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Patent landscape, scope, and claims: |
United States Patent RE46791: Scope, Claim Coverage, and US Patent Landscape for Herpesviridae (Including HCMV/CMV) Antivirals
RE46791 reissues to the same core US claim set (formula-driven small molecule) and expands practical enforceability through broad chemical genus coverage, downstream method-of-use and medicament claims, and a corresponding synthetic process claim. The claim language is structured to capture: (1) wide aryl substitution patterns on a defined scaffold, (2) multi-site substitution on the scaffold (R1-R8), (3) specific positional constraints on the aryl substituents (ortho/meta relationships), (4) piperazine ring substitution via an optional “methylene bridge” construct (R4/R5), and (5) stereochemical embodiments (ee >90%). Enforceability risk for generic entry centers on whether a competitor’s active falls within the Markush-style genus limits for R1-R8 and the aryl positional constraints, and whether any Paragraph IV-style design-around targets carveouts created by the claim’s specific R6/R1/R3 and substitution-position combinations.
What does RE46791 claim: What is the formula coverage and how broad is the chemical genus?
Core claim 1 structure: Markush variables driving breadth
Claim 1 is a genus claim to “a compound of the formula (I)” (the formula is not reproduced in your prompt, but the variable definitions are complete and define scope). Coverage is driven by eight substitution variables plus an aryl group variable (Ar). The claim is broad because:
- Ar is any aryl substituted by 1 to 3 substituents from a large list (alkyl, alkoxy, formyl, carboxyl, alkylcarbonyl/alkoxycarbonyl, CF3, halogen, cyano, hydroxyl, amino, alkylamino, aminocarbonyl, nitro).
- R1-R3 allow multiple atomics and heteroatom-containing substituents including amino and halogen and CF3, with R3 permitting sulfone-like substituents (“alkylsulphonyl” / “alkylaminosulphonyl”).
- R4/R5 describe a special structural feature on the piperazine ring: either each is H/alkyl, or R4 and R5 are attached to opposing carbons and form a methylene bridge that is optionally methyl-substituted (0-2 methyls).
- R6-R8 expand chemical space by allowing many substituents (alkyl/alkoxy/alkylthio/carboxyl/aminocarbonyl/acyl derivatives/CF3/halogen/cyano/hydroxyl/nitro; some R variables do not list amino explicitly but do list multiple carbonyl and CF3/halogen).
Positional constraints: the main “hard” boundaries
Claim 1 contains two positional constraints that materially affect infringement analysis:
- R1 is attached to the phenyl ring at the position ortho to the point of attachment of the phenyl ring.
- Dependent claim 10 adds: R1 is ortho and R3 is meta opposite to that of R1 (“meta to the point of attachment … opposite to that of R1”).
These positional constraints reduce the “design-around” options compared with purely substitution-count/genus-only claims.
Salt/solvate coverage
Claim 1 explicitly includes “a salt, solvate, or solvate of a salt”. That matters for enforcement against not only the free base but also crystalline or protonated forms, and for generic development because reformulation into a different salt can still stay within the claim if it qualifies as a “physiologically acceptable salt” and/or a salt contemplated by the patent.
Enantiomeric excess embodiments
Claims 41-43 (and their dependent chain) narrow to stereoisomeric forms: ee >90% for specific dependent compounds. That is enforceability-relevant if a challenger markets an enantiomeric mixture but the active is not supplied at >90% ee.
How do claims 2-15 narrow Ar and R1-R8: Which dependent claim restrictions matter for infringement?
Claim 2: phenyl Ar with limited substituent set
Claim 2 fixes Ar to phenyl substituted by 1 to 3 substituents, but narrows substituent classes compared with claim 1:
- Ar substituents: C1-C6-alkyl, C1-C6-alkoxy, carboxyl, C1-C6-alkylcarbonyl, C1-C6-alkoxycarbonyl, CF3, fluorine/chlorine/bromine, cyano, hydroxyl, amino, C1-C6-alkylamino, nitro.
- R1: H or C1-C3-alkyl/alkoxy/alkylthio, F/Cl.
- R2: H or C1-C3-alkyl/alkoxy/alkylthio, F/Cl.
- R3: C1-C4-alkyl, cyano, F/Cl, nitro, CF3, or C1-C3-alkylsulphonyl.
- R4: H or methyl; R5: H only.
- R6: C1-C3-alkyl/alkoxy/carbonyl/carboxyl forms, CF3, halogen, cyano, hydroxyl, nitro.
- R7: H or C1-C3-alkyl/alkoxy, F/Cl, cyano, hydroxyl.
- R8: H or C1-C3-alkyl/alkoxy, F/Cl, cyano, hydroxyl.
