Executive summary
United States Patent 10,010,498 protects a route- and target-dependent intramuscular (IM) treatment of ALS using a follistatin fusion protein. The independent claim is limited to (i) ALS, (ii) IM delivery to a targeted muscle, and (iii) a specific bifunctional fusion architecture: a follistatin sequence chosen from SEQ ID NOs: 15 or 16 directly linked (no spacer other than the linker) to an IgG constant domain via a 1–10 amino-acid linker. Dependent claims narrow the biological and immunological profile to localized muscle growth/strength with minimal systemic effect, with optional constraints intended to suppress ADCC and CDC, and with additional fallback identity claims to specific sequence sets (SEQ ID NOs: 42 and 43, with optional or absent terminal lysine) and linker identity (SEQ ID NO: 46). The practical consequence for a competitor is that working around the claim is easiest by changing the sequence architecture, the IgG constant domain behavior, or the delivery paradigm away from IM targeted-muscle administration. Working around by minor formulation changes is unlikely to defeat the core sequence-structure and route limitations.
United States Patent 10,010,498 follistatin fusion protein for ALS: claim-by-claim scope and patent landscape
US 10,010,498 centers on a method of treating ALS with an IM administered follistatin fusion protein that is built from (a) a follistatin domain sequence and (b) an IgG constant domain connected by a short linker. Claim scope is primarily determined by (1) the exact sequence selections (SEQ ID NOs), (2) the linker length and identity, and (3) the IM targeted muscle treatment effect constraints, with additional layers aimed at minimizing immunological cytotoxicity.
What does US 10,010,498 claim for ALS treatment with intramuscular follistatin-Fc fusion?
Core independent claim (Claim 1) requires all of the following elements:
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Disease and patient
- A method of treating amyotrophic lateral sclerosis (ALS) in a patient.
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Route and anatomical delivery specificity
- Administer an effective amount of a follistatin fusion protein by an intramuscular route to a targeted muscle.
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Fusion architecture: two sequence blocks with a direct linker
- The follistatin fusion protein comprises:
- a first amino acid sequence consisting of an amino acid sequence selected from SEQ ID NO: 15 or 16
- a second amino acid sequence comprising a constant domain of an immunoglobulin G (IgG)
- a linker that directly connects the C-terminal portion of the first sequence to the N-terminal portion of the second sequence
- the linker is 1–10 amino acids in length
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Biological mechanism constraints are mostly implicit in the sequence choices
- Claim 1 does not explicitly require myostatin/GDF-11/activin binding, but that appears in dependent Claim 7.
Why this matters legally
Even without reaching dependent claims, Claim 1 is narrower than a generic “follistatin for ALS” patent because it is constrained to:
- ALS indication
- IM targeted muscle delivery
- a specific follistatin sequence (SEQ ID 15 or 16)
- IgG constant domain presence
- direct short linker (1–10 aa)
How do the dependent claims narrow efficacy, distribution, and “localized-only” effects?
Claims 2–6 focus on where growth/strength occurs and what does not happen.
- Claim 2: Increased muscle size or strength occurs in the targeted muscle.
- Claim 3: The fusion protein does not have a substantial systemic effect on muscle size or strength.
- Claim 4: Administration to only one targeted muscle.
- Claim 5: Administration to more than one targeted muscle.
- Claim 6: The contralateral muscle does not substantially increase in size or strength.
Litigation-style implications
These dependent claims create fact-specific infringement hooks:
- Localized response can be used to argue infringement (Claim 2).
- Absence of systemic effects and absence of contralateral effects can be used to frame the inventive goal and influence claim construction. The claims do not require that systemic effects never occur; they require “not substantial.” That term becomes critical in damages and claim construction, but it is still anchored to measurable endpoints.
What binding specificity and potency limits are included (myostatin, GDF-11, activins)?
- Claim 7: The fusion protein binds to one or more ligands selected from:
- myostatin
- GDF-11
- activin A
- activin B
- with a dissociation constant (KD) less than thresholds:
- 1 nM, 100 pM, 50 pM, or 10 pM (claim wording reflects multiple possible thresholds as options)
Scope effect
This claim introduces a biophysical potency/affinity filter. For an accused product, infringement analysis will shift to:
- whether the specific construct exhibits the claimed binding profile under defined assays
- whether affinity meets any recited KD cutoff
Because this is dependent, infringement of Claim 1 alone does not require Claim 7’s potency. But Claim 7 strengthens the patent’s support for utility and specificity and provides an additional narrowing layer in validity and infringement disputes.
How do the claims handle Fc dimerization, ADCC, and CDC?
Dimerization / Fc architecture
- Claim 8: The fusion protein forms a dimer.
- Claim 9: The fusion protein comprises an Fc portion of an IgG.
Immunotoxicity limitations
- Claim 10: Does not mediate substantial ADCC.
- Claim 11: Does not mediate substantial CDC.
