US Patent 8,293,752: What Is Covered by the Claims and Where the Landscape Sits
United States Patent 8,293,752 is claimed around a core small-molecule scaffold defined by Formula I with variable dual aromatic/heteroaromatic rings (Cy1, Cy2), a linker (L1), and an amide-type linkage (L2 = —C(O)N(R)), with additional substituent freedom at an anilide/amide nitrogen (R) and at two positions labeled Rx/Ry and R1/R2. Claim coverage extends to salts, a tighter family defined as Formula II (and sub-forms II-a/II-b), and formulations including combinations with broad therapy classes.
The enforceable scope is driven by (i) the breadth of permitted heteroaryl identities and substitution counts; (ii) the generic definitions for Rx/Ry (halo or diamino substitution) and R2 (H or C1-6 aliphatic); and (iii) the fact that the claim language reads like a Markush-style combination of ring families plus substituent vectors, not a single named compound.
1) What Does Claim 1 Actually Cover? (Core scaffold and full variable set)
Claim 1: “A compound of formula I”
Claim 1 is the dominant independent claim. It covers compounds of Formula I (and pharmaceutically acceptable salts) where the variable elements are defined as follows:
- Cy1: an optionally substituted 5-membered aromatic ring with 1 to 3 heteroatoms, independently selected from N, O, S.
- Cy2: an optionally substituted 6-membered aromatic ring with 1 to 2 heteroatoms, independently selected from N, O, S.
- L1: an optionally substituted straight or branched C1-6 alkylene chain.
- L2: —C(O)N(R) (amide linkage).
- R: each instance independently H or an optionally substituted C1-6 aliphatic group.
- R1: H or an optionally substituted C1-6 aliphatic group.
- Rx and Ry: each independently selected from:
- R2: independently H or an optionally substituted C1-6 aliphatic group.
Where the scope is broadest
Claim 1 grants wide coverage because it simultaneously:
- allows broad heteroaryl ring classes (5-membered heteroaryl for Cy1; 6-membered heteroaryl for Cy2),
- allows C1-6 alkylene linking,
- allows amide N substituent vectors (R),
- and permits a wide set of Rx/Ry options (halo or amino, with amino N alkylation controlled by R2).
In practical landscape terms, this is a “two-heteroaryl + alkylene linker + carboxamide” family with substituent vectors on the aromatic system and amino nitrogens.
2) How Narrowing Dependent Claims Carve Out Specific Subspaces
Claim 2: Ry as a diamino substitution
This removes the “halo” option for Ry and forces the Ry position into a disubstituted amino form.
Claim 3: Specific Ry substituent exemplars
Claim 3 enumerates Ry = —NH2, —NHCH3, —NHCH2CH3, —NHCH2CH2CH3, —NHCH(CH3)2, —NH(C3H5), —NHCH2CH2CH2OH, or —NHCH2CH2CH2NH(CH3)2.
This is a fenced but still sizable list focused on common alkylamino variants, including one hydroxyalkyl and one aminoalkyl.
Claim 4: R1 = H and L1 restricted to C1-4
- R1 = H
- L1 = optionally substituted straight or branched C1-4 alkylene (tightens L1 from C1-6 to C1-4).
Claim 5: Cy1 enumerates heterocycles
Claim 5 is a specific list of permitted Cy1 ring types:
- pyrrolyl, pyrazolyl, imidazolyl, triazolyl, thiophenyl, furanyl, thiazolyl, isothiazolyl, thiadiazolyl, oxazolyl, isoxazolyl, oxadiazolyl.
This narrows Cy1 from “any 5-member aromatic ring with 1-3 heteroatoms” to a defined set of named ring archetypes, though the claim remains broad inside that set.
Claim 6: L2 = —C(O)N(H)
This forces the amide nitrogen to be unsubstituted (R = H).
Claim 7: Cy2 restricted to four heteroaryl subclasses
- Cy2 selected from: pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl.
This narrows the 6-member ring heteroaromatic options.
Claims 8 and 9: Formula II and sub-forms II-a/II-b
- Claim 8: compound of formula II.
- Claim 9: formula II is of formula II-a or II-b.
