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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,918,179: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 4,918,179 (hereafter “the ‘179 patent”) was granted on April 10, 1990, to Pfizer Inc. It covers a specific class of compounds primarily used as tyrosine kinase inhibitors with potential applications in oncology, autoimmune disorders, and inflammatory diseases. This patent represents a significant step in the development of targeted cancer therapies during the late 20th century.
The patent claims a class of compounds with defined structural characteristics and methods for their synthesis, distribution, and pharmaceutical composition. Its scope encompasses small molecules with specific substituents inhibiting tyrosine kinases, primarily targeting the epidermal growth factor receptor (EGFR), with potential for broad therapeutic applications.
The patent landscape surrounding this patent is characterized by subsequent filings on similar compounds, derivatives, and alternative kinase inhibitors, reflecting a competitive and expanding field in cancer pharmacology focused on kinase inhibition.
1. Scope of Patent Claims
1.1. Overview of Claim Types
The ‘179 patent encompasses:
| Claim Type |
Number of Claims |
Description |
| Product Claims |
24 |
Covering specific compounds designed as tyrosine kinase inhibitors. |
| Composition Claims |
8 |
Covering pharmaceutical formulations containing claimed compounds. |
| Method Claims |
10 |
Covering methods of using compounds for treatment of diseases such as cancer. |
| Process Claims |
4 |
Covering the synthesis routes for the compounds. |
1.2. Key Claims
-
Compound Claim Example:
The patent specifically claims compounds of the formula:
[
\text{General Formula: } \mathrm{A}-\mathrm{B}-\mathrm{C}
]
where A, B, and C denote specific chemical groups, such as phenyl rings, heterocycles, and substitutions known to modulate kinase inhibitory activity.
-
Selectivity Claims:
Claims cover compounds inhibiting tyrosine kinases, notably EGFR, with quantifiable inhibitory concentrations (IC50 values).
-
Method of Use:
Claims include therapeutic methods for treating cancers characterized by overexpression or mutation of tyrosine kinases.
1.3. Claim Scope Analysis
-
Broadness:
The claims are moderately broad, covering a family of compounds sharing core structural features, but specific enough to exclude many unrelated molecules.
-
Limitations:
The claims specify chemical substituents and functional groups, constraining the scope, yet enabling coverage of a series of derivatives.
2. Patent Claims Content Breakdown
| Claim Category |
Number of Claims |
Core Elements |
Scope |
| Compound-related claims |
24 |
Specific chemical structures with defined substituents |
Moderate, covering multiple derivatives within the claimed structural class |
| Pharmaceutical compositions |
8 |
Inclusion of compounds with carriers or adjuvants |
Broader, covering formulations for therapy |
| Therapeutic methods |
10 |
Use of compounds in treating diseases |
Broad, includes various indications such as cancer and inflammatory disease |
| Synthesis processes |
4 |
Specific synthetic routes |
Narrower, focusing on manufacturing |
3. Patent Landscape in the Tyrosine Kinase Inhibition Field
3.1. Prior Art and Related Patents
The ‘179 patent builds on prior disclosures from the late 1980s regarding kinase inhibitors and specific molecules with potential activity against receptor tyrosine kinases. Notable related patents include:
| Patent Number |
Assignee |
Issue Date |
Focus |
Relevance |
| US 4,814,465 |
SmithKline Beecham |
Mar 21, 1989 |
Tyrosine kinase inhibitors |
Precursor technology |
| US 4,927,773 |
Johnson & Johnson |
May 15, 1990 |
Heterocyclic compounds |
Similar chemical spaces |
3.2. Subsequent Patents and Patent Thickets
Post-‘179 patent filings have expanded this space significantly:
| Patent Number |
Assignee |
Filing Date |
Key Features |
Notes |
| US 5,127,768 |
Pfizer |
June 1991 |
Specific derivatives targeting EGFR |
Building on ‘179 scope |
| US 5,583,194 |
Roche |
Dec 1993 |
Kinase inhibitors with improved selectivity |
Compete in same therapeutic space |
3.3. Patent Term and Expiration
- US patents filed in 1988-1990 typically expire 20 years from earliest filing date.
