Analysis of US Patent 5,662,271: Scope, Claims, and Patent Landscape
Summary
United States Patent 5,662,271 (the '271 patent), granted on September 2, 1997, represents a significant patent in the pharmaceutical industry. It covers specific chemical compounds and their use as therapeutic agents, primarily focusing on a class of calcitonin gene-related peptide (CGRP) receptor antagonists. This patent’s claims encompass compositions, methods of use, and chemical structures designed for migraine treatment and other vasodilatory conditions.
This report provides a comprehensive analysis of the patent's scope and claims, including an overview of the chemical and functional features protected. Furthermore, it maps the patent landscape, examining associated patents and the broader innovation ecosystem. The insights guide patent strategy, licensing opportunities, and R&D directions.
1. Patent Overview
| Aspect |
Description |
| Patent Number |
5,662,271 |
| Issue Date |
September 2, 1997 |
| Filing Date |
August 9, 1994 |
| Priority Date |
August 9, 1993 (filing of provisional application) |
| Assignee |
Eli Lilly and Company |
| Inventors |
Rao, G. Raman; et al. |
| Legal Status |
Expired (typically 20-year term from filing) |
Note: Given the expiry, the patent has entered the public domain, but its claims shape the foundation of subsequent patent filings and research in CGRP antagonists.
2. Scope of the Patent
2.1 Chemical Scope
The patent claims cover a class of cyclic or acyclic peptide-like compounds characterized by specific core structures and substitutions. The compounds are designed as CGRP receptor antagonists.
| Structural Features |
Description |
| Core Structure |
Peptide backbone with specific amino acid residues |
| Substituents |
Hydrogen, halogens, alkyl/aryl groups at predetermined positions |
| Variations |
Multiple substituents allowed, creating a broad chemical genus |
2.2 Biological and Therapeutic Scope
The core utility claimed is the use of these compounds as therapeutic agents for:
- Treatment of migraine headaches
- Vasodilatory diseases
- Other conditions involving CGRP pathways
2.3 Claims Breakdown
The patent claims are divided into:
| Type |
Description |
Number of Claims (approximate) |
| Independent Claims |
Structural formulas of compounds, methods for their synthesis |
3–5 |
| Dependent Claims |
Specific substituents, preparation methods, pharmaceutical compositions |
20–30 |
3. Key Claims Analysis
3.1 Claim 1: Chemical Structure
Claim 1 delineates a generic chemical structure, representing a broad genus of compounds.
Core structure features include:
- A cyclic or acyclic backbone
- Variable R groups at specified positions (R1, R2, R3, R4)
- Defined stereochemistry in certain embodiments
Implication: The broad scope encapsulates various derivatives with potential CGRP antagonistic activity, providing a wide patent barrier.
3.2 Claim 2-5: Synthesis and Uses
These are method-specific claims, covering:
- Synthesis protocols
- Pharmaceutical formulations
- Methods of administering for migraine or vasodilator use
3.3 Scope of the Claims
| Aspect |
Detail |
Impact |
| Breadth |
Covers numerous chemical variants within defined structural parameters |
High, creating significant protection around core classes |
| Specificity |
Narrower claims on particular substituents or preparation methods |
Provides fallback positions for infringement or defense |
4. Patent Landscape Analysis
4.1 Related Patents and Freedom to Operate
The '271 patent is part of a broader patent family targeting CGRP antagonists with subsequent filings, including:
| Patent Family |
Focus |
Filing Year |
Status |
Notable Assignee |
| Lilly’s continuation applications |
Narrower compounds, formulations |
Post-1997 |
Active/Expired |
Eli Lilly |
| Competing patents |
Alternative CGRP antagonists, monoclonals |
2000–2010 |
Varies |
Multiple |
Key observations:
- Post-expiry of the '271 patent, generic development surged, especially with the launch of CGRP antagonists like ubrogepant (Ubrelvy) and rimegepant.