These are typical claim family refinements that in practice constrain the substituent placements and/or ring connectivity as compared with Formula I. They also function as fallback positions if Formula I is attacked or read narrowly.
Claim 10: Pharmaceutical composition
- Composition comprising claim 1 compound + pharmaceutically acceptable carrier/adjuvant/vehicle.
Claim 11: Combination with broad therapeutic agent categories
- Combination with a therapeutic agent selected from:
- chemotherapeutic or anti-proliferative agent,
- anti-inflammatory agent,
- immunomodulatory agent,
- neurotrophic factor,
- cardiovascular disease agent,
- destructive bone disorder agent,
- liver disease agent,
- anti-viral agent,
- blood disorder agent,
- diabetes agent,
- immunodeficiency disorder agent.
This claim is structurally broad because it ties the claimed molecule to combination therapy with high-level therapeutic classes rather than naming specific drugs or mechanisms.
Claim 12 and 13: Additional composition chain anchored to a narrower compound definition
- Claim 12: compound according to claim 1, wherein the compound is: [a second drawn structure in your text].
- Claim 13: composition comprising the compound of claim 12 + pharmaceutically acceptable carrier/adjuvant/vehicle.
Because the actual chemical drawings are not reproduced as text, the narrowing effect depends on those missing structure details. But claims 12–13 clearly create a further subset anchored to a different drawn formula (often representing a specific substitution pattern or ring selection).
3) Claim Scope Map: What a FTO/Validity Review Should Focus On
A. Ring definition and permissibility
The claim uses:
- Cy1: 5-member aromatic with 1-3 heteroatoms (but Claim 5 narrows).
- Cy2: 6-member aromatic with 1-2 heteroatoms (but Claim 7 narrows).
Landscape implication: competitors can design around by using:
- ring systems outside the permitted heteroatom counts,
- or ring cores not captured by the claim’s aromatic definitions,
- or by changing topology so the ring-to-linker-to-amide pattern no longer matches Formula I/II.
B. Linker constraints
- L1 is C1-6 alkylene (Claim 4 tightens to C1-4).
- L2 is an amide carbonyl attached to N(R).
Landscape implication: design-around usually targets the amide linkage or the immediate linker geometry. If a competitor uses a non-amide bioisostere (e.g., urea without matching N vector, sulfonamide, ester), it may escape the literal “—C(O)N(R)” requirement, but doctrine of equivalents risk depends on claim construction.
C. Rx/Ry substituent logic
Rx and Ry each independently can be:
- halo, or
- —N(R2)2 (diamino-like moiety; R2 can be H or C1-6 alkyl).
Landscape implication: the widest competitive overlap is when Rx/Ry positions carry either halogen or primary/secondary dialkyl amino substituents. If a competitor changes to other groups (e.g., hydroxyl, cyano, methoxy), literal coverage weakens.
D. Amide nitrogen substitution
- R can be H or C1-6 aliphatic (Claim 6 locks to H).
- R2 similarly governs amino N substitution (H or C1-6 aliphatic).
Landscape implication: changing amide N substitution and amino N substitution patterns can land outside Claim 1 but still remain within some dependent-claim pockets.
4) Pharmaceutical Composition and Combination Coverage (How the patent reaches real-world use)
Composition claim coverage
- Claim 10: drug + carrier.
- Claim 13: drug + carrier for the narrowed claim 12 compound.
These are standard formulation claims. They matter for:
- product labels,
- ANDA paragraph IV litigation where “formulation” claims can be asserted if a generic introduces the same chemical and dosage form.
Combination therapy coverage
- Claim 11 covers combination with a large list of therapy class categories.
This is less about specific drugs and more about:
- the presence of the claimed compound in combination therapy with a therapeutic agent falling into those categories.
Landscape implication: even if a rival develops a distinct molecule, they may still fall into combination exposure if they co-administer the claimed compound with an agent that fits one of the broad categories and the claim construction reads the combination broadly.
5) Patent Landscape: Scope-driven competitive clustering (without external record dependence)
With only the claim text provided, the landscape can still be mapped by what structural territories are most likely to be crowded.
