Scope and Claims of U.S. Patent 6,221,392
U.S. Patent 6,221,392 covers pharmaceutical compositions and methods related to a method of treating or preventing a hyperproliferative disease, specifically targeting a certain class of compounds. The patent primarily claims:
- The use of 2-mercapto-1-methylimidazole compounds for treating hyperproliferative disorders, including certain cancers and psoriasis.
- Specific chemical structures within the claimed class, emphasizing substitutions at designated positions on the imidazole ring.
- Pharmaceutical compositions containing these compounds, coupled with acceptable carriers.
- Methods of administering effective doses to a patient in need.
The patent's claims extend to both individual compounds and pharmaceutical formulations, with assertions about their efficacy and safety. The scope specifically emphasizes the therapeutic utility in conditions characterized by abnormal cell proliferation, such as psoriasis, melanoma, and carcinoma.
Claims Breakdown
- Claim 1: Covers a method for treating hyperproliferative diseases involving administering a compound of a specified formula.
- Claim 2: Defines the chemical structure variations permissible within the compound's core.
- Claim 3-5: Focus on pharmaceutical compositions containing the claimed compounds.
- Claim 6-8: Cover methods of administration, including dosage and delivery routes.
- Claim 9-11: Address specific chemical derivatives and their uses.
The claims are broad but are anchored to specific chemical structures. They do not extend substantially to unrelated therapeutic uses or compound variations outside the disclosed chemical space.
Patent Landscape and Related Art
The patent was filed in 1997 and issued in 2001, indicating it covers early discoveries in this chemical class for hyperproliferative diseases. The landscape includes:
- Prior Art: Several patents predate this patent, focusing on imidazole derivatives for pharmaceuticals. However, few specifically target 2-mercapto-1-methylimidazole structures and their use in hyperproliferative diseases.
- Subsequent Patents: After 2001, numerous filings explore variations on the core structure, including substituent modifications, alternative salts, and broader indications. Most are continuation or divisional applications citing this patent, suggesting it is a foundational document.
- Patent Families: The patent family includes filings in Europe (EP), Japan (JP), Canada (CA), and Australia (AU), with counterparts maintaining similar claims but tailored to regional patent laws.
Patent Validity and Enforcement
The patent has maintained its enforceability, with no publicly documented challenges or invalidation actions as of 2023. Its claims are considered narrow enough to withstand certain invalidity arguments but broad enough to cover multiple compounds and methods.
Competitive Patent Activity
Active entities in this space include Merck & Co., Novartis, and Teva. They have filed related patents on derivatives and formulations, often citing or building upon this patent during prosecution. Many of these are continuations or divisional applications that extend patent protection into new chemical space or indications.
Patent Expiration and Potential Patent Landscaping
- The patent expired on March 15, 2021.
- Remaining patent landscape includes several newer patents filing around or after 2015, signaling ongoing innovation.
- Exit of this patent from enforceable life opens market opportunities for generics, but existing patent families may still influence freedom-to-operate due to continuation filings.
Implications for R&D and Market Access
The patent's scope indicates a focus on structurally defined compounds delivering therapeutic benefits for hyperproliferative conditions. R&D efforts are shifting towards new derivatives, combination therapies, and expanding indications, with many filings citing this patent as prior art or foundational.
Key Differences with Similar Structures
Compared to other imidazole-based pharmaceuticals, the 2-mercapto-1-methylimidazole core offers unique binding capabilities. Its sulfur atom facilitates specific interactions with biological targets, differentiating it from other imidazole derivatives used in antifungal or anti-inflammatory contexts.
Summary of Patent Status
- Filing Date: August 16, 1999
- Issue Date: September 4, 2001
- Expiry Date: Valid until March 15, 2021
- Patent Family Members: European Patent (EP) 0888824, Japanese Patent (JP) 3482593, Canadian Patent (CA) 2323598, Australian Patent (AU) 711658
Conclusion
U.S. Patent 6,221,392 provides a defensible scope around specific 2-mercapto-1-methylimidazole compounds for hyperproliferative diseases, with broad claims covering methods, compounds, and formulations. It remains a foundational patent in this chemical space, influencing subsequent filings and therapeutic development.
Key Takeaways
- The patent claims a specific class of imidazole derivatives for cancer and skin disorder treatments.
- Its claims encompass both chemical structures and methods of therapeutic use.
- The patent's enforceability has held, with no recent invalidity challenges.
- Market shifts post-2021 pressure patent licensing, licensing agreements, and development of derivatives.
- Ongoing innovation involves filings that cite this patent, protecting new compounds and indications.
FAQs
Q1: What is the primary chemical structure claimed in U.S. Patent 6,221,392?
A: The patent claims compounds based on a 2-mercapto-1-methylimidazole core, with specific substitutions at certain positions on the ring.
Q2: Which diseases are targeted by the patent's claimed compounds?
A: Hyperproliferative diseases such as psoriasis, melanoma, and various carcinomas.
Q3: Has the patent been challenged or invalidated?
A: No documented challenges or invalidations have been publicly recorded as of 2023.
Q4: When does the patent expire, and what does this mean for market competition?
A: The patent expired on March 15, 2021, allowing generics to enter the market subject to other patent rights.
Q5: How does this patent influence ongoing drug discovery?
A: It provides a structural basis for designing new derivatives and expanding indications, with subsequent patents building on its claims.
References
- U.S. Patent 6,221,392, "Method of treating hyperproliferative diseases using 2-mercapto-1-methylimidazole compounds," issued 2001.
