US Patent 7,300,935: Claim Scope, Patent Term, Litigation Risk, and Competitive Landscape
US Patent 7,300,935 protects two narrowly defined thieno[2,3-d]pyrimidine compounds and their salts. The claims do not cover a broad chemical genus, therapeutic method, dosage regimen, formulation, manufacturing process, or biologic. They are composition-of-matter claims directed to two discrete small molecules.
The patent issued on November 27, 2007. Its commercial importance depends on whether either claimed compound entered development, whether related continuation or divisional patents issued, and whether the patent received patent-term adjustment. The ordinary 20-year term for a US nonprovisional patent would place expiration roughly between 2023 and 2025, subject to the application’s effective filing date and any term adjustment. The patent is therefore unlikely to represent a currently enforceable blocking right in 2025 unless an unusual term adjustment or related unexpired patent applies. [1][2]
What does US Patent 7,300,935 claim?
The patent contains two independent composition claims based on a common thieno[2,3-d]pyrimidine-2,4-dione core.
| Claim |
Key substituents |
Protected subject matter |
| 1 |
2,6-Difluorobenzyl at N1; 2-pyridyl at C3; substituted aminomethyl group at C5; para-N-methoxyurea phenyl at C6 |
One specifically defined compound and its salts |
| 2 |
2,6-Difluorobenzyl at N1; 6-methoxy-3-pyridazinyl at C3; dimethylaminomethyl at C5; para-N-methoxyurea phenyl at C6 |
A second specifically defined compound and its salts |
The common structural framework is:
- A tetrahydrothieno[2,3-d]pyrimidine-2,4-dione nucleus.
- A 2,6-difluorobenzyl substituent on the ring nitrogen.
- A 4-substituted phenyl group at the 6-position.
- An N-methoxyurea substituent on that phenyl ring.
- A heteroaryl group and aminomethyl substituent defining the individual compound.
The claims use “or a salt thereof.” That language generally extends protection to salts of the specifically claimed molecular entity, subject to ordinary claim-construction principles and the salt’s relationship to the claimed active moiety. It does not create an independent genus covering unrelated analogues.
How narrow is the chemical scope of the claims?
The claims are narrow. Each claim fixes nearly every atom-level substituent.
Claim 1 scope
Claim 1 requires all of the following:
- A 2,6-difluorobenzyl group at the N1 position.
- A 2-pyridinyl group at the 3-position.
- A 5-position aminomethyl substituent in which the nitrogen is attached to:
- a 2-ethoxyethyl group; and
- a methyl group.
- A 6-position para-phenyl substituent.
- An N-methoxyurea group attached to that phenyl ring.
- The specified thieno[2,3-d]pyrimidinedione stereochemical and connectivity arrangement.
Changing the 2-ethoxyethyl group to an ethyl, hydroxyethyl, propyl, or other alkyl group would move the resulting compound outside the literal wording of claim 1. Replacing the 2-pyridyl group with a substituted pyridyl, pyridazinyl, phenyl, or another heteroaryl group would also avoid literal infringement of this claim.
Claim 2 scope
Claim 2 requires:
- The same 2,6-difluorobenzyl N1 substituent.
- A 6-methoxy-3-pyridazinyl group at the 3-position.
- A dimethylaminomethyl substituent at the 5-position.
- The same para-N-methoxyurea phenyl group at the 6-position.
Claim 2 is structurally independent from claim 1. A compound that falls outside claim 1 may still infringe claim 2 if it contains the precise pyridazinyl and dimethylaminomethyl combination recited in claim 2.
What the claims do not cover
Based on the supplied claims, US 7,300,935 does not directly claim:
- A broad Markush genus.
- Any compound with a different urea substituent.
- Any compound with a different benzyl substitution pattern.
- Any compound with a different heteroaryl group.
- Pharmaceutical compositions as a separate claim category.
- Tablets, capsules, injectable products, or other dosage forms.
- A method of treating cancer, inflammation, or another disease.
- A dosage regimen or administration schedule.
- A crystalline polymorph, hydrate, solvate, or particle-size specification.
- A synthetic process or intermediate.
- A prodrug or metabolite.
Those subject matters could be covered by other patents in the same family or by separate patent families, but they are not established by the two claims supplied.
What is the likely pharmacological and commercial significance?
The claimed molecules belong to a medicinal-chemistry series built around a substituted thieno[2,3-d]pyrimidinedione core. The N-methoxyurea phenyl group and heteroaryl substituents indicate a targeted small-molecule discovery program rather than a conventional generic-drug formulation patent.
The claims alone do not identify:
- The biological target.
- The intended therapeutic indication.
- The clinical development code.
- The sponsor or licensee.
- Whether either compound reached an investigational new drug application.
- Whether an approved product contains either claimed molecule.
A patent claim is not evidence of clinical advancement. Without an identified approved product, the direct revenue exposure from this patent cannot be quantified from the claims alone.
