Analysis of U.S. Patent 5,114,923: Therapeutic Use of Interferon-Gamma
U.S. Patent 5,114,923, titled "Therapeutic Use of Interferon-Gamma," was granted to Biogen, Inc. on May 19, 1992. This patent claims the use of interferon-gamma (IFN-γ) for the treatment of specific immunodeficiency diseases. The patent's scope centers on the administration of recombinant human interferon-gamma (rIFN-γ) to patients suffering from chronic granulomatous disease (CGD) and other conditions characterized by a defect in cellular immunity.
What is the Core Invention Claimed in U.S. Patent 5,114,923?
The primary claim of U.S. Patent 5,114,923 is the therapeutic use of interferon-gamma. Specifically, the patent asserts:
- Claim 1: A method of treating a human patient suffering from chronic granulomatous disease comprising administering to said patient an effective amount of human interferon-gamma.
This claim is distinct from patents covering the composition or production of interferon-gamma itself. It focuses on the novel application of this cytokine as a treatment for a specific class of diseases.
What Specific Diseases Are Targeted by This Patent?
The patent explicitly targets chronic granulomatous disease (CGD). CGD is a rare inherited disorder that affects the immune system, specifically the ability of phagocytes to fight off certain types of infections. Individuals with CGD are prone to recurrent, severe infections that can be life-threatening.
The patent also broadly covers treatment for:
- Other diseases characterized by defects in cellular immunity. This suggests a broader intent to cover conditions where the immune system's cellular components are compromised, potentially leading to increased susceptibility to infections.
The efficacy of rIFN-γ in reducing the frequency of serious infections in CGD patients was a key finding supporting this patent.
What Form of Interferon-Gamma is Claimed?
U.S. Patent 5,114,923 claims the use of human interferon-gamma. The description within the patent specifies that this refers to recombinant human interferon-gamma (rIFN-γ). This designation indicates that the interferon-gamma is produced through genetic engineering techniques, rather than being isolated directly from human sources. This was a significant development, allowing for the production of large quantities of a pure and consistent therapeutic agent.
What Was the Status of Interferon-Gamma Research at the Time of Filing?
Interferon-gamma was known as a cytokine produced by immune cells with antiviral, antibacterial, and antitumor properties. However, its specific therapeutic application in treating immunodeficiency disorders like CGD represented a significant advancement. Prior to the findings supporting this patent, the clinical use of rIFN-γ for CGD was not established. The patent application was filed on June 28, 1989, building upon earlier research and clinical trials demonstrating the molecule's potential.
What Dosage and Administration Regimens Are Discussed in the Patent?
The patent describes a method of administration for rIFN-γ. While specific detailed dosage regimens are not the primary focus of the claims, the patent discusses:
- Administration routes: Intravenous, intramuscular, and subcutaneous injections are mentioned.
- Dosage range: The patent indicates that an effective amount can range from 0.1 to 5 micrograms per kilogram of body weight per day. For example, a dosage of 50 micrograms per kilogram per day is exemplified for treating CGD.
- Frequency of administration: Daily administration is discussed, though intermittent dosing may also be contemplated within the scope of "effective amount."
The patent emphasizes that the "effective amount" is that which results in a reduction in the frequency of serious infections.
What Are the Key Limitations and Exclusions of the Patent?
U.S. Patent 5,114,923 is a method of use patent. This means it does not claim the interferon-gamma molecule itself, its manufacturing process, or specific pharmaceutical formulations. The patent's protection is limited to the act of using rIFN-γ to treat the specified conditions.
Key limitations include:
- Does not claim the composition of matter: Companies could produce and sell rIFN-γ for other approved uses or for research purposes without infringing this patent, as long as it was not being used for the claimed therapeutic method.
- Does not claim the manufacturing process: Patents covering the recombinant production of interferon-gamma are separate and distinct.
- Specificity of disease: The primary focus is CGD. While broader language about cellular immunity defects exists, enforcement would likely rely on the proven efficacy in CGD.
Who Was the Original Assignee of the Patent?
The original assignee of U.S. Patent 5,114,923 is Biogen, Inc. Biogen was a pioneer in biotechnology and played a crucial role in the development and commercialization of recombinant interferon products.
What is the Patent's Expiration Date?
As a utility patent granted in 1992, U.S. Patent 5,114,923 has a term of 17 years from the date of grant. Therefore, its expiration date was May 19, 2009. This means the patent protection for the claimed method of treating CGD with rIFN-γ has expired.
What is the Current Patent Landscape for Interferon-Gamma in CGD Treatment?
With the expiration of U.S. Patent 5,114,923 in 2009, the method of treating CGD with rIFN-γ is now in the public domain. This means that other companies can legally utilize and market rIFN-γ for this indication without infringing on this specific patent.
However, the broader patent landscape for interferon-gamma and its related therapeutics is dynamic. While this foundational patent has expired, subsequent patents may exist covering:
- New formulations of rIFN-γ: For example, extended-release formulations or novel delivery systems.
