US Patent 10,702,521: Zoliflodacin Gonorrhea-Treatment Claims, Scope, Expiration and Patent Landscape

US Patent 10,702,521 protects methods of treating Neisseria gonorrhoeae infection with zoliflodacin, including the free base, the defined (2R) stereoisomer, pharmaceutically acceptable salts, mesylate salt, and pharmaceutical compositions. The patent is a method-of-use patent rather than a broad compound, manufacturing, or formulation patent. It is most relevant to U.S. commercialization of zoliflodacin, also known as ETX0914, if approved for gonorrhea.

The claims are narrow in disease indication but broad across product form. They cover administration of the specified compound for treating gonorrhea, whether administered as the free compound, a permitted acid-addition salt, the mesylate salt, or a composition containing the active ingredient. The patent does not, on its face, require a particular dose, route, treatment duration, patient subgroup, bacterial resistance profile, or formulation technology.

What drug does US Patent 10,702,521 protect?

The claimed compound is zoliflodacin, a spiropyrimidinetrione antibacterial developed for treatment of gonorrhea. The chemical structure in the claims is described as:

2-({4-[(3,4-dihydro-2H-pyrano[2,3-c]pyridin-6-ylmethyl)amino]-1-piperidinyl}methyl)-1,2-dihydro-3H,8H-2a,5,8a-triazaacenaphthylene-3,8-dione

The claims encompass:

Product form	Covered by claims
Unspecified compound or stereochemical form	Claims 1-4
(2R) stereoisomer	Claims 5-12
Pharmaceutically acceptable salts	Claims 1, 3, 5, 7, 10 and 11
Mesylate salt	Claims 8, 9 and 12
Pharmaceutical compositions with excipients	Claims 3, 4 and 10-12
Treatment of N. gonorrhoeae infection	All claims

Zoliflodacin is a small-molecule antibiotic. It is not a biologic, so biosimilar pathways do not apply. A future competitor would generally pursue an abbreviated new drug application, or ANDA, if the reference product receives FDA approval and the regulatory requirements are satisfied.

What is the scope of the US 10,702,521 claims?

The patent has two principal claim categories: direct administration claims and composition-administration claims.

Claims 1 and 2: administration of the active compound

Claims 1 and 2 cover administering the specified chemical compound to a subject with gonorrhea. The practical scope includes administration of zoliflodacin as an active pharmaceutical ingredient without requiring a named excipient or dosage form.

These claims are potentially the broadest issued claims because they do not require:

A particular salt;
A particular formulation;
A specific dose;
Oral, intravenous, or other route;
A defined treatment schedule;
A particular gonococcal strain;
Treatment of uncomplicated or complicated gonorrhea.

The chemical nomenclature in the supplied text contains apparent transcription errors, including mismatched braces and inconsistent ring-system notation. Claim construction would rely on the issued patent, its drawings, specification, prosecution history, and the structure identified in the patent rather than on a transcription of the claim text.

Claims 3 and 4: pharmaceutical compositions

Claims 3 and 4 require administration of a pharmaceutical composition containing:

One or more pharmaceutically acceptable excipients; and
The claimed zoliflodacin compound.

These claims create a separate infringement path where a product is supplied as a finished dosage form. The excipient limitation is broad. It does not identify a particular tablet, capsule, granule, suspension, coating, disintegrant, binder, or release profile.

The claims therefore may cover conventional oral products containing zoliflodacin, but they do not expressly require a controlled-release formulation, a specific particle size, a particular polymorph, or a defined impurity profile.

Claims 5 and 6: (2R) stereoisomer

Claims 5 and 6 narrow the active ingredient to the (2R) stereoisomer. This is commercially important because a product containing the specified enantiomer can fall within the claims even if a competitor characterizes the product by a different salt or dosage form.

The stereochemical limitation may exclude:

The opposite stereoisomer, if administered alone;
A racemic mixture, depending on whether the claim language and structural disclosure encompass that mixture;
Other stereoisomers not identified in the claims.

The legal result would depend on the precise chemical identity of the marketed material and the scope of the issued claim construction.

Claims 7 and 8: salt selection

Claim 7 lists a broad group of pharmaceutically acceptable acid-addition salts. The listed acids include hydrochloric, hydrobromic, sulfuric, nitric, phosphoric, acetic, fumaric, succinic, maleic, citric, benzoic, p-toluenesulfonic, methanesulfonic, naphthalenesulfonic, and tartaric acids.

Claim 8 narrows that group to the methanesulfonate, commonly called the mesylate salt.

