United States Patent 8,618,075: Claim Scope, Cedazuridine Coverage and Cytidine Deaminase Patent Landscape

U.S. Patent No. 8,618,075 protects kits and administration methods using a difluorinated cytidine deaminase inhibitor, identified in the claims as Formula I and Compound 1a. The claims cover the inhibitor alone, formulations containing the inhibitor, combinations with cytidine deaminase substrate drugs, and methods intended to prevent degradation of those substrate drugs.

The patent is particularly relevant to oral decitabine and cedazuridine products such as Inqovi. Its strongest commercial relevance is claim 18, which targets administration of the inhibitor to a patient receiving a cytidine deaminase substrate drug, including decitabine. The patent does not, based on the supplied claims, claim decitabine alone, a broad class of all CDA inhibitors, or every formulation of a CDA inhibitor.

What does U.S. Patent 8,618,075 cover?

The patent has four independent claim categories:

Independent claim	Protected subject matter	Key limitations
Claim 1	Kit containing Formula I compound	R1 and R2 must be fluoro; starred carbon may be R or S
Claim 9	Kit containing a pharmaceutical composition	Requires Formula I compound and a pharmaceutically acceptable excipient
Claim 15	Method of inhibiting CDA	Requires administration of the composition to a subject
Claim 18	Method of inhibiting degradation of a CDA substrate drug	Patient must be undergoing treatment with the substrate drug

The claims are narrower than a conventional composition-of-matter patent because the independent claims are directed to kits and methods rather than to the inhibitor as an unqualified chemical composition.

What chemical structure is protected?

The claims define Formula I by requiring:

A specified molecular scaffold shown in the patent;
Fluorine at both R1 and R2 positions;
Either R or S configuration at the carbon marked with an asterisk;
The compound itself or a pharmaceutically acceptable salt.

Claims 2, 3, 10, 11, 16, 17, 19 and 20 narrow the scope to Compound 1a. Claims 2, 10, 16 and 19 cover Compound 1a or a pharmaceutically acceptable salt. Claims 3, 11, 17 and 20 are limited to Compound 1a itself.

The supplied claim text does not reproduce the chemical drawings for Formula I or Compound 1a. The compound associated with this CDA-inhibitor program is cedazuridine, the CDA inhibitor used with oral decitabine in Inqovi. The patent document should control the final structural identification and stereochemical interpretation. [1]

How are the claims organized?

Claims 1 through 8: broad kit claims

Claim 1 covers a kit containing the Formula I compound or a pharmaceutically acceptable salt. It does not require a second active pharmaceutical ingredient, an excipient, a dosage form, or treatment instructions.

The dependent claims add different commercial configurations:

Claim	Limitation
2	Compound 1a or a pharmaceutically acceptable salt
3	Compound 1a without the salt alternative
4	A listed CDA substrate drug: 5-azacytidine, gemcitabine, ara-C, tezacitabine, 5-fluoro-2'-deoxycytidine or cytochlor
5	A CDA substrate drug other than decitabine
6	Decitabine
7	Unit dosage form
8	Information included in the kit

Claim 1 is structurally broad within the defined Formula I genus. Claim 6 is commercially important because it expressly covers a kit containing the inhibitor and decitabine.

Claims 4, 5 and 6 create overlapping dependent-claim positions. Decitabine falls outside claim 5 but within claim 6. The listed compounds in claim 4 are not an exhaustive definition of all possible CDA substrate drugs in the patent’s broader disclosure, but claim 4 itself is limited to that recited group.

Claims 9 through 14: pharmaceutical-composition kit claims

Claim 9 requires:

A kit;
A pharmaceutical composition containing the Formula I compound or salt; and
A pharmaceutically acceptable excipient.

This limitation distinguishes claim 9 from claim 1. A package containing the active compound alone may fall within claim 1 but not claim 9. A dosage form containing the active compound and excipient is more likely to implicate claim 9 if the kit requirement is satisfied.

Claims 10 and 11 narrow the compound to Compound 1a. Claims 12 through 14 mirror claims 4 through 6 by adding specified CDA substrate drugs, non-decitabine CDA substrates, or decitabine.

The kit requirement matters. A standalone tablet or capsule may not infringe claim 9 merely because it contains the claimed inhibitor. The claim requires a kit comprising the pharmaceutical composition. Whether commercial packaging qualifies depends on the product configuration, labeling, and the factual interpretation of “kit.”

