United States Patent 9,540,394: Claim Scope, Expiration, Litigation Risk, and Patent Landscape for Zoliflodacin

U.S. Patent No. 9,540,394 protects the use of a specific antibacterial compound, identified in the zoliflodacin patent family, for four treatment categories: gonorrhea caused by Neisseria gonorrhoeae, pneumonia, Burkholderia infections, and complicated skin and skin structure infections. The patent is a method-of-use patent, not a broad composition-of-matter patent. Its commercial value depends on whether the protected compound is approved and marketed for one of the claimed indications before the patent term ends.

The patent issued on January 10, 2017. Its nominal expiration date is March 30, 2032, based on the earliest claimed U.S. priority or filing date identified for the family. The effective expiration date should be confirmed against the USPTO patent-term-adjustment record.

What drug does U.S. Patent 9,540,394 protect?

The compound described by the claims is zoliflodacin, also known as ETX0914 and previously AZD0914, a first-in-class spiropyrimidinetrione antibacterial agent developed for drug-resistant N. gonorrhoeae.

Zoliflodacin inhibits bacterial DNA gyrase and topoisomerase IV through a mechanism distinct from fluoroquinolones. The compound has been developed primarily as an oral treatment for uncomplicated urogenital gonorrhea.

The claims do not protect every antibacterial compound. They require administration of the specific claimed molecular structure or a pharmaceutically acceptable salt.

Patent element	Scope
Protected subject matter	Treatment methods
Active compound	The specific claimed zoliflodacin structure
Permitted chemical form	Compound or pharmaceutically acceptable salt
Claim type	Therapeutic method-of-use
Route	Not expressly limited in the quoted claims
Dose	Not expressly limited
Patient population	A subject in need of treatment
Required disease	One of four expressly recited infection categories
Patent number	U.S. 9,540,394
Issue date	January 10, 2017
Nominal expiration	March 30, 2032

What do the four claims cover?

The claims are composition-specific treatment claims with disease limitations. Each claim requires proof of three core elements:

The defendant administers the claimed compound or a pharmaceutically acceptable salt.
The administration is in an effective amount.
The patient has the infection or condition identified in the claim.

Claim 1: Neisseria gonorrhoeae infection

Claim 1 covers administering the compound to treat an infection caused by Neisseria gonorrhoeae. It is the commercially most important claim because zoliflodacin’s principal development program has focused on gonorrhea.

The claim does not appear limited to:

Urogenital disease;
Rectal infection;
Pharyngeal infection;
Uncomplicated disease;
A particular age group;
A specific dosing schedule;
Monotherapy;
Oral administration; or
Drug-resistant strains.

A product label covering treatment of gonorrhea could therefore fall within the claim if it uses the patented compound during the patent term. The claim’s practical reach would depend on the final FDA indication and dosing regimen.

Claim 2: Pneumonia

Claim 2 covers treatment of pneumonia with the claimed compound. The text does not limit the claim to community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, or a specified pathogen.

The claim could potentially reach multiple pneumonia subtypes if the drug is administered for pneumonia and the compound is used in an effective amount. Its commercial importance is lower than Claim 1 unless the sponsor develops and obtains approval for a pneumonia indication.

Claim 3: Burkholderia infection

Claim 3 covers treatment of an infection caused by a Burkholderia species. The genus-level wording is broader than a claim limited to a single species such as B. pseudomallei or B. mallei.

The claim could cover treatment of infections involving different Burkholderia species, subject to ordinary claim-construction requirements and proof that the species falls within the claimed genus. The commercial market is specialized, but the claim may have strategic value because Burkholderia infections can present major treatment challenges and limited therapeutic options.

Claim 4: Complicated skin and skin structure infection

Claim 4 covers treatment of a complicated skin and skin structure infection, commonly abbreviated cSSSI. Unlike Claim 3, this claim is defined by a clinical disease category rather than a named organism.

The scope may include infections caused by Gram-positive or Gram-negative bacteria, provided the treated condition qualifies as a complicated skin and skin structure infection and the claimed compound is administered in an effective amount.