A. Most crowded likely subspaces
The broadest independent claim (Claim 1) points to a chemical class where the market and litigation risk typically cluster around:
- Heteroaryl-to-heteroaryl connectivity with a short alkylene linker (C1-6).
- Carboxamide linkage in the form —C(O)N(R).
- Aromatic substituents Rx/Ry that are either:
- halogens or
- amino groups with alkyl substitutions.
- Variants constrained by:
- Cy2 = pyridinyl/pyrimidinyl/pyrazinyl/pyridazinyl (Claim 7),
- Cy1 enumerated heterocycles (Claim 5),
- amide N unsubstituted (Claim 6).
B. “Non-overlap” design territories that usually avoid the claim
Given the literal language, competitors generally avoid one or more of:
- replacing the amide (L2 = —C(O)N(R)) with non-amide motifs,
- changing the heteroaryl identities so Cy1/Cy2 are outside the defined sets (or outside permissible heteroatom counts),
- placing substitution such that Rx/Ry do not meet “halo or —N(R2)2” at the relevant positions,
- changing topology so Formula I or Formula II no longer matches.
C. How Formula II and II-a/II-b shift invalidity/overbreadth leverage
Formula II and its sub-forms likely represent:
- narrower regimens (specific substitution patterns or specific ring selections),
- fallback claim coverage after an infringement/validity attack.
From a landscape standpoint, Formula II often becomes the more litigation-resistant subset because it narrows the Markush space.
6) Practical Enforcement and Litigation Posture (what the claims support)
Best infringement targets
- Any product whose API matches Formula I (or Formula II) with:
- permissible Cy1 and Cy2 rings,
- C1-6 alkylene L1 and carboxamide L2,
- Rx/Ry at the relevant aromatic positions being halo or amino (—N(R2)2),
- and salts/formulation.
Best generic pressure points
- Attacks typically focus on whether the accused compound truly falls within:
- the exact Markush boundaries for Cy1/Cy2,
- the definition of Rx/Ry substituents,
- and the literal existence of L2 as —C(O)N(R) with matching N substitution.
Combination claims as leverage
- Claim 11 can be used when the API is common in a combination regimen with agents in the listed therapeutic classes.
- In enforcement posture, this supports settlement leverage because combination therapy can increase prescribing and labeling contexts.
Key Takeaways
- Claim 1 defines a broad two-heteroaryl + C1-6 alkylene + carboxamide scaffold with extensive substituent freedom for Rx/Ry (halo or —N(R2)2) and R/R1/R2 (H or optionally substituted C1-6 aliphatic).
- Dependent claims sharpen coverage via Cy1/Cy2 enumerations (Claims 5 and 7), amide N lock (Claim 6), L1 shortening and R1 restriction (Claim 4), and Ry as diamino with enumerated dialkyl examples (Claims 2 and 3).
- Formula II/II-a/II-b provides narrower fallback claim territory inside the broader Formula I space.
- Composition claims (10, 13) and combination claim (11) expand the patent’s reach into formulation and co-therapy contexts without requiring specific named co-drugs.
FAQs
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Which element most directly controls structural infringement for US 8,293,752?
Claim 1’s L2 = —C(O)N(R) plus the Cy1/Cy2 heteroaryl pairing and L1 = C1-6 alkylene are the primary literal anchors.
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Do the claims require specific heteroatoms counts or ring types?
Yes for Cy1 and Cy2 by definition in Claim 1 (counts and heteroatom types), with further narrowing in Claims 5 and 7.
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Can replacing Rx/Ry with a non-halo, non-amino group avoid Claim 1?
Literal avoidance is likely if Rx and/or Ry are changed to groups other than halo or —N(R2)2, assuming substitution placement still aligns with Formula I.
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Does Claim 6 matter for narrower coverage?
Yes. Claim 6 forces L2 = —C(O)N(H), limiting the amide N substitution pattern relative to the broader Claim 1.
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What is the practical value of Claim 11?
It provides combination-therapy coverage tied to broad therapeutic categories, which can increase enforcement options when the claimed API is used alongside agents fitting those classes.
References
[1] United States Patent US 8,293,752, claims 1-13 (provided claim text).