Claims 3-6: specific permutations that anchor key infringement points
- Claim 3: Ar phenyl with 1-2 substituents from {methyl, methoxy, F, Cl}; R1/R2/R3/R4/R5/R6/R7/R8 are heavily constrained to smaller sets.
- Claim 4/5/6: add “R1 is” methoxy/methyl etc and reiterate positional “ortho” requirement.
These dependent claims are useful in settlement leverage because they can match a commercial candidate more closely than the broad independent claim, and can limit prosecution history estoppel arguments depending on claim construction at trial.
Claims 7-9: narrowing R2 and R3
- Claim 7: R2 = hydrogen.
- Claim 8-9: R3 in {CF3, Cl, methyl, isopropyl, tert-butyl} then narrowed further to {CF3, Cl, methyl}.
Claim 10: R1 ortho + R3 meta opposite
This is the key “positional relationship” dependent claim. If the accused product’s aryl substitution pattern does not satisfy both positions simultaneously, there is a direct infringement attack vector against this narrower dependent claim, though the independent genus may still capture it unless the accused structure falls outside claim 1’s positional requirement (which also embeds R1 ortho).
Claims 11-14: piperazine bridge and R6/R7/R8 constraints
- Claim 11: R4 and R5 = H.
- Claim 12: R6 = fluorine.
- Claim 13: R7 = H.
- Claim 14: R8 = H/methyl/F.
These are likely to map onto specific marketed analogs or closely related salts.
What is claimed for synthesis: How does claim 16 define the process scope?
Claim 16: reaction of formula II with base/acid
Claim 16 is a method-of-preparation claim:
- Reacts a “compound of formula II” where Ar and R1-R9 are defined (with R9 = methyl/ethyl/tert-butyl) with a base or an acid.
The breadth depends on what formula II corresponds to in the full patent, but the claim language is minimalistic: it does not limit catalysts, solvents, temperatures, times, or specific base/acid identity. That tends to broaden process coverage so long as the transformation “reacting compound II with a base or acid” is performed as claimed.
Infringement angle
For manufacturing-side disputes, the method claim can still be valuable even if the final API is a salt form within claim 1. Typical generic counter-strategies include process redesign, use of different intermediates that do not fall within formula II, or use of neutral conditions not qualifying as “base or an acid” in a literal sense.
Do RE46791 claims cover medicaments and methods of treating herpesviridae or HCMV?
Claims 17-22: medicament and antiviral methods
- Claim 17: medicament comprising claim 1 compound + inert non-toxic auxiliary.
- Claims 18-20: method for treating infection by Herpes viridae in humans and animals; includes a list that explicitly includes cytomegalovirus (CMV) and human cytomegalovirus (HCMV) and others in the group; claim 20 narrows to HCMV.
- Claims 21-22: method for treating infection by HCMV in humans by administering an antiviral-effective amount of the compound or a physiologically acceptable salt; claim 22 repeats the compound selection.
Commercial implication
These are classic enforcement hooks: if the generic product is within claim 1’s chemical scope, then sales for HCMV treatment can be framed as direct infringement of method claims and/or contributory infringement if there is induced off-label use coupled to labeling, while medicament claims often strengthen product-form enforcement.
What US exclusivity timeline does RE46791 affect: When does it lose exclusivity?
Direct answer cannot be produced from the provided record
RE46791 is a reissue number, but your prompt does not include:
- the underlying US application publication/patent numbers,
- original filing date,
- reissue date,
- expiration terms,
- any terminal disclaimer,
- PTA/PTE,
- or FDA-related exclusivity (Orange Book listing) tied to a specific NDA/BLA.
Without those items, producing a date-accurate “when exclusivity ends” analysis would be incomplete and non-actionable.
What Orange Book status exists for the RE46791-covered drug: Which NDA/BLA should be mapped to claims?
Not derivable from provided text
The prompt includes only RE46791 claim language and does not identify:
- the commercial drug name,
- active ingredient(s),
- NDA/BLA numbers,
- sponsor(s),
- or Orange Book entries.
A mapping from RE46791 to Orange Book listings is necessary to evaluate generic entry timing and patent-by-patent listing coverage. That mapping is not present in the supplied information.
Which companies are most likely exposed: What competitive landscape does the claim language target?
No company assignments can be verified from the provided record
The claim set alone does not identify assignees, applicants, inventor names, or known marketed analogs. Without those, an accurate competitive exposure list would be fabricated.
How strong is the RE46791 patent estate: What do the claim features imply for validity and enforceability?
Strength factors
- Genus breadth with defined substituent lists: claim 1 includes a wide Markush range. That can make design-arounds harder if the accused API falls within the allowed substituent chemistry and the piperazine bridging constraint.
- Positional restrictions are explicit: R1 ortho requirement in claim 1 is a clear infringement boundary. If accused products match that, the independent claim can be hard to avoid.
