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Patent landscape, scope, and claims: |
US Patent 7,378,423 Scope, Claim Breadth, and US Patent Estate for Formula [I] Compounds (and Specific N-phenyl acetamide/solvate Members)
US Drug Patent 7,378,423 is a broad, structure-claim patent centered on a Markush-style “compound of formula [I]” that spans wide substituent variability across multiple substituent positions (R1, R2, R3/R4/R5, R6) and multiple allowed ring systems (C3-12 carbocycles and heterocycles with 1–4 hetero atoms). The claims also expressly cover pharmaceutically acceptable salts, hydrates, and solvates, plus a pharmaceutical composition and combination compositions.
The claim set includes (i) a general Markush claim (claim 1) with extremely wide genus scope; (ii) dependent formula claims (claims 2 and 3) that further tether to narrower, enumerated embodiments of formula [I-1] and [I-3]; (iii) a cascade of dependent limitations that carve out specific preferred subgroups (e.g., R1 C1-6 alkyl; m=0; cyclopropyl; particular simplifications of R3/R4/R5 hydrogen); (iv) a direct, fully specified compound claim (claim 13) that anchors the protected genus to a specific molecule; and (v) multiple dependent solvate embodiments (claims 14–24) to protect crystal/solvate forms for that specific compound, plus (vi) pharmaceutical compositions (claims 25–26).
What claims define the scope of US Patent 7,378,423 and how broad is claim 1?
Claim 1: “A compound represented by formula [I] … or a pharmaceutically acceptable salt, hydrate, or solvate”
Claim 1 is a Markush genus claim built from:
- A core structural template “formula [I]”.
- Variable substituents at key positions: moiety, R1 and R6 (substituted alkyl/alkenyl or ring systems), R2 (substituted alkenyl or ring systems), and R3/R4/R5 (hydrogen, hydroxyl, alkyl/alkenyl, optionally substituted; also ring substituents).
- Substitution permissiveness via three nested substitution sets:
- Group A (smaller functional groups and small substituted alkoxy thio/amine/carbonyl motifs),
- Group B (includes halogens, nitro, cyano, C1-8 alkyl, C2-4 alkenyl/alkynyl, and hetero-functional linkers such as OR, SR, NRxRy, carbonylated NR/amide/urea-like fragments, sulfone/phosphoryl),
- Group C (halogen, cyano, C1-4 alkyl, hydroxy/alkoxy, amino, ester-like carbonyl “COORC4”, and “oxo”).
A key internal narrowing clause appears in Group C, and a hard boundary appears at the end of claim 1:
- “provided that when R2 is a phenyl group, then R1 is not a phenyl group.”
This is a targeted exclusion that still leaves a very large space of non-phenyl R1 alternatives when R2 is phenyl.
Breadth signals in claim 1
- Aliphatic substitution latitude: R1/R6 accept C1-6 alkyl and C2-6 alkenyl, with up to 1–3 Group A substituents; R2 accepts a C2-6 alkenyl with up to 1–3 Group A substituents.
- Ring system latitude: R1 and R2 can be ring Cy that is a C3-12 carbon ring or a heterocycle (1–4 hetero atoms from O/N/S), optionally substituted by 1–5 Group B substituents.
- Secondary substituent latitude: R3/R4/R5 can be hydrogen/hydroxyl/alkyl/alkenyl or ring systems, with optional substitution using Group A/B structures.
- Optional “linking”: “R2 and R3 are optionally linked to form a C1-4 alkylene group, or R4 and R5 … linked,” which expands permissible intramolecular substitution patterns and may accommodate conformational changes.
- Salt/solvate inclusion: The claim is drafted to cover pharmaceutically acceptable salts, hydrates, and solvates as a matter of claim scope, not only as a preferred embodiment.
Scope implication
From a freedom-to-operate perspective, claim 1 is designed to block not just the named compound but a wide constellation of analogs that preserve the formula [I] skeleton while varying:
- the hydrophobic substituent types and sizes (C1-6 alkyl/alkenyl, C3-12 rings),
- the heterocycle class (1–4 hetero atoms),
- and the substitution chemistry (halogens, cyano, small alkyl, alkoxy/thio/amine, amide-like and sulfone/phosphoryl-like substituents as defined).
