or uses an unclaimed regimen |
A composition patent covering sparsentan itself would normally create the strongest barrier because it could reach the active ingredient regardless of indication. A method patent has narrower enforcement because infringement depends on the use, dose, and labeling or actual administration.
The patent is stronger against a generic that seeks an IgA nephropathy label with 200 mg or 400 mg once-daily dosing. It is weaker against:
- A product labeled only for an unclaimed disease;
- A regimen below 200 mg/day;
- A product using a different active ingredient;
- A product that obtains approval through a lawful indication carve-out;
- A treatment protocol not directed to glomerulosclerosis or IgA nephropathy.
What formulation and manufacturing patents protect Filspari?
US Patent 9,993,461, based on the quoted claims, does not claim a particular tablet formulation, excipient system, dissolution profile, polymorph, salt-selection process, or manufacturing method.
Separate patent families may protect:
- Sparsentan pharmaceutical compositions;
- Tablet formulation and stability;
- Solid-state forms;
- Salt or solvate forms;
- Processes for producing sparsentan;
- Analytical methods;
- Combination or coadministration protocols;
- Additional clinical uses.
Those rights must be analyzed separately from US Patent 9,993,461. A generic could avoid this patent but still face a formulation, process, or drug-substance patent.
How does the patent compare with regulatory exclusivity?
| Protection |
Source |
Subject matter |
Commercial effect |
| US Patent 9,993,461 |
Patent law |
Sparsentan treatment at specified doses for two kidney disorders |
Supports infringement litigation |
| Orphan-drug exclusivity |
FDA statute |
Approved IgA nephropathy indication |
Restricts approval of the same drug for the same orphan indication |
| Accelerated approval |
FDA regulatory pathway |
IgA nephropathy approval based on surrogate endpoint |
Requires confirmatory evidence |
| Other patents |
Separate patent families |
Possible formulation, process, compound, or additional-use rights |
May extend or diversify entry barriers |
Regulatory exclusivity and patent rights operate independently. FDA exclusivity can prevent approval even after a patent challenge succeeds, while a patent can remain enforceable after a regulatory exclusivity period ends.
What generic launch scenarios exist?
The main launch scenarios are:
- Paragraph III delay. A generic applicant accepts the patent and waits until the relevant patent term ends.
- Paragraph IV challenge. The applicant challenges validity, enforceability, or infringement and risks patent litigation.
- Section viii carve-out. The applicant removes the patented IgA nephropathy or glomerulosclerosis use from its labeling, if FDA permits approval on the remaining indications.
- Noninfringing dose strategy. The applicant uses a regimen outside the 200-800 mg/day range, subject to clinical and regulatory feasibility.
- Alternative active ingredient. A competing endothelin or renin-angiotensin pathway drug avoids direct infringement but competes commercially.
The most difficult route is a generic sparsentan product seeking the same IgA nephropathy indication and the same 200 mg or 400 mg daily dosing. That product would face both the Orange Book patent and orphan-drug exclusivity considerations.
Key Takeaways
- US Patent 9,993,461 is a sparsentan method-of-treatment patent.
- Its core scope covers glomerulosclerosis and IgA nephropathy at 200-800 mg/day.
- Dependent claims separately protect 200 mg/day, 400 mg/day, and 800 mg/day.
- The patent is particularly relevant to Filspari’s IgA nephropathy indication.
- It does not, based on the quoted claims, protect a formulation, manufacturing process, or sparsentan as a chemical entity.
- Generic risk is highest for an applicant seeking the same IgA nephropathy indication and dosing regimen.
- Section viii and noninfringing-dose strategies may reduce exposure but depend on FDA labeling and the complete patent estate.
- Orphan-drug exclusivity and patent protection are separate barriers and must be evaluated together.
- The patent’s ultimate strength depends on its specification, prosecution history, terminal disclaimers, patent-term calculation, and related sparsentan patents.
FAQs
Does US Patent 9,993,461 cover all uses of sparsentan?
No. The quoted claims are limited to treatment of glomerulosclerosis or IgA nephropathy using 200-800 mg/day.
Does the patent cover Filspari tablets specifically?
Not expressly. The quoted claims cover administration of sparsentan or a pharmaceutically acceptable salt, without a specific tablet composition or excipient limitation.
Can a generic launch below 200 mg/day avoid this patent?
A regimen below 200 mg/day would fall outside the express dose range in claim 1, but other patents, regulatory requirements, and infringement theories could remain relevant.
Is IgA nephropathy orphan-drug exclusivity the same as patent exclusivity?
No. Orphan-drug exclusivity is a regulatory approval barrier. Patent exclusivity is an enforceable property right. The periods and legal standards differ.
Does an Orange Book listing prove that the patent is valid?
No. Listing identifies a patent that the NDA holder asserts is relevant to the approved product. Validity and infringement remain subject to FDA certification procedures and potential litigation.
References
-
U.S. Food and Drug Administration. (2023). Filspari (sparsentan) prescribing information. FDA.
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United States Patent and Trademark Office. (2018). U.S. Patent No. 9,993,461, methods of treating glomerulosclerosis and IgA nephropathy. USPTO.
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U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
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21 U.S.C. § 355(j). Abbreviated new drug applications and patent certifications.
