United States Drug Patent RE49353: Claim Scope, Exclusivity, Litigation Risk, and Patent Landscape

US Patent RE49353 is a method-of-treatment patent directed to androgen-receptor inhibition in male patients with non-metastatic castration-resistant prostate cancer, or nmCRPC. The claims require four core elements: a male human patient, nmCRPC, administration of one of three specified anti-androgens at about 30 mg/day to about 480 mg/day, and concurrent administration of a GnRH agonist.

The principal commercial relevance is apalutamide, marketed as Erleada by Johnson & Johnson subsidiary Janssen. The claim language also recites enzalutamide and a third spirocyclic anti-androgen structure, creating potential overlap with other androgen-receptor inhibitor programs. RE49353 is a method patent, not a composition-of-matter patent. Its enforceability therefore depends on the accused product's indication, dosing, patient population, and use with androgen-deprivation therapy.

What does US Patent RE49353 protect?

RE49353 protects specified treatment regimens for nmCRPC rather than the underlying chemical compounds in the abstract.

Required claim element	Scope
Patient	Male human
Disease	Non-metastatic castration-resistant prostate cancer
Higher-risk limitation	Present in dependent claims 2, 27, and 43
Drug class	Anti-androgen
Covered compounds	Three expressly recited chemical structures
Dose range	About 30 mg/day to about 480 mg/day
Hormonal backbone	Concurrent GnRH agonist administration
Administration route	Oral administration in dependent claims
Schedule	Daily or continuous daily dosing in dependent claims
Specific GnRH agonists	Leuprolide, buserelin, nafarelin, histrelin, goserelin, or deslorelin

The broadest independent claims are claims 1, 14, 26, 39, 42, and 54. Claims 1, 14, 26, 42, and 54 cover combination treatment with any one of the recited anti-androgens and a GnRH agonist. Claims 39 and 54 use “consisting essentially of,” which narrows the permissible additional treatment components compared with “comprising.”

Which drugs are named in RE49353?

The patent names three distinct anti-androgen chemical structures.

Chemical structure in the claims	Common identity or commercial relevance
4-[7-(6-cyano-5-trifluoromethylpyridin-3-yl)-8-oxo-6-thioxo-5,7-diazaspiro[3.4]oct-5-yl]-2-fluoro-N-methylbenzamide	ARN-509, apalutamide
4-(3-(4-cyano-3-(trifluoromethyl)phenyl)-5,5-dimethyl-4-oxo-2-thioxoimidazolidin-1-yl)-2-fluoro-N-methylbenzamide	Enzalutamide
4-[7-[4-cyano-3-(trifluoromethyl)phenyl]-8-oxo-6-thioxo-5,7-diazaspiro[3.4]oct-5-yl]-2-fluoro-N-methylbenzamide	A separate spirocyclic androgen-receptor antagonist expressly covered by the patent

The claims do not cover every androgen-receptor inhibitor. They are limited to the three identified structures and their use within the specified dose and treatment setting.

How broad are the independent claims?

Claim 1 is the principal broad claim. A potentially infringing regimen would need to satisfy all of the following:

The patient is a male human.
The patient has nmCRPC.
The anti-androgen is one of the three claimed molecules.
The dose is approximately 30 mg/day to approximately 480 mg/day.
A GnRH agonist is also administered.

The claim does not require:

A particular PSA doubling time.
A particular imaging modality.
A specified metastasis-free survival outcome.
A particular formulation.
A particular timing relationship between the anti-androgen and GnRH agonist.
A specific GnRH agonist in claim 1.
Oral dosing in claim 1.
Continuous daily dosing in claim 1.

Those limitations appear in dependent claims.

The use of “about” creates a factual boundary issue. A dose slightly outside the stated numerical range could still raise literal-infringement or doctrine-of-equivalents questions, depending on the intrinsic record, prosecution history, and clinical dosing practice.

What are the key dependent claims?

The dependent claims subdivide the commercial use case into product, dose, route, schedule, disease-risk, and GnRH-agent limitations.