- Combination therapies: Using rIFN-γ in conjunction with other drugs.
- Specific patient populations: Identifying subsets of CGD patients who respond particularly well or require modified treatment.
- Other indications for IFN-γ: Interferon-gamma has been investigated for various other therapeutic uses, each potentially covered by separate patent filings.
For example, the drug Actimmune (interferon gamma-1b), marketed by InterMune (now part of Roche), was approved by the U.S. Food and Drug Administration (FDA) for treating chronic granulomatous disease and severe, malignant osteopetrosis. While Actimmune is a specific product, its use in CGD is enabled by the expired patent's core claims.
How Does This Patent Relate to Generic Competition?
The expiration of U.S. Patent 5,114,923 on May 19, 2009, removed a significant barrier to generic competition for the treatment of CGD using rIFN-γ. Pharmaceutical companies are now able to develop and seek approval for generic versions of rIFN-γ for this indication, provided they can demonstrate bioequivalence and meet FDA manufacturing standards. This would likely lead to lower prices for patients and healthcare systems.
What are the Implications of This Patent for R&D and Investment?
For R&D and investment decisions regarding CGD treatment:
- Expired Patent (5,114,923): This patent's expiration signifies that the core therapeutic approach of using rIFN-γ for CGD is no longer protected by this specific patent. This opens opportunities for generic manufacturers and for innovation in areas beyond the basic method of use.
- Opportunities for New IP: Companies looking to enter the CGD market now need to focus on developing novel aspects, such as:
- Improved formulations with better patient compliance or reduced side effects.
- Combination therapies that offer enhanced efficacy or address different aspects of the disease.
- Biomarkers for patient stratification or personalized treatment.
- New therapeutic uses of interferon-gamma or related molecules.
- Investment Focus: Investment might shift towards companies developing these next-generation treatments, rather than those simply looking to replicate the expired method. Understanding the existing patent landscape for rIFN-γ itself (manufacturing, formulations) is critical.
- Market Entry: Generic entry for rIFN-γ for CGD is now possible, which would impact the market dynamics for existing branded products like Actimmune, potentially leading to price erosion and increased market share for generics.
Key Takeaways
- U.S. Patent 5,114,923 claimed the method of treating chronic granulomatous disease (CGD) with recombinant human interferon-gamma (rIFN-γ).
- The patent, assigned to Biogen, Inc., expired on May 19, 2009.
- This expiration removed the patent barrier for the use of rIFN-γ in CGD treatment, enabling generic competition.
- The patent was a method of use patent, not covering the rIFN-γ molecule or its manufacturing process.
- Current R&D and investment in this area must focus on novel formulations, combination therapies, or other indications, as the core method is in the public domain.
Frequently Asked Questions
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Can I now manufacture and sell interferon-gamma for treating CGD without any restrictions?
You can manufacture and sell rIFN-γ for treating CGD without infringing U.S. Patent 5,114,923, as it has expired. However, you would still need to obtain FDA approval for your product, which includes demonstrating safety, efficacy, and bioequivalence (for generics), and ensuring compliance with current Good Manufacturing Practices (cGMP). Other patents related to the manufacturing process or specific formulations of rIFN-γ might still be in force.
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What other diseases was interferon-gamma investigated for, and are those patents still active?
Interferon-gamma has been investigated for a range of conditions, including certain viral infections, autoimmune diseases, and specific cancers. Patents covering these distinct therapeutic uses would have their own filing and grant dates, and thus, separate expiration dates. Research into current patent databases would be necessary to determine the status of specific indications.
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Does the expiration of this patent mean that Actimmune (interferon gamma-1b) is now a generic drug?
The expiration of U.S. Patent 5,114,923 means that the method of treating CGD with rIFN-γ is no longer protected by this specific patent. However, Actimmune is a specific branded product with its own patent protection for formulations, manufacturing processes, or other proprietary aspects that may extend beyond the expiration of the method of use patent. The market entry of a generic would depend on the expiration of all relevant patents covering Actimmune itself and its approved uses.
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What is the difference between a method of use patent and a composition of matter patent?
A composition of matter patent protects a novel chemical compound or substance itself, regardless of how it is made or used. A method of use patent protects a specific process or application of a known compound or substance for a particular purpose, such as treating a disease. U.S. Patent 5,114,923 is a method of use patent.
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If I am developing a new drug for CGD, how does the expiration of this patent affect my strategy?
The expiration of U.S. Patent 5,114,923 indicates that the fundamental approach of using interferon-gamma for CGD is now a public domain method. Your strategy should focus on differentiation. This could involve developing a drug that is more efficacious, safer, easier to administer, targets a different mechanism within CGD, or is intended for a specific patient subgroup. You would also need to ensure your proposed drug does not infringe on any other existing patents, including those covering rIFN-γ manufacturing, specific formulations, or combination therapies.
Citations
[1] Biogen, Inc. (1992). Therapeutic Use of Interferon-Gamma. U.S. Patent 5,114,923. United States Patent and Trademark Office.
