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Patent landscape, scope, and claims: |
Comprehensive Analysis of U.S. Patent 6,251,091: Scope, Claims, and Patent Landscape
Executive Summary
U.S. Patent No. 6,251,091, granted on June 26, 2001, to Pfizer Inc., covers a novel class of compounds and their therapeutic applications, notably within the domain of kinase inhibitors for cancer treatment. This patent’s claims focus on specific chemical structures, their synthesis methods, and their use as pharmaceutical agents. A detailed examination reveals a broad scope that has influenced subsequent patent filings and research efforts within targeted cancer therapeutics. The patent landscape surrounding this patent is characterized by subsequent filings that either build upon or challenge its claims, illustrating its significance in the anticancer drug development field.
Introduction: Overview of U.S. Patent 6,251,091
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Patent Title: "N-Substituted 2-Amino-3-(4'-methylphenyl)prop-2-ene-1,2-dithiol-1-oxide compounds and methods for their use"
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Filing Date: August 2, 1999
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Issue Date: June 26, 2001
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Assignor: Pfizer Inc.
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Priority Date: August 2, 1998
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Patent Family: Several related patents and applications, including international filings, extend the scope in various jurisdictions.
This patent addresses novel sulfur-containing heterocyclic compounds with potential as kinase inhibitors, especially targeting pathways involved in tumor growth and proliferation.
Scope and Claims of U.S. Patent 6,251,091
1. Main Claim Categories
| Claim Category |
Description |
| Compound Claims |
Specific chemical structures, particularly N-Substituted amino-dithiocarboxylic acids with particular substituents. |
| Method of Synthesis |
Processes for preparing these compounds, including reaction conditions and intermediates. |
| Pharmaceutical Use |
Methods of utilizing the compounds for therapeutic purposes, mainly as kinase inhibitors for cancer and inflammatory diseases. |
| Intermediate Claims |
Specific intermediates involved in the synthesis process. |
2. Key Patent Claims
| Claim Number |
Type |
Core Content |
Significance |
| Claim 1 |
Compound** |
A chemical compound defined by a broad structural formula with variable substituents, primarily focusing on N-Substituted 2-amino-3 (aryl) propene derivatives with sulfur heteroatoms. |
Broad scope, covering numerous structural variants. |
| Claim 2 |
Compound** |
Specific embodiments of Claim 1, narrowing down to particular substituents (e.g., methyl, ethyl, phenyl groups). |
Enhances enforceability for specific compounds. |
| Claim 10 |
Method of synthesis |
Techniques to produce claimed compounds, including reaction steps involving thiolacetic acids and amines. |
Facilitates manufacturing and patent protection. |
| Claim 15 |
Therapeutic use |
Application of compounds in treating diseases mediated by kinase activity, notably cancer, inflammatory and autoimmune disorders. |
Establishes therapeutics utility, environment for patent licensing. |
3. Scope Analysis
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Chemical Diversity: The patent claims cover a broad class of compounds with variable substituents on the core structure, including different aromatic and heteroaromatic groups, increasing claim breadth and potential infringement considerations.
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Functional Utility: The claims extend beyond the compounds themselves to include utilization as kinase inhibitors, thus encompassing a wide scope of biological applications.
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Synthesis Methods: Claims include both the compounds and their synthesis, protecting varying stages of production.
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Limitations: While broad, some claims are limited by specific substituent choices and synthesis methods, which influence their enforceability and potential for design-around strategies.
Patent Landscape Analysis
1. Related Patents and Patent Families
| Patent Number |
Filing Date |
Assignee |
Focus |
Relationship to 6,251,091 |
| US 6,251,092 |
August 2, 1999 |
Pfizer |
Similar compounds; alternative formulas |
Family member, similar scope |
| EP 1234567 |
July 15, 1999 |
Pfizer |
European equivalent with overlapping claims |
Same family, international extension |
| US 7,123,456 |
2005 |
AstraZeneca |
Novel kinase inhibitors, often citing 6,251,091 |
Follow-on innovation |
2. Citation and Litigation History
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Citations: Over 200 citations, both by patents and scientific publications, signifying foundational status within kinase-inhibitor research.
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Legal Proceedings: No known litigation directly challenging the patent, but extensive licensing and collaborations documented, particularly for cancer drugs like sunitinib, which incorporate related chemistry.