Apalutamide claims

Claims 3 through 8 and 15 through 25 focus on ARN-509, now known as apalutamide. The most commercially relevant limitations are:

Daily administration.
Oral administration.
Dose of about 180 mg/day to about 480 mg/day.
Specific doses of about 30, 60, 90, 120, or 240 mg/day.
Continuous daily dosing.
Use with leuprolide, buserelin, nafarelin, histrelin, goserelin, or deslorelin.
A specific 240 mg/day regimen.

The 240 mg/day limitation is particularly significant because 240 mg once daily is the approved Erleada dose for adults in the FDA-approved nmCRPC indication.[1]

Enzalutamide claims

Claims 9, 10, 18, and 26 through 41 focus on the dimethyl thiohydantoin compound corresponding to enzalutamide.

The central dependent claim is claim 18, which specifies oral administration at about 160 mg/day. Enzalutamide is approved at 160 mg once daily for prostate-cancer indications, including nmCRPC.[2]

The claims therefore track clinically relevant commercial dosing for both apalutamide and enzalutamide. That alignment increases the potential relevance of the patent to ANDA applicants seeking approval for a generic product labeled for nmCRPC.

Third spirocyclic anti-androgen

Claims 11 through 12 and 42 through 55 cover the third spirocyclic chemical structure. These claims preserve the same nmCRPC, dose-range, oral-administration, daily-schedule, and GnRH-agonist framework.

No commercial identity should be assigned to this third compound solely from the supplied claim text. Its commercial significance depends on whether it has an approved product, clinical development program, or separate composition-of-matter estate.

What is the legal significance of “comprising” and “consisting essentially of”?

Claims 1, 26, and 42 use “comprising.” This is open-ended language. A regimen may include additional treatments and still fall within the claim if all required elements are present.

Claims 14, 39, and 54 use “consisting essentially of.” This language is narrower. It generally permits components that do not materially affect the basic and novel characteristics of the claimed method. The practical boundary would depend on the claim construction record and evidence concerning additional anticancer agents, radiation, surgery, or supportive therapies.

The “consisting essentially of” claims may provide narrower but potentially important fallback positions if the broader “comprising” claims are challenged on validity or claim-construction grounds.

Are there claim-drafting defects in the supplied claim text?

Yes. Several dependencies appear malformed:

Claims 4, 5, 6, 7, 17, 19, and 20 through 25 state “claim 3 1.”
Claims 15 and 16 state “claim 15 14.”
Similar drafting artifacts appear throughout the supplied text.
Claim 4 appears to depend on claim 3 but repeats the wording of claim 3.
Claims 14 and 39 use “consisting essentially of” while also requiring further GnRH-agonist administration.

These defects may reflect OCR, transcription, or formatting errors rather than the issued patent text. In a validity or freedom-to-operate analysis, the certified patent document, reissue certificate, prosecution history, and any certificate of correction control. Dependency errors can affect claim construction, written-description analysis, indefiniteness arguments, and the scope of enforceable claims.

When does RE49353 lose exclusivity?

A reissue patent generally retains the expiration date of the original patent term. Reissue does not ordinarily restart the 20-year term from the reissue grant date.

The relevant term analysis requires:

The earliest effective nonprovisional priority date.
Patent-term adjustment.
Any patent-term extension.
Terminal disclaimers.
The original patent from which RE49353 issued.
Any disclaimer or correction affecting the patent term.

The claim text alone does not establish the operative expiration date. The original patent and USPTO Patent Center record must be used to determine the enforceable expiration date.

The commercial exclusivity analysis also requires separation of:

Patent protection for apalutamide or enzalutamide as compounds.
Formulation patents.
Method-of-use patents.
FDA regulatory exclusivity.
RE49353's particular nmCRPC treatment claims.

A generic applicant may face several independent barriers even if RE49353 expires, while RE49353 may have limited practical effect if earlier composition-of-matter patents remain enforceable.

What is the Orange Book status of RE49353?

RE49353 is potentially relevant to Orange Book-listed products only if the patent is listed against an approved drug product and satisfies FDA listing requirements.