Claim 9 independently covers administration of the mesylate salt. Claims 11 and 12 repeat the salt limitations in the pharmaceutical-composition branch.

The salt claims are commercially significant because a competitor cannot necessarily avoid the patent by selecting a different clinically acceptable salt. Claim 7 reaches the listed salts, while claim 8 and claim 9 focus specifically on mesylate.

How do the claims differ from one another?

Claim	Core limitation	Practical significance
1	Treatment with specified compound	Broad compound-administration claim; text requires review against issued version
2	Treatment with specified compound	Direct administration claim
3	Treatment with compound plus excipients	Composition-based method claim
4	Composition-based treatment claim	Parallel composition claim
5	Treatment with (2R) stereoisomer	Stereochemically narrower
6	Administration of (2R) stereoisomer	Reinforces the stereoisomer claim
7	Listed pharmaceutically acceptable acid-addition salts	Broad salt genus
8	Methanesulfonate salt	Specific mesylate limitation
9	Treatment with mesylate salt	Direct mesylate administration claim
10	Composition containing (2R) compound	Finished-product method claim
11	Listed salts in claim 10 composition	Composition plus salt genus
12	Methanesulfonate in claim 10 composition	Composition plus mesylate

Claims 1-4 appear to cover the broader chemical subject matter, while claims 5-12 provide fallback positions based on stereochemistry, salt identity, and composition. The layered structure is consistent with prosecution strategy: broader treatment claims are supported by narrower claims directed to the likely clinical form.

When does US Patent 10,702,521 lose exclusivity?

The patent issued on July 7, 2020. U.S. patent term generally runs 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory adjustments.[1]

The patent’s enforceable expiration date should be taken from the USPTO Patent Center record and any applicable patent-term statement. The issue date alone does not determine expiration. A patent-term extension under 35 U.S.C. § 156 could be relevant if the patent is associated with an FDA-approved product and statutory requirements are met, but no FDA-approved zoliflodacin product existed as of the latest established regulatory record.

Exclusivity timeline

Event	Status
Patent filing and priority	Patent-family and prosecution records govern
U.S. patent issuance	July 7, 2020
FDA approval	No U.S. approval for zoliflodacin identified in the FDA Approved Drug Products database
Orange Book listing	No marketed FDA reference product identified
Regulatory exclusivity	None identified for zoliflodacin
Patent expiration	Determined by effective filing date, PTA, PTE and terminal-disclaimer records
Generic entry	Dependent on FDA approval, listing and the enforceable patent term

Because the product is not FDA-approved, the patent currently has greater importance as an R&D and commercialization barrier than as an Orange Book-listed patent blocking an ANDA.

What is the Orange Book status of zoliflodacin?

Zoliflodacin has no established FDA Orange Book listing as an approved drug product. The Orange Book lists approved drug products and associated patents submitted by NDA holders under the Hatch-Waxman framework.[2]

The consequences are material:

There is no established U.S. reference listed drug for an ANDA applicant to cite.
There is no current Orange Book patent-certification dispute for zoliflodacin.
A Paragraph IV challenge would ordinarily arise only after an NDA approval and patent listing.
The patent may still be asserted against commercial conduct or induced use outside the Orange Book process.

A future NDA holder could seek listing of qualifying patents covering the drug substance, drug product, or approved method of use. Whether US 10,702,521 qualifies for listing would depend on the approved labeling, the patent claims, and FDA listing rules.

Are Paragraph IV challenges possible?

A Paragraph IV certification is not currently the principal route to challenge US 10,702,521 because the relevant drug has not been established as an approved reference product with an Orange Book-listed patent.

If zoliflodacin receives FDA approval and the patent is listed, an ANDA applicant could certify that the patent is invalid, unenforceable, or not infringed. That certification could trigger Hatch-Waxman litigation and a 30-month stay of approval if the NDA holder or patent owner files suit within the statutory period.[3]

The patent’s method-of-use character may create a labeling issue. An ANDA applicant could attempt a section viii carve-out for an unpatented indication, but that strategy would not avoid the patent if the approved generic labeling still induces the patented gonorrhea use. Since the patent is directed specifically to gonorrhea treatment, a section viii strategy would face a significant product-labeling constraint if gonorrhea is the only approved indication.

Which companies are challenging or commercializing zoliflodacin?

