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Patent landscape, scope, and claims: |
United States Patent 8,461,169 (US8461169): Scope, Claim Strength, and C-kit/C-fms Kinase Method-of-Use Landscape
US 8,461,169 is a US method-of-treatment patent that claims dosing of a defined small-molecule chemical class (Formula III compounds and salts/prodrugs/tautomers/stereoisomers) to treat diseases “mediated by an increase in c-kit and/or c-fms kinase activity.” The practical scope is broad on disease identification and broad on chemistry variability inside Formula III. It is narrow on the core requirement: infringement requires use of Formula III compounds (as claimed), not merely any c-KIT/c-FMS kinase inhibitor.
What does US 8,461,169 claim for treating diseases mediated by c-kit and c-fms activity?
Direct answer: It claims a method of treating a subject by administering an “effective amount” of a Formula III compound (or salt/prodrug/tautomer/stereoisomer) where the condition is mediated by increased c-KIT and/or c-FMS kinase activity.
Core infringement trigger
- Treatment endpoint: disease or condition mediated by increased c-KIT and/or c-FMS kinase activity.
- Actus reus: administration of an “effective amount.”
- Molecular requirement: administered compound must fall within Formula III definition:
- L4 is —CH2— or —C(O)—
- R81 is a capped list: hydrogen, —CN, fluoro, chloro, lower alkyl, fluoro-substituted lower alkyl, lower alkoxy, fluoro-substituted lower alkoxy
- R82 is hydrogen
- R83 is nitrogen-containing heteroaryl with optional substitutions
- R41 is lower alkyl or cycloalkyl (with optional fluoro substitution)
Claim construction pressure points
Because this is a method-of-use claim with a heavy chemical prerequisite, infringement analyses hinge on:
- Whether the accused product is literally (or under DOE) within the Formula III limitations.
- Whether the alleged use qualifies as treating a disease “mediated by” increased c-KIT and/or c-FMS activity. This is often litigated through label indications, scientific literature, biomarkers, and therapeutic rationales.
How broad is the chemical scope of US 8,461,169’s Formula III definition?
Direct answer: Formula III is moderately-to-broadly permissive on substituent types (R81 and R83) but tightly bound to a specific scaffold and linker logic (L4 and fixed R82).
Substitution breadth
- R81 (variable): includes typical medicinal chemistry options (H, CN, F, Cl, lower alkyl, fluoro-lower alkyl, lower alkoxy, fluoro-lower alkoxy).
- R83 (variable): nitrogen-containing heteroaryl with optional 1–2 substituents chosen from halogens, lower alkyl/fluoro-lower alkyl, cycloalkylamino, NHR41/NR41R41, OR41, and sulfonamide-like fragments —S(O)2R41.
- R41 (variable at each occurrence): lower alkyl or cycloalkyl with possible fluoro substitution.
L4 gate
- L4 is restricted to —CH2— or —C(O)—. This is a structural narrowing element; it prevents substitution outside those linker classes.
R82 lock-in
- R82 = hydrogen reduces the number of potential scaffold variants relative to a fully generic kinase-inhibitor claim.
What compounds are explicitly covered in US 8,461,169 (claim 2 and dependent examples)?
Direct answer: Claim 2 provides a long, enumerated set of Formula III embodiments. Claims 3–19 further narrow to specific named compounds (individual examples), each “or a pharmaceutically acceptable salt thereof.”
Enumerated compounds (claim 2)
The claim text enumerates a large set of specific structures, all tied to the same core scaffold with variable heteroaryl substituents. Examples include:
- Pyridinylmethyl–pyrrolopyridinyl–pyridinyl amines (multiple positional isomers)
- Methoxy- and fluoro-substituted pyridylmethyl analogs
- Chloro-substituted analogs
- Morpholine substituted analogs
- Pyrazine- and nicotinamide-related analogs
- Benzoimidazole- or imidazole-methyl analogs
- Carbonitrile-containing heteroaryl variants (pyrrolo[2,3-b]pyridine-5-carbonitrile pattern appears in multiple dependent claims)
- Trifluoromethyl and trifluoroethoxy pyridinylmethyl analogs
- Various substituted amide forms (e.g., pyrazole carboxylic acid amide; isonicotinamide carboxamide analogs)
Specific “picked species” covered by dependent claims
The patent then isolates multiple specific embodiments as separate dependent claim fallbacks, including (as provided in your text):
- Claim 3: pyridine-2-carboxylic acid [5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethyl)-pyridin-2-yl]-amide (salt form included)
- Claim 4: 5-methyl-pyrazine-2-carboxylic acid [5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethyl)-pyridin-2-yl]-amide
- Claim 5–6: two specific trifluoromethyl pyridinylmethyl variants
- Claim 7: 1-methyl-1H-benzimidazol-2-ylmethyl analog
- Claim 8–9: 6-methoxy and 5-methoxy pyridinylmethyl variants
- Claim 10: 3-fluoro-pyridin-4-ylmethyl analog
- Claim 11–12: pyrrolo[2,3-b]pyridine-5-carbonitrile analogs bearing specific anilide-type amino link patterns to substituted pyridines
- Claim 13–14: additional chloro and methoxy carbonitrile-linked patterns
- Claim 15–17: methoxy and chloro + fluoro variants
- Claim 18: trifluoroethoxy variant
- Claim 19: pyrimidin-5-ylmethyl analog
Impact: This pattern of broad independent coverage (Formula III) plus “picked species” dependent claims typically strengthens enforcement by giving multiple claim pathways if an accused product is near the border of literal definition.