How broad is the patent’s legal scope?

The patent has meaningful therapeutic coverage but limited structural breadth. The claims do not cover:

New chemical compounds unrelated to the claimed structure;
Generic manufacturing routes;
Formulations that do not use the claimed compound;
Diagnostic testing;
Vaccines;
Combination products that omit the claimed compound;
Treatment of diseases outside the four claimed categories; or
Commercial activity involving the compound for nontherapeutic research, subject to the applicable statutory framework.

The absence of an express dosage or route limitation gives the claims flexibility. A potential infringer would not necessarily avoid infringement by changing the dose, tablet strength, treatment duration, or administration schedule.

The disease limitations narrow the claims. Use of zoliflodacin for an indication not listed in Claims 1 through 4 would not literally infringe these claims, although other patents in the family could provide separate coverage.

What patent protects the compound itself?

U.S. Patent 9,540,394 is principally a method-of-use patent based on the quoted claims. The provided claims do not establish composition-of-matter protection for zoliflodacin.

Composition-of-matter rights, crystalline-form rights, formulation rights, manufacturing rights, and additional indication rights must be evaluated separately across the zoliflodacin patent family. A generic or competing developer would need to review the complete family rather than rely only on U.S. 9,540,394.

The distinction is commercially important:

Patent category	Effect on competition
Composition of matter	Can block making, using, selling, or importing the compound broadly
Method of treatment	Can block use for specified diseases
Formulation	Can block a particular dosage form, excipient system, or release profile
Manufacturing process	Can block a particular production route
Polymorph or solid form	Can block a specific crystalline or amorphous form
Method of manufacture or purification	Can increase development and scale-up barriers
Pediatric or dosing patent	Can extend protection for a particular regimen or population

When does U.S. Patent 9,540,394 expire?

The patent has a nominal term ending approximately March 30, 2032. The final term can be affected by patent-term adjustment, terminal disclaimers, or other USPTO-recorded events.

Event	Date or status
Earliest relevant family priority	March 30, 2012
U.S. patent grant	January 10, 2017
Nominal 20-year term	March 30, 2032
Patent-term adjustment	Must be taken from the USPTO patent record
Patent-term extension	No confirmed extension identified for this patent
Patent status	Issued U.S. patent; enforceability depends on maintenance and legal status

Patent expiration does not automatically create unrestricted commercial freedom. Other unexpired patents may cover the compound, a salt, a formulation, a manufacturing method, or an approved indication.

What is the FDA and Orange Book status?

Zoliflodacin was not an FDA-approved commercial drug based on the cited development record available through June 2024. It was under clinical development for gonorrhea, including Phase 3 testing supported by Entasis Therapeutics and the Global Antibiotic Research and Development Partnership.

Because no approved NDA for a marketed zoliflodacin product had been identified through that period, U.S. Patent 9,540,394 was not an ordinary Orange Book-listed patent for an approved reference product.

This has several consequences:

No conventional ANDA applicant could rely on an approved zoliflodacin reference product until FDA approval occurs.
There was no ordinary Orange Book Paragraph IV dispute tied to a marketed zoliflodacin NDA.
A future NDA holder could seek listing of eligible patents after approval.
The patent may still be asserted against commercial use even before Orange Book listing, if the statutory infringement requirements are met.
FDA approval would not automatically validate the patent or determine its ultimate enforceability.

QIDP designation, Fast Track status, or other FDA development designations do not themselves create patent rights. They may affect regulatory exclusivity and development timing but are separate from patent protection.

Have there been Paragraph IV challenges or patent litigation?

No publicly established Paragraph IV challenge or major federal infringement action involving U.S. 9,540,394 had been identified in the cited development record through June 2024.

The absence of a Paragraph IV case is consistent with the drug’s pre-commercial status. Paragraph IV litigation normally follows an ANDA filing against an approved reference product and an Orange Book-listed patent. A pre-approval patent can still create freedom-to-operate risk, but it does not generate the standard Orange Book litigation pathway.

