US Patent 12,458,649 Scope and Claims Analysis: Estetrol/DRSP Method-of-Use for QT and CRP Risk Reduction Versus Comparator COCs

Executive summary: US Patent 12,458,649 claims a method-of-treatment (not a new composition per se) using a specific estetrol/drospirenone (estetrol/DRSP) combined oral contraceptive (COC) to treat or reduce risks of DRSP-related adverse effects when compared to comparator COCs that use DRSP plus an estrogen other than estetrol. Claim scope is built around (i) patient history of DRSP-related adverse effects, (ii) dose ranges for estetrol and DRSP, (iii) two adverse-effect endpoints: QT prolongation and CRP elevation, and (iv) pharmacokinetic (PK) exposure bands for DRSP (AUC0-24 and Cmax) tied to achieving the risk reduction.

What does US 12,458,649 claim: method-of-use for reducing drospirenone adverse effects using estetrol/DRSP?

Core claim concept (Claim 1): A clinician administers daily an estetrol/DRSP COC within defined estrogen and progestin dose windows to a female subject who has experienced DRSP-related adverse effects, and the method is effective to treat or reduce risks of QT interval prolongation and/or CRP elevation as compared to a comparator COC containing DRSP and an estrogen other than estetrol.

Claim 1 structural elements you can map to infringement and validity risk

Treatment population
- Female subject in need thereof.
- Subject has experienced one or more DRSP-related adverse effects (history requirement).
Drug being administered
- COC with:
  - Progestogenic component: DRSP
  - Estrogenic component: estetrol (E4)
- Dose ranges in a “daily active dosage unit”:
  - Estetrol: 10 mg to 20 mg
  - DRSP: 1 mg to 5 mg
Purpose and endpoints (risk reduction)
- Must treat/reduce risks of adverse effects selected from:
  - (i) QT interval prolongation of at least 5 ms
  - (ii) increase in C-reactive protein (CRP) concentration to an elevated level
- Each is defined by comparison to a comparator COC:
  - DRSP plus an estrogen other than estetrol
PK-based linkage to the risk effect
- Daily administration results in DRSP PK exposure meeting one or both:
  - Geometric mean AUC0-24: 150 to 1000 ng·h/mL
  - Geometric mean Cmax: 10 to 100 ng/mL

Legal character: Method-of-use with both clinical endpoints and PK thresholds, using an inherently comparative standard versus another COC.

What “risk reduction” means in claim construction terms

The claim uses “effective to treat or reduce the risks of” endpoints compared to a comparator regimen. That language typically requires a comparative showing tied to the comparator COC. For enforcement, the party asserting infringement will likely rely on:

clinical trial data,
bridging studies,
or label/PK correlations that support “at least X%” risk reductions where dependent claims recite percentage thresholds.

How broad is the claim scope: what dose ranges, endpoints, and PK limits drive coverage?

Dose ranges in independent Claim 1

Estetrol: 10–20 mg
DRSP: 1–5 mg

This covers a wide swath of potential E4/DRSP formulations as long as they are “combined oral contraceptives” and are administered daily as a “daily active dosage unit.”

Endpoint thresholds

QT: ≥ 5 ms prolongation
CRP: “elevated level” (not numerically specified in Claim 1, but becomes narrower in dependent claims)

PK exposure bands (DRSP)

The claim limits method to those daily administrations that yield:

AUC0-24: 150–1000 ng·h/mL
Cmax: 10–100 ng/mL

This is a major scope feature:

It narrows “effective method” to exposure regimes that plausibly map to the observed adverse-risk reduction.
It also creates a basis to argue non-infringement if real-world PK is outside bands, or if a product’s geometric mean exposure differs.

Comparator-driven framing

The comparator COC is:

DRSP plus estrogen “other than estetrol” (explicitly broad).

That breadth can cut both ways:

It enlarges the set of possible comparator estrogen types that courts may accept as within the definition.
It also makes validity and enforceability more dependent on what “comparison” means (trial design, study population, and endpoint measurement).

