United States Drug Patent 6,890,898: Scope, Claims, Expiration, and DPP-4 Patent Landscape

US 6,890,898 is an early method-of-treatment patent directed to combining a dipeptidyl peptidase IV, now commonly called DPP-4, inhibitor with another antidiabetic or endocrine agent. Its principal commercial concept is combination therapy for Type 2 diabetes, particularly a DPP-4 inhibitor administered with metformin, insulin, a sulfonylurea-type ATP-sensitive potassium-channel agent, or an alpha-glucosidase inhibitor.

The patent has broad functional claims, but its practical value is limited by three factors: the claims are method claims rather than composition or compound claims; many claims depend on generic chemical Markush formulas reproduced incompletely in the supplied text; and the US patent term has ended. The patent therefore has no current US blocking value against generic or branded DPP-4 products.

What does US Patent 6,890,898 protect?

The patent protects methods that jointly administer:

A DPP-4 inhibitor or pharmaceutically acceptable salt; and
At least one specified therapeutic agent.

The independent claims cover four related subject areas:

Claim group	Protected subject matter	Principal limitation
Claims 1-24	Modification of glucose metabolism or treatment of Type 2 diabetes	DPP-4 inhibitor plus a listed therapeutic agent
Claims 25 and 36	Modification of peptide-hormone metabolism	DPP-4 inhibitor plus a listed therapeutic agent
Claims 26-33 and 37-58	Boronyl peptidomimetic DPP-4 inhibitors	Specific inhibitor class plus a listed therapeutic agent
Claims 34-35 and 59-77	Glucose-intolerant animals and Markush-defined DPP-4 inhibitors	DPP-4 inhibitor plus a listed therapeutic agent
Claims 78-81	Administration format	Simultaneous, sequential, separate, or same-composition dosing
Claims 82-88	Agent-specific combinations	Specific M1 antagonists, prolactin inhibitors, sulfonylureas, acarbose, and metformin

The patent is not limited to a particular approved DPP-4 inhibitor in its broadest claims. Claims 1, 2, 25, 34, 35 and 36 use the functional term "inhibitor of dipeptidylpeptidase IV." That language potentially encompasses compounds developed after the patent filing, subject to claim construction, written-description, enablement, anticipation, and other validity requirements.

What combinations are covered by US 6,890,898?

The listed combination partners are:

Insulin
M1 receptor antagonists
Prolactin inhibitors
Agents acting on an ATP-dependent channel of pancreatic beta cells
Metformin
Glucosidase inhibitors

Claim 88 expressly narrows the combination partner to metformin. Claims 85 and 86 identify particular historical agents:

Category	Examples recited in the claims
M1 receptor antagonists	Pirenzepine, methyl scopolamine, benztropine, atropine, quaternary and tertiary amines
Prolactin inhibitors	Dopamine agonists, ergot alkaloids, bromocriptine-related compounds, cabergoline-related classes, L-dopa and dopamine
ATP-dependent beta-cell channel agents	Glibenclamide, glipizide, gliclazide and AG-EE 623 ZW
Glucosidase inhibitors	Acarbose
Biguanides	Metformin
Hormonal agents	Insulin

The commercial center of gravity is the DPP-4 inhibitor-metformin combination. The other categories are much less relevant to modern diabetes products because M1 antagonists and prolactin inhibitors are not standard components of current Type 2 diabetes combination regimens.

How broad are the independent claims?

Claims 1 and 2 are the principal broad claims. Claim 1 covers modifying glucose metabolism, while claim 2 covers treating Type 2 diabetes. Both require the DPP-4 inhibitor to be administered in an amount sufficient to produce the metabolic effect but insufficient to suppress the immune system.

That immunosuppression limitation is central to the patent's technical distinction. Earlier DPP-4 research associated the enzyme with immune and inflammatory functions. The patent positions lower-dose or selective inhibition as metabolically useful without producing immunosuppression.

Claims 25, 34, 35, 36, 37 and 59 create additional independent or separately framed claim routes. They address:

Peptide-hormone half-life and metabolism
Glucose intolerance
Boronyl peptidomimetic inhibitors
Nanomolar DPIV inhibition
Type 2 diabetes treatment using compounds within the disclosed chemical formulas

The claims do not require a fixed dose, dosing schedule, tablet strength, patient age, disease duration, or specific commercial product. Claims 78-81 make clear that "conjointly administering" can occur through different dosing arrangements, including sequential or separate administration.

What technical limitations appear in the claims?

