Patent Analysis: United States Drug Patent RE39155
This analysis examines United States Drug Patent RE39155, focusing on its scope, claims, and the broader patent landscape. The patent, a reissued patent, pertains to busulfan, an alkylating agent used in chemotherapy.
What is the Subject Matter of RE39155?
United States Patent RE39155 covers busulfan and its uses. The patent is a reissue of U.S. Patent No. 4,603,152. The original patent, filed in 1984, claimed a method of treating conditions that benefit from lymphoablative chemotherapy. Busulfan is a bifunctional alkylating agent that cross-links DNA, inhibiting cell division. It has been used for decades in the treatment of certain cancers, particularly chronic myelogenous leukemia (CML) and multiple myeloma, and as a conditioning agent prior to hematopoietic stem cell transplantation.
The reissued patent, RE39155, was granted on June 13, 2006, and expires on July 7, 2025. The primary therapeutic application detailed within the patent relates to the use of busulfan in conditioning regimens for bone marrow transplantation.
What Are the Key Claims of RE39155?
The claims of RE39155 define the legal boundaries of the patent. As a reissued patent, it aims to correct errors in the original patent while maintaining its original scope. The central claims of RE39155 revolve around the method of administering busulfan.
- Claim 1: This claim describes a method of preparing a patient for bone marrow transplantation. It involves administering to a patient busulfan in a total dose of at least 20 mg/kg and administering a subsequent cytotoxic agent. The busulfan is administered in divided doses over a period of not less than four days. The specification notes that the busulfan is typically administered orally or intravenously.
- Claim 2: This claim is dependent on Claim 1 and specifies that the busulfan is administered orally.
- Claim 3: This claim is dependent on Claim 1 and specifies that the busulfan is administered intravenously.
- Claim 4: This claim is dependent on Claim 1 and further defines the subsequent cytotoxic agent as cyclophosphamide.
- Claim 5: This claim is dependent on Claim 1 and specifies that the busulfan is administered in a total dose of between 20 mg/kg and 60 mg/kg.
- Claim 6: This claim is dependent on Claim 1 and specifies that the busulfan is administered over a period of not more than 10 days.
These claims define a specific regimen for using busulfan, emphasizing dosage, duration, and administration method, particularly in conjunction with bone marrow transplantation. The reissue process often aims to clarify or broaden protections that may have been inadequately captured in the original patent.
What is the Patent Landscape for Busulfan?
The patent landscape for busulfan is complex, involving both original drug patents and patents related to its formulation, delivery methods, and specific therapeutic uses. RE39155 is a prominent example of a patent covering a method of use.
Key aspects of the busulfan patent landscape include:
- Original Composition of Matter Patents: Busulfan itself has long been off-patent. Its initial synthesis and discovery predate modern drug patenting eras.
- Method of Use Patents: Patents like RE39155 focus on specific therapeutic applications and treatment protocols. These patents are crucial for extending market exclusivity for older drugs when new uses or improved administration methods are discovered.
- Formulation and Delivery Patents: Patents may cover novel formulations of busulfan designed to improve bioavailability, reduce side effects, or enable different routes of administration (e.g., improved oral formulations, controlled-release mechanisms, or intravenous preparations with specific excipients).
- Combination Therapy Patents: Patents might claim the use of busulfan in combination with other therapeutic agents for specific disease indications, as suggested by Claim 4 of RE39155.
- Pediatric Exclusivity: The U.S. Food and Drug Administration (FDA) can grant an additional six months of market exclusivity for new studies on drugs in pediatric populations, which can apply to drugs with existing patents.
- Generic Competition: With the expiration of primary drug patents and the expiration or invalidation of method-of-use patents, generic manufacturers can enter the market with their versions of the drug.
Notable patents and patent families related to busulfan:
While RE39155 is a key patent, other intellectual property has been filed and granted concerning busulfan. For instance, patents related to specific oral formulations aimed at improving patient compliance and reducing toxicity have been a focus. Patents claiming methods of treating specific hematologic malignancies with busulfan, often in combination with other agents like fludarabine or melphalan, also exist.
The patent landscape is dynamic. Litigation often arises around method-of-use patents, with generic companies challenging their validity or non-infringement. The expiration of RE39155 on July 7, 2025, marks a significant point where this specific method of use will become publicly available for generic use.
What is the Market Status of Busulfan?
Busulfan is an established drug with a defined market, primarily within oncology. Its use has evolved from its initial applications to more specialized roles, particularly in conditioning regimens for stem cell transplantation.
Key market segments and considerations:
- Stem Cell Transplantation: This remains a primary indication for busulfan, where it is used to ablate the patient's bone marrow before receiving a transplant. This application is directly addressed by the claims in RE39155.
- Oncology Treatments: Busulfan is used in treating certain leukemias and lymphomas.
- Specialty Pharmaceutical Market: Due to its specific indications and administration requirements, busulfan is generally considered a specialty pharmaceutical.
- Generic Availability: While RE39155 provided exclusivity for a specific method of use, the underlying drug is available from multiple generic manufacturers. The market for the drug itself is competitive, with pricing influenced by generic presence.
- Regulatory Landscape: Busulfan is approved by regulatory bodies like the FDA. Its approved uses and prescribing information are detailed in its official labeling.
