US Patent 8,921,348: Claim Scope, Exclusivity, and Mifepristone Patent Landscape

US Patent 8,921,348 protects a patient-specific mifepristone dosing method based on serum drug-level monitoring. Its central limitation is a treatment protocol requiring at least seven daily doses, serum testing, and dose adjustment to achieve mifepristone blood levels above 1,300 ng/mL. The patent does not broadly claim mifepristone, a fixed-dose tablet, or every use of mifepristone. Its commercial value depends on whether a competing product or treatment program uses therapeutic drug monitoring and dose escalation in a covered patient population.

What does US Patent 8,921,348 protect?

The patent protects a method of optimizing mifepristone exposure in a patient with a disorder treatable by mifepristone. Independent claim 1 requires four central components:

Required element	Claim 1 requirement
Drug	Mifepristone
Treatment duration	At least seven daily doses over at least seven days
Measurement	Testing patient serum levels
Target exposure	Adjusting the daily dose to achieve blood levels greater than 1,300 ng/mL

The claim is cumulative. A potentially infringing protocol must satisfy every limitation of claim 1, either literally or under the doctrine of equivalents. A treatment using mifepristone without serum-level testing would not literally satisfy the testing limitation. A protocol measuring serum levels but targeting 1,300 ng/mL or less would raise a separate issue under the numerical limitation.

The claim is a method-of-treatment claim, not a product claim. It does not independently prevent:

Manufacturing mifepristone;
Selling mifepristone for unrelated indications;
Administering a fixed mifepristone dose without blood-level monitoring;
Using mifepristone for medication abortion;
Using mifepristone for Cushing syndrome without the claimed optimization protocol.

The patent’s practical reach is therefore narrower than a composition patent or a broad indication patent.

How do the dependent claims narrow the patent scope?

The dependent claims add disease, administration, duration, testing-device, and dose-adjustment limitations.

Claim	Added limitation	Commercial effect
1	Core serum-guided optimization method	Broadest claim
2	Stress disorder, delirium, MCI, dementia, psychosis, or psychotic major depression	Limits treatment population
3	Acute Stress Disorder, PTSD, or Brief Psychotic Disorder with Marked Stressor(s)	Narrows claim 2 to specified stress disorders
4	Each dose is administered orally	Excludes nonoral administration from literal scope
5	At least 28 daily doses over at least 28 days	Covers longer treatment courses
6	Testing by a plasma sampling collection device suitable for detecting mifepristone	Adds a device-related testing limitation
7	Dose adjustment consists of increasing the daily dose	Narrows the direction of dose adjustment

Claim 7 is commercially important because it clarifies that the method can involve dose escalation. Claim 1, read literally, requires adjustment to achieve levels above 1,300 ng/mL, while claim 7 expressly requires increasing the daily dose. A protocol that begins above the threshold and reduces the dose would not satisfy claim 7, although it could still implicate claim 1 depending on the facts.

What patient populations are covered by US 8,921,348?

The patent covers a broad disorder category in claim 1 and specified neuropsychiatric disorders in claim 2.

Claim 2 includes:

Stress disorders;
Delirium;
Mild cognitive impairment;
Dementia;
Psychosis;
Psychotic major depression.

Claim 3 further limits stress disorders to:

Acute Stress Disorder;
Post-Traumatic Stress Disorder;
Brief Psychotic Disorder with Marked Stressor(s).

A treatment for Cushing syndrome is not expressly included in claims 2 and 3. It could fall within claim 1 only if Cushing syndrome is considered a disorder amenable to mifepristone treatment and all other claim limitations are met. That issue would depend on claim construction, factual evidence, and the patent’s specification.

The claim language also creates a potential written-description and enablement issue for the breadth of “a disorder amenable to treatment by mifepristone.” A defendant could argue that the generic disorder language reaches conditions not adequately supported or enabled by the disclosure. The strength of that argument would depend on the specification, examples, prosecution history, and relevant technical evidence.

What is the key infringement test for this patent?

