United States Drug Patent 8,129,346: Claim Scope, Expiration, Patent Landscape, and Generic Entry Risk

U.S. Patent No. 8,129,346 covers methods of administering broad classes of N-terminal nucleophile hydrolase inhibitors, including proteasome-related compounds, for inhibiting the enzyme or treating inflammation and fever. The patent does not, based on the supplied claims, claim a single active pharmaceutical ingredient, dosage form, formulation, manufacturing process, or composition of matter.

The strongest practical coverage is concentrated in the narrower claim family directed to compounds having an amino-acyl or related scaffold with isobutyl substituents and a morpholine-containing carbonyl substituent. The broad genus claims face greater exposure to written-description, enablement, definiteness, anticipation, and obviousness challenges.

The patent’s nominal expiration depends on its earliest effective nonprovisional priority date, terminal disclaimers, patent-term adjustment, and any patent-term extension. The issue date alone does not establish the expiration date. No Orange Book listing, FDA-approved product, Paragraph IV dispute, biosimilar proceeding, or commercial product can be established from the supplied claims alone.

What does U.S. Patent 8,129,346 protect?

U.S. Patent 8,129,346 protects treatment methods involving compounds represented by Formula I or Formula II. The claimed methods have two principal elements:

Administration to a subject of a compound within a large Markush-defined chemical genus.
Use of that compound to inhibit an N-terminal nucleophile hydrolase or treat inflammation or fever.

The claims are method claims. They do not independently claim:

A compound per se.
A pharmaceutical composition.
A tablet, capsule, injectable, or other dosage form.
A crystalline or amorphous form.
A salt, polymorph, solvate, or hydrate as a standalone composition.
A manufacturing method.
A specific dosing regimen.
A specific inflammatory disease.

Claim 1 is directed to Formula I. Claim 48 is directed to Formula II. Claims 49 through 51 recite the principal therapeutic uses. Claims 58 through 62 narrow Formula II to a defined subgroup containing isobutyl substituents and heterocyclic groups, including morpholine.

How are the claims structured?

Independent claims

The patent contains several independent or substantially independent method claims:

Claim	Main subject matter	Practical scope
1	Formula I compounds used to inhibit an N-terminal nucleophile hydrolase or treat inflammation or fever	Broad genus
48	Formula II compounds used for the same purposes	Broad genus
49	Formula I or II compounds for inhibiting an N-terminal nucleophile hydrolase	Therapeutic-use claim
50	Formula I or II compounds for treating inflammation	Therapeutic-use claim
51	Formula I or II compounds for treating fever	Therapeutic-use claim
58	Narrow Formula II subgroup with carbonyl linker, oxygen, isobutyl groups, and heterocyclic substituent	Focused genus
60	Narrow Formula II subgroup for enzyme inhibition	Narrow use claim
61	Narrow Formula II subgroup for inflammation	Narrow use claim
62	Narrow Formula II subgroup for fever	Narrow use claim

Claims 2 through 47 and 52 through 57 provide dependent limitations. Claims 59 and 60 through 62 further narrow the morpholine-containing subgroup.

Claim 1 and Formula I

Claim 1 includes R1 and R3 as independently substituted C1-6 aralkyl groups and R2 and R4 as substituted or unsubstituted C1-6 alkyl groups. It also defines:

A as carbonyl, thiocarbonyl, sulfone, or, in specified positions, a covalent bond.
L as absent, carbonyl, thiocarbonyl, or sulfone.
Q as absent, oxygen, NH, or N-C1-6 alkyl.
X as oxygen, NH, or N-C1-6 alkyl.
Y and Z as variable heteroatom-containing linkers.
R5 as N(R6)LQR7.
R7 as a broad substituent class that includes alkyl, alkenyl, alkynyl, aralkyl, heteroaralkyl, aryl, heteroaryl, phosphates, aminoalkyl groups, cyclic groups, sulfonyl groups, and heterocyclic substituents.

The genus is unusually broad because it permits both acyclic and cyclic R6/R7 arrangements. The claims also cover prodrug-like phosphate and aminoalkyl substituents.

Claim 48 and Formula II

Claim 48 contains a similar substituent framework but omits R1 and R3 from the text supplied. Formula II therefore appears to represent a related but structurally distinct scaffold. The precise legal boundary depends on the structural drawing and definitions in the issued patent specification.