For the commercial products most closely associated with the claimed molecules:

Product	Active ingredient	Brand holder	Relevant FDA indication	Regulatory pathway
Erleada	Apalutamide	Janssen	nmCRPC and metastatic castration-sensitive prostate cancer	NDA
Xtandi	Enzalutamide	Astellas and Pfizer	Multiple prostate-cancer indications	NDA

FDA Orange Book listing must be checked by patent number, product, active ingredient, and use code. A method patent may be listed with a use code limited to nmCRPC or a related prostate-cancer indication. Listing does not establish validity or enforceability, but it can trigger a Paragraph IV certification dispute for an ANDA applicant.

What Paragraph IV risks exist for generic apalutamide and enzalutamide?

A generic applicant seeking approval before expiration of a listed patent may submit a Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed.

RE49353 creates several potential Paragraph IV defenses:

Non-infringement arguments

A generic applicant could argue that:

The proposed label does not include nmCRPC.
The label does not require or recommend concurrent GnRH-agonist use.
The dose is outside the claimed range.
The product is intended for a different prostate-cancer population.
The third-party prescribing decision, rather than the ANDA label, controls the claimed method.
The relevant compound is not one of the three claimed structures.

Invalidity arguments

Potential validity issues include:

Written description for a claim covering multiple named compounds and broad dose ranges.
Enablement across the entire 30 mg/day to 480 mg/day range.
Obviousness based on known androgen-receptor antagonists, androgen-deprivation therapy, and nmCRPC treatment strategies.
Indefiniteness arising from “about,” dependency errors, or inconsistent claim language.
Double-patenting over earlier composition, treatment, or formulation patents.
Lack of patentable distinction between known anti-androgen therapy and the claimed patient population.

These are potential litigation positions, not determinations that the claims are invalid.

Does RE49353 create biosimilar risk?

No. Apalutamide and enzalutamide are small-molecule drugs approved through the NDA framework. Their follow-on products would generally be ANDA generics, not biosimilars under the Public Health Service Act.

The applicable competitive risks are:

Paragraph IV ANDA litigation.
Label carve-outs under section viii.
Authorized generic launches.
Patent settlements.
Formulation and manufacturing challenges.
State-law substitution and payer adoption.

What formulation patents protect Erleada or Xtandi?

RE49353 does not claim a tablet composition, excipient system, particle-size distribution, polymorph, salt, coating, or manufacturing process. It is therefore not a formulation patent.

A complete freedom-to-operate review for apalutamide or enzalutamide must separately examine:

Composition-of-matter patents.
Crystalline-form and polymorph patents.
Tablet and solid-dosage-form patents.
Stability and dissolution patents.
Manufacturing and synthetic-process patents.
Combination-treatment patents.
Pediatric exclusivity and FDA exclusivity periods.

A generic applicant can avoid some method-of-use claims through a section viii statement and label carve-out, but that strategy does not avoid composition or formulation patents.

Which companies are most exposed to RE49353?

Company	Product or program	Exposure
Janssen/J&J	Erleada, apalutamide	Direct commercial alignment with claims 3-8 and 15-25
Astellas/Pfizer	Xtandi, enzalutamide	Direct alignment with claims 9, 18, and 26-41
Generic manufacturers	Future apalutamide or enzalutamide ANDAs	Potential Paragraph IV and induced-infringement exposure
Other AR-inhibitor developers	Competing products	Limited exposure unless the product uses one of the claimed structures and regimen

Apalutamide has direct label overlap with the 240 mg/day claims. Enzalutamide has direct overlap with the 160 mg/day claim. The patent is therefore more commercially relevant to generic entry than to competition from chemically distinct products such as darolutamide.

How strong is the patent estate around apalutamide compared with RE49353?

RE49353 is narrower than a composition-of-matter patent but can remain commercially valuable because it tracks the approved indication and dosing regimen.

Protection type	Relative strength against a generic
Composition-of-matter patent	Usually strongest; difficult to design around if the generic uses the same active ingredient
Formulation patent	Variable; depends on whether the generic duplicates the claimed formulation
Method-of-use patent	Dependent on label, indication, physician conduct, and claim construction
RE49353	Potentially strong for labeled nmCRPC use with GnRH agonist, weaker for non-nmCRPC or carved-out uses
Manufacturing patent	Variable; can be avoided through an alternative process

RE49353 cannot substitute for the core apalutamide composition patent. Its value is as an indication-and-regimen layer that may extend practical market protection after broader compound claims become less effective, subject to the actual term and Orange Book status.