Claims 15 through 17: CDA-inhibition method claims

Claim 15 covers a method for inhibiting cytidine deaminase by administering a composition containing the Formula I compound and an excipient to a subject.

The claim does not expressly require:

Decitabine;
Another CDA substrate drug;
A particular disease;
A particular dose;
A specified route of administration;
A particular treatment outcome.

Claims 16 and 17 narrow the method to Compound 1a, with claim 16 covering the salt alternative and claim 17 directed to Compound 1a.

These claims may reach uses of the inhibitor outside the decitabine combination, provided the accused conduct satisfies administration, subject, composition and CDA-inhibition limitations.

Claims 18 through 20: protection against CDA-mediated drug degradation

Claim 18 is the most directly relevant combination-treatment claim. It requires:

A subject undergoing treatment with a CDA substrate drug;
Administration of a composition containing Formula I or a pharmaceutically acceptable salt; and
The purpose or result of inhibiting degradation of the CDA substrate drug by CDA.

Claims 19 and 20 narrow claim 18 to Compound 1a.

This claim category is functionally tied to pharmacokinetic protection. The inhibitor is used to reduce enzymatic degradation of a substrate drug, allowing greater systemic exposure to the substrate. Decitabine is the most commercially important example because oral decitabine is vulnerable to rapid metabolism by CDA.

What products and uses are most exposed?

Product or use	Claim exposure
Cedazuridine-containing kit	Claims 1-3
Cedazuridine formulation kit with excipient	Claims 9-11
Cedazuridine plus decitabine kit	Claims 1, 6, 9 and 14
Cedazuridine plus azacytidine, gemcitabine or ara-C	Claims 4 and 12
Cedazuridine administered to inhibit CDA	Claims 15-17
Cedazuridine administered during decitabine therapy	Claims 18-20
Cedazuridine tablet sold without a qualifying kit	Potentially weaker exposure under the supplied claims
A chemically different CDA inhibitor	Outside the literal Formula I and Compound 1a limitations

The patent is strongest against a product that is packaged and promoted as a combination kit containing Compound 1a and decitabine. It is less direct against a standalone CDA inhibitor product whose packaging does not satisfy the kit limitations.

Does the patent cover Inqovi?

Inqovi contains decitabine and cedazuridine. The FDA approved Inqovi for certain adult patients with myelodysplastic syndromes and chronic myelomonocytic leukemia. The product is an oral fixed-dose combination, making it commercially aligned with the patent’s CDA-substrate and inhibitor combination claims. [2]

The relevant claim paths are:

Claim 1, if the product is treated as a kit containing the Formula I inhibitor;
Claim 6, because decitabine is expressly recited;
Claim 9, if the product is characterized as a kit containing a pharmaceutical composition and excipient;
Claim 14, for the corresponding composition-kit formulation;
Claim 18, because the patient receives a CDA substrate drug and the inhibitor is intended to inhibit its degradation;
Claims 19 and 20, if Compound 1a is the relevant compound configuration.

The patent does not by itself establish that every Inqovi commercial configuration infringes every listed claim. Product classification, labeling, packaging, formulation, and the exact identity of Compound 1a remain material to an infringement analysis.

What is the patent strength?

Strengths

The patent has four meaningful protection layers:

A Formula I inhibitor genus with two fluorine substituents;
Compound 1a and its salt;
Combination kits with CDA substrate drugs, including decitabine;
Method claims directed to preventing degradation of a substrate drug.

The decitabine-specific dependent claims improve commercial alignment with oral decitabine therapy. The method claims also create potential exposure for conduct involving administration and treatment instructions even if a competing product attempts to avoid kit-based claims.

Limitations

The main limitations are claim-format and proof requirements:

Claims 1 and 9 require a kit;
Claim 9 requires an excipient;
Claims 15 and 18 require administration to a subject;
Claim 18 requires treatment with a CDA substrate drug;
The method claims require proof of the claimed functional purpose or effect;
No supplied claim independently covers every formulation, salt, polymorph, dosage strength or manufacturing process.

A competitor may seek to design around the patent by using a different CDA inhibitor, excluding Compound 1a, separating products rather than selling a kit, changing labeling, or developing a formulation not covered by the kit limitations. Such strategies would require claim construction and fact-specific analysis.

