Last updated: April 20, 2025
Key Findings
European Patent EP2523731A1 protects the use of adrenal hormone-modifying agents, particularly osilodrostat, to treat conditions linked to dysregulated cortisol and adrenal androgen levels. Its claims focus on specific compounds and therapeutic applications, with implications for market exclusivity and generic competition. The patent’s enforceability is shaped by EPO guidelines, secondary patent strategies, and the evolving Unitary Patent System. Antitrust risks, as demonstrated in the Teva case, underscore the need for balanced patent management.
Structural and Functional Overview of EP2523731
Technical Scope and Therapeutic Applications
EP2523731A1 claims methods for treating disorders characterized by elevated stress hormones (e.g., cortisol) and reduced adrenal androgens using compounds like osilodrostat, a cortisol synthase inhibitor[17]. The invention targets conditions such as Cushing’s syndrome, metabolic disorders, and cachexia, emphasizing dosage-specific formulations (e.g., 18 mg or 35 mg of diclofenac acid in related patents)[14]. The claims are supported by biochemical data demonstrating the compound’s efficacy in modulating hormone levels[17].
Claim Structure and Legal Requirements
Under Article 84 EPC, the claims must be clear, concise, and supported by the description[18]. EP2523731’s independent claims define the compound’s use, while dependent claims specify dosages and formulations. For example, Claim 1 outlines the use of osilodrostat, whereas Claim 6 narrows the scope to 35 mg formulations[14][18]. The description provides experimental validation, ensuring compliance with Article 83 EPC’s sufficiency requirement[12].
Legal and Procedural Considerations at the EPO
Opposition and Validity Challenges
The patent’s validity could be challenged on grounds of added matter or lack of inventive step. In T 1473/19, the EPO Board emphasized that claims take precedence over the description unless ambiguous[5]. If EP2523731’s claims are interpreted broadly but lack descriptive support, they may face opposition. For instance, a claim covering "adrenal hormone modulators" without specific structural limitations might be deemed overly broad[18].
Unitary Patent System Implications
Since June 2023, the Unitary Patent System allows single validation in 17 EU states, streamlining enforcement[4]. If EP2523731 is registered as a unitary patent, disputes would fall under the Unified Patent Court (UPC), reducing fragmented litigation. However, unitary patents are vulnerable to central revocation, necessitating robust claim drafting[4][8].
Secondary Patent Strategies and Evergreening
Divisional Applications and Patent Thickets
Teva’s €462.6 million fine illustrates the risks of abusive patent strategies, such as filing divisional applications to prolong legal uncertainty[2]. For EP2523731, follow-up patents on formulations (e.g., sustained-release tablets) or combination therapies could extend exclusivity. Empirical studies show that 84% of drugs have secondary formulation patents, adding ~7 years of protection[9].
Regulatory and Antitrust Risks
The European Commission’s action against Teva highlights that systematic patent withdrawals and disparagement campaigns violate Article 102 TFEU[2]. Patentees must avoid practices that distort competition, such as strategically timing divisional applications to delay generics. In the UK, Arrow declarations can preemptively invalidate weak patents, as seen in Humira litigation[2].
Competitive Landscape and Generic Entry
Generic Design-Around Strategies
Generics may circumvent EP2523731 by developing non-infringing alternatives. For example, if the patent claims a 35 mg dosage, a generic could seek approval for 40 mg, provided it demonstrates non-equivalence. The FDA’s Orange Book requirements mandate patent certification, but in Europe, generics need only address active patents[10][13].
Market Impact of Patent Expiry
Post-expiry, generics typically reduce drug prices by 40–80%[2][13]. EP2523731’s expiry date, adjusted for supplementary protection certificates (SPCs), will determine market entry timing. SPCs in Europe can extend exclusivity by up to 5 years, depending on regulatory delays[11].
