United States Patent 6,956,041: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
The United States Patent 6,956,041, titled "Crystalline 3-{4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate," is a significant patent in the pharmaceutical industry, particularly in the context of protein kinase inhibitors. This patent is associated with Pfizer's drug Xeljanz (tofacitinib), which is used to treat various autoimmune diseases.
Patent Overview
Publication and Assignment
The patent was issued on November 15, 2005, and is duly and legally assigned to Pfizer Inc. C.P. Pharmaceuticals International C.V. holds the exclusive license for this patent and has conveyed rights to Pfizer Pharmaceuticals LLC, among others[2].
Claim Scope
Compound Description
The patent describes a specific crystalline form of the compound 3-{4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate. This compound is an inhibitor of the enzyme protein kinases, including Janus Kinase 3 (JAK3)[2][4].
Structural Variations
The compounds covered by this patent can exist in various forms, including different enantiomeric and diastereomeric forms, as well as cis and trans configurations and mixtures thereof. They can also exist as tautomers and include all conformational isomers[1][4].
Substituents and Functional Groups
The patent specifies that the compounds can have various substituents such as alkyl, amino, halo, hydroxy, nitro, carboxy, and other functional groups. These groups can be linear, branched, or cyclic and may be optionally substituted by additional groups[1][4].
Pharmaceutical Applications
Protein Kinase Inhibition
The compounds described in the patent are inhibitors of protein kinases, which are enzymes involved in the regulation of various cellular processes. The inhibition of these enzymes is crucial in treating autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis[2][4].
Pharmaceutical Compositions and Methods of Treatment
The patent encompasses pharmaceutical compositions containing the described compounds and their prodrugs. It also covers methods of treating or preventing disorders that can be treated or prevented by the inhibition of protein kinases[1][4].
Patent Landscape and Litigation
Patent Expiration and Generic Challenges
The patent expired on December 8, 2020. However, the expiration of related patents, such as the '023 and RE'783 patents, extended the protection period for Xeljanz until December 8, 2025[2][5].
Litigation Against Generic Manufacturers
Pfizer has been involved in litigation against generic manufacturers, such as Zydus Pharmaceuticals, to protect the patent rights of Xeljanz. These lawsuits often involve claims of patent infringement related to the filing of Abbreviated New Drug Applications (ANDAs) by generic manufacturers[2].
Regulatory Aspects
FDA Approval and Bioequivalence
The FDA has approved several ANDAs for generic versions of tofacitinib, but these approvals are contingent upon the expiration of the relevant patents. For instance, Prinston Pharmaceutical, Inc.'s ANDA for tofacitinib tablets was approved with the condition that marketing would not commence until the expiration of the '041, '208, and '221 patents[5].
Importance of Claim Scope
Avoiding Overly Broad Claims
The scope of the claims in this patent is carefully defined to avoid the pitfalls of overly broad claims, which can be invalidated due to the abstract idea exception or failure to meet the written description requirement. This is a critical consideration in patent drafting to ensure the validity and enforceability of the patent[3].
Conclusion
The United States Patent 6,956,041 is a pivotal patent in the field of protein kinase inhibitors, specifically for the drug tofacitinib (Xeljanz). The patent's scope is meticulously defined to cover various structural forms and pharmaceutical applications, ensuring robust protection for Pfizer's intellectual property. The patent landscape and litigation history highlight the importance of patent protection in the pharmaceutical industry.
Key Takeaways
- The patent covers a specific crystalline form of a protein kinase inhibitor.
- The compound can exist in various enantiomeric, diastereomeric, and tautomeric forms.
- The patent includes pharmaceutical compositions and methods of treatment for autoimmune diseases.
- The patent expired on December 8, 2020, but related patents extended protection until December 8, 2025.
- Pfizer has engaged in litigation to protect the patent rights against generic manufacturers.
- The FDA has approved generic versions of tofacitinib contingent upon patent expiration.
FAQs
What is the primary compound described in the United States Patent 6,956,041?
The primary compound is 3-{4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate.
What is the therapeutic use of the compound described in the patent?
The compound is used as an inhibitor of protein kinases, specifically Janus Kinase 3 (JAK3), for treating autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis.
When did the United States Patent 6,956,041 expire?
The patent expired on December 8, 2020.
Why is the claim scope important in this patent?
The claim scope is important to avoid overly broad claims that could be invalidated due to the abstract idea exception or failure to meet the written description requirement.
What is the current status of generic versions of tofacitinib?
Generic versions of tofacitinib have been approved by the FDA, but their marketing was contingent upon the expiration of the relevant patents.
Cited Sources:
- US6956041B2 - Pyrrolo[2,3-d]pyrimidine compounds - Google Patents
- Case 1:20-cv-00300-UNA Document 1 Filed 02/28/20 Page 1 of 12 - Insight.RPXCorp
- The Importance of Getting the Claim Scope Right in a US Patent Application - Rimon Law
- US7091208B2 - Pyrrolo[2,3-D]pyrimidine compounds - Google Patents
- ANDA 209923 - accessdata.fda.gov - FDA.gov