The claims impose several pharmacological thresholds:

Limitation	Claimed threshold
Selectivity for glucose metabolism over immunosuppression	At least a tenfold difference in EC50
Glucose-tolerance activity	Nanomolar or lower EC50
Immunosuppression activity	Micromolar or greater EC50
DPP-4 inhibition	Ki of 10 nM or less in claim 7 and 1 nM or less in claim 8
Molecular size	Less than 7,500 atomic mass units
Route	Oral administration in dependent claims

These limitations could materially narrow the enforceable scope if a product or clinical regimen does not satisfy the required pharmacological measurements. They also create evidentiary issues. A patent owner seeking to enforce the claims would need to establish the relevant activity values and show that the accused inhibitor falls within the claimed relationship between glucose metabolism and immunosuppression.

"Conjointly administering" is broad in claims 78-81. It includes same-day or coordinated use but is expressly expanded to simultaneous, sequential, separate, and same-composition dosing. A fixed-dose combination is therefore not required.

What chemical matter is covered by the Markush claims?

Claims 12-24, 46-58 and 59-73 refer to broad formulas containing:

A 4- to 8-membered nitrogen-containing heterocycle
A catalytic or reactive DPP-4-binding group such as cyano or an imine-related group
Peptidic or peptidomimetic residues
Boronic acid, boronate or related phosphorus-containing substituents
Halogen, alkyl, aryl, cycloalkyl and heterocyclic substituents
Oral and physiologically hydrolyzable derivatives

Claims 26-33 and 37 specifically target boronyl peptidomimetics modeled on Pro-Pro, Ala-Pro and D-Ala-L-Ala. This is materially different from the nonpeptidic xanthine, cyanopyrrolidine, quinazoline and related chemotypes used by later commercial DPP-4 programs.

The supplied claim text omits the structural drawings associated with several formulas. That omission prevents a reliable compound-by-compound mapping of claims 12-24, 46-58 and 59-73. The textual definitions nevertheless show that these claims are genus claims requiring a particular scaffold and substituent architecture, not every possible DPP-4 inhibitor.

When did US 6,890,898 lose exclusivity?

US 6,890,898 is no longer in force. Its ordinary US patent term ended approximately 20 years after the relevant nonprovisional filing date, subject to any patent-term adjustment or terminal-disclaimer treatment recorded in the USPTO file. The patent therefore cannot presently block US manufacture, sale, use, or combination therapy involving DPP-4 inhibitors.

Event	Status
US patent grant	May 24, 2005
Patent type	Utility patent
Claim type	Methods of treatment and related pharmaceutical use
Current enforceability	Expired
Current US exclusivity	None
Patent-term extension under Hatch-Waxman	No current commercial relevance identified
Regulatory exclusivity	Separate from patent term and product-specific

The grant date does not determine the expiration date. For a pre-1995 filing, the former 17-year-from-grant rule could apply, but this patent belongs to the modern 20-year-from-filing regime. The controlling expiration and maintenance information should be taken from the USPTO patent record and prosecution file, rather than calculated solely from the issue date (USPTO, n.d.-a; USPTO, n.d.-b).

What is the Orange Book status of US 6,890,898?

US 6,890,898 is not a product-specific Orange Book patent for Januvia, Janumet, Onglyza, Tradjenta, Nesina, or another approved DPP-4 product.

The Orange Book lists patents submitted by an NDA holder for an approved drug and its approved uses, formulations, or methods. An early platform patent can be scientifically relevant to a drug class without being listed for a later-approved product. Orange Book listing depends on the NDA holder's submission and FDA's listing criteria, not simply on whether a patent broadly mentions the active mechanism (FDA, 2024).

Consequences include:

An ANDA applicant would not ordinarily certify to US 6,890,898 as an Orange Book-listed patent.
The patent would not create a standalone Paragraph IV filing obligation.
Any Paragraph IV challenge involving a DPP-4 product would target patents listed for that product's NDA.
The patent's expiration does not remove or shorten separate formulation, salt, crystalline-form, or method-of-use patents.

Which DPP-4 products are relevant to the patent landscape?

The principal approved DPP-4 inhibitors and their original sponsors are:

Product	Active ingredient	Original sponsor	Main commercial combination
Januvia	Sitagliptin	Merck	Sitagliptin, often with metformin
Janumet	Sitagliptin/metformin	Merck	Fixed-dose combination
Onglyza	Saxagliptin	AstraZeneca/Bristol Myers Squibb	Saxagliptin, including with metformin
Kombiglyze XR	Saxagliptin/metformin	AstraZeneca/Bristol Myers Squibb	Extended-release combination
Tradjenta	Linagliptin	Boehringer Ingelheim/Eli Lilly	Linagliptin, including with metformin
Jentadueto	Linagliptin/metformin	Boehringer Ingelheim/Eli Lilly	Fixed-dose combination
Nesina	Alogliptin	Takeda	Alogliptin, including with metformin
Kazano	Alogliptin/metformin	Takeda	Fixed-dose combination
Vipidia/other regional products	Vildagliptin or alogliptin	Novartis or Takeda	Regional combination products

These products may fall within the conceptual subject matter of claims 1 and 2 because they are DPP-4 inhibitors used with metformin. That does not establish infringement during the patent term. It also does not establish that the claims would have survived validity challenges against later-developed compounds.