What formulation patents are relevant?

Patent 8,618,075 is not a broad formulation patent. Claim 9 requires a pharmaceutical composition and a pharmaceutically acceptable excipient, but it does not specify:

Tablet composition;
Capsule composition;
Excipients;
Release profile;
Particle size;
Polymorph;
Solid-state form;
Dissolution characteristics;
Manufacturing process;
Dose strength.

The claim can therefore reach a qualifying kit containing a composition with an excipient, but it does not provide detailed formulation protection comparable to a patent directed specifically to a tablet, stability system, solid form or manufacturing process.

For freedom-to-operate purposes, later patents and applications directed to cedazuridine formulations, fixed-dose decitabine combinations, solid forms and manufacturing processes must be evaluated separately from U.S. 8,618,075.

What is the Orange Book status?

The FDA Orange Book lists patents submitted by an NDA holder for an approved drug product. A patent directed to kits or methods is not automatically listed merely because it relates to the drug’s mechanism or commercial use. Listing depends on whether the patent claims the approved drug, an approved method of use, or another qualifying statutory category under FDA Orange Book rules. [3]

The practical analysis is:

Issue	Relevance to U.S. 8,618,075
Drug substance listing	The supplied claims are not standalone composition-of-matter claims
Drug product listing	Claim 9 may be relevant only if the approved product satisfies the kit and composition limitations
Method-of-use listing	Claims 15 and 18 may be relevant if they correspond to the approved labeling
Paragraph IV exposure	Depends on whether the patent is listed against the relevant NDA
Regulatory exclusivity	Separate from patent term and does not arise from this patent

A Paragraph IV certification against an Orange Book-listed patent would require a generic applicant to assert that the patent is invalid, unenforceable or not infringed. If the patent is not listed against the relevant NDA, a Paragraph IV certification would not be the ordinary pathway for challenging that patent.

When does U.S. Patent 8,618,075 lose exclusivity?

The patent number alone does not establish the final expiration date. The controlling date depends on:

The earliest effective nonprovisional filing date;
Patent-term adjustment;
Any terminal disclaimer;
Any patent-term extension;
Whether the patent remains enforceable for the relevant claims.

Under the Hatch-Waxman patent-term framework, the ordinary term is generally 20 years from the earliest effective U.S. nonprovisional filing date, subject to statutory adjustments. [4] A precise expiration calculation requires the USPTO patent record, including the term-adjustment statement and any disclaimer or extension records.

The patent’s issuance in 2013 does not mean that exclusivity runs for 20 years from issuance. Patent term generally runs from the relevant filing date, not the grant date.

Are there Paragraph IV or generic launch risks?

The principal generic-risk pathways are:

Direct fixed-dose combination challenge

A generic sponsor could challenge claims directed to a decitabine-cedazuridine kit or composition. The sponsor would likely focus on:

Whether its product is a “kit”;
Whether the product contains Compound 1a;
Whether the product includes the claimed excipient;
Whether its labeling induces the claimed administration method;
Whether the patent claims are anticipated or obvious over prior CDA inhibitor and decitabine disclosures.

Separate-component launch

A sponsor could market components separately, subject to regulatory and patent constraints. Separate packaging may reduce exposure to kit claims, but it would not necessarily avoid method claims if the product labeling directs administration of the inhibitor during substrate-drug treatment.

Alternative CDA inhibitor

A product using a chemically distinct CDA inhibitor may avoid literal infringement if it does not contain Formula I or Compound 1a. The doctrine of equivalents could still become relevant, but the structural limitations and fluorine substitutions would be central to that analysis.

Which companies are commercially relevant?

The commercial landscape includes:

Taiho Pharmaceutical, associated with the development and commercialization of Inqovi;
Astex Pharmaceuticals and related development entities associated with the CDA-inhibitor program;
Generic-drug companies evaluating oral decitabine and cedazuridine combinations;
Developers of alternative oral hypomethylating-agent technologies;
Companies developing CDA inhibitors for use with cytidine analogs.

The competitive issue is not limited to decitabine. The claims also identify azacytidine, gemcitabine, cytarabine, tezacitabine, 5-fluoro-2'-deoxycytidine and cytochlor as potential substrate drugs. This expands the technical disclosure and dependent-claim relevance beyond the marketed decitabine combination.

What is the geographic scope?

