United States Patent 12,263,146 (Mirdametinib, Oral Treatment of NF1 Inoperable Plexiform Neurofibromas): Claims Scope and US Patent Landscape
What does US 12,263,146 claim at the method-of-treatment level?
US 12,263,146 is directed to a method of treating a defined subgroup of human patients with neurofibromatosis type 1 (NF1) who have inoperable plexiform neurofibromas (PN), using oral mirdametinib with body-surface-area (BSA) tailored starting doses, and optionally with a response-rate-based selection criterion.
Core claim architecture
The patent is structured around three repeated building blocks:
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Patient disease and eligibility
- Age: “2 years or older”
- Condition: “NF1 associated inoperable plexiform neurofibromas (PN)”
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Oral drug administration
- Active: “mirdametinib”
- Route: “orally administering an effective amount”
- Initial dose is BSA-dependent (1 mg, 2 mg, 3 mg, or 4 mg)
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Optional “objective response rate” selection / eligibility refinement
- Prior to treatment:
- (i) determine whether to select mirdametinib
- (ii) select mirdametinib at least partially based on an objective response rate
- Response rate definition:
- “at least a 20% decrease in tumor size using centrally read MRI volumetric analysis”
- Additional dependent refinement:
- “selected based on a response rate of at least 70%”
Claim set coverage (BSA windows and initial dose schedules)
Across independent and dependent claims provided, the patent maps BSA strata to starting doses, with a further dependent limitation to twice-daily administration in each stratum.
| Claim (as provided) |
Patient BSA limitation |
Initial mirdametinib dose |
Twice-daily dependent limitation |
| Claim 1 |
1.5 to 1.74 m² |
4 mg |
Not specified in Claim 1; implied by “twice daily” in Claim 1 |
| Claim 4 |
≤ 0.69 m² |
1 mg |
Claim 5: 1 mg twice daily |
| Claim 8 |
0.7 to 1.04 m² |
2 mg |
Claim 9: 2 mg twice daily |
| Claim 12 |
1.05 to 1.49 m² |
3 mg |
Claim 13: 3 mg twice daily |
| (Selection criterion) Claims 2,6,10,14 |
Applies when “prior to treatment” selection is made |
N/A |
N/A |
Key scope point: even where dependent claims state dosing frequency as “twice daily,” the independent claim in the 1.5 to 1.74 m² stratum already requires “4 mg … twice daily,” so the frequency limitation exists at least for that stratum even without dependence.
What is the practical claim scope: patient selection, dosing, and response criteria?
US 12,263,146 is not a broad “mirdametinib for NF1 PN” composition claim. It is a method claim with tight definitional gates in three dimensions.
1) Treatment population gate
The claims require:
- NF1 diagnosis
- Inoperable plexiform neurofibromas
- Age ≥ 2 years
This means generic “NF1 PN treatment” does not fall under the claim language unless the inoperability criterion and the age threshold are satisfied.
2) Dosing gate using BSA windows
The claims require that the initial administered dose aligns to the patient’s BSA range:
- BSA ≤ 0.69 m²: start 1 mg
- 0.7 to 1.04 m²: start 2 mg
- 1.05 to 1.49 m²: start 3 mg
- 1.5 to 1.74 m²: start 4 mg
If a clinician starts a different dose than claimed for the patient’s BSA (or begins with a titration not matching the “initially administered” value), the method claim may not be met.
3) Frequency gate (where explicitly required)
Where dependent claims specify, the method further requires twice-daily administration for the BSA strata (1 mg, 2 mg, 3 mg). For the 4 mg stratum, “twice daily” is in Claim 1 as written.
This matters for enforcement because a regimen that uses the same daily total but different schedule could fall outside the literal claim language.
4) Optional selection gate based on objective response rate (MRI volumetrics)
Several claims add a biomarker-like selection criterion tied to imaging response:
- Before starting treatment, the physician:
- determines whether to select mirdametinib
- selects mirdametinib at least in part based on objective response rate
Where “objective response rate” is defined as:
- “at least a 20% decrease in tumor size”
- “using centrally read MRI volumetric analysis”
Dependent refinements also add:
- selection is based on a response rate threshold of “at least 70%.”
Scope implication: this adds a diagnostic/decision step to the method. A regimen that treats but does not use selection criteria tied to response rate (as defined) may not satisfy dependent claim limitations.
How broad are these method claims versus prior art and other mirdametinib patents?