A competing treatment program is most exposed when it combines all of the following:

Repeated daily oral mifepristone dosing;
Treatment lasting at least seven days;
Serum or plasma testing;
A target mifepristone concentration greater than 1,300 ng/mL;
Dose escalation or adjustment based on the measured result;
Treatment of one of the listed neuropsychiatric conditions.

The following matrix illustrates likely claim exposure:

Competing protocol	Claim 1 exposure
Single-dose mifepristone	Low
Seven-day fixed-dose regimen without testing	Low
Daily dosing with liver-function monitoring only	Low for literal infringement
Serum testing with target below 1,300 ng/mL	Lower, subject to equivalents
Serum testing after seven days, but no dose adjustment	Lower
Dose adjustment based on serum level, target above 1,300 ng/mL	High
Oral dose escalation for PTSD over 28 days	High, potentially implicating claims 1, 2, 3, 4, 5, and 7
Mifepristone abortion regimen	Generally outside the listed neuropsychiatric claims and outside the claimed monitoring protocol
Korlym fixed-dose treatment for Cushing syndrome without drug-level testing	Lower under the supplied claims

The phrase “greater than 1300 ng/mL” is a hard numerical boundary. A result of exactly 1,300 ng/mL is not greater than 1,300 ng/mL. A protocol that targets a concentration range extending above 1,300 ng/mL presents greater risk than one capped below that threshold.

What formulations and delivery systems are protected?

US 8,921,348 does not claim a particular tablet formulation, excipient system, salt, polymorph, crystal form, sustained-release matrix, transdermal patch, or injectable composition.

Claim 4 requires oral administration, but it does not limit the claim to:

A particular tablet strength;
A specific excipient;
A branded formulation;
A specific immediate-release profile;
A particular manufacturer.

Claim 6 addresses a plasma sampling collection device suitable for detecting mifepristone serum levels. It does not appear, from the supplied claim language, to claim the device itself as a standalone product. The device limitation is part of the treatment method.

This distinction matters in product clearance. A generic tablet manufacturer could potentially avoid the formulation-related scope of this patent while still facing method-of-use risk if its labeling, clinical support materials, or mandated dosing instructions direct physicians to perform the claimed serum-guided optimization.

How strong is the patent estate for generic entry?

The patent has moderate method-of-use strength but limited standalone product-blocking strength.

Factors supporting enforcement

The 1,300 ng/mL threshold is specific and potentially easy to map to clinical protocols.
Claims 2 and 3 identify commercially relevant psychiatric populations, particularly PTSD and psychotic depression.
Claim 5 extends protection to treatment lasting at least 28 days.
Claim 7 directly captures dose escalation.
A protocol documented in labeling or clinical materials may create evidence of induced infringement.

Factors limiting enforcement

The claims require serum-level testing.
The claims require at least seven daily doses.
The neuropsychiatric indications are narrower than all potential mifepristone uses.
A generic manufacturer may seek a section viii “skinny label” excluding patented uses under the Hatch-Waxman framework.[2]
Physicians may prescribe outside the generic label, complicating induced-infringement theories.
The claim does not prevent sale of mifepristone for unrelated indications.
The patent does not cover the active pharmaceutical ingredient or a broad formulation.

The most material litigation question is whether the generic label affirmatively encourages the claimed monitored, dose-escalation method. A label that merely describes a fixed dose without serum monitoring would present a substantially different risk profile from a label that recommends concentration testing and adjustment above 1,300 ng/mL.

What is the FDA and Orange Book relevance?

Mifepristone has multiple FDA-regulated products and indications that must be separated.

Product	Sponsor or principal commercial party	General indication	Relevance to US 8,921,348
Korlym	Corcept Therapeutics	Hyperglycemia secondary to endogenous Cushing syndrome	Mifepristone product and patent-estate context
Mifeprex	Danco Laboratories	Medication abortion in combination with misoprostol	Separate indication and regulatory history
Generic mifepristone	Multiple potential ANDA applicants	Depends on approved reference product and label	Potential paragraph IV and section viii issues

Korlym was approved by the FDA in 2012 for controlling hyperglycemia secondary to hypercortisolism in adults with endogenous Cushing syndrome who have type 2 diabetes mellitus or glucose intolerance and are not candidates for surgery or have failed surgery.[3]

Mifeprex was approved for medication abortion and has a separate regulatory and labeling history.[4] The supplied claims do not cover the standard medication-abortion regimen merely because that regimen uses mifepristone.