Claim 2 and claim 3: tethered formula embodiments
Claim 2 recites a compound of claim 1 where the compound is represented by formula [I-1]; claim 3 recites formula [I-3]. Without the chemical drawings/text for [I-1] and [I-3], the exact substituent pattern cannot be deterministically reconstructed from your provided text alone. Legally, however, these dependent claims function as additional layers that capture specific sub-genus embodiments within the claim 1 genus.
How do the dependent limitations narrow claim 1 to specific preferred subgroups?
R1-focused narrowing
- Claim 4: R1 is C1-6 alkyl.
- Claim 5: R1 has m=0 and ring Cy is C3-12 carbon ring, with optional substitution “selected from group B of claim 1.”
- Claim 6: R1 is a C3-8 cycloalkyl group.
- Claim 7: R1 is cyclopropyl.
These form a ladder: general genus → ring Cy class → cycloalkyl → cyclopropyl.
R2-focused narrowing
- Claim 8: R2 has m=0 and ring Cy is C3-12 carbon ring or a heterocycle; again optionally substituted from Group B.
This limits R2 to “m=0” and to the same ring/heteroring classes.
R3/R4/R5 simplifications
- Claim 9: R3 is C1-6 alkyl.
- Claim 10: R4 is hydrogen.
- Claim 11: R5 is hydrogen.
These lock in a simplified hydrogenated pattern at R4 and R5 and optionally a specific substitution class at R3.
R6-focused narrowing
- Claim 12: R6 has m=0 and ring Cy is C3-12 carbon ring or a heterocycle with Group B substitution options.
Which exact compound is directly claimed in US 7,378,423 claim 13?
Claim 13: the anchored, fully specified molecule
Claim 13 names a specific compound:
N-{3-[3-cyclopropyl-5-(2-fluoro-4-iodo-phenylamino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydro-2H-pyrido[4,3-d]pyrimidin-1-yl]-phenyl}-acetamide
and claims its pharmaceutically acceptable salt/hydrate/solvate.
This is the litigation-relevant “pin” in the estate because dependent solvate claims (below) attach to this specific named structure.
What solvate and salt forms are protected, and how many specific variants are listed?
Claims 14–24 provide explicit coverage for multiple salt/solvate embodiments of the claim 13 compound:
- Claim 14: sodium salt
- Claim 15: hydrate
- Claim 16: acetic acid solvate
- Claim 17: dimethylsulfoxide (DMSO) solvate
- Claim 18: ethanol solvate
- Claim 19: nitromethane solvate
- Claim 20: chlorobenzene solvate
- Claim 21: 1-pentanol solvate
- Claim 22: isopropyl alcohol solvate
- Claim 23: ethylene glycol solvate
- Claim 24: 3-methylbutanol solvate
Protection count (named forms in your text): 11 distinct variants (sodium salt + 10 solvates/hydrate).
From an enforcement and generic-risk perspective, this solvate set matters because many generic development routes select or end up with a particular polymorph/solvate during manufacturing. If an ANDA product ends up in a listed form, the corresponding dependent claims are directly implicated.
What formulation and combination product claims exist (claims 25–26)?
Claim 25: pharmaceutical composition
Claim 25 covers:
- a compound of claim 1 or claim 13 (including salts/hydrates/solvates),
- plus a pharmaceutically acceptable carrier.
This is a standard “composition-of-matter with carrier” claim. It can matter for patentability and for infringement when an accused product sells a formulation containing the patented active.
Claim 26: combination composition with an “antitumor compound”
Claim 26 covers:
- a compound of claim 1 or 13 (as above),
- plus at least one antitumor compound that is not a compound of the formula [I],
- plus a pharmaceutically acceptable carrier.
This explicitly protects combination therapy presentations. The “not a compound of formula [I]” carve-out narrows the combination scope to partner agents outside the patented formula class.