Based on the claim text you provided, the patent’s breadth is constrained by:
- Specific disease and subtype: NF1 + inoperable PN
- Specific route and active: oral mirdametinib
- Patient-specific dosing: BSA strata plus “initially administered” dose
- Optional decision protocol: MRI volumetric response definition and 70% threshold
This is typically the kind of claim set used to capture:
- dosing initiation rules tied to pediatric/adolescent body size
- decision-making frameworks tied to imaging response endpoints
It is less likely to cover:
- other dosing schedules outside the “initial” dose or the twice-daily requirement (where stated)
- alternative mirdametinib administration patterns (titration-first, intermittent dosing, once-daily starting regimens)
- selection without MRI volumetric centrally read criteria
How does the claim language map to enforceable “single-step” versus multi-step treatment actions?
Method claims can be infringed by either single actors (e.g., physician directly) or multiple actors (e.g., testing lab plus physician). Here, the claims clearly list both clinical actions and pre-treatment selection steps.
Claims without the selection requirement
Claims 1,4,8,12 (as provided) require:
- administering mirdametinib orally as an effective amount
- with BSA-constrained initial dosing
- with twice-daily where specified
These can be performed by the treating clinician at the point of prescribing/starting therapy.
Claims with the selection requirement
Claims 2,6,10,14 require the method to include:
- pre-treatment determination and selection
- based at least in part on objective response rate
- using centrally read MRI volumetric analysis and a ≥20% tumor size decrease definition
- in dependent form, response rate selection threshold ≥70%
This can raise attribution/enforcement complexity in practice because it embeds:
- a decision criterion tied to evidence from prior or ongoing studies, or potentially from the patient’s own imaging pathway depending on construction
- a defined “centrally read” element, which can rely on third-party reading mechanisms
Even so, the claim language is drafted as a treatment method including a decision step, which is often directly actionable when the clinical protocol follows the claimed selection framework.
What does the “objective response rate” definition do to the landscape?
The patent’s decision-step language makes the claims sensitive to:
- MRI volumetric analysis method
- central reading workflow
- tumor size reduction threshold: at least a 20% decrease
- selection threshold: response rate at least 70%
Competitive risk points for generic or biosimilar entrants
Even if a competitor has a legal right to use mirdametinib itself (through composition patent expiry or licensing), this patent can still be relevant if that competitor uses a protocol matching the claimed method elements.
Two high-risk areas for “design around”:
- Starting dose not matching the BSA strata or “initially administered” value
- Patient selection not tied to the MRI central volumetric endpoint definition and 70% response rate threshold
What design-arounds are suggested by the claim text itself?
The claims you provided indicate straightforward levers for competitors to avoid literal infringement:
-
Use a different initial dose than the BSA-mapped starting doses
- The claims use “initially administered” dose as a hard limitation.
-
Alter administration frequency where it is explicitly required
- For BSA ≤0.69, 0.7 to 1.04, and 1.05 to 1.49 strata, the twice-daily requirement appears in dependent claims.
- For the 1.5 to 1.74 stratum, twice daily is in Claim 1.
-
Avoid the “centrally read MRI volumetric analysis” objective response definition
- Replace with non-central reading, different quantification method, or a different volumetric threshold.
-
Avoid the “≥70% response rate” selection threshold
- Selection based on other endpoints, or thresholds not equal to 70%.
These are based on claim wording rather than clinical feasibility.
What is the US patent landscape implication for mirdametinib in NF1 inoperable PN?
From a landscape perspective, US 12,263,146 reads like a second-tier protection layer: it does not claim the molecule itself from the description you provided. Instead, it claims how to treat a particular subgroup with BSA-tailored dosing and an imaging-based selection protocol.
Likely roles relative to broader patent categories (framework, not an assertion of specific documents)
In a typical NF1 PN development set, patent families often split across:
- molecular composition and/or salts
- formulations and dosing regimens
- use claims tying the compound to the indication and patient population
- method-of-treatment and clinical decision criteria
US 12,263,146 belongs to the last two categories by its own claim language: method-of-treatment plus objective response-based patient selection.
Enforcement leverage
Method claims with precise dosing and imaging criteria can:
- deter label-aligned protocol adoption by competitors
- support “protocol infringement” theories even if a competitor sells the same active ingredient
What are the claim-by-claim scope boundaries (literal element check)?
Below is an element checklist that mirrors the claim text you provided.