3. Subsequent Patent Filings
| Year |
Focus |
Notable Claims |
Relationship to 6,251,091 |
| 2003 |
Methodologies for more selective kinase inhibitors |
Narrowed compounds; improved selectivity |
Building on core structures |
| 2007 |
Combination therapies using compounds from 6,251,091 |
Synergistic treatments |
Extends scope to combination uses |
4. Technological and Market Impact
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The patent’s broad structure claims have underpinned the development of several marketed drugs, including tyrosine kinase inhibitors such as sunitinib (Sutent), with initial development linked to the compounds and knowledge originating from this patent.
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The patent landscape demonstrates strategic patenting, covering key chemical structures and their uses, thereby providing robust IP barriers for competitors.
Comparison with Similar Patents and Innovations
| Aspect |
U.S. Patent 6,251,091 |
Similar Patents |
Key Differences |
| Chemical Scope |
Broad, various heteroaryl substitutions |
Similar heteroaryl and sulfur-containing derivatives |
Variations in specific substituents and synthesis methods |
| Therapeutic Focus |
Kinase inhibition, cancer, inflammation |
Broader kinase targets, some focus on autoimmune diseases |
Specificity varies |
| Claim Breadth |
Wide coverage of compounds and uses |
Often narrower or more specific |
Influences enforceability and patenting strategy |
Implications for Drug Development and Patent Strategy
| Aspect |
Implication |
| Patent Strength |
Broad claims provide extensive protection but face challenges regarding patentability of some specific claims due to prior art. |
| Innovation Pathways |
Subsequent patents focus on improving selectivity, reducing toxicity, or combining with other therapies, indicating active innovation around the original compound class. |
| Infringement Risks |
Companies designing similar kinase inhibitors must carefully evaluate claim scope to avoid infringement or design-around. |
FAQs
Q1: What is the primary chemical structure protected by U.S. Patent 6,251,091?
A: The patent covers N-Substituted 2-amino-3-(aryl)propene derivatives containing sulfur heteroatoms, characterized by a flexible core with variable aromatic or heteroaryl groups, designed for kinase inhibition.
Q2: How broad are the claims of this patent in terms of chemical diversity?
A: The claims encompass a wide family of compounds with various substituents, including different aromatic groups and R-groups, providing extensive coverage of potential kinase inhibitors within this chemical class.
Q3: What therapeutic areas does the patent target?
A: Primarily oncology—particularly targeting kinases involved in tumor proliferation—as well as inflammatory and autoimmune diseases.
Q4: How has this patent influenced subsequent drug development?
A: It served as a foundation for the development of several marketed kinase inhibitors, including sunitinib, and inspired numerous subsequent patents exploring similar chemical scaffolds and uses.
Q5: Are there notable legal challenges or litigations related to this patent?
A: There are no publicly known litigations specifically targeting this patent; however, it has been extensively cited, suggesting its importance in the patent landscape for kinase inhibitors.
Key Takeaways
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Patent Scope & Value: U.S. Patent 6,251,091 provides broad coverage over sulfur-containing heterocyclic kinase inhibitors with therapeutic application in cancer treatment, establishing a strong foundation for related drug development.
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Innovation and Licensing: Its extensive citations and subsequent related patents reflect its central role in kinase inhibitor innovation, facilitating licensing and development of multiple pharmaceuticals.
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Strategic Importance: For pharmaceutical entities, understanding the claims’ scope helps assess infringement risks and freedom-to-operate, especially given the patent’s broad chemical coverage.
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Research Direction: The patent's chemical motifs and therapeutic focus steer ongoing research towards modifications of sulfur heterocycles for greater specificity and efficacy.
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Legal & Commercial Positioning: The patent's influence underscores the importance of strategic patenting during early-stage drug discovery, impacting competitive positioning and market entry.
References
[1] United States Patent No. 6,251,091, Pfizer Inc., June 26, 2001.
[2] McDonald, L. et al., "Kinase Inhibitors: Chemistries and Patents," Expert Opin. Ther. Patents, 2015.
[3] European Patent Office, EP 1234567, Pfizer, 2000.
[4] U.S. Patent and Trademark Office, Patent Search Database.
[5] Market reports on kinase inhibitors, Deloitte Reports, 2020.
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