- Multiple claim types: independent chemical claim (1/33), dependent chemical narrowings, process claim (16), medicament (17), and HCMV treatment (21). This creates multiple theoretical infringement pathways.
- Stereochemical narrowing: ee>90% dependent claims provide an additional enforcement layer against enantiomeric purity specifications.
Validity risk factors commonly seen with this structure
- Overbreadth risk: wide genus claims can face enablement or written description challenges if the specification does not support the full substitution space.
- Definiteness/construction risk: multi-variable Markush claims with positional constraints typically turn on how the “point of attachment” is defined in the scaffold and the exact naming/structure interpretation.
- Process claim vagueness: claim 16’s base/acid reaction language is broad; accused manufacturers can attack on indefiniteness or scope mismatch with actual synthetic steps disclosed.
Those are general issue types; your prompt does not provide the specification or prosecution history.
What generic entry risks exist for RE46791: How can a competitor avoid infringement?
Most plausible design-around levers (based on claim text only)
- Displace the aryl positional pattern: violate R1 ortho requirement (for claim 1) by using a different substitution position relative to phenyl attachment point.
- Change the R4/R5 piperazine bridge architecture: if claim 1 demands either (a) R4/R5 are H/alkyl in allowed combinations or (b) a methylene bridge with optional methyl substitution, a different ring-closure may avoid the literal scope.
- Alter substituent classes at R6-R8: R6-R8 accept many substituent types, but not all possible functional groups. If the competitor uses a substituent not in the permitted lists (for example, specific heteroaryl moieties not listed), infringement risk drops.
- Avoid defined stereochemical presentation: if the product is supplied as a mixture where none of the dependent ee>90% embodiments are practiced/sold with the requisite ee, dependent claim infringement may be easier to challenge. (Independent claim 1, however, is not limited to ee.)
Paragraph IV litigation posture
A Paragraph IV notice would likely argue non-infringement by structure and/or that the independent genus does not cover the exact substitution pattern. Settlement often turns on whether the generic can credibly show the marketed API falls outside one of the “hard” boundaries: R1 ortho positioning, piperazine methylene bridge condition, or the allowed substituent sets.
How do claims 29-43 expand coverage to specific embodiments: what’s the practical “hit list” for enforcement?
Claims 29-30: explicit R6 = fluorine and specific formula sub-sets
Claims 29 and 30 define compounds of the formula with R6 = fluorine and tie to dependent definitions of claim 6 or claim 3 respectively. This indicates that at least one commercially relevant analog includes R6 fluorine and that the patent anticipates those embodiments as enforceable anchor points.
Claims 33-34: restatement and R6-specific broadening
- Claim 33: compound of formula (I) or salt.
- Claim 34: expands by specifying R6 can be various functional groups including alkoxy, alkylthio, formyl, carboxyl, aminocarbonyl, acyl derivatives, CF3, halogen, cyano, hydroxyl, nitro.
Claims 41-43: ee>90%
These depend on earlier narrowings (claims 26-28 in your list). Practically, this suggests the patent includes at least one specific stereochemically enriched compound as a protected marketed candidate.
Key Takeaways
- RE46791 claim 1 is a broad genus claim over a defined chemical scaffold with multiple substitution variables (Ar and R1-R8), including explicit aryl positional constraint that R1 is ortho to the phenyl attachment point.
- Dependent claims add enforceability granularity via narrowed Ar substitution sets, specific R3/R6 selections (including CF3/Cl/methyl permutations and R6 = fluorine embodiments), piperazine “methylene bridge” constraints (R4/R5), and ee >90% stereochemical limitations.
- The patent estate includes product, process, medicament, and HCMV method-of-use claims, supporting multi-angle infringement arguments if an accused API fits claim 1.
- A competitor’s most credible design-around is structural, especially by changing the aryl substitution positions (to avoid R1 ortho) and/or selecting substituent classes not listed for R1-R8 and/or altering the piperazine bridge architecture.
FAQs
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Does RE46791 cover both free base and salt forms?
Yes. Claim 1 includes “a salt, solvate, or solvate of a salt thereof.”
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Is the aryl substitution position a required element for claim 1?
Yes. Claim 1 states R1 is attached to the phenyl ring via the position ortho to the attachment point of the phenyl ring.
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Do the claims include HCMV-specific treatment methods?
Yes. Claims 21-22 specify methods for treating HCMV in humans using the claim 1 compound (or physiologically acceptable salt).
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Is there a stereochemical limitation in RE46791?
Yes. Claims 41-43 require an enantiomeric excess of more than 90% for compounds covered by those dependent chains.
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What is the process scope for manufacturing protection?
Claim 16 broadly covers reacting a compound of formula II with a base or an acid, with R9 limited to methyl, ethyl, or tert-butyl.
References (APA)
- United States Patent RE46791 (Reissue Patent). (Claim text provided in prompt).
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