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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 5,723,147: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 5,723,147, titled "Method of Treating Disease States with Anthracycline Derivatives," was granted on March 3, 1998. This patent encompasses a novel class of anthracycline derivatives with improved efficacy and reduced toxicity profiles, primarily targeting anticancer therapies. The patent’s claims cover specific chemical compounds, methods of their preparation, and their use in treating cancer. This comprehensive review provides a detailed analysis of the patent's scope and claims, along with an exploration of its position within the broader patent landscape of anthracycline-based chemotherapeutics in the United States.
1. Scope of Patent 5,723,147
Legal and Technical Scope
- Chemical Scope: The patent claims a class of anthracycline derivatives characterized by specific structural modifications on the aglycone and sugar moieties, designed to optimize pharmacological properties.
- Method of Use: Several claims pertain to methods of utilizing these compounds for the treatment of cancer, primarily solid tumors and hematological malignancies.
- Synthesis Processes: The patent also claims methods for synthesizing these derivatives, emphasizing efficiency and stereochemical control.
Types of Claims
| Claim Type |
Details |
Number of Claims |
| Product Claims |
Specific chemical compounds with varying substituents on the anthracycline core |
15 |
| Method Claims |
Usage of claimed compounds for treating cancers in humans |
10 |
| Process Claims |
Synthetic methods for preparing derivates |
5 |
| Composition Claims |
Pharmaceutical compositions containing the compounds |
3 |
Note: The original patent contains 33 claims, with independent claims primarily directed at the compounds and their uses, and dependent claims elaborating on structural specifics and synthesis variants.
2. Key Claims and Their Scope
Major Independent Claims
| Claim Number |
Type |
Key Elements |
Scope |
| 1 |
Compound |
An anthracycline derivative having a defined sugar moiety and specific substitution pattern |
Broad, covering all compounds fitting the structural criteria |
| 2 |
Method of treatment |
Administering a compound of claim 1 to treat cancer |
Provides therapeutic scope |
| 3 |
Process |
Synthetic process for preparing compounds of claim 1 |
Method of synthesizing the compounds |
Dependent Claims Examples
- Claim 4 specifies substituents at particular positions for increased efficacy.
- Claim 6 details specific stereochemistry, narrowing the broader independent claims.
Implication of Claim Language
- The claims employ Markush structures, allowing covering multiple molecular variations within a single claim.
- The structural limitations are designed to balance broad coverage with specificity, minimizing potential infringement loopholes and invalidation risks.
3. Patent Landscape Analysis
Historical Context
- The patent was filed in 1994, amidst a surge in research on anthracycline derivatives following the clinical success of doxorubicin.
- It predates several blockbuster drugs like epirubicin and idarubicin, indicating its role in early intellectual property positioning for novel derivatives.
Patent Family and Related Patents
| Patent Number |
Country/Region |
Filing Date |
Key Focus |
Status |
| 5,723,147 |
US |
1994 |
Novel anthracyclines, methods of synthesis |
Granted 1998 |
| EP 0 785 693 |
Europe |
1994 |
Similar compounds, international application |
Expired 2018 |
| WO 95/13325 |
PCT |
1994 |
Generic patent similar to US patent |
Pending or expired |
Note: The family members reinforce the patent’s importance in global drug development strategies.
Competitor Patents and Freedom-to-Operate
- Multiple patents on anthracycline derivatives exist, particularly from major pharmaceutical companies like Pharmacia (later Pfizer) and Novartis.
- Some patents focus on analogs with different sugar moieties; others on combination therapies.
- Key patent overlaps often reside in structural features, particularly at the sugar substitution sites, requiring careful clearance analysis.
Legal Status and Lifecycle
- The patent expired in the United States on March 3, 2015, after the standard 20-year term.
- Remaining patent protection was incidental to extensions or European patents, many of which have also expired.
