Overview of U.S. Patent 4,522,807
United States Patent 4,522,807 covers a method of inhibiting tumor growth using a class of compounds, specifically, a particular glucocorticoid derivative. Filed on September 28, 1983, granted on June 11, 1985, the patent claims a method for cancer treatment exploiting the anti-inflammatory and tumor-inhibitory properties of the specified compound.
Scope and Claims
Main Claims
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Method of Tumor Inhibition: The patent primarily claims the use of a corticosteroid derivative—specifically, a 6α-methylprednisolone compound—for inhibiting tumor growth in mammals. The claim explicitly states the administration of effective amounts of this compound for therapeutic purposes.
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Formulations and Dosage: The patent covers methods involving systemic administration, including oral, injectable, or topical forms. It specifies dosage ranges, generally between 0.1 mg/kg and 10 mg/kg, tailored to tumor type and patient physiology.
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Combination Therapy: Claims include the method of using the compound synergistically with other chemotherapeutic agents, expanding its scope to combination regimes.
Dependent Claims
Dependent claims specify particular formulations, such as pharmaceutically acceptable salts of the compound, as well as specific tumor types, including certain carcinomas, sarcomas, and lymphomas.
Legal and Technical Scope
- The claims focus on therapeutic application rather than the compound's synthesis.
- The scope extends to any pharmaceutical preparation containing the compound, not just the pure substance.
- Claims are limited to tumor types explicitly mentioned or implied through the drug's anti-inflammatory properties, mainly carcinomas and lymphomas.
Claim Construction and Limitations
- The use of "effective amount" introduces variability, allowing broad interpretation based on tumor type and patient response.
- The patent does not delineate specific molecular pathways but relies on the compound's general corticosteroid activity to infer anti-tumor effects.
- The scope may be challenged based on prior art related to corticosteroids’ anti-inflammatory and anti-tumor activities cited in literature before 1983.
Patent Landscape Analysis
Historical Context
- The patent was filed during a period of burgeoning research into corticosteroids' anti-cancer potential, following early findings of tumor growth suppression in preclinical models.
- It was granted during a time when the patent landscape for steroid-based anti-cancer agents was less congested, but key prior art on corticosteroids’ anti-inflammatory uses existed.
Major Patent Families & Related Patents
| Patent Number |
Title |
Filing Date |
Grant Date |
Assignee |
Key Claims |
| 4,522,807 |
Method of inhibiting tumor growth |
1983-09-28 |
1985-06-11 |
Upjohn Co. |
Use of methylprednisolone derivatives for tumor inhibition |
| 4,567,055 |
Corticosteroid compositions |
1984-09-05 |
1986-02-25 |
Upjohn Co. |
Pharmaceutical formulations of methylprednisolone derivatives |
| 4,720,519 |
Use of corticosteroids in cancer therapy |
1985-12-23 |
1988-01-26 |
University of California |
Application of corticosteroids with other anti-cancer agents |
Freedom to Operate and Infringement Risks
- The patent's reliance on known corticosteroid chemistry limits its novelty claims, but its specific therapeutic claims regarding tumor inhibition remain protected.
- Later patents citing or building upon 4,522,807 include those related to different corticosteroid derivatives, combination therapies, and delivery systems.
Legal Status and Expiry
- The patent expired on June 11, 2002, 17 years after its grant, adhering to pre-AIA patent term standards.
- Public domain status allows access for generic development.
Litigation and Challenges
- No significant litigation or invalidity challenges have been publicly documented.
- Its broad therapeutic claims have been cited as prior art in subsequent patent applications related to corticosteroid-based anti-tumor agents.
Summary of Key Points
- The patent claims a method of inhibiting tumor growth by administering specific corticosteroid derivatives, mainly methylprednisolone compounds.
- The scope is relatively broad, covering methods, formulations, and combination therapies across multiple tumor types.
- The patent landscape includes related filings that expand on corticosteroids' pharmaceutical uses and formulations.
- The patent is expired; therefore, the claims are now in the public domain, enabling R&D and commercialization without infringement concerns in the U.S.
Key Takeaways
- The patent's broad claims cover fundamental corticosteroid-based tumor inhibition methods, emphasizing the compound's therapeutic versatility.
- Its expiration opens opportunities for generic development and research.
- Further innovation may require overcoming existing prior art, particularly regarding specific molecular mechanisms.
- The existing patent landscape indicates a trend toward combining corticosteroids with other anti-cancer agents to improve efficacy.
- Legal challenges are minimal, but future patent filings should clarify distinctions from this foundational patent.
FAQs
1. Does U.S. Patent 4,522,807 cover all corticosteroid use for tumor inhibition?
No. It specifically covers methylprednisolone derivatives used in methods of tumor inhibition, not all corticosteroids or applications.
2. Can a company freely develop methylprednisolone-based anti-cancer drugs now?
Yes. The patent expired in 2002, placing the claims in the public domain.
3. What is the scope of the claims regarding tumor types?
The claims cover methods for treating any tumor that responds to corticosteroid therapy, explicitly including carcinomas, lymphomas, and sarcomas.
4. Are there existing patents that improve upon or expand these claims?
Yes. Various subsequent patents have explored corticosteroid formulations, combinations with chemotherapeutics, and delivery methods, expanding the patent landscape.
5. Could prior art limit future patent claims related to corticosteroid-based cancer therapy?
Yes. Prior art focusing on corticosteroids' anti-inflammatory and anti-tumor effects before 1983 could influence patentability of similar claims.
References
- U.S. Patent 4,522,807. "Method of inhibiting tumor growth." Filed September 28, 1983, granted June 11, 1985.
- Patent landscape reports on corticosteroids in oncology (e.g., WIPO and EPO patent databases).
- Scientific literature on corticosteroids’ anti-tumor activity available in PubMed and relevant patent citations.
[1] U.S. Patent and Trademark Office. "Public PAIR," https://portal.uspto.gov/pair.
[2] Espacenet Patent Search. European Patent Office, https://worldwide.espacenet.com.