Claim 1 scope (BSA 1.5 to 1.74 m²)
- Patient: human, age ≥2
- Disease: NF1 associated inoperable PN
- Route: oral
- Drug: mirdametinib
- Initial dose: 4 mg
- Frequency: twice daily
- Dose basis: BSA 1.5 to 1.74 m²
- Uses: “effective amount” (functional)
Claim 2 (adds selection step)
- All Claim 1 limitations
- Prior to treatment:
- determine whether to select
- select based at least in part on objective response rate
- Objective response rate definition:
- at least 20% decrease in tumor size
- centrally read MRI volumetric analysis
Claim 3 (adds selection threshold)
- All Claim 2 limitations
- Selection based on response rate of at least 70%
Claim 4 scope (BSA ≤0.69 m²)
- Patient: human, age ≥2
- Disease: NF1 associated inoperable PN
- Route: oral
- Drug: mirdametinib
- Initial dose: 1 mg
- BSA limitation: no more than 0.69 m²
- Frequency not included in Claim 4 as provided; it appears in Claim 5
Claim 5 (adds twice daily)
- All Claim 4 limitations
- Administered 1 mg twice daily
Claim 6 (adds selection step)
- All Claim 4 limitations
- Prior selection based on objective response rate per MRI volumetric central reading and ≥20% decrease definition
Claim 7 (adds selection threshold)
- All Claim 6 limitations
- Selection based on response rate of at least 70%
Claim 8 scope (BSA 0.7 to 1.04 m²)
- Same core as Claim 4/1
- Initial dose: 2 mg
- BSA limitation: 0.7 to 1.04 m²
Claim 9 (adds twice daily)
- All Claim 8 limitations
- Administered 2 mg twice daily
Claim 10 (adds selection step)
- All Claim 8 limitations
- Selection using centrally read MRI volumetric objective response definition (≥20% decrease)
Claim 11 (adds selection threshold)
- All Claim 10 limitations
- Selection based on ≥70% response rate
Claim 12 scope (BSA 1.05 to 1.49 m²)
- Initial dose: 3 mg
- BSA limitation: 1.05 to 1.49 m²
Claim 13 (adds twice daily)
- All Claim 12 limitations
- Administered 3 mg twice daily
Claim 14 (adds selection step)
- All Claim 12 limitations
- Selection based on objective response rate per centrally read MRI volumetric analysis (≥20% decrease)
Claim 15 (adds selection threshold)
- All Claim 14 limitations
- Selection based on ≥70% response rate
Key Takeaways
- US 12,263,146 is a BSA-tailored, oral mirdametinib method-of-treatment patent for NF1-associated inoperable plexiform neurofibromas in patients age ≥2.
- The initial dose is the central structural limiter: 1 mg (BSA ≤0.69), 2 mg (0.7 to 1.04), 3 mg (1.05 to 1.49), 4 mg (1.5 to 1.74), with twice-daily requirements appearing either directly (4 mg) or in dependent claims (1 mg, 2 mg, 3 mg).
- Several dependent claims add a pre-treatment selection protocol tied to centrally read MRI volumetric analysis, requiring an objective response definition of ≥20% tumor size decrease, and in further dependence a selection threshold of ≥70% response rate.
- In the US landscape, the patent’s enforcement leverage is highest where competitors follow label-like dosing initiation by BSA and incorporate MRI central volumetric response-based decision-making.
FAQs
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Does US 12,263,146 claim mirdametinib as a composition?
The claims you provided are framed as methods of treating and specify oral administration and patient-specific starting dose regimens, not a compound composition claim.
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What triggers claim coverage in these method claims?
Coverage triggers on treating a human patient ≥2 with NF1-associated inoperable plexiform neurofibromas, using oral mirdametinib with BSA-constrained initial dosing.
-
Is twice-daily dosing required for all BSA bands?
For BSA 1.5 to 1.74 m², twice-daily appears in Claim 1 as written. For other BSA bands (≤0.69, 0.7 to 1.04, 1.05 to 1.49 m²), twice-daily appears in dependent claims.
-
What does “objective response rate” mean in the selection-step claims?
It means at least a 20% decrease in tumor size measured by centrally read MRI volumetric analysis.
-
What role does the “at least 70%” response rate play?
In dependent claims (as provided), it tightens the selection step so that mirdametinib is selected based on a response rate threshold of ≥70%.
References
[1] US Patent application/registration details are not included in the prompt beyond the provided claim text; no external citation material is present in the supplied information.