Orange Book significance depends on whether the patent is listed against an approved drug and whether the listed claims correspond to an approved use. A method patent can be relevant to Orange Book listing, paragraph IV certification, a 30-month stay, and a potential patent-infringement action under 35 U.S.C. §271(e)(2).[2] The existence of US 8,921,348 alone does not establish that a particular generic application is blocked. The applicant’s certification, proposed labeling, and the patent’s listing status control that analysis.

When does US Patent 8,921,348 lose exclusivity?

The patent issued on December 30, 2014. Its expiration date cannot be determined from the claim text or grant date alone because US patent term generally runs 20 years from the earliest effective nonprovisional filing date, subject to terminal disclaimers, patent-term adjustment, patent-term extension, and applicable priority claims.[1]

For business planning, the controlling records are:

The front page of the issued patent;
The continuity and priority statements;
USPTO Patent Center;
Any terminal disclaimer;
Any patent-term adjustment calculation;
FDA Orange Book listing data;
Any patent-term extension under 35 U.S.C. §156.

Patent expiration is separate from regulatory exclusivity. FDA new-drug exclusivity, orphan-drug exclusivity, pediatric exclusivity, and patent term can overlap but are calculated under different rules.[5]

A patent’s expiration also does not eliminate regulatory requirements for an ANDA or 505(b)(2) application. It removes the patent-based exclusion after the relevant term ends, subject to other unexpired patents and regulatory barriers.

Which companies are relevant to the mifepristone patent landscape?

The competitive landscape has three distinct groups.

Corcept Therapeutics

Corcept is the principal commercial company associated with Korlym and the Cushing syndrome mifepristone market. Its estate has included patents directed to mifepristone treatment, dosing, drug interactions, patient selection, and related clinical use.

Danco Laboratories

Danco is associated with Mifeprex for medication abortion. Its product, indication, distribution controls, and regulatory history differ materially from Korlym. A patent directed to serum-guided psychiatric treatment does not automatically block Mifeprex competition.

Generic pharmaceutical companies

Potential ANDA applicants may challenge listed patents through:

Paragraph IV certifications;
Section viii carve-outs;
Paragraph III certifications accepting delayed launch;
Declaratory or district-court proceedings;
Noninfringement and invalidity defenses.

The principal generic-entry risk from US 8,921,348 is therefore indication-specific. A generic seeking approval only for noncovered uses may have a stronger design-around position than a generic whose labeling includes monitored dose escalation for PTSD, psychotic depression, or related conditions.

What patent litigation affects US 8,921,348?

The patent number should be evaluated together with the full Korlym patent family and any Orange Book-listed continuation patents. A single patent rarely determines market entry where the sponsor has overlapping patents covering:

Mifepristone treatment methods;
Dosing regimens;
CYP3A-mediated drug interactions;
Patient subgroups;
Formulations;
Manufacturing processes;
Additional approved or investigational indications.

The critical litigation documents are the ANDA notice letter, complaint, patent list, claim construction record, and any settlement agreement. A settlement may permit an agreed launch date without validating the patent or confirming that the generic infringes.

No conclusion about a particular paragraph IV challenge, settlement date, or court judgment follows from the supplied claims alone. Those outcomes require the relevant docket and Orange Book records.

How does US 8,921,348 compare with formulation and manufacturing patents?

Patent category	What it protects	Relevance to this patent
Active-ingredient patent	Mifepristone molecule or chemical form	Usually broader product control
Formulation patent	Tablet, excipient, release profile, stability	Can block a particular product design
Method-of-use patent	Treatment of a disease or patient group	US 8,921,348 falls in this category
Dosing patent	Dose, duration, titration, or schedule	US 8,921,348 includes these limitations
Diagnostic-monitoring patent	Biomarker or drug-level testing and adjustment	US 8,921,348 has this functional structure
Manufacturing patent	Synthesis, purification, or process controls	Creates supply-chain and API barriers
Device patent	Sampling, assay, or delivery hardware	Claim 6 incorporates a device limitation

US 8,921,348 is unlikely to prevent independent API manufacture or a noncovered mifepristone formulation. Its leverage is concentrated in the clinical-use pathway.

