United States Patent 11,268,128 (LEMS + NAT2 genotype): What the claims cover and how to map the patent landscape
United States Drug Patent 11,268,128 claims a genotype-guided dosing method for 3,4-diaminopyridine (3,4-DAP; fampridine) in Lambert-Eaton myasthenic syndrome (LEMS) based on the patient’s N-acetyl transferase 2 (NAT2) alleles, with two distinct dosing regimes: (i) patients with at least one NAT2 fast allele and (ii) patients with two NAT2 slow alleles (specified NAT25/6/7/14). The core protection is framed as a method of treating LEMS by administering specified total daily dose ranges, optionally as divided doses, with further dependent claim refinements covering wild-type fast alleles, specific NAT2 slow mutations, and 3,4-DAP phosphate salt dosing equivalents.
1) What exactly is claimed in US 11,268,128 (independent claim structure)?
Claim 1 is the pivot
Claim 1 is a single method claim with two alternative genotype/dose formulations:
A. NAT2 fast genotype pathway
- Treat a human patient diagnosed with LEMS
- Administer total daily dose of:
- about 30 mg to about 240 mg of 3,4-DAP, or a pharmaceutically acceptable salt
- Optional regimen format: “optionally provided as a series of divided doses”
- Genotype requirement: patient has at least one NAT2 fast allele
B. NAT2 slow genotype pathway
- Genotype requirement: patient has two NAT2 slow alleles
- Each NAT2 slow allele is one of:
- NAT25, NAT26, NAT27, or NAT214
- Total daily dose range:
- about 7.5 mg to about 40 mg of 3,4-DAP, or salt
- Optional regimen format: “optionally provided as a series of divided doses”
This creates a dose-reduction prescription for slow acetylators versus fast acetylators, with the lower band capped at 40 mg/day.
Dependent claims constrain genotype detail and dosing granularity
From the claim text provided, dependent claims cover:
- Claim 2: NAT2 fast allele is wild-type.
- Claim 3: NAT2 slow alleles are defined via specific mutation positions: 282T, 341C, 191A, 481T, 590A, 857A.
- Claim 4: narrows to 282T and/or 341C combination structures.
- Claims 5 and 11: dose delivered via 3,4-DAP phosphate salt (as an “equivalent amount”).
- Claims 6–10: for NAT2 fast genotype, tighter daily dose ranges (30–100 mg/day in dependent claims) and dividing patterns (up to 5 divided doses/day; specific 3–4 or 2–3 dose/day options; specified unit doses like 10/15/20/25/30 mg and total day examples like 30/50/60/80/100 mg).
- Claims 12–14: for NAT2 slow genotype, narrower band (15–30 mg/day) and divided dose patterns (3–4 or 2–3); day examples 15 mg or 30 mg.
- Claims 15–17: for NAT2 slow genotype, narrowest band (7.5–15 mg/day); divided dose options (2–3 per day); unit example 7.5 mg.
2) How does the claim set map to specific NAT2 genotypes (and what is “in” vs “out”)?
In-scope NAT2 slow alleles
The independent claim restricts “two NAT2 slow alleles” to:
- *NAT25**
- *NAT26**
- *NAT27**
- *NAT214**
Dependent claim 3 expands by mapping slow alleles to a mutation set:
- 282T
- 341C
- 191A
- 481T
- 590A
- 857A
Dependent claim 4 constrains further to:
- 282T
- 341C
- either 282T alone, 341C alone, or 282T + 341C depending on the allele composition formulation in the claim.
In-scope NAT2 fast alleles
- Independent claim 1 only requires at least one fast allele.
- Claim 2 narrows one fast allele embodiment to wild-type.
Key boundary effects
- If a patient does not have the required NAT2 allele pattern (no fast allele; or not exactly two slow alleles matching the specified alleles), the method claim language in Claim 1 is not satisfied.
- If a patient has two slow alleles but one slow allele is outside NAT25/6/7/14, the independent claim does not match the genotype prerequisite.
- If a patient meets the genotype but the dose falls outside the claimed ranges, the method claim does not cover that administration.
3) What is the dosing scope (mg/day bands and divided-dose detail)?