What diseases and conditions are listed in US 8,461,169 (claim 20)?
Direct answer: Claim 20 lists an extensive, heterogeneous set of diseases. The key legal element is not the list itself but the recited requirement that the condition is “mediated by an increase in c-KIT and/or c-FMS kinase activity.”
Examples of the enumerated diseases
From the provided claim text, the list includes:
- Oncology and hematologic malignancies: mast cell tumors, small cell lung cancer, testicular cancer, gastrointestinal stromal tumors (GIST), glioblastoma, astrocytoma, neuroblastoma, colorectal carcinoma, multiple myeloma, mastocytosis, melanoma, breast cancer, ovarian cancer, prostate cancer, acute myeloid leukemia, acute lymphocytic leukemia, chronic myelogenous leukemia, and multiple others
- Immune-inflammatory and autoimmune: rheumatoid arthritis, allergic rhinitis, asthma, inflammatory bowel syndrome, transplant rejection, systemic lupus erythematosis, ulcerative colitis, Crohn’s disease, lupus nephritis, Kawasaki’s disease, inflammatory pain, chronic pain
- Cardiometabolic and degenerative: atherosclerosis, type I/II diabetes, insulin resistance, hyperglycemia, obesity, osteoporosis/Paget’s disease, stroke, Alzheimer’s disease, Parkinson’s disease
- Renal and skeletal: glomerulonephritis, interstitial nephritis, tubular necrosis, diabetic nephropathy, hypercalcemia, osteomyelitis, peri-prosthetic or wear-debris-mediated osteolysis, bone pain
Enforcement effect: In litigation, a defendant may attack whether the accused use actually meets the c-KIT/c-FMS mediation rationale for the asserted indication. A long list helps plaintiffs argue that at least some uses for each therapeutic area fit within the claimed mediation theory.
How narrow are the “selected disease” dependent claims (claims 21–22)?
Direct answer: Claims 21–22 reduce the universe to a smaller set: cancer-related options including glioblastoma, systemic lupus erythematosis, lupus nephritis, breast cancer, and rheumatoid arthritis.
- Claim 21: “disease is a cancer, metastatic cancer, glioblastoma, systemic lupus erythematosis, Lupus nephritis, breast cancer or rheumatoid arthritis.”
- Claim 22: same disease set (for claim 2’s compound list dependency).
Why that matters
These dependent claims function as cleaner enforcement handles. They help plaintiffs avoid broader medical-necessity fights over the full claim 20 universe by anchoring infringement to a narrower, preselected disease subset that is more likely to be supported by mechanistic evidence and clinical context.
What does US 8,461,169 cover on combination therapy with chemotherapeutic agents (claims 23–32)?
Direct answer: It includes method claims where the compound is co-administered with one or more chemotherapeutic agents, including specified classes such as taxanes and other drug-type categories.
Timing and regimen
- Claim 23–26: compound and agents can be administered simultaneously, separately, or sequentially.
Chemotherapeutic agent categories (claims 27–28)
Includes:
- alkylating agents
- antibiotics
- hormone or hormone antagonists
- taxane
- antiangiogenic agents
- kinase inhibitors
- targeted signal transduction inhibitors
- biological response modifiers
- “other chemotherapeutics”
Taxane-specific dependent claims
- Claim 29–30: further comprises administering a taxane.
- Claim 31–32: further comprises administering paclitaxel or DHA-paclitaxel.
Enforcement effect: Combination-specific dependent claims can matter where the accused regimen uses taxanes (including paclitaxel/DHA-paclitaxel). That creates an additional infringement pathway even if some monotherapy arguments are contested.
What is the patent estate’s likely strength pattern given the claim structure?
Direct answer: US 8,461,169’s strength is anchored in a standard medicinal-chemistry approach: broad generic definition (Formula III) plus numerous specific species and indication breadth.
Strength drivers
- Tight chemistry predicate: infringement depends on using compounds within Formula III. If an accused product is outside that chemical envelope, method claims fail.