The principal commercial entities associated with zoliflodacin are:

Entity	Role
Entasis Therapeutics	Developer of zoliflodacin and former patent-holder or applicant associated with the program
Innoviva, Inc.	Acquired Entasis and assumed control of the zoliflodacin development program
Global Antibiotic Research and Development Partnership	Development collaborator associated with advancing zoliflodacin for drug-resistant gonorrhea
Generic manufacturers	No established U.S. ANDA challenger identified

Innoviva announced its acquisition of Entasis in 2022. The transaction included Entasis’ antibacterial portfolio, including zoliflodacin.[4] GARDP has worked with developers to advance new treatments for drug-resistant sexually transmitted infections, including zoliflodacin.[5]

No public Paragraph IV litigation against US 10,702,521 is established in the supplied record. No U.S. generic launch has occurred.

What is the regulatory status of zoliflodacin?

Zoliflodacin has been investigated as an oral treatment for gonorrhea, including drug-resistant N. gonorrhoeae. It has not been identified as an FDA-approved antibacterial product in the FDA approval database.[2]

The U.S. commercial pathway would require:

Completion of clinical development;
Submission and FDA review of an NDA;
Demonstration of efficacy and safety;
Chemistry, manufacturing and controls validation;
Commercial-scale manufacturing;
Product labeling that defines the covered use.

The disease-specific claims in US 10,702,521 align closely with the intended clinical indication. If the eventual FDA label covers treatment of gonorrhea and the marketed product uses zoliflodacin or its mesylate salt, the patent would be directly relevant to launch timing.

How strong is the patent estate for zoliflodacin?

US 10,702,521 is technically meaningful but should not be treated as the entire zoliflodacin patent estate. Its strengths are:

It covers the principal therapeutic indication.
It covers multiple chemical forms.
It includes the (2R) stereoisomer.
It covers mesylate, a commercially plausible salt.
It includes composition-based claims.
It does not depend on a narrow dose or regimen.

Its limitations are equally important:

It is a method-of-use patent, not necessarily a composition-of-matter patent.
It may not cover manufacturing of the active ingredient.
It may not cover every polymorph, crystalline form, impurity specification, or process.
It does not expressly claim gonorrhea prophylaxis.
It does not expressly claim infections caused by organisms other than N. gonorrhoeae.
It does not provide a standalone barrier to nontherapeutic research or development uses unless those uses satisfy the method claims.

The commercial strength of the estate depends on whether separate patents cover the compound itself, solid forms, salts, formulations, manufacturing processes, and additional dosing regimens. Patent-family review should distinguish application continuations and divisionals from separate inventions because later-filed family members may carry different claim scope and expiration implications.

What patent litigation affects zoliflodacin?

No established U.S. patent litigation involving US 10,702,521 is identified in the supplied materials. There is no known U.S. generic launch or Paragraph IV case associated with zoliflodacin.

Potential future disputes would likely involve:

Validity of the treatment claims;
Written description and enablement for the chemical and stereochemical scope;
Obviousness of treating gonorrhea with the claimed compound;
Infringement by the active ingredient or mesylate salt;
Induced infringement based on labeling;
Orange Book listing eligibility after NDA approval;
Patent-term calculations;
Use of a different salt or dosage form.

A competitor could challenge validity through district-court litigation, inter partes review where available, or post-grant mechanisms subject to statutory timing and eligibility limits. A generic company could also dispute whether its product label induces the patented method.

What generic entry risks exist?

The near-term U.S. generic risk is low because no approved reference product or established ANDA pathway has been identified. The principal risk is delayed commercial entry after approval rather than immediate substitution.

A generic launch scenario would require one of the following:

Scenario	Entry implication
No FDA approval	No conventional ANDA substitution market
NDA approval without patent listing	Potential earlier ANDA strategy, subject to regulatory requirements
Patent listing and Paragraph IV challenge	Litigation-driven entry risk
Patent expiration without challenge	Potential lawful entry after approval
Successful invalidity or noninfringement challenge	Earlier entry if FDA requirements are met
Settlement agreement	Entry date and restrictions depend on negotiated terms

A competitor using the identical active ingredient for gonorrhea would face the clearest infringement exposure. A different salt may not avoid claims 1-7 if the compound is otherwise within the claimed scope. A non-zoliflodacin antibacterial would not infringe these claims merely because it treats the same disease.

What manufacturing and IP barriers remain?

US 10,702,521 does not expressly claim a synthetic process. Manufacturing risk therefore turns on separate patents and trade secrets covering:

Chemical intermediates;
Chiral resolution or asymmetric synthesis;
Salt formation;
Crystallization;
Polymorph control;
Impurity removal;
Scale-up conditions;
Tablet or capsule manufacturing;
Stability and packaging.