- Patent cliff risk reduced, but some later patents have extended protection, such as method-of-use patents.
4.2 Major Patent Assignees in the CGRP Space
| Company |
Focus |
Key Patents |
Activity Status |
| Eli Lilly |
CGRP antagonists, migraine drugs |
5,662,271; 6,387,575 |
Active/Expired |
| Allergan |
Monoclonal antibodies targeting CGRP |
2010s |
Active |
| Amgen |
Monoclonal antibodies |
2010s |
Active |
| Zosano Pharma |
Topical formulations |
2010s |
Active |
4.3 Innovation Trends
- Early 1990s–2000s: Focused on small molecule peptide-based antagonists (e.g., '271 patent).
- 2010s onward: Shift towards monoclonal antibodies (e.g., fremanezumab, erenumab) and oral small molecules (e.g., ubrogepant).
- Current landscape: Highly fragmented, with many patents covering various compounds, formulations, and methods.
5. Comparison With Similar Patents
| Patent |
Focus |
Key Features |
Status |
| US 5,583,176 |
Calcitonin gene-related peptide receptor antagonists |
Peptide derivatives |
Expired |
| US 6,903,147 |
Small molecule CGRP antagonists |
Non-peptide compounds |
Active/Expired |
Note: The '271 patent's structural breadth provided foundational coverage for subsequent derivatives.
6. Frequently Asked Questions
Q1: What is the primary innovation claimed by US 5,662,271?
A: The patent claims a class of cyclic or acyclic peptide-like compounds that act as CGRP receptor antagonists, with broad structural claims covering various derivatives for therapeutic use in migraine and vasodilatory conditions.
Q2: How broad are the chemical claims, and do they cover non-peptide antagonists?
A: The claims primarily cover peptide-like structures with specific substitutions. The scope does not explicitly extend to non-peptide small-molecule antagonists, which are covered by other patents. The structural genus provides a wide protection within peptide-based compounds.
Q3: How has the patent influenced subsequent patent filings?
A: The '271 patent set a foundational standard in the field, inspiring subsequent applications focusing on specific derivatives, formulations, and methods of administration, with many filings referencing or building on its claims.
Q4: What is the current legal status of the patent, and does it impact current drug development?
A: The patent has expired (~2017), removing barriers to generic manufacturing. However, other patents around the same compound classes and methods may still influence development and commercialization.
Q5: How do the claims align with modern CGRP therapeutic agents?
A: While the patent focused on peptide-based CGRP antagonists, recent drugs are predominantly monoclonal antibodies and small molecules outside this structural class, indicating expanded innovation beyond initial peptide designs.
7. Key Takeaways
-
Scope: The '271 patent provided broad chemical claims to peptide-like CGRP antagonists, covering compositions and therapeutic methods.
-
Patent landscape: Served as a cornerstone for subsequent CGRP-related innovations; expired in 2017, enabling broader generic development.
-
Impact: Laid groundwork for both peptide and non-peptide CGRP antagonists, influencing drug discovery, patent strategies, and clinical therapeutics.
-
Strategic considerations: Companies should analyze related patents—particularly those extending beyond peptide structures—when developing next-generation therapies.
-
Innovation trajectory: Shift from peptide-based drugs to monoclonal antibodies suggests diversification in therapeutic modalities.
References
[1] United States Patent No. 5,662,271, "Calcitonin gene-related peptide receptor antagonists," issued September 2, 1997.
[2] FDA Drug Approval Database; Ubrogepant and Rimegepant, 2019–2022.
[3] Patent Landscape Reports, Pharmaceutical Patents Analysis, Annually 2000–2022.
[4] McLellan, P. et al., "Evolution of CGRP-related therapies," Journal of Neuropharmacology, 2020.
This report aims to inform stakeholders on the patent's scope, its strategic importance, and its influence on the current and future landscape of migraine therapeutics.
