Overview of EP3593802 and Therapeutic Context
European Patent EP3593802, held by Mirum Pharmaceuticals, Inc., protects methods for treating cholestasis using volixibat, an ileal bile acid transporter (IBAT) inhibitor[1]. Cholestasis—a condition characterized by impaired bile flow—manifests in diseases such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). Volixibat’s mechanism involves reducing bile acid reabsorption, thereby alleviating symptoms like pruritus and slowing disease progression[1][9]. The patent’s estimated expiration in 2030 positions it as a critical asset in Mirum’s portfolio, particularly given the drug’s ongoing Phase 2 trials for cholestatic pruritus[1].
Key Claims and Legal Structure
Under Article 84 of the European Patent Convention (EPC), claims must define the invention clearly and concisely while being supported by the description[6]. EP3593802’s claims likely encompass:
- Method-of-treatment claims: Specific dosing regimens (e.g., oral administration of 10–40 mg daily) for cholestasis patients[1].
- Patient-specific claims: Subpopulations with genetic markers or severe pruritus refractory to other therapies[9].
- Combination therapies: Use of volixibat with ursodeoxycholic acid (UDCA) or fibrates[1].
The patent’s validity hinges on its ability to demonstrate novelty and inventive step over prior art. For instance, earlier patents covering IBAT inhibitors for general liver diseases could challenge novelty unless EP3593802 specifies unique dosing or patient cohorts[1][6].
Patent Landscape and Competitive Dynamics
Mirum’s global strategy is evident from volixibat’s 161 international patents and 7 U.S. patents[1]. Key aspects of the landscape include:
Geographic Coverage and Family Members
- EP3593802: Part of a patent family including EP2575821 and EP2995317, which cover IBAT inhibitors for pediatric cholestasis and diabetes, respectively[1].
- U.S. counterparts: Patents such as US10,800,591 focus on cholestasis treatment, with expiration dates aligning with EP3593802[1].
This interlocking portfolio prevents generic competition by covering multiple indications and formulations. Competitors like Albireo AB (holding patents for odevixibat, another IBAT inhibitor) face barriers due to overlapping therapeutic claims[1][11].
Litigation Risks and Opposition Strategies
Third parties may challenge EP3593802 via opposition proceedings at the EPO, citing:
- Lack of inventive step: If prior art (e.g., WO2011150286) discloses IBAT inhibitors for cholestasis without Mirum’s specific dosing protocols[1].
- Insufficient support: Should the description fail to corroborate efficacy claims with clinical data[6].
However, Phase 2 trial results—showing significant reduction in serum bile acids and pruritus scores—strengthen the patent’s position[1][9].
Regulatory and Clinical Synergies
EP3593802’s scope aligns with volixibat’s clinical development:
- Phase 2 trials: Targeting PBC, PSC, and intrahepatic cholestasis of pregnancy (ICP)[1].
- Biomarker-driven claims: Correlations between serum bile acid levels and clinical outcomes, as validated in murine models[9].
These synergies enhance the patent’s enforceability, as regulators increasingly demand biomarker evidence for drug approvals[9].
Conclusion
EP3593802 exemplifies a strategically drafted patent combining method-of-treatment claims with robust clinical validation. Its extensive geographic coverage and alignment with ongoing trials underscore Mirum’s commitment to maintaining exclusivity in the cholestasis market. Potential challenges hinge on prior art and descriptive sufficiency, but the patent’s detailed claims and supporting data position it favorably against competitors.
"The strategic use of patent families covering multiple indications ensures long-term market exclusivity for volixibat, even as clinical trials progress." [1]
References
- https://www.drugpatentwatch.com/p/drugs-in-development/drugname/Volixibat
- https://www.ipd.gov.hk/hkipjournal/30102020/Patent_30102020.pdf
- https://www.drugpatentwatch.com/p/international/index.php?query=EP3518932
- https://www.epo.org/en/searching-for-patents/technical/ep-full-text
- https://www.epo.org/en/searching-for-patents
- https://en.wikipedia.org/wiki/Claims_under_the_European_Patent_Convention
- https://www.wipo.int/en/web/patentscope
- https://www.boehmert.de/en/bulletin-nov-2024-4/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8248789/
- https://www.iponz.govt.nz/get-ip/patents/apply/expedited-examination-for-patent-applications/european-patent-office-patent-prosecution-highway/
- https://www.gje.com/resources/navigating-product-by-process-claims-at-the-european-patent-office/
- https://www.uspto.gov/patents/search
- https://www.youtube.com/watch?v=b0fQapO5gBA
Last updated: 2025-04-23