Which adverse effects are covered: QT interval prolongation and CRP elevation and how exactly are they defined?

QT interval prolongation prong

Claim 1: QT prolongation of at least 5 milliseconds compared to comparator COC.

Dependent claims tighten:

Claim 5: method effective to reduce risk of QT prolongation ≥ 5 ms
Claim 6: risk reduced by at least 10%
Claim 7: mean QT prolongation at least 20% shorter than comparator
Claim 8: reduced estrogenic-related effects on QT interval vs comparator

The QT package is unusually robust because it includes both:

a risk reduction percentage (Claim 6), and
a mean QT improvement metric (Claim 7).

CRP prong

Claim 1: increase of CRP concentration “to an elevated level” compared to comparator COC.

Dependent claims narrow:

Claim 9: reduce risk of CRP increase to elevated level
Claim 10: CRP elevation reduced by at least 10% higher than baseline, baseline defined pre-COC
Claim 11: CRP concentration < 2.00 mg/L

That combination provides both a relative baseline comparison and a hard numeric cap.

What is the dosage form and regimen scope: kits, continuous cycles, and administration-free intervals?

Kit coverage (Claim 2)

The daily active dosage unit is in a contraceptive kit with packaging units each containing:
- 21 to 28 daily active dosage units.

This can cover standard COC pack sizes and may support infringement theories that use commercial packaging.

Treatment schedule (Claim 3 and Claim 12)

Claim 3: “administered continuously in cycles of 21 to 28 daily administrations”
Claim 12: periodic cycles with an administration-free interval of 4 to 7 days

Together, these align with conventional COC “active days followed by pill-free days” regimens.

Specific unit dosage example (Claim 13)

A single daily active dosage unit comprises about:
- 15 mg DRSP and 3 mg estetrol

Practical note on claim logic: Claim 13 is a dependent narrowing example that recites a precise dosage ratio. If enforced, it would require matching the “about” ranges in the unit.

How does US 12,458,649 compare against estrogen substitutes: what if the comparator uses ethinyl estradiol?

Explicit comparator in Claim 4

Comparator COC uses ethinyl-estradiol (EE) as “the estrogen other than estetrol.”

That matters for:

trial comparators,
label-to-patent comparisons,
and litigation where EE-containing drospirenone COCs are commercially entrenched.

Comparator breadth in Claim 1 vs specificity in Claim 4

Claim 1 allows any estrogen other than estetrol.
Claim 4 specifically anchors EE, which is often the default reference estrogen in COC datasets.

From a landscape angle, the patent’s enforceability and evidentiary strength likely improves when the comparator is EE, because public clinical comparators and industry study designs routinely include EE arms.

Patent estate scope: what types of claims likely surround a method like this in the same US family?

Given the claim content, the broader US patent family for US 12,458,649 (and related filings) typically clusters into four invention themes:

Method-of-use for risk reduction tied to:
- QT and/or CRP outcomes
- historical DRSP-related adverse events in the subject
Dose regimen features:
- pack counts (21–28)
- active-cycle length and pill-free intervals (4–7 days)
PK-limited method language:
- DRSP AUC0-24 and Cmax bands
Formulation/dose specificity:
- unit mg ranges, including exemplars such as the fixed unit described in Claim 13

This patent reads like a late-stage differentiation strategy that uses:

exposure targets,
and comparative clinical outcomes, to distinguish from earlier DRSP/estrogen COC generations.

What generic entry risks exist for competitors using drospirenone COCs with estetrol or other estrogens?

If a competitor uses estetrol/DRSP with different PK

A competitor can attempt non-infringement by designing:

formulation or administration to shift DRSP geometric mean AUC0-24 and/or Cmax outside claimed bands (150–1000 AUC; 10–100 Cmax).
or using PK profiles that fail the “results in” requirement of Claim 1.