Total daily dose ranges by genotype
| Genotype condition |
Total daily dose range claimed (3,4-DAP base equivalent) |
Core claim basis |
| At least one NAT2 fast allele |
~30 mg to ~240 mg/day |
Claim 1A |
| Two NAT2 slow alleles (each NAT25/6/7/14) |
~7.5 mg to ~40 mg/day |
Claim 1B |
Dependent claims narrow the fast and slow bands
| Genotype condition |
Narrower total daily dose range in dependents |
Representative examples in dependents |
| NAT2 fast (at least one fast allele) |
~30 mg to ~100 mg/day |
Claim 10 examples: 30/50/60/80/100 mg/day |
| NAT2 slow (two slow alleles) |
~15 mg to ~30 mg/day |
Claim 12; Claim 14 examples: 15 mg or 30 mg/day |
| NAT2 slow (two slow alleles) |
~7.5 mg to ~15 mg/day |
Claim 15; Claim 17 example: 7.5 mg/day |
Divided-dose frequency and unit-dose specificity
The dependents add regimen granularity.
Fast genotype (Claims 7–10)
- Maximum divided doses: up to 5 divided doses/day (Claim 7)
- Frequency options:
- 3 to 4 divided doses/day, or
- 2 to 3 divided doses/day (Claim 8)
- Unit doses (Claim 9): ~10, ~15, ~20, ~25, or ~30 mg per divided dose
- Total daily examples (Claim 10): ~30, ~50, ~60, ~80, or ~100 mg/day
Slow genotype (Claims 13–14 and 16–17)
- For 15–30 mg/day (Claims 12–14):
- 3 to 4 divided doses/day or 2 to 3 divided doses/day (Claim 13)
- Daily examples: ~15 mg or ~30 mg/day (Claim 14)
- For 7.5–15 mg/day (Claims 15–17):
- Divided doses: 2 to 3 divided doses/day (Claim 16)
- Daily/unit example: ~7.5 mg/day (Claim 17)
Salt form coverage
- Claims explicitly allow dosing via 3,4-DAP phosphate salt using an “equivalent amount”:
- Fast regime salt: Claim 5
- Slow regime salt: Claim 11
This matters for product selection and whether a commercial formulation uses phosphate as the salt form.
4) What is the practical scope for enforceability (method claim logic)?
US 11,268,128 is framed as a patient treatment method. That typically means enforceability attaches to:
- Clinical selection: the physician (or sponsor-controlled protocol) must identify the patient as NAT2 fast or slow based on the claimed allele set; and
- Dose administration: the physician (or care team) must administer 3,4-DAP within the claimed daily dose ranges; and
- Regimen format: if the asserted dependent claims are used, the regimen must fall within their divided-dose structures and/or salt equivalents.
From a landscape perspective, this claim architecture is designed to capture:
- real-world “label-plus-genotype” prescribing where dosing changes by genotype;
- genotype stratification protocols in clinical practice, and
- potentially sponsor-driven dosing schedules in trials if the trial is framed as treating LEMS patients with genotype-based dose selection.
5) Claim-by-claim coverage map (what each dependent claim adds)
| Claim |
Added limitation |
Scope impact (what gets narrower) |
| 1 |
Two pathways: fast allele band (~30–240 mg/day) vs slow alleles band (~7.5–40 mg/day) |
Defines genotype-linked dosing threshold |
| 2 |
NAT2 fast allele is wild-type |
Narrows fast-allele embodiment |
| 3 |
NAT2 slow alleles described by mutation list (282T/341C/191A/481T/590A/857A) |
Narrows genotype characterization method |
| 4 |
NAT2 slow alleles described via 282T and/or 341C |
Further narrows mutation combinations |
| 5 |
Fast-pathway dose via 3,4-DAP phosphate |
Adds salt form limitation to fast band |
| 6 |
Fast-pathway narrowed to ~30–~100 mg/day |
Tightens total daily dosing |
| 7 |
Fast-pathway: up to 5 divided doses/day |
Controls dosing regimen frequency |
| 8 |
Fast-pathway: 3–4 or 2–3 divided doses/day |
Controls frequency further |
| 9 |
Fast-pathway: per-dose options 10/15/20/25/30 mg |
Adds unit dose granularity |
| 10 |
Fast-pathway: daily options 30/50/60/80/100 mg |
Adds daily dosing examples |
| 11 |
Slow-pathway dose via 3,4-DAP phosphate |
Adds salt form limitation to slow band |
| 12 |
Slow-pathway narrowed to ~15–~30 mg/day |
Tightens slow band dosing |
| 13 |
Slow-pathway divided dosing: 3–4 or 2–3 |
Controls frequency |
| 14 |
Slow-pathway daily examples 15 mg or 30 mg |
Adds daily dosing examples |
| 15 |
Slow-pathway narrowed to ~7.5–~15 mg/day |
Tightens low slow band |
| 16 |
Slow-pathway: 2–3 divided doses/day |
Controls frequency |
| 17 |
Slow-pathway daily example 7.5 mg |
Adds a single dosing anchor |
6) Patent landscape read-through (what this claim set is likely trying to block)
A. Blocks genotype-blind dosing changes
The independent claim uses NAT2 genotype as a prerequisite. If competitors dose LEMS patients with 3,4-DAP without genotype testing or with genotype-agnostic dosing outside the claimed bands, they can avoid the strict letter of Claim 1 as written.