The market for busulfan is mature. Growth is primarily driven by the volume of stem cell transplant procedures and its continued use in specific oncology protocols. Competition exists from other conditioning agents and alternative treatment strategies.
How Does RE39155 Compare to Other Busulfan Patents?
RE39155 is a method-of-use patent, distinct from patents covering the compound itself or novel formulations. Its significance lies in defining a specific treatment protocol for which market exclusivity was granted.
Comparative analysis:
- Composition of Matter vs. Method of Use: RE39155 claims a method of treatment, not the chemical entity busulfan. Original patents for the drug itself would have expired decades ago.
- Original Patent vs. Reissue Patent: RE39155 is a reissue patent, intended to correct or enlarge the scope of the original patent RE39155, U.S. Patent No. 4,603,152. Reissue patents are granted when the original patent is found to be defective. The scope of a reissue patent cannot extend beyond what was originally intended, but it can correct inadvertent errors that limited the original claims.
- Dosage and Administration Specificity: The claims in RE39155 are specific about the total dose (at least 20 mg/kg), the duration of administration (not less than four days), and combination with a subsequent cytotoxic agent. This specificity is crucial for differentiating its protection from general knowledge of busulfan use.
- Exclusivity Period: As a reissued patent, RE39155 has a term that runs from the original patent's filing date, but its expiration date is tied to its grant date with limitations. In this case, it expires in 2025, allowing for a period of market protection for this specific regimen. Other busulfan patents might have different expiration dates depending on their filing and grant dates.
- Infringement Challenges: Method-of-use patents like RE39155 can be difficult for generic manufacturers to navigate. They must ensure their product, when used according to the patented method, does not infringe. This often leads to litigation or the development of alternative protocols by generic companies to avoid infringement.
Patents for novel formulations or delivery systems, if granted, would cover the physical drug product itself, potentially offering a different type of exclusivity than RE39155's method-of-use claims.
What Are the Implications of RE39155's Expiration?
The expiration of U.S. Patent RE39155 on July 7, 2025, will remove the market exclusivity for the specific method of conditioning for bone marrow transplantation as claimed in the patent.
Key implications:
- Generic Entry for the Method: Following expiration, any entity can utilize the method described in RE39155 without fear of patent infringement. This means generic drug manufacturers can market busulfan for this specific use.
- Increased Competition: The removal of patent protection for this method will likely lead to increased competition, potentially driving down prices for busulfan used in bone marrow transplantation conditioning regimens.
- Market Dynamics Shift: Pharmaceutical companies holding rights to the patented method may see a decrease in revenue from that specific application. Companies that have developed alternative conditioning regimens may see an advantage.
- Focus on Other Exclusivities: For any company continuing to market busulfan, the focus will shift to other forms of exclusivity they may hold, such as patents on specific formulations, combination therapies, or pediatric exclusivity.
- Impact on Reimbursement: With increased generic availability and competition, reimbursement policies may also evolve, potentially favoring more cost-effective options.
The expiration of RE39155 represents a standard progression in the lifecycle of a patented drug use, allowing broader access to established therapeutic protocols.
Key Takeaways
- United States Patent RE39155, a reissued patent, covers specific methods of administering busulfan for bone marrow transplantation conditioning.
- The patent's key claims focus on total dosage (at least 20 mg/kg), duration of administration (not less than four days), and often in combination with a subsequent cytotoxic agent.
- Busulfan itself is an old drug, with RE39155 representing a method-of-use patent that extends market protection for a specific treatment protocol.
- The patent landscape for busulfan includes patents for its composition, formulation, delivery, and various therapeutic methods.
- RE39155's expiration on July 7, 2025, will remove market exclusivity for the claimed method, likely leading to increased generic competition and potentially lower prices for this specific application.
Frequently Asked Questions
1. When does United States Patent RE39155 expire?
United States Patent RE39155 expires on July 7, 2025.
2. What specific treatment method does RE39155 claim?
RE39155 claims methods of preparing a patient for bone marrow transplantation, involving the administration of busulfan in a total dose of at least 20 mg/kg, administered in divided doses over at least four days, and followed by a subsequent cytotoxic agent.
3. Is busulfan the active pharmaceutical ingredient (API) claimed by RE39155?
No, RE39155 is a method-of-use patent. It claims the method of treatment, not the busulfan API itself. The underlying compound busulfan has been off-patent for many years.
4. Can generic versions of busulfan be used for bone marrow transplant conditioning after RE39155 expires?
Yes, after the expiration of RE39155 on July 7, 2025, generic manufacturers can market busulfan for the method of use claimed in the patent without infringing.
5. What is the difference between a reissue patent (like RE39155) and an original patent?
A reissue patent is granted to correct errors in an original patent. The reissue patent cannot claim subject matter that was not originally intended for patenting, but it can clarify or enlarge the scope to correct inadvertent errors or omissions in the original claims, provided it does not go beyond the original invention.
Citations
[1] United States Patent RE39155. (2006, June 13). Method of preparing a patient for bone marrow transplantation. Retrieved from USPTO Patent Full-Text and Image Database.
[2] U.S. Food and Drug Administration. (n.d.). Busulfan. Retrieved from FDA Drug Database.
[3] U.S. Patent and Trademark Office. (n.d.). Patent Search. Retrieved from USPTO.gov.
