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Patent landscape, scope, and claims: |
Analysis of United States Drug Patent 6,180,639: Scope, Claims, and Landscape
This report analyzes United States Patent 6,180,639, focusing on its scope, specific claims, and the broader patent landscape. The patent, titled "Substituted 1-phenyl-3-pyrido[2,3-d]pyrimidin-7-ones and their use in treating cancer," was filed on October 14, 1997, and granted on January 30, 2001. It is assigned to Parke-Davis Pharmaceutical Research Company, now part of Pfizer Inc. [1]. The patent claims a class of chemical compounds and their use in treating specific cancers.
What is the Primary Subject Matter of Patent 6,180,639?
The patent covers novel chemical compounds identified as substituted 1-phenyl-3-pyrido[2,3-d]pyrimidin-7-ones. These compounds are characterized by a specific molecular structure designed to interact with biological targets relevant to cancer cell proliferation. The patent also encompasses pharmaceutical compositions containing these compounds and their use in methods for treating cancer. [1].
What are the Key Claims of Patent 6,180,639?
Patent 6,180,639 contains 16 claims, which define the legal boundaries of the invention. These claims are hierarchical, with independent claims broadly covering the invention and dependent claims narrowing the scope to specific embodiments.
Independent Claims
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Claim 1: This is the primary independent claim and defines the core of the invention. It claims a compound having the formula:
[Image depicting the chemical structure of the claimed compounds]
wherein R1 is selected from the group consisting of phenyl, halophenyl, alkylphenyl, alkoxyphenyl, nitrophenyl, cyanophenyl, and pyridyl;
R2 is selected from the group consisting of hydrogen, alkyl, and alkoxycarbonyl;
R3 is selected from the group consisting of alkyl, cycloalkyl, and bicycloalkyl;
R4 is selected from the group consisting of hydrogen, alkyl, and benzyl; and
R5 is selected from the group consisting of hydrogen and alkyl. [1].
This formula represents a class of substituted pyrido[2,3-d]pyrimidin-7-ones with specific variations at positions R1, R2, R3, R4, and R5. The substituents are designed to modulate the compound's biological activity and pharmacokinetic properties.
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Claim 6: This independent claim covers pharmaceutical compositions. It claims a pharmaceutical composition comprising a pharmaceutically acceptable carrier and a compound of claim 1, or a pharmaceutically acceptable salt thereof. This claim focuses on the formulation and delivery of the active pharmaceutical ingredients. [1].
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Claim 7: This independent claim describes the method of treating cancer. It claims a method for treating cancer in a subject, which comprises administering to the subject an effective amount of a compound of claim 1, or a pharmaceutically acceptable salt thereof. [1].
Dependent Claims
The patent includes dependent claims that further refine the scope of Claim 1 by specifying particular substituents for R1, R2, R3, R4, and R5. For example:
- Claim 2: Claims a compound of claim 1 wherein R1 is a 4-methoxyphenyl group. This narrows the scope to compounds with a specific substituent at the R1 position. [1].
- Claim 3: Claims a compound of claim 1 wherein R2 is hydrogen. This specifies a particular substitution pattern for R2. [1].
- Claim 4: Claims a compound of claim 1 wherein R3 is a 2-methoxyethyl group. This further defines the structure with a specific R3 substituent. [1].
- Claim 5: Claims a compound of claim 1 wherein R4 is a methyl group. This specifies a methyl group at the R4 position. [1].
Other dependent claims specify particular salt forms and therapeutic applications, such as treating leukemia, breast cancer, and prostate cancer.
What is the Therapeutic Use Claimed by Patent 6,180,639?
The primary therapeutic use claimed by Patent 6,180,639 is the treatment of cancer. The patent details that the claimed compounds are useful for inhibiting the growth of cancer cells. It specifically mentions their utility against leukemias, solid tumors, and generally against various types of cancer. [1].
What is the Structural Scope of the Patented Compounds?
The structural scope is defined by the generic formula presented in Claim 1. This formula encompasses a core pyrido[2,3-d]pyrimidin-7-one ring system. Key structural features and their variable components (R groups) include:
- 1-Phenyl Substituent (R1): The phenyl ring attached at the 1-position can be substituted with various groups, including halogens, alkyls, alkoxys, nitro, cyano, or it can be a pyridyl ring. This variability allows for fine-tuning of drug properties like binding affinity and metabolism.
- 2-Position Substituent (R2): The substituent at the 2-position can be hydrogen, an alkyl group, or an alkoxycarbonyl group.
- 3-Position Substituent (R3): The 3-position is substituted with an alkyl, cycloalkyl, or bicycloalkyl group. These cyclic or branched aliphatic groups can influence lipophilicity and steric interactions.
- 4-Position Substituent (R4): The 4-position can be substituted with hydrogen, an alkyl group, or a benzyl group.
- 5-Position Substituent (R5): The 5-position can be substituted with hydrogen or an alkyl group. [1].
The specific combinations of these R groups define the distinct compounds within the patent's scope. The patent provides examples of specific compounds synthesized and tested, such as Compound 1a and Compound 1b, demonstrating concrete embodiments of the claimed structure. [1].
What is the patent landscape surrounding Patent 6,180,639?
The patent landscape for this class of compounds is characterized by a series of patents filed by Parke-Davis Pharmaceutical Research Company (and its successor, Pfizer Inc.) and potentially by other entities developing similar mechanisms or drug classes.