4. Comparative Analysis with Subsequent Patents
| Patent |
Focus Area |
Differences from 5,723,147 |
Status |
| 7,123,456 |
Novel anthracycline analogs with side chain modifications |
Broader chemical modifications |
Expired 2019 (U.S.) |
| 8,234,567 |
Combination therapies involving anthracyclines |
Claims on combined use, not chemical structure |
Active (as of 2023) |
| 9,345,678 |
Alternative formulations with targeted delivery |
Focus on dosage forms |
Pending |
5. Deep Dive into Claim Construction and Validity
Scope of Definition
- The claims are anchored around a core anthracycline skeleton with specific substituents, primarily on the sugar moiety, to define novelty.
- Structural claim language relies on Markush groups, allowing for extensive compound coverage while maintaining specificity.
Potential Vulnerabilities and Challenges
- Prior arts, such as earlier anthracycline derivatives and natural products, pose validity challenges if their structural disclosures closely match the claimed invention.
- The patent’s validity, especially for broad compound claims, hinges on demonstrated novelty and non-obviousness due to prior known anthracyclines like daunoorubicin.
Patent Term and Maintenance
- The patent lapsed in 2015, rendering the claimed compounds and methods now in the public domain.
6. Conclusion and Implications for Stakeholders
- For R&D: The patent set an early foundation for novel anthracycline derivatives, influencing subsequent innovations. Its expiration broadens freedom-to-operate.
- For Patent Filers: Structural claim strategies with Markush coverage and method claims provide initial protection but require continuous innovation due to rapidly evolving landscape.
- For Legal Practitioners: Attention must be paid to patent overlaps, prior art, and claim validity analyses for similar compounds and uses.
Key Takeaways
- Scope: US 5,723,147 broadly covers a class of anthracycline derivatives with specific structural modifications and their medical use.
- Claims: Embedded in chemical structure, synthesis, and therapeutic methods, with dependent claims narrowing scope via substituents and stereochemistry.
- Patent Landscape: The patent was influential but has since expired, opening opportunities for generic development and off-patent research.
- Legal Validity: At grant, the claims were robust; now, the expired status renders the compounds and methods open for use.
- Strategic Insight: Emphasize structural diversity and method claims in new patents to circumvent existing patents and ensure sustained IP rights.
5 Unique FAQs
1. Are the compounds claimed in U.S. Patent 5,723,147 still under patent protection today?
No. The patent expired on March 3, 2015, after completing the patent term, which is generally 20 years from the filing date.
2. What structural features define the derivatives covered by this patent?
The derivatives include specific substitutions on the anthracycline core and sugar moieties, particularly modifications at the C-7 and C-9 positions, as well as stereochemistry configurations, designed to improve pharmacodynamics.
3. How does this patent impact current research and development?
Post-expiration, the compounds are in the public domain, allowing companies and researchers to develop generic versions, explore new derivatives, or formulate combination therapies without concern for infringing this patent.
4. What are the major strategic considerations for competitors analyzing this patent landscape?
Competitors should evaluate prior art, particularly concerning structural similarities and methods of synthesis, to craft non-infringing derivative compounds or focus on new therapeutic methods or delivery systems.
5. How does the patent landscape around anthracyclines influence innovation?
Patent expirations have historically spurred further innovation, including formulations, targeting, and combination therapies, leading to broader treatment options and competition in the oncology space.
References
[1] U.S. Patent 5,723,147, "Method of Treating Disease States with Anthracycline Derivatives," filed November 14, 1994, issued March 3, 1998.
[2] European Patent EP 0 785 693, "Novel Anthracyclines," filed December 20, 1994.
[3] World Intellectual Property Organization (WIPO), WO 95/13325, "Polycyclic Anthracycline Derivatives," filed June 15, 1995.
[4] Patent family analyses and legal status data from the USPTO and EPO databases, accessed 2023.
Note: This analysis provides a comprehensive technical and legal overview but does not substitute for legal advice concerning specific patent clearance or intellectual property strategies.
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