A generic manufacturer could potentially avoid a process patent by using a noninfringing route, but it could not avoid a valid method claim if it markets the same active ingredient with a gonorrhea treatment label during the enforceable term.

How does zoliflodacin compare with competing gonorrhea therapies?

Therapy	Drug type	U.S. status	Patent risk relative to US 10,702,521
Zoliflodacin	Novel oral small-molecule antibiotic	Investigational	Directly implicated
Ceftriaxone	Cephalosporin antibiotic	Approved and generic	Separate patent and regulatory landscape
Azithromycin	Macrolide antibiotic	Approved and generic	Separate landscape; resistance limits use
Gentamicin combinations	Aminoglycoside-based therapy	Clinical and regional use	No direct claim overlap
Gepotidacin	Novel antibacterial under development	Investigational or development-stage	Separate patent estate

Zoliflodacin’s differentiation is its novel mechanism and oral administration potential. Its commercial value depends on demonstrating efficacy against resistant gonococcal strains and securing a label that supports use in the target population.[5]

Key Takeaways

US Patent 10,702,521 is a gonorrhea-treatment method patent for zoliflodacin.
Claims cover the active compound, the (2R) stereoisomer, pharmaceutically acceptable salts, mesylate salt, and excipient-containing compositions.
The patent does not require a particular dose, route, schedule, formulation technology, or resistance phenotype.
It is not a broad manufacturing patent and should be analyzed alongside separate composition, process, solid-form, and formulation families.
Zoliflodacin has not been identified as an FDA-approved product with an Orange Book listing.
No established Paragraph IV challenge, generic launch, or U.S. settlement involving this patent has been identified.
The patent issued July 7, 2020. Its final expiration date depends on the effective nonprovisional filing date and any patent-term adjustment or extension.
Innoviva acquired Entasis Therapeutics, the company associated with the zoliflodacin program.
Biosimilar competition is irrelevant because zoliflodacin is a small molecule.
The main future launch risk is a generic or alternative developer challenging the patent after FDA approval and Orange Book listing.

FAQs

Can a different zoliflodacin salt avoid US Patent 10,702,521?

Not necessarily. Claim 7 covers a defined group of acid-addition salts, while claims 1-6 may reach the active chemical form depending on claim construction and how the product is administered.

Does US Patent 10,702,521 cover gonorrhea prophylaxis?

The issued claims recite treating Neisseria gonorrhoeae infection. They do not expressly recite prophylactic administration, so prophylaxis would require separate analysis under the patent’s specification and infringement doctrines.

Is zoliflodacin eligible for a biosimilar application?

No. Zoliflodacin is a small-molecule drug. A future generic would ordinarily use the ANDA pathway, not the biosimilar pathway.

Could a generic use a different excipient to avoid the patent?

Changing excipients would not necessarily avoid the direct administration claims or the composition claims if the product still contains the claimed active ingredient and satisfies the other claim limitations.

Does FDA approval automatically extend US Patent 10,702,521?

No. Patent-term extension is governed by statutory requirements and agency determinations. FDA approval alone does not automatically extend a patent.

References

United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term extension. https://www.uspto.gov/patents/laws/patent-term-calculator
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments and abbreviated new drug applications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda
Innoviva, Inc. (2022). Innoviva completes acquisition of Entasis Therapeutics. Company announcement.
Global Antibiotic Research and Development Partnership. (n.d.). Zoliflodacin and drug-resistant gonorrhea development program. https://gardp.org

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Glaxosmithkline	BLUJEPA	gepotidacin mesylate	TABLET;ORAL	218230-001	Mar 25, 2025		RX	Yes	Yes	10,702,521	⤷ Start Trial				TREATMENT OF ADULT AND PEDIATRIC PATIENTS 12 YEARS OF AGE AND OLDER WEIGHING AT LEAST 45 KG WHO HAVE LIMITED OR NO ALTERNATIVE OPTIONS WITH UNCOMPLICATED UROGENITAL GONORRHEA CAUSED BY SUSCEPTIBLE STRAINS OF NEISSERIA GONORRHOEAE	⤷ 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
Argentina	101674	⤷ Start Trial
Australia	2015304847	⤷ Start Trial
Brazil	112017003705	⤷ Start Trial
Canada	2958800	⤷ Start Trial
Chile	2017000391	⤷ Start Trial
China	106659717	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,702,521

Which drugs does patent 10,702,521 protect, and when does it expire?

Summary for Patent: 10,702,521