What generic launch scenarios exist?

Scenario 1: Noncovered-use launch

A generic launches with labeling limited to an indication and regimen that do not require serum monitoring or a target above 1,300 ng/mL. This reduces literal infringement exposure but does not eliminate potential induced-infringement or off-label-use theories.

Scenario 2: Carved-out indication

The applicant removes psychiatric indications or the claimed monitoring instructions under section viii. The commercial value depends on whether the remaining label is clinically useful and whether the carved-out information is necessary for safe and effective use.

Scenario 3: Paragraph IV litigation

The applicant alleges that the patent is invalid, unenforceable, or not infringed. The principal defenses would likely focus on anticipation, obviousness, enablement, written description, indefiniteness, and the absence of encouragement in the proposed label.

Scenario 4: Delayed or negotiated entry

The parties settle and establish a launch date. The settlement may preserve the patent until a negotiated date while allowing the generic to enter before patent expiration under agreed conditions.

Key Takeaways

US 8,921,348 is a method-of-treatment patent focused on serum-guided mifepristone dose optimization.
Claim 1 requires at least seven daily doses, serum testing, and adjustment to achieve levels above 1,300 ng/mL.
Claims 2 and 3 concentrate risk in psychiatric and stress-related disorders, including PTSD and psychotic major depression.
Claim 5 covers treatment courses lasting at least 28 days.
Claim 7 specifically targets dose escalation.
The patent does not broadly cover mifepristone, Korlym tablets, Mifeprex, or every mifepristone use.
Generic exposure is highest when labeling or clinical materials recommend serum monitoring and titration above 1,300 ng/mL.
Patent expiration must be determined from the USPTO term calculation, including priority, terminal disclaimer, and patent-term adjustment data.
Orange Book status, paragraph IV challenges, litigation, and settlement outcomes require review of the current FDA and court records.
Formulation, API, manufacturing, and separate method-of-use patents may create additional barriers after this patent is no longer enforceable.

FAQs About US Patent 8,921,348

Does US Patent 8,921,348 cover Korlym itself?

No. The supplied claims cover a method of administering and monitoring mifepristone. They do not claim the Korlym product, mifepristone as a compound, or a particular tablet formulation.

Does the patent cover mifepristone abortion treatment?

Not on the supplied claim language alone. The claims focus on prolonged dosing, serum-level testing, a concentration above 1,300 ng/mL, and specified psychiatric or stress-related disorders.

Can a generic avoid the patent by omitting serum monitoring from its label?

Potentially, but omission does not automatically eliminate all infringement risk. The analysis depends on the proposed label, promotional conduct, physician use, and the scope of any listed patent claims.

Is a 28-day mifepristone regimen automatically infringing?

No. Duration alone is insufficient. The protocol must also satisfy the drug, serum-testing, concentration, disorder, administration, and dose-adjustment limitations applicable to the asserted claim.

Does a serum level of exactly 1,300 ng/mL satisfy the patent?

No, not literally under the phrase “greater than 1300 ng/mL.” A concentration must exceed 1,300 ng/mL, subject to any doctrine-of-equivalents analysis.

References

United States Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation guidance. https://www.uspto.gov
35 U.S.C. §§ 271(e)(2), 355(j).
U.S. Food and Drug Administration. (2012). FDA approves first drug for patients with Cushing’s syndrome. https://www.fda.gov
U.S. Food and Drug Administration. (2000). Mifeprex prescribing information. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Corcept Therap	KORLYM	mifepristone	TABLET;ORAL	202107-001	Feb 17, 2012	AB	RX	Yes	Yes	8,921,348	⤷ Start Trial				TREATING CUSHING'S SYNDROME	⤷ 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

Details for Patent: 8,921,348

Which drugs does patent 8,921,348 protect, and when does it expire?

Summary for Patent: 8,921,348