What patent litigation and settlements affect RE49353?

The supplied claim text does not establish a current infringement action, Paragraph IV case, or settlement involving RE49353. Patent litigation must be verified through the USPTO, FDA Orange Book, PACER, and relevant district-court dockets.

For commercial planning, the key litigation triggers are:

An ANDA Paragraph IV notice involving apalutamide or enzalutamide.
A 30-month FDA stay under Hatch-Waxman.
A section viii label carve-out.
A patent settlement with an agreed launch date.
A covenant not to sue or license affecting the claimed indication.
A terminal disclaimer or post-grant claim cancellation.

A settlement can materially alter the effective launch date even when RE49353 remains unexpired.

Key Takeaways

RE49353 is a method-of-treatment patent for male patients with nmCRPC.
The required regimen combines one of three specified anti-androgens with a GnRH agonist.
Apalutamide at 240 mg/day is the clearest commercial overlap.
Enzalutamide at 160 mg/day is also expressly covered.
The patent does not claim every androgen-receptor inhibitor and does not itself claim formulations or manufacturing processes.
“Comprising” claims are open-ended; “consisting essentially of” claims are narrower.
Reissue does not ordinarily restart the patent term.
The enforceable expiration date requires review of the original patent, PTA, PTE, and terminal-disclaimer records.
Generic risk is primarily an ANDA Paragraph IV issue, not a biosimilar issue.
The patent’s commercial strength depends on Orange Book listing, use-code wording, remaining compound and formulation patents, and any litigation settlement.

FAQs

Does RE49353 cover Erleada at its FDA-approved dose?

Yes, the supplied claims expressly cover apalutamide, including dependent claims directed to oral administration and about 240 mg/day, together with a GnRH agonist.

Does RE49353 cover Xtandi at 160 mg per day?

Yes. Claim 18 expressly recites oral administration of the enzalutamide chemical structure at about 160 mg/day.

Can a generic avoid RE49353 by omitting nmCRPC from its label?

Potentially. A properly structured section viii carve-out may reduce method-of-use infringement risk, but it does not avoid composition, formulation, or other listed patents.

Is RE49353 a patent on apalutamide itself?

No. Based on the supplied claims, RE49353 is directed to methods of treating nmCRPC using specified anti-androgens. A separate composition-of-matter patent would govern apalutamide as a chemical compound.

Does RE49353 cover darolutamide?

Not on the supplied claim language. Darolutamide is chemically distinct from the three expressly recited structures and is not identified in these claims.

References

U.S. Food and Drug Administration. (2018). Erleada (apalutamide) prescribing information. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (2018). Xtandi (enzalutamide) prescribing information. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
United States Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov
U.S. Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j).
U.S. Patent and Trademark Office. (n.d.). Patent term adjustment and patent term extension resources. https://www.uspto.gov/patents/laws/patent-term-adjustment-patent-term-extension-and-terminal-disclaimers

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Janssen Biotech	ERLEADA	apalutamide	TABLET;ORAL	210951-001	Feb 14, 2018	AB	RX	Yes	No	RE49353	⤷ Start Trial				TREATMENT IN COMBINATION WITH A GNRH AGONIST OF NON-METASTATIC, CASTRATION-RESISTANT PROSTATE CANCER (NM-CRPC)	⤷ Start Trial
Janssen Biotech	ERLEADA	apalutamide	TABLET;ORAL	210951-002	Feb 17, 2023		RX	Yes	Yes	RE49353	⤷ Start Trial				TREATMENT IN COMBINATION WITH A GNRH AGONIST OF NON-METASTATIC, CASTRATION-RESISTANT PROSTATE CANCER (NM-CRPC)	⤷ 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
Australia	2013323861	⤷ Start Trial
Australia	2018206695	⤷ Start Trial
Australia	2020244431	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: RE49353

Which drugs does patent RE49353 protect, and when does it expire?

Summary for Patent: RE49353