How does the patent compare with commercial DPP-4 patent estates?

US 6,890,898 is a platform or combination-use patent. Commercial DPP-4 estates are usually layered across compound, salt, crystalline form, formulation, manufacturing process, dosing, and combination patents.

Estate type	Typical protected subject matter	Relative commercial importance
US 6,890,898	DPP-4 inhibition plus specified therapy	Historical platform relevance
Compound patent	Specific active molecule	Usually highest during launch period
Salt or polymorph patent	Solid form or pharmaceutical salt	Can delay generic substitution
Formulation patent	Extended release, tablet, excipient or dosage form	Relevant to ANDA design-around
Combination patent	Active ingredient plus metformin or another agent	Relevant to fixed-dose products
Method-of-use patent	Renal dosing, cardiovascular use, glycemic control	Depends on listing and claim construction
Process patent	Synthesis, purification or crystallization	Manufacturing barrier, often easier to design around

For sitagliptin, the core Merck compound and related formulation and combination patents were more commercially important than this earlier broad method patent. The same analysis applies to saxagliptin, linagliptin and alogliptin. A later compound patent can block a product even when US 6,890,898 has expired.

What formulation patents are relevant?

US 6,890,898 does not principally claim a tablet formulation, extended-release matrix, coating system, particle-size distribution, or fixed-dose composition. Claim 87 recites a composition containing a pharmaceutically acceptable carrier, a DPP-4 inhibitor and another therapeutic agent, but it remains tied to the claimed treatment methods.

The patent does not provide a strong formulation barrier against:

Immediate-release DPP-4 tablets
Extended-release metformin combinations
Bilayer tablets
Multilayer fixed-dose products
Separate co-packaged products
Alternative excipient systems

A generic manufacturer could therefore avoid any surviving formulation patent by using a different dosage form or excipient system. Because US 6,890,898 has expired, its composition language has no current exclusionary effect.

What method-of-use protection remains?

The patent's method-of-use concepts include:

Treating Type 2 diabetes
Modifying glucose metabolism
Reducing insulin resistance
Reducing glucose intolerance
Reducing hyperglycemia
Reducing hyperinsulinemia
Reducing obesity
Reducing hyperlipidemia or hyperlipoproteinemia
Increasing the plasma half-life of selected peptide hormones
Avoiding immunosuppression while producing metabolic effects

These uses are broad and functional. They do not resemble the narrower, product-specific use patents commonly listed in the Orange Book, such as a defined patient subgroup, dosing interval, renal-impairment regimen, or cardiovascular-risk indication.

Were Paragraph IV challenges or litigation directed to US 6,890,898?

No current Paragraph IV or patent-litigation significance attaches to US 6,890,898 because the patent is expired and is not the principal Orange Book patent for an approved DPP-4 product.

DPP-4 litigation has generally centered on product-specific patents asserted by the NDA holder against ANDA applicants. The relevant disputes have involved compound, crystalline-form, formulation, combination, and dosing patents for products such as sitagliptin, saxagliptin and linagliptin. Those proceedings do not convert an expired platform patent into an enforceable barrier.

A Paragraph IV certification against a DPP-4 product must be assessed against the patents listed for the relevant NDA, including patent-use codes and expiration information in the current Orange Book. US 6,890,898 should not be treated as a substitute for that product-level analysis (FDA, 2024).

What biosimilar risk exists for this patent?

No biosimilar issue arises directly. DPP-4 inhibitors are generally small-molecule drugs approved through the NDA and ANDA pathways, not biologics regulated under the biosimilar provisions of the Public Health Service Act.

The relevant competitive risks are:

ANDA filings for generic sitagliptin, saxagliptin, linagliptin or alogliptin
Authorized generics
Generic fixed-dose DPP-4/metformin combinations
Regional generic products for vildagliptin
Therapeutic substitution by GLP-1 receptor agonists and SGLT2 inhibitors

US 6,890,898 does not create a biosimilar-style exclusivity period and does not affect the biologic reference-product framework.

How strong is the patent estate for US 6,890,898?

The estate was conceptually broad but technically vulnerable.

Strengths

Broad functional coverage of DPP-4 inhibitor combination therapy
Express coverage of metformin combinations
Multiple fallback claim groups
Claims covering simultaneous, sequential and separate dosing
Chemical subgenera directed to boronyl peptidomimetics
Claims addressing both glucose metabolism and peptide-hormone metabolism

Weaknesses

The broadest claims depend on functional definitions of DPP-4 inhibition and metabolic benefit.
"Sufficient to modify" and "not sufficient to suppress" may create claim-construction and proof issues.
The immunosuppression distinction requires comparative pharmacology.
The Markush claims cover large chemical spaces and may face written-description and enablement scrutiny.
Several supplied claims contain apparent transcription, typographical or dependency errors.
The formula claims cannot be evaluated fully without the missing structural drawings.
The claims are method claims, so direct infringement requires performance of the claimed treatment steps.
Expiration eliminates present enforcement value.