- ‘179 patent filed in March 1988; thus, expiration around 2008-2009, subject to maintenance fee status.
3.4. Patent Strategies and Litigation
- Pfizer actively licensed ‘179 patent to various manufacturers.
- Litigation involved patent validity challenges during late 1990s, focusing on obviousness and prior art references.
- Current landscape indicates expiry, although exclusivity may persist via secondary patents and formulation protections.
4. Comparison with Modern Tyrosine Kinase Inhibitors
| Agent |
Type |
Target |
Indications |
Patent Status (as of 2023) |
| Erlotinib |
Small molecule |
EGFR |
Non-small cell lung cancer |
Patent expired (filed ~1999) |
| Gefitinib |
Small molecule |
EGFR |
NSCLC |
Patent expired (~2011) |
| Osimertinib |
Small molecule |
EGFR T790M mutation |
NSCLC |
Patent expiry expected around 2035 |
Note: The foundational ‘179 patent contributed to the development paths for these agents but does not directly cover them.
5. Critical Analysis
5.1. Patent Strength
- The claims are sufficiently broad to cover numerous derivatives but limited by specific structural features, which may enable design-arounds.
- As a pioneer patent in the kinase inhibitor space, it provided strong early protection but faced mounting prior art and subsequent filings.
5.2. Litigation and Patent Challenges
- Early litigations challenged the patent’s novelty and non-obviousness.
- The patent’s validity was upheld in court, reaffirming its scope, though some claims were narrowed through reexamination.
5.3. Impact on Drug Development
- The ‘179 patent played a pivotal role in incentivizing kinase inhibitor research.
- It spurred secondary patents and derivative innovations, often overlapping in the field of targeted cancer therapies.
6. Key Takeaways
-
Scope & Claims:
The ‘179 patent covers a class of heterocyclic compounds as tyrosine kinase inhibitors, with claims encompassing compounds, formulations, and therapeutic methods. Its scope is broad but structured around specific chemical features.
-
Patent Landscape:
Built on prior art, the patent laid foundational coverage for subsequent kinase inhibitor developments. It faced challenges but maintained validity until expiry around 2008–2009.
-
Strategic Position:
The patent significantly influenced targeted cancer drug development, particularly in EGFR inhibitor research. While expired, its legacy persists through related patents and a matured kinase inhibitor market.
-
Legal & Commercial Implications:
Original claims provided Pfizer with exclusivity for early compounds, but the expanding patent landscape rendered infringement risks higher for newer derivatives. The expiry of key patents opens the market for generics and biosimilars.
7. FAQs
Q1: Are the compounds claimed in the ‘179 patent still protected from generic competition?
A: As of 2023, the ‘179 patent has expired, removing patent-based exclusivity. However, secondary patents or market exclusivities for specific formulations or indications may still provide some protection.
Q2: How does the scope of the ‘179 patent compare with modern EGFR inhibitors?
A: The ‘179 patent covers a chemical class rather than specific compounds, whereas modern drugs often benefit from multiple patents covering structure, formulation, or use, enabling extended market exclusivity beyond initial compounds.
Q3: Did the ‘179 patent face significant legal challenges?
A: Yes. The patent was challenged in reexamination processes and litigation, but its claims were upheld until expiry, affirming the validity of Pfizer’s early kinase inhibitor innovations.
Q4: What future potential do derivatives of compounds in the ‘179 patent have?
A: They could still be protected under newer patents, especially those claiming specific uses, formulations, or improved structures, facilitating new drug development opportunities.
Q5: How does this patent influence current kinase inhibitor research?
A: It provided foundational knowledge and intellectual property rights that guided subsequent research, enabling advances in targeted therapies for cancers driven by tyrosine kinase dysregulation.
References
- U.S. Patent 4,918,179 (Pfizer Inc., April 10, 1990).
- Prior art references including US 4,814,465; US 4,927,773.
- Market data from WHO and FDA drug approvals.
- Legal case documentation involving patent disputes.
- Scientific literature on kinase inhibitors and targeted cancer therapy.
This comprehensive analysis offers insight into the patent's scope, strategic relevance, and evolution within the kinase inhibitor landscape—valuable for legal, R&D, and business decision-makers.
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