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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,915,950: Scope, Claims, and Patent Landscape
What Does U.S. Patent 4,915,950 Cover?
U.S. Patent 4,915,950 issued on April 10, 1990, is titled "Synthetic Retinoids," assigned to Hoffman-La Roche Inc. It claims a specific class of synthetic retinoid compounds designed for pharmaceutical applications, notably in dermatology and oncology.
Patent Scope
The patent's scope encompasses:
- Chemical compounds: Structurally defined retinoid derivatives, particularly those with modifications to the β-ionone ring and side chains, intended to stabilize the molecule and enhance selective receptor activity.
- Methods of synthesis: Procedures to produce the specified compounds, including reaction conditions, intermediates, and purification processes.
- Therapeutic use: Application of these compounds in treating dermatological conditions such as acne and psoriasis, and in cancers such as leukemia.
Claims Breakdown
The patent contains 15 claims, broadly categorized into:
-
Composition claims: Cover specific retinoid compounds with defined chemical structures, such as compounds of the formula:
##STR1##
where R represents various functional groups modifying the retinoid backbone.
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Method claims: Cover methods of synthesizing these compounds, including steps, intermediates, and reaction conditions.
-
Use claims: Cover uses in treating dermatological and oncological disorders.
The key claim (Claim 1) covers a compound of formula:
A retinoid derivative characterized by a specific substituent R on the retinoic acid backbone, stabilizing activity and receptor selectivity.
Dependent claims specify various R groups, including methyl, ethyl, propyl, and phenyl substitutions, expanding patent coverage over a broad class of derivatives.
Patent Landscape and Related Intellectual Property
Overlapping Patents and Inventive Hierarchy
The patent landscape around retinoids includes:
- Prior art references: Earlier retinoid compounds, such as all-trans retinoic acid (Section 1), and other synthetic derivatives detailed in patents filed during the 1970s and 1980s [1].
- Subsequent patents: Numerous patents have emerged claiming further modifications, novel methods of delivery, or optimized compounds, forming a dense patent landscape.
Key Patent Assignees & Patent Families
- Hoffman-La Roche Inc. holds the original patent and subsequent continuation and divisionals.
- Patent families extending from this include U.S. Patent 5,057,620 and European counterparts, claiming similar retinoid derivatives with incremental structural modifications.
Patent Term & Life Cycle
- Patent filed: September 18, 1987
- Patent granted: April 10, 1990
- Expected expiration: April 10, 2007, with possible terminal extensions and pediatric exclusivity periods.
Market Impact & Competitive Position
- The patent's expiration allowed generic manufacturers to market similar retinoid formulations.
- Roche maintained a competitive edge during the patent life through formulation patents, delivery methods, and specific use claims.
Regulatory & Commercial Status
- Some compounds covered in the patent were developed into prescription drugs, notably for dermatology (e.g., adapalene derivatives in Differin).
- The patent's claims do not cover the marketed drugs directly but establish the inventive groundwork for later formulations.
Evaluation of Patent Strength and Limitations
- The broad chemical claims provide significant coverage of a class of compounds; however, prior art references limit scope.
- Synthesis claims are specific but can be circumvented via alternative synthetic routes.
- Use claims are narrow; many later patents expanded on indications and formulations.
Summary Table
| Aspect |
Details |
| Patent Number |
4,915,950 |
| Filing Date |
September 18, 1987 |
| Issue Date |
April 10, 1990 |
| Expiration Date |
April 10, 2007 (possible extensions) |
| Patent Type |
Composition, method of synthesis, use claims |
| Main Focus |
Synthetic retinoids with structural modifications |
| Market Application |
Dermatology, oncology |
| Overlapping Patents |
U.S.: 5,057,620; European equivalents |
Key Takeaways
- U.S. Patent 4,915,950 covers a class of synthetic retinoid compounds with specific structural features.
- Claims include composition, synthesis, and therapeutic use, with the core claim protecting a broad chemical class.
- The patent landscape is extensive, with subsequent patents refining, expanding, or circumventing the original claims.
- The patent's lifespan ended in 2007, allowing generics to enter the market, but derivative patents continue to extend Roche's market control.
- The patent played a vital role in the development of retinoid-based dermatologic and oncologic therapies.
FAQs
Q1: Does U.S. Patent 4,915,950 cover all retinoid derivatives?
No. It covers specific structural classes with defined modifications; others outside this scope are not protected.
Q2: Are compounds from this patent still under patent protection?
No, expired in 2007, opening the market to generics.
Q3: How broad are the claims in terms of chemical diversity?
Claims cover a specific set of derivatives with variations in R groups but do not encompass all possible retinoids.
Q4: Can a competitor synthesize similar compounds developed after this patent expired?
Yes, provided their compounds fall outside the scope of any later-expiring patents.
Q5: What is the likelihood that later patents could block generic entries?
Pediatric extensions, formulation patents, and use-specific patents can create barriers even after original patents expire.
References
[1] Bright, D. B. (1997). Antioxidant drugs and retinoids: Patents involved in dermatology and oncology. Patent Journal Review, 12(3), 145-160.
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