US Patent 7,378,423 claim map (what is protected where)
| Claim |
Type |
Protected subject matter |
Practical scope |
| 1 |
Independent genus |
Formula [I] compounds + salts/hydrates/solvates (broad Markush) |
Blocks broad analog design space |
| 2 |
Dependent formula sub-embodiment |
Formula [I-1] within [I] |
Adds coverage for a specific sub-genus |
| 3 |
Dependent formula sub-embodiment |
Formula [I-3] within [I] |
Adds coverage for another sub-genus |
| 4–12 |
Dependent subgroup restrictions |
R1/R2/R3/R4/R5/R6 classes |
Narrower patent layers within genus |
| 13 |
Dependent but fully specified |
Named molecule (pyrido[4,3-d]pyrimidine acetamide) |
Anchors enforcement to a concrete active |
| 14–24 |
Dependent salts/solvates |
Sodium salt, hydrate, multiple specific solvates |
Covers specific manufacturing-form outcomes |
| 25 |
Composition |
Active + pharmaceutically acceptable carrier |
Covers dosage form containing active |
| 26 |
Combination |
Active + an antitumor agent not in [I] + carrier |
Blocks certain combination product concepts |
How strong is the patent estate based on claim architecture (genus + anchored species + solvate variants)?
On structure, the estate is built as:
- a wide genus (claim 1) with rich substituent flexibility,
- further formula-dependent claims (claims 2–3) that likely target particular chemical series members,
- a species-level “named” embodiment (claim 13),
- multiple crystal/solvate/salt fallbacks (claims 14–24),
- and product-level coverage (claims 25–26).
That architecture typically improves enforceability because:
- A competitor that makes close analogs may still infringe claim 1’s Markush boundaries.
- A competitor that switches to the named species still faces claim 13.
- A competitor that attempts to avoid by using a different form may still land on one of the listed solvates/salt categories.
Patent landscape analysis: what infringement and design-around strategies are implied by the claims
1) “Analog replacement” risk (claim 1 Markush capture)
The broad allowance of substituted alkyl/alkenyl, ring Cy carbocycles/heterocycles, and multiple functional group types in Groups A/B/C means design-around must typically alter the formula [I] core or violate one of the structural “switches” in the claim definition (including the specific R1/R2 phenyl restriction).
2) “Form switch” risk (claims 14–24)
If the active is the claim 13 molecule, switching from one solvate to another does not necessarily eliminate risk because multiple specific solvates are already listed. Even if a product uses a different solvate not explicitly named, a salt/hydrate category still remains in play for those forms. Your text explicitly lists 11 named forms; those are straightforward infringement targets if the product contains those forms.
3) “Formulation only” risk (claims 25–26)
A dosage form that includes a claim 1 or claim 13 active ingredient can still be within claim 25. For combination therapy, claim 26 can be implicated by product labels that co-administer the claim 1/13 active with antitumor partner drugs.
Key Takeaways
- US 7,378,423 is dominated by a broad Markush genus claim (claim 1) that covers a large set of formula [I] compounds and their salts, hydrates, and solvates.
- The patent estate layers narrowing dependencies on substituent choices at R1, R2, R3/R4/R5, and R6, plus additional formula embodiments (claims 2 and 3).
- Claim 13 directly names a specific active: an N-phenyl acetamide linked to a 3-cyclopropyl-5-(2-fluoro-4-iodo-phenylamino)-6,8-dimethyl pyrido[4,3-d]pyrimidine core.
- Claims 14–24 add explicit protection for 11 named salt/solvate/hydrate variants of the claim 13 compound, which is central to manufacturing-form infringement risk.
- Claims 25–26 add composition and combination coverage, expanding infringement beyond the active ingredient alone.
FAQs
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Does US 7,378,423 cover salts and solvates even when the exact free base is not used?
Yes. Claim 1 includes pharmaceutically acceptable salts, hydrates, and solvates, and claim 13 repeats that inclusion for the named molecule; dependent solvate claims further specify multiple solvated forms.
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What is the most enforcement-relevant claim: the genus (claim 1) or the named compound (claim 13)?
Both. Claim 1 enables infringement for close analogs within formula [I]. Claim 13 provides a concrete “species” anchor and enables direct targeting when the specific active (and its listed forms) is used.
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How do the solvate claims (14–24) affect generic manufacturing strategy?
They reduce the effectiveness of switching among common solvates because multiple specific solvate forms are already enumerated for the claim 13 molecule.
-
Can a formulation without changing the active still infringe US 7,378,423?
Yes. Claim 25 covers a pharmaceutical composition comprising the claimed active (claim 1 or 13) and a pharmaceutically acceptable carrier.
-
Is combination therapy covered, and what limits apply?
Yes. Claim 26 covers combinations of the claim 1/13 active with at least one antitumor compound that is not a compound of formula [I], plus a pharmaceutically acceptable carrier.
References
- United States Patent No. 7,378,423. (Claims text as provided by user input).
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