B. Targets genotype-based precision dosing protocols
Even where genotype testing is performed, the claims only capture:
- the specified NAT2 allele categories (fast: at least one fast; slow: two slow within NAT25/6/7/14), and
- the specified total daily dose ranges.
So the claim set is designed to cover genotype-based dosing instructions and regimens in:
- investigator brochures,
- protocolized trial dosing,
- and prescribing guidelines where the treatment method is explicitly or effectively defined.
C. Provides salt-specific coverage to deter formulation workarounds
By specifying 3,4-DAP phosphate salt as an equivalent dose vehicle in dependent claims, it narrows attempts to argue around dosing by changing salt form.
7) How to assess freedom-to-operate posture from the claim text alone
A practical “infringement risk grid” based strictly on the claim language:
High risk (within-claim administration)
- A LEMS patient is treated with 3,4-DAP and is classified as:
- NAT2 fast (or at least one fast allele), with ~30–~240 mg/day dosing, with salt/phosphate equivalence allowed, and/or
- NAT2 slow (two slow alleles each in NAT25/6/7/14), with ~7.5–~40 mg/day dosing.
- If a specific dependent claim embodiment is followed (e.g., fast-pathway 30–100 mg/day and divided dosing formats with unit doses 10–30 mg), the risk increases.
Lower risk (avoid the genotype or the dose band)
- Treat LEMS patients with 3,4-DAP using a regimen that does not fall inside the claimed daily ranges for the patient’s NAT2 category, or
- Use a dosing strategy that does not match the required genotype categories as stated (especially the slow allele constraint to NAT25/6/7/14).
Salt workarounds are partially blocked
- Switching to phosphate is explicitly within dependent claim scope; switching to other salts is not covered by the phosphate-specific dependent claims, but the independent claim still covers “pharmaceutically acceptable salt thereof” generically, so salt switching alone is not a safe exit if the dosing regimen is still within the genotype-linked mg/day bands.
8) Key Takeaways
- US 11,268,128 is a genotype-guided dosing method for LEMS using 3,4-DAP, keyed to NAT2 alleles.
- The independent claim sets two total daily dose regimes:
- NAT2 fast (at least one fast allele): ~30–~240 mg/day
- NAT2 slow (two slow alleles: NAT25/6/7/14): ~7.5–~40 mg/day
- Dependent claims tighten scope by specifying:
- fast allele wild-type (Claim 2),
- slow allele mutation markers (Claims 3–4),
- phosphate salt equivalents (Claims 5 and 11),
- narrower dosing bands (fast ~30–~100 mg/day; slow ~15–~30 and ~7.5–~15 mg/day) and
- divided dosing formats (frequency and unit dose options).
- For landscape planning, the claim targets precision dosing protocols that implement NAT2 stratification and dose selection consistent with the claimed mg/day and regimen patterns.
FAQs
1) Is US 11,268,128 about a new drug or a dosing method?
It is a method-of-treatment claim: the active is 3,4-diaminopyridine (3,4-DAP), with patent protection centered on NAT2 genotype-specific dosing ranges for LEMS.
2) What NAT2 genotypes matter most in the claims?
For slow acetylators, the claim requires two NAT2 slow alleles, each being NAT25, 6, 7, or 14. Fast acetylators are covered by having at least one NAT2 fast allele, with a dependent embodiment where the fast allele is wild-type.
3) Do the claims require divided dosing?
No for the independent claim, because it states divided dosing is “optionally” used. Several dependents do require or define divided dosing frequency and unit dose amounts.
4) Does the patent cover 3,4-DAP phosphate specifically?
Yes, dependent claims state dosing via 3,4-DAP phosphate salt using an “equivalent amount,” for both the fast and slow genotype pathways.
5) What are the key dosing numbers to focus on for risk mapping?
The most consequential total daily ranges are ~30–~240 mg/day for NAT2 fast and ~7.5–~40 mg/day for NAT2 slow. Dependent claims emphasize narrower bands like ~30–~100 mg/day, ~15–~30 mg/day, and ~7.5–~15 mg/day, plus example unit and total doses.
References
[1] Provided claim text for US Patent 11,268,128 (claims 1–17).