No publicly reported settlement agreement involving U.S. 9,540,394 and a generic zoliflodacin applicant had been identified through that period.

What generic entry risks exist?

Generic entry risk is currently more regulatory than litigation-driven because zoliflodacin had not yet established an approved U.S. reference product as of June 2024.

A future generic or follow-on manufacturer could face several barriers:

Method-of-use infringement

An ANDA applicant seeking approval for a patented indication could face an infringement claim if the proposed labeling encourages use of zoliflodacin for gonorrhea, pneumonia, Burkholderia infection, or cSSSI before patent expiry.

A skinny-label strategy could reduce risk if the applicant omits patented indications and FDA permits approval for an unpatented use. That strategy would not necessarily avoid infringement if the remaining label, promotional activity, or product design induces use for a patented indication.

Compound and salt coverage

The claims expressly cover the compound and pharmaceutically acceptable salts. A different salt may not avoid infringement if it falls within the claim’s salt language.

Label and inducement risk

The specification, prescribing information, medical education, and promotional materials would matter. Induced infringement under 35 U.S.C. §271(b) can arise where a manufacturer encourages a patented use, even if the manufacturer does not administer the drug itself.

Manufacturing and supply risk

A competitor may need to clear separate process, intermediate, polymorph, purification, and formulation patents. These rights can matter even when the method-of-use patent is narrow or expired.

How strong is the patent estate?

U.S. 9,540,394 has moderate strategic strength as an indication patent and limited standalone strength as a complete product barrier.

Strength factor	Assessment
Claim specificity	High; the compound is specifically defined
Indication coverage	Four clinically relevant categories
Dose flexibility	Broad because no dose is recited
Route flexibility	Broad because no route is recited
Composition protection	Not established by the quoted claims
Manufacturing protection	Not established by the quoted claims
Dependence on FDA label	High for practical enforcement
Pre-approval commercial value	Limited but relevant to licensing and development
Post-approval value	Potentially significant for patented indications
Design-around potential	Moderate if alternative uses or products are available

The patent is strongest where zoliflodacin is approved and marketed for gonorrhea. Its pneumonia, Burkholderia, and cSSSI claims could become valuable if those development programs advance, but they have less immediate commercial significance without corresponding regulatory indications.

How does this patent compare with competing antibacterial estates?

Zoliflodacin’s patent position differs from conventional antibiotic portfolios in three ways.

First, the central commercial thesis is a novel mechanism directed at drug-resistant gonorrhea. That can reduce direct substitutability with older cephalosporins, macrolides, and fluoroquinolones, but it does not eliminate clinical competition.

Second, the quoted claims are indication claims rather than broad composition claims. If the underlying composition patent estate is weak, expired, or absent, the method patent may not prevent off-label use or development for other indications after the patent term.

Third, zoliflodacin has no biosimilar pathway. It is a small molecule, so the relevant competitive route is an ANDA or, depending on the product and regulatory record, a 505(b)(2) application. Biosimilar litigation under the Public Health Service Act is not applicable.

Potential competitors include:

Ceftriaxone-based gonorrhea regimens;
Other investigational oral antibiotics for gonorrhea;
Fluoroquinolones where susceptibility permits;
Gepotidacin, another investigational antibacterial with activity against N. gonorrhoeae;
Delafloxacin and other agents used in skin infection settings; and
Specialized therapies for Burkholderia infections.

The competitive threat is therefore partly patent-based and partly clinical. A product with a different mechanism and non-overlapping patent estate could compete without infringing U.S. 9,540,394.

What licensing and commercial issues affect the patent?

Entasis Therapeutics has been the principal development company associated with zoliflodacin, with development support from GARDP. Entasis became part of Innoviva’s portfolio after Innoviva acquired Entasis in 2022.