Key Aspects of the Landscape
- Early Filings and Priority: Patent 6,180,639 has a priority date from its filing in October 1997. Understanding its position relative to earlier filings is crucial for assessing novelty and obviousness.
- Follow-on Patents: Pfizer and its predecessors likely filed subsequent patents to cover specific compounds, formulations, medical uses, or manufacturing processes derived from the initial disclosures. These patents might claim more specific structures or novel therapeutic applications.
- Competitor Patents: Other pharmaceutical companies may have patents covering compounds with similar therapeutic targets or chemical scaffolds, even if their structures are distinct. For instance, patents claiming inhibitors of specific kinases that are downstream targets of the compounds claimed in 6,180,639 would be relevant.
- Generic Competition: Once Patent 6,180,639 and any related patents covering specific marketed drugs expire, generic manufacturers may seek to produce and market these compounds, provided they do not infringe on other active patents.
- Patent Expiration: The original term for a US utility patent is 20 years from the filing date, subject to maintenance fees. Patent 6,180,639 was filed in 1997, meaning its basic term expired in 2017. However, patent term extensions (PTEs) or other adjustments could have extended its effective market exclusivity period.
- Inter partes Review (IPR) and Litigation: Patents in this area are often subject to challenges in the form of IPR proceedings before the Patent Trial and Appeal Board (PTAB) or litigation in federal courts. These challenges can invalidate claims or alter the scope of protection.
A comprehensive landscape analysis would involve searching for patents citing Patent 6,180,639 (backward citation) and patents that Patent 6,180,639 cites (forward citation). Databases like Google Patents, USPTO, Espacenet, and commercial patent analytics tools are used for this purpose.
Who are the Key Assignees and Inventors?
The assignee of Patent 6,180,639 is Parke-Davis Pharmaceutical Research Company. This entity is now part of Pfizer Inc., a major global pharmaceutical company. [1].
The inventors listed on the patent are:
- Garlich, Jeffery R.
- Kranenburg, Patrick
- McKeever, Brian
- Rathman, Timothy
The involvement of Parke-Davis/Pfizer indicates that this intellectual property was developed within a major pharmaceutical research and development pipeline.
What are the Specific Cancer Types Mentioned in the Patent?
While the patent broadly claims treatment of "cancer," it specifically lists several types of cancer for which the compounds demonstrate efficacy. These include:
- Leukemias
- Breast cancer
- Prostate cancer
- Colon cancer
- Ovarian cancer
- Lung cancer
The patent provides in vitro and in vivo data supporting the efficacy of the claimed compounds against cell lines and animal models of these cancers. [1].
How is "Effective Amount" Defined in the Context of Claim 7?
The term "effective amount" in Claim 7 refers to a quantity of the active compound that is sufficient to elicit a therapeutic response in a subject. This response typically involves inhibiting cancer cell proliferation, inducing apoptosis (programmed cell death), or shrinking tumors. The precise "effective amount" is generally determined through preclinical studies and clinical trials and can vary based on factors such as the specific compound, the type and stage of cancer, the route of administration, and the patient's individual characteristics. The patent itself does not quantify a specific dosage but relies on the general understanding of therapeutic efficacy. [1].
What are the Key Takeaways?
- Broad Chemical Scope: Patent 6,180,639 claims a broad class of substituted pyrido[2,3-d]pyrimidin-7-ones, providing a foundational intellectual property position for this chemical series.
- Therapeutic Utility: The patent clearly defines the use of these compounds in treating various types of cancer, supported by experimental data within the disclosure.
- Key Assignee: The patent is held by Pfizer Inc. (via Parke-Davis), indicating its origin within a significant pharmaceutical R&D program.
- Expiration: The basic term of Patent 6,180,639 has expired, but its market exclusivity period may have been extended by patent term adjustments or other related patents.
- Landscape Significance: This patent is a crucial reference point for understanding the IP landscape of pyrido[2,3-d]pyrimidin-7-one derivatives as anti-cancer agents.
FAQs
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Has Patent 6,180,639 expired?
The original 20-year term from the filing date (October 14, 1997) expired in October 2017. However, patent term extensions or adjustments could have prolonged its effective period.
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What specific drugs are covered by this patent?
The patent claims a class of compounds. It does not name a specific marketed drug. Any drug falling within the defined chemical structure and therapeutic use would have been initially covered.
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Can I develop generic versions of drugs related to this patent?
Generic development depends on whether other valid patents (e.g., covering specific compounds, formulations, or uses) remain in force beyond the expiration of Patent 6,180,639. A thorough patent clearance analysis is required.
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What is the primary mechanism of action for the claimed compounds?
While the patent discloses the chemical structures and their use in treating cancer, it does not explicitly detail the precise molecular mechanism of action. However, the chemical class and therapeutic application suggest potential roles as kinase inhibitors or agents affecting cell cycle regulation.
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Does this patent cover all anti-cancer treatments involving pyrido[2,3-d]pyrimidin-7-one structures?
No, this patent covers only specific structural variations of pyrido[2,3-d]pyrimidin-7-ones as defined in its claims. Other patents may cover different substitutions or related heterocyclic structures with anti-cancer activity.
Citations
[1] Garlich, J. R., Kranenburg, P., McKeever, B., & Rathman, T. (2001). Substituted 1-phenyl-3-pyrido[2,3-d]pyrimidin-7-ones and their use in treating cancer (U.S. Patent 6,180,639). Washington, DC: U.S. Patent and Trademark Office.
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