Because the claim is “method effective … wherein daily administration … results in a pharmacokinetic profile,” PK becomes central to both:

infringement analysis, and
motion practice at the claim construction stage.

If a competitor changes only estrogen away from estetrol

If the competitor’s estrogen is “other than estetrol,” the method is likely outside the “administering daily … a daily active dosage unit of an estetrol/DRSP COC” limitation. That said, competitors using DRSP plus non-estetrol estrogen will still be potential targets only insofar as they are accused under some separate composition or use claims not contained in the prompt.

If a competitor markets a regimen but does not target the claimed adverse-effect history

Claim 1 requires a female subject who “has experienced one or more DRSP-related adverse effects.” If a competitor markets broadly without such a specified patient selection, enforcement becomes fact-dependent on:

prescribing patterns,
label instructions (if any),
and evidence of patient history in the treated cohort.

Orange Book status and FDA exclusivity: what is the regulatory trigger for enforcement versus generic substitution?

No Orange Book or FDA pathway data is provided here, so a precise Orange Book mapping (listed drug, reference product, patent listing numbers, and expiration dates) cannot be produced from the claim text alone.

The regulatory exposure that matters for this patent is tied to whether:

the claimed method is asserted under FDA “patent listed” method-of-use entries (typically for Orange Book-listed drug product patents), and
any exclusivity periods (3-year/5-year data exclusivity, patent exclusivity, or pediatric exclusivity) attach to the reference product at the time of ANDA or 505(b)(2) filings.

Without those listing details, enforcement timing cannot be anchored.

How strong is the patent estate for QT/CRP risk reduction methods: what in the claim design supports enforceability?

Key strength levers in the claim language:

Dual adverse endpoints
- QT and CRP are both explicitly anchored, with separate dependent claim sets.
Comparator framework
- “compared to a comparator COC” provides a built-in benchmark and supports measurable differences.
Quantitative improvement requirements in dependent claims
- At least 10% reduction in QT risk (Claim 6)
- at least 20% shorter mean QT prolongation (Claim 7)
- CRP reduction quantified against baseline and absolute cap (<2.00 mg/L) (Claims 10–11)
PK constraints
- AUC and Cmax geometric means provide a second axis that can be independently assessed.

These elements reduce reliance on subjective endpoints and increase the ability to argue direct correlation between treatment and outcome.

What patent litigation theories does US 12,458,649 support: comparative endpoints, PK proof, and patient selection

Typical litigation theories for this claim structure would use:

Infringement

show prescribing aligns with:
- DRSP adverse-effect history,
- dosing within estetrol/DRSP ranges,
- and regimen schedule (if claims 2/3/12 are asserted),
show DRSP PK geometric mean falls in claimed bands,
show that QT and/or CRP endpoints meet comparative thresholds versus an eligible comparator.

Validity challenges

If prior art exists for estetrol/DRSP COCs and QT/CRP endpoints, challengers may argue lack of novelty or obviousness by combining:
- known DRSP QT risks,
- known CRP inflammatory markers changes in COC use,
- and known PK differences among estrogen types.

But the claim is structured to require:

the specific comparator definition,
and the PK exposure windows, which can be used to argue that prior art combinations do not disclose the claimed quantitative boundaries.

Key comparisons: what makes this patent distinct from earlier drospirenone COC patents?

Distinction 1: estrogen-specific differentiation

Many DRSP COC patents focus on:

the composition,
the contraceptive efficacy,
or general safety.

This patent narrows to:

estetrol/DRSP specifically,
and defines the risk reduction relative to:
- DRSP with other estrogen(s).

Distinction 2: clinically measurable QT and inflammatory biomarker outcome

The claim ties method efficacy to:

QT prolongation threshold (ms),
CRP elevation thresholds (baseline-relative and absolute).

Distinction 3: PK band requirement

Using AUC0-24 and Cmax bands as part of method definition is more specific than typical general safety claims.

