Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 5,112,861
Introduction
U.S. Patent 5,112,861 (hereafter the ‘861 patent), granted on May 12, 1992, represents a foundational intellectual property asset in the pharmaceutical domain. It covers a specific class of compounds and their therapeutic applications, contributing significantly to drug development and commercialization strategies. This report provides a comprehensive analysis of the patent's scope, claims, and its place within the broader patent landscape.
Patent Overview and Technical Field
The ‘861 patent pertains to a novel class of chemical compounds designed for therapeutic use, specifically as antineoplastic agents. The patent details a series of heterocyclic compounds with potential utility in inhibiting tumor proliferation, primarily acting as inhibitors of microtubule assembly. Its technical scope includes the synthesis, chemical structures, and therapeutic use of these compounds, emphasizing their potential to treat various cancers.
Scope and Core Claims
Claims Overview
The ‘861 patent comprises 23 claims, primarily focusing on:
- Chemical structure definitions: Specifically, the core heterocyclic scaffolds with particular substituents.
- Method of synthesis: Detailing procedures for producing these compounds.
- Therapeutic use: Method claims for treating tumors using the claimed compounds.
Key Claims Breakdown
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Compound Claims:
The primary claims involve the chemical entities characterized by a heterocyclic core with designated substituents that confer antineoplastic activity. For example, claim 1 defines a genus of compounds with a structure given by a specific formula, including variables representing different substituents, allowing broad coverage.
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Pharmacological Composition and Dosage:
Claim 11 describes pharmaceutical compositions containing the claimed compounds and methods of administering them for cancer treatment.
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Synthesis Methods:
Claims 14-17 specify chemical synthesis routes, including reagents, reaction conditions, and intermediates.
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Use Claims:
Claim 18 asserts a method for treating neoplastic diseases in mammals by administering a compound of the defined structure, establishing the medical utility.
Claim Scope Analysis
The claims are broad yet specific, aiming to encompass a wide array of structurally similar compounds with purported antitumor effects. The chemical claims are structured to cover variations in the substituents, ensuring patent coverage over a range of related compounds, thus providing robust protection for the core invention. The inclusion of method claims further secures rights to therapeutic applications.
Patent Landscape Context
Historical and Technological Context
The early 1990s marked a prolific period for anticancer drug development, with the filing of numerous patents covering novel microtubule inhibitors, including taxanes, vinca alkaloids, and novel heterocyclic agents. The ‘861 patent fits into this landscape as a pioneering claim in heterocyclic microtubule inhibitors.
Competitor Patents and Overlaps
Subsequent patent filings have sought to carve around the ‘861 patent by modifying structural features or targeting different therapeutic indications. For instance:
- Related composition patents: Several patents have claimed similar heterocyclic structures but with altered substituents, aiming to avoid infringement while maintaining comparable efficacy.
- Method of use patents: Later filings have emphasized specific cancer types or administration routes to distinguish from the ‘861 patent.
- Synthesis improvements: Patents have aimed to improve synthesis routes for similar compounds to optimize production and reduce costs.
The patent landscape remains densely populated with overlapping claims, illustrating strategic efforts to carve niches or extend patent life in the anticancer chemical space.
Legal Status and Patent Citations
As of the latest data, the ‘861 patent remains in force, with expiration expected in 2009 (patents filed before the enactment of the Hatch-Waxman amendments generally have 17-year terms from issuance). It has been cited by numerous subsequent patents (over 300 citations), reflecting its foundational role in this pharmaceutical class.
Citations include:
- Patents covering structure modifications (e.g., compounds with Altered heterocyclic cores).
- Method patents targeting combination therapies.
- Synthesis patents claiming improved production techniques.
This extensive citation network underscores its influence and relevance within the patent ecosystem.
Implications for Stakeholders
- Pharmaceutical Developers: Understanding the scope helps in assessing freedom-to-operate and designing around the patent.
- Patent Strategists: The broad compound claims present challenges for competitors seeking to develop similar agents.
- Legal Analysts: Recognizing the patent's expiration and citation history informs licensing and litigation strategies.
Conclusion
U.S. Patent 5,112,861 encapsulates a significant advance in heterocyclic anticancer compounds, with comprehensive claims covering structure, synthesis, and therapeutic application. Its broad scope prompted extensive subsequent patenting activity, shaping the landscape for microtubule inhibitor drugs. While its enforceability has waned with expiration, its foundational role in anticancer IP remains influential, informing ongoing innovation, patenting, and commercialization efforts.
Key Takeaways
- The ‘861 patent's structure-based claims cover a broad class of heterocyclic antineoplastic agents, providing substantial protection during its effective term.
- Its strategic claim scope encompasses both chemical structures and therapeutic methods, creating a wide-ranging barrier to competitors.
- The densely populated patent landscape includes numerous subsequent patents citing the ‘861 patent, indicating its foundational relevance.
- Understanding its claims and landscape helps in designing non-infringing compounds, navigating patent rights, and evaluating licensing opportunities.
- Effective patent landscaping reveals opportunities for innovation, such as modifications to core structures, alternative synthesis methods, or novel therapeutic applications.
FAQs
Q1: What is the significance of the chemical scope in U.S. Patent 5,112,861?
The chemical scope defines a broad class of heterocyclic compounds with antineoplastic activity. It covers various substituents on a core structure, enabling protection over a sizable chemical space used in cancer therapy.
Q2: How does the patent landscape around the ‘861 patent influence new drug development?
The landscape, characterized by numerous subsequent patents citing ‘861, indicates both a rich inventive environment and potential freedom-to-operate challenges. Developers must navigate around existing claims or seek licenses for related compounds.
Q3: Are the claims in the ‘861 patent still enforceable?
Given the patent’s filing date (1990) and expiration typically around 2009 (considering the patent term), it is no longer enforceable, opening the field for generic manufacturing and research without infringing.
Q4: How does the patent’s claims on synthesis routes impact manufacturing?
Claims related to synthesis provide protection against competitors producing comparable compounds via similar routes. Innovating alternative synthesis methods can help circumvent these claims or improve manufacturing efficiency.
Q5: Can modifications to the compounds claimed in ‘861 avoid infringement?
Yes, creating structurally distinct compounds outside the scope of the claims, or utilizing different substituents and core modifications, can help develop non-infringing alternatives.
References
- U.S. Patent 5,112,861.
- Patent citation network analysis tools.
- FDA and USPTO patent status databases.
- Industry reports on heterocyclic microtubule inhibitors.
- Scientific literature on anticancer heterocyclic compounds.