U.S. Patent 8,618,075 provides rights only in the United States. Foreign protection requires separate national or regional patents. The existence of a U.S. patent does not establish protection in:

Europe;
Japan;
China;
Canada;
Australia;
South Korea;
Other jurisdictions.

For global launch planning, the U.S. patent must be mapped against its international family, national-phase grants, expiration dates, claim amendments and local maintenance status.

What manufacturing and IP barriers remain?

The patent does not, on the supplied claims, directly claim:

A process for synthesizing Compound 1a;
A specific intermediate;
A crystalline polymorph;
A salt-selection process;
A tablet-compression process;
A stability-improvement process;
A specific container-closure system.

Manufacturing risk may therefore arise from separate process, intermediate, solid-state or formulation patents. A generic developer could avoid U.S. 8,618,075 yet still face other patents covering the active ingredient, combination product, manufacturing route or approved use.

Key Takeaways

U.S. Patent 8,618,075 protects kits and methods involving a difluorinated CDA inhibitor identified as Compound 1a and associated with cedazuridine.
Claims 1 and 9 focus on kits; claims 15 and 18 focus on administration methods.
Decitabine is expressly covered by claims 6 and 14.
Claim 18 is the most commercially relevant claim for oral decitabine-cedazuridine treatment.
The patent is not, based on the supplied claims, a broad standalone composition-of-matter patent.
A competitor may face different risks depending on packaging, labeling, excipients, administration instructions and the identity of its CDA inhibitor.
Exact patent expiration requires the USPTO term-adjustment and disclaimer records.
Orange Book relevance depends on whether the patent is listed against the applicable NDA and whether its claims correspond to the approved product or method of use.
Separate patents may control formulations, solid forms, manufacturing processes and later fixed-dose combination technology.
U.S. rights do not establish equivalent protection in foreign jurisdictions.

FAQs

Is decitabine itself patented by U.S. Patent 8,618,075?

No. The supplied claims do not claim decitabine alone. They cover kits and methods involving a Formula I CDA inhibitor, with decitabine recited as a second compound in dependent claims 6 and 14 and as the substrate drug contemplated by claim 18.

Can a generic avoid the patent by selling cedazuridine without decitabine?

Possibly for the decitabine-specific claims, but not necessarily for claims 1, 9 or 15. Exposure would depend on whether the product satisfies the kit, composition and CDA-inhibition limitations.

Does claim 18 cover any use of cedazuridine with any cytidine analog?

Claim 18 is broader than the decitabine-specific dependent claims, but it requires treatment with a CDA substrate drug and administration intended to inhibit degradation of that drug by CDA. The exact scope depends on claim construction and the accused product’s labeling and use.

Is a tablet automatically a “kit” under the patent?

No. A tablet may be part of a kit, but a standalone tablet is not automatically a kit. The packaging, accompanying components, information and commercial presentation are relevant to the analysis.

Does patent expiration eliminate FDA exclusivity at the same time?

No. Patent term and FDA regulatory exclusivity are separate. A patent may expire before or after an applicable period of new-drug, orphan-drug or other regulatory exclusivity.

References

United States Patent and Trademark Office. (2013). U.S. Patent No. 8,618,075, Cytidine deaminase inhibitors.
U.S. Food and Drug Administration. (2020). INQOVI (decitabine and cedazuridine) prescribing information.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Code, 35 U.S.C. § 154. Patent term.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Taiho Oncology	INQOVI	cedazuridine; decitabine	TABLET;ORAL	212576-001	Jul 7, 2020		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				METHOD FOR INHIBITING CYTIDINE DEAMINASE BY ADMINISTERING CEDAZURIDINE	⤷ Start Trial
Taiho Oncology	INQOVI	cedazuridine; decitabine	TABLET;ORAL	212576-001	Jul 7, 2020		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				METHOD FOR INHIBITING DEGRADATION OF A CDA SUBSTRATE BY ADMINISTERING CEDAZURIDINE	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	2207786	⤷ Start Trial	301256	Netherlands	⤷ Start Trial
European Patent Office	2207786	⤷ Start Trial	301257	Netherlands	⤷ Start Trial
European Patent Office	2207786	⤷ Start Trial	CA 2023 00037	Denmark	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,618,075

Which drugs does patent 8,618,075 protect, and when does it expire?

Summary for Patent: 8,618,075