A claim chart based solely on the text supplied cannot determine all Formula II limitations. In particular, the missing structural representation affects:

The identity and position of the core substituents.
Whether Formula II is a stereochemical or constitutional variant of Formula I.
The relationship between R2, R4, X, and the central scaffold.
Whether the formula includes additional ring or linker restrictions.

For infringement analysis, the issued patent image and formal claim text should control over OCR-derived versions.

What compounds are covered by the narrower claims?

Claims 2 through 7 define a more specific subgroup:

R1: 2-phenylethyl.
R2: isobutyl.
R3: benzyl.
R4: isobutyl.
X: oxygen.
L and Q: absent.
R6: C1-6 alkyl.
R7: butyl.

Claims 8 through 15 extend the same scaffold to allyl, propargyl, benzyl, and pyridyl substituents.

Claims 16 through 21 cover sulfone-linked compounds, including methyl and phenyl substituents. Claims 22 through 47 cover carbonyl-linked compounds with substantially broader R7 options.

The most commercially relevant subset is likely the carbonyl-containing group in claims 22 through 47 because it includes:

Alkyl and aralkyl substituents.
Phenyl groups.
Cyclopropyl and cyclohexyl groups.
Morpholine, piperidine, piperazine, and pyrrolidine groups.
Aminoalkyl and quaternary ammonium groups.
Phosphate-containing substituents.

What do claims 58 through 62 specifically cover?

Claims 58 through 62 define the most concentrated claim cluster.

The required elements include:

Limitation	Required feature
Formula	Formula II
L	Carbonyl
M	CH2
Q	Absent
X	Oxygen
R2 and R4	Both isobutyl
R5	N(R6)LQR7
R6	Hydrogen
R7	Heterocyclyl-M
Heterocycle	Morpholine, piperidine, piperazine, or pyrrolidine

Claim 59 narrows the heterocycle to morpholine. Claims 60 through 62 then recite enzyme inhibition, inflammation treatment, and fever treatment.

These claims are materially narrower than claims 1 and 48. A product would need to satisfy the complete structural combination. A compound with a different core, a non-isobutyl R2 or R4 group, a non-carbonyl L group, or a different linker could fall outside claims 58 through 62 while potentially remaining within a broader claim.

What N-terminal nucleophile hydrolases are implicated?

N-terminal nucleophile hydrolases are enzymes in which the catalytic residue is exposed or generated at the N-terminus of a mature protein. The class includes proteasome catalytic subunits and other enzymes with N-terminal catalytic serine, threonine, cysteine, or related nucleophiles.

The patent’s functional language does not limit the claims to one named enzyme. Claim 49 therefore potentially reaches administration of a covered compound for inhibiting any N-terminal nucleophile hydrolase within the scope supported by the specification.

The practical relevance depends on the patent’s written description and experimental data. A broad functional claim may be vulnerable if the specification demonstrates activity against only one enzyme or a narrow subgroup while claiming an expansive range of N-terminal nucleophile hydrolases.

How strong is the patent estate for U.S. Patent 8,129,346?

The estate appears stronger for specific compounds than for the full Markush genus.

Issue	Broad claims 1 and 48	Narrow claims 58 through 62
Chemical breadth	Very broad	Focused
Functional breadth	Enzyme inhibition, inflammation, or fever	Same uses but limited scaffold
Written-description risk	High	Lower
Enablement risk	High if examples are limited	Lower if specifically exemplified
Definiteness risk	Moderate to high because of complex definitions	Lower, subject to formula clarity
Design-around potential	Significant	More limited
Proof of infringement	Potentially complex	More direct if product matches
Litigation value	Depends heavily on prosecution history	Potentially stronger for an exact analog

The claims contain several drafting features that could attract validity challenges:

Extensive nested Markush definitions.
Multiple optional covalent bonds.
Repeated Z-A-Z sequences.
Functional language covering inhibition of an enzyme class.
Apparent OCR or transcription errors, including “0” for oxygen and inconsistent linker notation.
Different R7 definitions in related claims.
Broad therapeutic categories without disease-specific limitations.

Under 35 U.S.C. §112, the patent must provide written description and enablement for the claimed subject matter, and the claims must define the invention with reasonable certainty. The Federal Circuit has applied heightened scrutiny to very large chemical genera where the specification does not reasonably demonstrate possession of the full scope or enable practicing the full genus without undue experimentation. See 35 U.S.C. §112; Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010); Amgen Inc. v. Sanofi, 598 U.S. 594 (2023).

When does U.S. Patent 8,129,346 lose exclusivity?