- Redundant claim fallbacks: independent method claim (claim 1) plus extensive dependent claim species (claims 2–19) provide multiple ways to map accused compounds.
- Combination support: taxane and paclitaxel/DHA-paclitaxel dependent claims give plaintiffs leverage for combination regimens.
Strength vulnerabilities
- Mediation requirement: “mediated by an increase in c-KIT and/or c-FMS kinase activity” can become a factual dispute per indication, especially where the clinical rationale is not explicitly mechanistic or where c-KIT/c-FMS is not central to disease pathology for the specific use.
How does this claim set typically interact with FDA labeling and Paragraph IV generic risk?
Direct answer: The patent is a method-of-treatment claim, so FDA regulatory exposure depends heavily on how an ANDA/505(b)(2) applicant’s proposed labeling matches the claimed method.
Practical FDA/Orange Book mapping logic for method-of-use patents
- If the Orange Book lists US 8,461,169 for a drug’s approved indications, applicants must consider:
- whether the generic’s proposed indications include the claimed disease descriptions, and
- whether dosing instructions could be read as “effective amount” administration for c-KIT/c-FMS mediated disease.
Risk concentration
- Highest risk generally arises when:
- the originator’s label includes cancer indications plausibly linked to c-KIT/c-FMS activity, and
- the generic’s carve-outs do not remove those indication statements.
- Combination risk increases where a generic label would support co-administration with taxanes or paclitaxel/DHA-paclitaxel.
Which generic entry scenarios are most threatened by US 8,461,169’s claim scope?
Direct answer: Scenarios involving marketing of a product containing an accused Formula III compound for cancer or inflammatory indications that align with claims 20–22, including combination use with taxanes.
Most exposed scenarios
- Monotherapy for cancer/metastatic cancer, glioblastoma, lupus nephritis, breast cancer, rheumatoid arthritis.
- Combination therapy including taxane regimens, especially paclitaxel or DHA-paclitaxel.
Lower risk scenarios
- Use restricted to indications not argued to involve c-KIT/c-FMS mediation.
- Regimens excluding taxane co-administration if the Orange Book listing or FDA label carve-outs track those dependent claims.
- Chemical-structure avoidance: any product not practicing the Formula III claim definition.
What patent landscape questions are answered by US 8,461,169’s claim language?
Direct answer: It answers “how” the invention is claimed: method-of-treatment using a Formula III chemical class for c-KIT/c-FMS mediated disease. It does not, by itself, define product manufacturing, dosing regimens, or formulation forms.
Not claimed (based on the provided claim text)
- specific formulation dosage forms (tablets, capsules, IV infusion)
- specific dosing amount schedules (beyond “effective amount”)
- manufacturing methods
- PK/PD biomarkers as explicit limitations
Implication: enforcement tends to target “use” rather than “how it is made” or “how it is formulated.”
Key Takeaways
- US 8,461,169 claims a method of treating c-KIT and/or c-FMS mediated diseases by administering Formula III compounds (and salts/prodrugs/tautomers/stereoisomers).
- The independent claim is broad on disease scope (claim 20) and moderate-to-broad on substituent chemistry within Formula III (R81/R83/R41), but strict on the scaffold and L4/R82 constraints.
- Dependent claims add enforcement redundancy through:
- extensive enumerated compound species (claim 2),
- multiple picked species (claims 3–19),
- tighter disease subsets (claims 21–22),
- and combination therapy with taxanes including paclitaxel/DHA-paclitaxel (claims 29–32).
- Generic entry risk is highest where the accused ANDA/505(b)(2) product uses a Formula III compound and the proposed labeling includes claimed c-KIT/c-FMS mediated indications, including taxane-based combination uses.
FAQs
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What makes US 8,461,169 a “chemical-dependent” method patent?
It requires administration of a Formula III compound; infringement is contingent on practicing within the claimed chemical structure boundaries.
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Does the claims list of diseases itself create universal infringement?
No. The legal requirement remains that the method treats a disease “mediated by an increase in c-KIT and/or c-FMS kinase activity.”
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How do taxane and paclitaxel-dependent claims change enforcement leverage?
They create additional dependent infringements if the accused regimen includes taxanes and specifically paclitaxel or DHA-paclitaxel.
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Can a competitor avoid infringement by changing the substituents outside R81/R83/L4?
The claim definition gates on specific scaffold and substituent categories, so structural changes outside those defined limitations reduce literal coverage.
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What indication carve-outs are most relevant for method-of-use patents like this?
Carve-outs that remove label-supported use for the narrower cancer and inflammatory diseases in claims 21–22, and where relevant, taxane combination language aligned with claims 29–32.
References (APA)
No sources were cited in the provided input; none are included.
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