Claims-by-Claims coverage map (quick reference)

Claim	Main narrowing element	Adds/changes compared to Claim 1
1	Daily estetrol/DRSP COC, patient has DRSP adverse effects; QT ≥5 ms and/or CRP elevation; DRSP AUC 150–1000 and/or Cmax 10–100	Baseline independent claim with dose ranges and PK bands
2	Kit with 21–28 active units per packaging unit	Packaging dimension
3	21–28 day active cycles	Treatment schedule
4	Comparator estrogen is EE	Comparator specificity
5	Effective to reduce QT risk (QT ≥5 ms)	QT-focused dependent claim
6	QT risk reduced by ≥10% vs comparator	Quantified risk reduction
7	Mean QT prolongation ≥20% shorter than comparator	Quantified mean improvement
8	Reduced estrogenic-related QT effects vs comparator	Additional qualitative narrowing
9	Effective to reduce CRP elevation risk	CRP-focused dependent claim
10	CRP elevation reduced to at least 10% higher than baseline? (as written: “reduced… to an elevated level that is at least 10% higher than baseline”; depends on claim interpretation)	Quantified baseline-relative improvement
11	CRP <2.00 mg/L	Hard numeric cap
12	Cycles with 4–7 day administration-free interval	Schedule dimension
13	Example unit: “about 15 mg drospirenone and about 3 mg estetrol”	Very specific dosage example

Key Takeaways

US 12,458,649 is a comparative method-of-use patent for estetrol/DRSP COC administration in women with prior DRSP-related adverse effects, targeting QT prolongation (≥5 ms) and/or CRP elevation relative to DRSP plus non-estetrol estrogen comparator COCs.
Claim scope is controlled by three high-impact constraints: (i) estrogen and DRSP dose ranges, (ii) DRSP PK geometric mean bands (AUC0-24 150–1000; Cmax 10–100), and (iii) the endpoint thresholds and dependent-claim quantitative improvements.
Enforcement leverage is strongest when an asserted product’s clinical and PK data can be aligned to the claimed comparative QT/CRP outcomes.
Portfolio and litigation strategy should treat this as an endpoint-and-PK-defined differentiation patent rather than a generic contraceptive formulation claim.

FAQs

Does US 12,458,649 require QT and CRP outcomes together or can either one satisfy infringement?
Claim 1 allows adverse effects selected from QT and/or CRP. Dependent claims then narrow to QT or CRP specifically.
What is the significance of the DRSP PK geometric mean AUC0-24 and Cmax bands in Claim 1?
They are part of the method definition: the daily administration must “result in” exposure within those ranges.
How does the EE comparator language in Claim 4 affect claim scope?
It provides a specific comparator example that is commonly relevant for COC studies and can anchor comparative evidence.
Can a competitor argue non-infringement by changing packaging or pill-free interval?
Yes for the dependent claims tied to kits (Claim 2) and dosing cycles/pill-free intervals (Claims 3 and 12), but Claim 1 is broader on regimen schedule.
What endpoints are directly tied to quantitative thresholds beyond Claim 1?
QT risk is quantified (≥10% risk reduction and ≥20% shorter mean QT prolongation), and CRP is quantified (baseline-relative threshold and an absolute cap of <2.00 mg/L).

References

[No external sources cited because no FDA/Orange Book, prosecution history, or family/patent-document identifiers beyond the claims provided were supplied.]

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Mayne Pharma	NEXTSTELLIS	drospirenone; estetrol	TABLET;ORAL	214154-001	Apr 15, 2021		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				USE BY FEMALES OF REPRODUCTIVE POTENTIAL TO PREVENT PREGNANCY	⤷ 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	121864	⤷ Start Trial
Australia	2021255908	⤷ Start Trial
Brazil	112022020710	⤷ Start Trial
Canada	3177556	⤷ Start Trial
China	115666582	⤷ Start Trial
European Patent Office	4135709	⤷ Start Trial
Israel	297282	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 12,458,649