The practical rating is therefore:

Criterion	Assessment
Historical scope	Broad
Compound specificity	Low in independent claims
Combination relevance	High for DPP-4 plus metformin
Formulation protection	Low
Manufacturing protection	Minimal
Orange Book relevance	Low or none
Current enforceability	None
Design-around difficulty during term	Moderate
Current commercial blocking value	Zero

What licensing or transaction relevance does the patent have?

The patent may have historical licensing significance because early DPP-4 intellectual property often originated in academic or biotechnology research programs and was later complemented by pharmaceutical-company compound patents. Its present standalone licensing value is limited because the US rights have expired.

A transaction involving a DPP-4 product should instead examine:

Surviving foreign counterparts
Product-specific compound patents
Combination patents
Formulation and crystalline-form patents
Patent-term adjustments and extensions
Regulatory exclusivity
Settlement agreements with generic applicants
Manufacturing know-how and process patents
Freedom to operate in each target jurisdiction

The patent may still have documentary value in diligence as prior art, a source of inventorship and priority information, or evidence of early DPP-4 combination concepts. It should not be valued as a current US exclusivity asset.

What geographic coverage does the patent provide?

US 6,890,898 provides US territorial rights only. Any foreign protection depends on separate national or regional family members. The existence of a US patent does not establish enforceability in Europe, Japan, China, Canada, Australia or other markets.

Geographic diligence should distinguish:

Patent-family members
National-phase grants
Expired and lapsed rights
Patent-term adjustments
Supplementary protection certificates
Local Orange Book or linkage systems
Local patent litigation and settlement records

A US expiration analysis cannot be exported to foreign jurisdictions.

Key Takeaways

US 6,890,898 is a historical DPP-4 combination-treatment patent.
Its core concept is a DPP-4 inhibitor administered with metformin or another specified therapeutic agent.
Claims 1 and 2 are broad method claims covering glucose metabolism modification and Type 2 diabetes treatment.
Claims 12-24, 46-58 and 59-73 add extensive chemical Markush limitations.
Claims 26-33 and 37 focus on boronyl peptidomimetic inhibitors.
Claims 78-81 broaden "conjointly administering" to simultaneous, sequential, separate or same-composition dosing.
The patent is expired and has no current US blocking effect.
It is not a current Orange Book barrier for Januvia, Janumet, Onglyza, Tradjenta, Nesina or related products.
Paragraph IV analysis must focus on product-specific listed patents.
No biosimilar pathway is implicated because DPP-4 inhibitors are small molecules.
Commercial risk now lies in later compound, formulation, combination, crystalline-form and manufacturing patents.

FAQs

Does US 6,890,898 cover Janumet?

Its broad combination language conceptually reaches DPP-4 inhibitor and metformin therapy, but the patent is expired. Current Janumet freedom to operate depends on surviving sitagliptin, metformin-combination, formulation and other Merck patents.

Can a generic manufacturer launch a DPP-4/metformin product despite US 6,890,898?

Yes, the expired patent does not independently prevent launch. The manufacturer must still address patents listed for the specific reference drug and any applicable non-Orange-Book patent claims.

Does the patent claim sitagliptin specifically?

The broad claims do not name sitagliptin. They claim DPP-4 inhibitors functionally. The chemical Markush claims cover defined structural classes and cannot be mapped reliably to sitagliptin without the complete formula drawings and claim construction.

Is the immunosuppression limitation important for infringement?

Historically, yes. An accused product would need to satisfy the claimed metabolic and immunosuppression relationship where that limitation appears. The limitation also creates substantial proof and validity issues.

Does US 6,890,898 protect a fixed-dose combination tablet?

Claim 87 reaches a composition used in the claimed method, and claims 78-81 recognize same-composition administration. The patent is expired, however, and it does not provide a current formulation monopoly.

References

U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: The Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
U.S. Patent and Trademark Office. (n.d.-a). Patent term calculator. https://www.uspto.gov/patents/laws/patent-term-calculator
U.S. Patent and Trademark Office. (n.d.-b). Patent Center. https://patentcenter.uspto.gov/
U.S. Patent No. 6,890,898. (2005). Methods for modifying glucose metabolism using dipeptidylpeptidase IV inhibitors. United States Patent and Trademark Office.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2003264609	⤷ Start Trial
Australia	2493599	⤷ Start Trial
Australia	766219	⤷ Start Trial
Canada	2319195	⤷ Start Trial
Canada	2755452	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,890,898

Summary for Patent: 6,890,898