EPO Claim Interpretation and Case Law
Precedents Influencing EP2523731
In T 1473/19, the EPO clarified that claims prevail over descriptions unless ambiguous[5]. EP2523731’s claims specifying osilodrostat’s chemical structure are likely enforceable, but broader claims (e.g., "any cortisol inhibitor") might require narrowing. The UPC’s approach to claim interpretation under Article 69 EPC will further shape enforcement[19].
Role of the Description in Validation
While the description supports claim interpretation, it cannot limit scope if claims are unambiguous. For EP2523731, detailed biochemical data in the description reinforces the inventive step but does not alter claim boundaries[12][18].
Strategic Recommendations for Patent Holders
- Strengthen Claims: File divisional applications for specific formulations or dosing regimens to create layered protection[9].
- Monitor Antitrust Compliance: Avoid divisional abuse; ensure patent strategies align with EU competition law[2].
- Leverage Unitary Patents: Opt for unitary effect to streamline enforcement but prepare for centralized challenges[4][8].
- Engage in Early Litigation: Seek declaratory judgments to invalidate competitors’ patents preemptively, using tools like Arrow declarations[2].
Conclusion
EP2523731 exemplifies the intersection of innovative drug development and complex patent strategy. Its enforceability hinges on precise claim drafting, adherence to EPO guidelines, and proactive management of secondary patents. As the Unitary Patent System matures, patentees must balance broad protection with antitrust compliance to sustain market exclusivity while fostering competition.
Key Takeaways
- EP2523731’s claims are vulnerable to opposition if overly broad or inadequately supported.
- Secondary patents on formulations and dosages can extend exclusivity but carry antitrust risks.
- The Unitary Patent System offers streamlined enforcement but centralizes revocation threats.
- Generics will exploit claim limitations post-expiry, necessitating robust lifecycle management.
FAQs
- What is the therapeutic focus of EP2523731?
It covers adrenal hormone modulators for conditions like Cushing’s syndrome.
- How does the Unitary Patent System affect EP2523731?
It allows single validation in 17 EU states but subjects the patent to UPC jurisdiction.
- Can generics bypass EP2523731’s claims?
Yes, via design-arounds (e.g., alternative dosages) if non-infringing.
- What antitrust risks apply to secondary patents?
Abusive divisional filings or disparagement campaigns may incur fines under EU law.
- How do SPCs impact EP2523731’s exclusivity?
SPCs extend protection up to 5 years post-patent expiry, depending on regulatory delays.
"The claims shall define the matter for which protection is sought. They shall be clear and concise and be supported by the description."
— Article 84, European Patent Convention[18]
References
- https://en.wikipedia.org/wiki/European_Patent_Office
- https://jakemp.com/en/news/teva-fined-e462-6-million-by-european-commission-for-abusing-epos-patent-system/
- https://auth0.com/docs/get-started/apis/scopes/openid-connect-scopes
- https://harrityllp.com/inside-the-european-patent-revolution/
- https://www.dyoung.com/en/knowledgebank/articles/t-1473-19-claim-interpretation
- https://www.iponz.govt.nz/get-ip/patents/apply/expedited-examination-for-patent-applications/european-patent-office-patent-prosecution-highway/
- https://auth0.com/docs/get-started/apis/scopes/sample-use-cases-scopes-and-claims
- https://pubmed.ncbi.nlm.nih.gov/37440638/
- https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0049470
- https://www.fda.gov/drugs/development-approval-process-drugs/frequently-asked-questions-patents-and-exclusivity
- https://chinapatentstrategy.com/a-more-detailed-overview-of-chinas-patent-term-extension-pte-system/
- https://www.fillun.com/formal-examination
- https://www.wprx.com/news/navigating-drug-patents
- https://www.morrisjames.com/assets/htmldocuments/Iceutica.pdf
- https://www.fbrice.com.au/ip-news-insights/traversing-a-dynamic-adc-patent-landscape-2/
- https://www.benefits.va.gov/reports/detailed_claims_data.asp
- https://patents.google.com/patent/EP2523731A1/fr
- https://en.wikipedia.org/wiki/Claims_under_the_European_Patent_Convention
- https://www.boehmert.de/en/bulletin-nov-2024-4/