The statutory term for a post-June 8, 1995 utility patent is generally 20 years from the earliest effective U.S. nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and patent-term extension. The issue date of February 28, 2012 does not itself establish the expiration date. See 35 U.S.C. §§154 and 156.

A reliable expiration analysis requires the patent’s:

Earliest claimed priority date.
U.S. nonprovisional filing date.
Patent-term adjustment.
Terminal disclaimer status.
Patent-term extension status.
Continuation and divisional relationships.

The supplied claim text does not contain those data. The nominal expiration date therefore cannot be stated accurately from the claims alone.

What is the Orange Book status of U.S. Patent 8,129,346?

No Orange Book status can be established from the claims supplied. The FDA Orange Book lists patents submitted for approved drug products, including applicable substance, formulation, and method-of-use patents. A patent number is not automatically an Orange Book-listed patent.

For Orange Book relevance, the following distinctions matter:

A method-of-use patent may be listed only for a corresponding approved use.
A patent covering an experimental compound has no Orange Book significance without an approved product.
A patent directed to a broad enzyme-inhibition method may not be listable unless it claims an approved method of use.
A patent can remain unexpired yet have no commercial relevance if no approved product practices it.

The FDA Orange Book database should be checked against the product name, active ingredient, applicant, and patent number. FDA, Approved Drug Products with Therapeutic Equivalence Evaluations.

Are there Paragraph IV challenges or generic litigation?

The supplied information does not establish a Paragraph IV certification, Abbreviated New Drug Application, district-court action, or settlement involving U.S. Patent 8,129,346.

Paragraph IV litigation would require an ANDA applicant to certify that a listed patent is invalid, unenforceable, or not infringed. That pathway is relevant only if:

The patent is listed in the Orange Book.
An approved or pending reference drug exists.
The ANDA applicant identifies the patent in its certification.

Because the claims are directed to broad methods and do not identify a marketed active ingredient, a conventional generic challenge cannot be inferred from the patent number alone. A competitor could still pursue invalidity or noninfringement litigation outside the Hatch-Waxman framework if it commercialized a product allegedly practicing the claims.

Do biosimilar rules apply?

Biosimilar risk is low as a direct matter because U.S. Patent 8,129,346 claims small-molecule chemical compounds and methods of use, not a biologic molecule.

The Biologics Price Competition and Innovation Act applies to biological products licensed under the Public Health Service Act. The patent’s N-terminal nucleophile hydrolase inhibitors would ordinarily proceed, if approved, through the small-molecule drug pathway rather than the biosimilar pathway. Relevant competitors would be generic-drug applicants, 505(b)(2) applicants, or new-drug applicants rather than biosimilar sponsors.

What formulation and manufacturing protection exists?

The supplied claims contain no independent formulation or manufacturing claims.

The patent does not expressly claim:

A specified excipient system.
Particle size.
Controlled release.
Liposomes or nanoparticles.
Sterile injectable formulation.
Solid-state form.
Salt-selection process.
Crystallization process.
Chemical synthesis route.

The broad allowance for pharmaceutically acceptable salts does not create a standalone composition claim. It operates as a limitation within the method claims.

A competitor could therefore seek protection or design-around positions through:

A different salt or polymorph.
A distinct formulation.
A prodrug outside the claimed R7 classes.
A structurally different inhibitor.
A different synthesis route.
A non-overlapping therapeutic target or use.

Those strategies would not automatically avoid infringement if the administered compound still falls within Formula I or Formula II and the accused use practices a claimed method.

How does this patent compare with proteasome-inhibitor patent estates?

Estate type	Typical claim focus	Relevance to 8,129,346
Compound-of-matter patent	Specific molecule and salts	Usually stronger against all uses
Method-of-use patent	Treatment of a disease or enzyme target	Core protection in 8,129,346
Formulation patent	Delivery system or dosage form	Not apparent in supplied claims
Process patent	Synthesis or purification	Not apparent in supplied claims
Proteasome-subunit patent	Specific biological target	Potentially overlapping depending on disclosure
Prodrug patent	Phosphate, aminoalkyl, or carrier group	Potentially overlapping with R7 definitions

Compared with a narrowly drafted compound patent, U.S. Patent 8,129,346 has broader chemical reach but weaker product-level control. A generic or competitor that uses a structurally different inhibitor may avoid the patent even if it achieves the same biological effect.

What generic launch scenarios exist?

Scenario 1: No approved reference product

If no approved drug practices the claims, there is no conventional Orange Book-driven generic launch pathway. Commercial risk would depend on direct infringement allegations and the patent’s remaining term.