When does US Patent 7,300,935 lose exclusivity?
US patent term is generally 20 years from the earliest effective filing date of the relevant nonprovisional application, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and continuity rules. The term does not run for 20 years from the 2007 grant date. [2][3]
| Event |
Date or rule |
| Patent grant |
November 27, 2007 |
| Ordinary US term |
20 years from the applicable earliest nonprovisional filing date |
| Possible adjustment |
Patent-term adjustment for USPTO delay |
| Possible extension |
Patent-term extension under 35 U.S.C. § 156, generally relevant only to an approved product |
| Current commercial implication |
The original patent is likely at or beyond its ordinary term by 2025 |
A precise expiration date requires the complete continuity chain and the USPTO patent-term calculation. Any continuation patent must be analyzed separately. A continuation may preserve an earlier priority date while receiving a later grant, but it does not automatically receive a new 20-year term from the continuation filing date.
Does patent-term extension appear commercially important?
Patent-term extension under 35 U.S.C. § 156 applies to certain regulatory review periods for approved products. The supplied claims do not identify an approved active ingredient, NDA, or regulated product. On that record, there is no established basis to treat § 156 extension as a material source of additional exclusivity. [3]
What is the Orange Book status of the claimed compounds?
The Orange Book lists patents associated with approved drug products and approved indications. It does not list every pharmaceutical patent issued by the USPTO. [4]
The supplied claims do not identify an approved drug, NDA number, or sponsor. There is therefore no established Orange Book listing tied directly to either claimed compound.
If a future or historical approved product had contained one of these molecules, the relevant Orange Book analysis would require:
- The NDA holder.
- The active ingredient name.
- The listed patent number.
- The patent-use code, if applicable.
- The patent expiration date.
- Any delisting, dispute, or Paragraph IV history.
Without an approved product association, US 7,300,935 should be treated as a standalone composition patent rather than an established Orange Book barrier.
What Paragraph IV challenges could apply?
A Paragraph IV certification is relevant to an ANDA applicant seeking approval of a generic drug for an approved reference listed drug. The applicant asserts that the listed patent is invalid, unenforceable, or will not be infringed. [5]
For US 7,300,935, Paragraph IV risk would arise only if:
- One of the claimed compounds were the active ingredient in an approved reference product.
- The patent were listed for that product.
- The patent remained within its enforceable term.
- A generic applicant filed an ANDA referencing the product.
The claims do not establish those conditions. If the patent was never linked to an approved drug, it would not create a conventional Orange Book Paragraph IV pathway. A company developing a chemically similar unapproved product could still face ordinary patent litigation, but that would be a different dispute from an ANDA certification case.
Does the patent create biosimilar risk?
No direct biosimilar issue exists. The claims cover small molecules, not biologics. Biosimilar applications proceed under the Public Health Service Act’s section 351(k) pathway, while small-molecule generics generally proceed through section 505(j) ANDAs. [6]
The relevant competitive pathways are:
- ANDA approval for an identical active ingredient.
- 505(b)(2) approval for a modified product or alternative clinical package.
- Independent new drug development for a chemically distinct analogue.
- Research and development of a non-infringing substitute.
A biosimilar applicant would not be an expected challenger to these claims.
What formulation patents are protected by US 7,300,935?
None are apparent from the supplied claims. The claims are directed to the active chemical entities and salts. They do not recite:
- A specific excipient.
- A release profile.
- A coating.
- A particle-size distribution.
- A formulation concentration.
- A route of administration.
- A device or delivery system.
A company could potentially develop a formulation of one claimed compound and still require freedom-to-operate clearance against separate formulation patents. Conversely, the absence of a formulation claim in US 7,300,935 does not establish that a finished dosage form is free of all patent risk.
What manufacturing and process risks remain?
The patent does not, on the supplied claims, cover a manufacturing process. A competitor using a different synthetic route could avoid process claims in this patent while still infringing the composition claim if the resulting product is one of the claimed compounds.
The most important manufacturing questions are:
| Issue |
Relevance |
| Salt selection |
A salt of the claimed active moiety may remain within the claim |
| Polymorph selection |
A separate solid-form patent could create additional risk |
| Synthetic route |
Relevant only if separately claimed |
| Intermediate chemistry |
Not covered by the supplied composition claims |
| Impurity profile |
May affect regulatory approval and product quality, but does not itself define infringement |
| Analytical characterization |
Needed to determine whether a manufactured compound matches the claimed structure |
For a small-molecule product, the composition claim generally presents the strongest form of patent protection because infringement can occur regardless of the manufacturing route.
How strong is the patent estate?