The principal commercial issues are:

Whether zoliflodacin obtains FDA approval;
Whether approval is limited to gonorrhea or includes broader infections;
Whether a commercial partner assumes U.S. launch responsibility;
Whether the patent family includes stronger composition or formulation rights;
Whether regulatory exclusivity overlaps with the remaining patent term; and
Whether the sponsor can obtain sufficient reimbursement and adoption in antimicrobial stewardship settings.

No confirmed commercial licensing agreement was identified in the record cited here that would independently alter the term or scope of U.S. 9,540,394.

What geographic coverage does the patent provide?

U.S. 9,540,394 provides protection in the United States only. It does not directly prevent commercial activity in Canada, Europe, Japan, China, or other jurisdictions.

The international position must be assessed through corresponding applications and national-phase patents. Foreign family members may have:

Different claim scope;
Different expiration dates;
Different prosecution outcomes;
Different patent-term adjustments or supplementary protection certificates; and
Different enforceability based on local law.

U.S. patent rights can still reach imported products and certain foreign activities involving U.S. commerce under 35 U.S.C. §271.

Key Takeaways

U.S. Patent 9,540,394 is a method-of-use patent covering the claimed zoliflodacin compound or its pharmaceutically acceptable salts.
The four claims target gonorrhea, pneumonia, Burkholderia infection, and complicated skin and skin structure infection.
Claim 1 is the most commercially important because zoliflodacin’s leading development program is directed to gonorrhea.
The quoted claims do not establish broad composition-of-matter, formulation, or manufacturing protection.
The nominal patent expiration date is March 30, 2032, subject to USPTO-recorded patent-term adjustment and other term events.
Zoliflodacin had not established an FDA-approved commercial reference product through June 2024, so no conventional Orange Book Paragraph IV litigation pathway had developed.
Biosimilar risk is not applicable because zoliflodacin is a small molecule.
Generic risk will depend on the final FDA label, remaining patent-family rights, salt and formulation coverage, and any future ANDA strategy.
The patent is strategically useful but should not be treated as the entire zoliflodacin freedom-to-operate analysis.

FAQs

Is U.S. Patent 9,540,394 a composition-of-matter patent?

No. The quoted claims are therapeutic method claims. They require administration of the specified compound for one of four listed disease categories.

Does changing the zoliflodacin dose avoid infringement?

Not necessarily. The quoted claims require an effective amount but do not recite a specific dose. A different dose could remain within the claim if the other elements are satisfied.

Does the patent cover all uses of zoliflodacin?

No. The quoted claims cover only the listed infections and disease category. Other uses would require separate claims or patents.

Can a generic manufacturer avoid the patent by using a different salt?

Not necessarily. The claims expressly include pharmaceutically acceptable salts. The exact salt and claim construction would determine the result.

Will zoliflodacin have biosimilar competition?

No. Zoliflodacin is a small-molecule antibacterial. The relevant competitive pathways are generic-drug and potentially 505(b)(2) pathways, not biosimilar approval.

References

United States Patent and Trademark Office. (2017). U.S. Patent No. 9,540,394, methods for treating bacterial infections.
U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (n.d.). Drug development and approval process: Fast Track, breakthrough therapy, accelerated approval, and priority review.
Global Antibiotic Research and Development Partnership. (n.d.). Zoliflodacin development program.
Innoviva, Inc. (2022). Annual report and corporate materials concerning the acquisition of Entasis Therapeutics.
U.S. Code, Title 35, §§ 154 and 271.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Entasis Therap	NUZOLVENCE	zoliflodacin	FOR SUSPENSION;ORAL	219491-001	Dec 12, 2025		RX	Yes	Yes	9,540,394	⤷ Start Trial				TREATMENT OF UNCOMPLICATED UROGENITAL GONORRHEA DUE TO 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	094565	⤷ Start Trial
Australia	2014208965	⤷ Start Trial
Brazil	112015017519	⤷ Start Trial
Canada	2897887	⤷ Start Trial
China	105229012	⤷ Start Trial
Cyprus	1122805	⤷ Start Trial
Denmark	2948461	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,540,394

Which drugs does patent 9,540,394 protect, and when does it expire?

Summary for Patent: 9,540,394