Scenario 2: Exact claimed compound

An applicant using a compound within claims 58 through 62 would face the highest risk if the patent remained enforceable and the intended use involved N-terminal nucleophile hydrolase inhibition, inflammation, or fever.

Scenario 3: Same scaffold, different substituent

A compound with a different R2, R4, L, R6, or R7 group could avoid the narrow claims but remain exposed to claims 1 or 48. The broader claims would then become the principal validity and construction battleground.

Scenario 4: Same compound, different indication

Changing the label may reduce method-of-use risk but does not eliminate it if the marketed instructions, promotional activity, or actual use practice a claimed method. A compound patent or broad enzyme-inhibition claim would create greater exposure than a disease-specific claim.

Scenario 5: Different N-terminal nucleophile hydrolase

The broad functional language may reach multiple enzymes, but infringement would depend on the administered compound and the claimed method, not merely on the existence of a different biological target.

What licensing and commercial information is available?

The supplied material does not identify:

The patent owner.
An exclusive licensee.
A development candidate.
A marketed product.
A licensing transaction.
Revenue attributable to the patent.
A royalty obligation.
A collaboration agreement.

Revenue exposure cannot be quantified from the claim text. The patent’s commercial value would depend on whether an approved or development-stage product uses a compound inside the claimed genera, whether the patent is enforceable, and whether later patents provide stronger compound, formulation, or process coverage.

Key Takeaways

U.S. Patent 8,129,346 is primarily a method-of-use patent for N-terminal nucleophile hydrolase inhibitors.
Claims 1 and 48 cover broad Formula I and Formula II chemical genera.
Claims 49 through 51 separately target enzyme inhibition, inflammation, and fever.
Claims 58 through 62 provide the most focused protection and center on Formula II compounds with isobutyl groups, a carbonyl linker, and morpholine or related heterocycles.
No formulation, manufacturing, standalone composition, or dosage-form claims appear in the supplied text.
The broad genus claims face higher written-description, enablement, definiteness, and obviousness risk than the narrower claims.
Orange Book listing, Paragraph IV activity, litigation, settlement, licensing, and revenue exposure are not established by the claim text.
The expiration date cannot be calculated accurately without the patent’s priority, filing, term-adjustment, and terminal-disclaimer data.
Biosimilar risk is not the relevant competitive framework; generic or 505(b)(2) risk would be more relevant for any small-molecule product.

FAQs

Does U.S. Patent 8,129,346 claim a specific marketed drug?

The supplied claims do not identify a specific marketed drug. They claim broad chemical genera and methods of use.

Can a compound infringe claims 58 through 62 without containing morpholine?

No. Claims 58 through 62 require a heterocycle selected from morpholine, piperidine, piperazine, or pyrrolidine. Claim 59 is limited specifically to morpholine.

Does a different salt avoid U.S. Patent 8,129,346?

Not necessarily. The claims expressly include pharmaceutically acceptable salts. A different salt may remain within the method claims if the underlying compound satisfies the structural limitations.

Is a new formulation protected by this patent?

The supplied claims do not recite a formulation, excipient, release profile, particle size, or dosage form. A formulation could still be used with a claimed compound, but the formulation itself is not independently claimed in the text provided.

Can a competitor avoid the patent by treating a disease other than inflammation or fever?

Potentially, but the answer depends on the full claims and the compound. Claims 49 and 60 are directed to enzyme inhibition rather than only inflammation or fever, while claims 50, 51, 61, and 62 are treatment claims for specified conditions.

References

United States Patent No. 8,129,346, claims 1-62 (2012). U.S. Patent and Trademark Office.
35 U.S.C. § 112 (2024).
35 U.S.C. § 154 (2024).
35 U.S.C. § 156 (2024).
Ariad Pharmaceuticals, Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010).
Amgen Inc. v. Sanofi, 598 U.S. 594 (2023).
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.

PCT Information
PCT Filed	April 14, 2005	PCT Application Number:	PCT/US2005/012740
PCT Publication Date:	November 10, 2005	PCT Publication Number:	WO2005/105827

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1781688	⤷ Start Trial	PA2016010	Lithuania	⤷ Start Trial
European Patent Office	1781688	⤷ Start Trial	93015	Luxembourg	⤷ Start Trial
European Patent Office	1781688	⤷ Start Trial	CA 2016 00014	Denmark	⤷ Start Trial
European Patent Office	1781688	⤷ Start Trial	300805	Netherlands	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,129,346

Summary for Patent: 8,129,346