The strength of US 7,300,935 should be characterized as narrow but potentially strong against exact copies of the claimed molecules.
| Dimension |
Assessment |
| Claim breadth |
Narrow |
| Claim type |
Composition of matter |
| Design-around flexibility |
Relatively high |
| Protection against exact active ingredient copying |
Potentially strong during term |
| Formulation coverage |
Not shown |
| Method-of-use coverage |
Not shown |
| Process coverage |
Not shown |
| Biosimilar relevance |
None |
| Orange Book significance |
Unestablished from the supplied record |
| Current-term significance |
Likely limited by 2025 unless an unexpired related right exists |
The key distinction is between claim strength and estate breadth. A precise composition claim can be difficult to challenge if the exact compound is copied, but a two-compound patent provides limited leverage against a competitor that changes a peripheral substituent and preserves pharmacological activity.
Which companies are challenging the patent?
No challenger, ANDA applicant, litigation matter, or settlement agreement is established by the supplied claims. The patent number alone does not show that a Paragraph IV notice, district-court action, Federal Circuit appeal, or licensing transaction occurred.
A litigation search should distinguish among:
- Cases involving US 7,300,935 itself.
- Cases involving continuation or divisional patents.
- Cases involving related foreign counterparts.
- Inter partes review or post-grant proceedings.
- Commercial disputes involving a different compound in the same research program.
The absence of a known litigation event does not prove that no dispute occurred, but the claims provide no evidence of one.
How does this patent compare with generic launch scenarios?
Exact-copy scenario
An exact copy of either claimed compound would present the highest infringement risk during the enforceable patent term. Salt conversion would not necessarily avoid infringement because the claims expressly include salts.
Single-substituent design-around
A competitor could evaluate changes to:
- The 2,6-difluorobenzyl group.
- The N-methoxyurea group.
- The pyridyl or pyridazinyl substituent.
- The aminomethyl side chain.
- The methoxy or ethoxy functionality.
Such a compound would require analysis under the doctrine of equivalents, written description issues in related patents, and any separate family patents. A small structural change does not automatically eliminate all patent risk.
Generic launch after expiration
Once the enforceable term ends, the composition claims generally cease to block manufacture and sale of the claimed compounds. Regulatory exclusivity, separate patents, trade secrets, controlled-substance rules, or product-specific barriers could still affect launch timing, but none is established by the supplied claims.
What is the geographic coverage of the patent estate?
US 7,300,935 has territorial effect in the United States. It does not itself protect the compounds in Europe, Japan, China, Canada, or other markets.
International protection would require separate national or regional patents, such as:
- European Patent Office designations.
- Japanese national patents.
- Chinese national patents.
- Canadian patents.
- Australian patents.
- Other PCT national-phase rights.
The existence, enforceability, and expiration of foreign counterparts cannot be inferred solely from the US patent number. A multinational launch requires a jurisdiction-by-jurisdiction review of corresponding family members.
Key Takeaways
- US 7,300,935 claims two specific thieno[2,3-d]pyrimidinedione compounds and their salts.
- The claims are narrow composition-of-matter claims, not broad genus claims.
- The patent does not, based on the supplied claims, cover formulations, methods of treatment, manufacturing processes, or biologics.
- Exact copies of either molecule would have faced the principal infringement risk during the patent term.
- The ordinary US patent term likely ended between 2023 and 2025, depending on the effective filing date and patent-term adjustment.
- No Orange Book listing, approved drug, Paragraph IV challenge, biosimilar dispute, license, settlement, or litigation event is established by the claims provided.
- The patent has no direct biosimilar relevance because it covers small molecules.
- Related continuation, divisional, foreign, formulation, method-of-use, or process patents could materially change the overall freedom-to-operate analysis.
FAQs
Is US Patent 7,300,935 a Markush patent?
No. The supplied claims identify two individual compounds. They do not recite broad variable substituent definitions characteristic of a conventional Markush genus claim.
Can changing the salt avoid claim 1 or claim 2?
Not necessarily. Each claim expressly covers the named compound “or a salt thereof.” A different pharmaceutically acceptable salt may remain within the claim if it contains the claimed active moiety.
Does the patent cover a tablet containing either compound?
The supplied claims do not expressly cover tablets, capsules, excipients, coatings, or release profiles. Separate formulation claims would be required for that protection.
Would an ANDA applicant automatically need a Paragraph IV certification?
No. Paragraph IV certification is tied to a patent listed for an approved reference drug. The claims do not establish that either compound was the subject of an approved product or Orange Book listing.
Can a competitor develop a different thienopyrimidine compound?
Potentially, but the design-around must be evaluated against the literal wording of these claims, the doctrine of equivalents, and any related patents covering broader analogues, therapeutic uses, formulations, salts, polymorphs, or manufacturing methods.
References
- United States Patent and Trademark Office. (2007). US Patent No. 7,300,935.
- United States Code, 35 U.S.C. § 154. Patent term.
- United States Code, 35 U.S.C. § 156. Extension of patent term.
- U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations (Orange Book).
- United States Code, 21 U.S.C. § 355(j)(2)(A)(vii)(IV). Paragraph IV certification.
- United States Code, 42 U.S.C. § 262(l). Biosimilar biological products.