- Claim 16: The IgG constant domain is selected to mediate:
- no substantial ADCC and/or
- no substantial CDC
Risk for competitors
Any competitor design that relies on a conventional IgG1 Fc capable of strong FcγR engagement may have difficulty meeting the “no substantial ADCC/CDC” dependent limitations, especially if their Fc is not engineered for effector-silencing.
What specific sequence fallback positions are protected (SEQ ID NOs: 42, 43; terminal lysine optional/absent)?
The patent includes identity-based dependent claims that narrow to particular constructs while addressing small C-terminal variants:
- Claim 12: Fusion protein comprises SEQ ID NO: 43, optionally with the final C-terminal lysine (K) absent.
- Claim 13: Final C-terminal lysine is absent.
- Claim 14: Fusion protein comprises SEQ ID NO: 42, optionally with final lysine absent.
- Claim 15: Final C-terminal lysine is absent.
- Claim 26: Fusion protein comprises SEQ ID NO: 42.
- Claim 27: Fusion protein comprises SEQ ID NO: 43.
Why terminal lysine matters
Terminal residues can change:
- stability and proteolysis profile
- charge distribution
- assay-recognized epitope
- potential binding or effector interactions
Even if competitors believe the change is minor, the patent’s sequence-identity coverage makes it difficult to argue non-infringement if the accused sequence matches these SEQ IDs (with or without the terminal K depending on which claim tier is asserted).
How are linker identity and linker sequence length used to constrain infringement?
- Claim 1 sets the architecture constraint: linker length 1–10 amino acids.
- Claim 22: linker comprises SEQ ID NO: 46.
- Claim 23: linker comprises SEQ ID NO: 46 (parallel to Claim 21 dependent layer).
- Claim 24: linker consists of SEQ ID NO: 46.
- Claim 25: linker consists of SEQ ID NO: 46.
Infringement impact
There are two layers:
- generic: linker 1–10 aa (Claim 1)
- specific: linker equals SEQ ID NO: 46 (Claims 22–25)
A competitor can attempt to change the linker identity to avoid those dependent claims. But that does not avoid Claim 1 unless the alternate architecture also avoids:
- the specific follistatin sequence selections (SEQ 15/16), and/or
- the direct connection of the specified sequences to an IgG constant domain with a 1–10 aa linker.
Which IgG constant domains are protected (IgG1 vs IgG2; SEQ ID NOs: 17 and 18)?
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Claim 18: IgG constant domain is an IgG1 constant domain.
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Claim 19: IgG1 constant domain comprises SEQ ID NO: 17.
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Claim 20: IgG constant domain is an IgG2 constant domain.
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Claim 21: IgG2 constant domain comprises SEQ ID NO: 18.
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Claim 16 further requires that the constant domain is chosen to mediate no substantial ADCC and/or CDC.
Design-around dynamics
A competitor could try to use:
- a constant domain outside IgG1/IgG2 or different engineered variants
- a constant domain that maintains minimal ADCC/CDC but differs from SEQ ID NO: 17 or 18
That strategy may reduce the chance of hitting dependent claims tied to exact SEQ IDs. Still, Claim 1 only requires “a constant domain of IgG” with the specified follistatin sequence and linker architecture. So a change to constant domain type helps most against the SEQ-ID-specific dependents, not necessarily against Claim 1.
What systemic biomarker and organ-size limitations are recited?
- Claim 17: The method causes no substantial effect on:
- serum FSH levels
- liver size
- hematocrit and
- reticulocyte levels
Why it matters
These dependent claims create a second axis of “localized effect” beyond muscle-only endpoints. They can become relevant to:
- defining the scope of what “substantial systemic effect” means
- pleading non-infringement based on biomarker outcome differences
- validity arguments if the prior art did not teach the safety profile
What patent landscape surrounds US 10,010,498 (families, continuation risk, and competing claim clusters)?
Published claim family structure: what can be inferred from the claim set alone
The claim set suggests the patent is part of a protein engineering family covering:
- follistatin-IgG fusion constructs defined by sequence IDs
- linker variants (length and identity)
- Fc effector silencing (ADCC/CDC)
- delivery paradigm (IM targeted muscle) and clinical endpoints (localized muscle size/strength; minimal systemic effects)
However, a comprehensive landscape requires:
- the publication number(s) for the application corresponding to US 10,010,498
- priority and filing dates
- related continuations/divisionals
- and other family members that cover alternative indications, dosing schedules, vectors, or manufacturing.
No such bibliographic data was provided in the prompt, and the full patent document content is not included. Without those elements, a complete landscape cannot be produced without risking inaccuracies.
How strong is the patent estate for infringement risk versus design-around strategies?
What is the most difficult element to change: “IM to targeted muscle” plus the specific fusion architecture
For infringement against Claim 1, a competitor must avoid at least one essential element:
- replace the follistatin sequence used (SEQ ID 15 or 16)
- remove the IgG constant domain element
- avoid the architecture of a directly connected follistatin C-terminus to an IgG constant domain via a 1–10 aa linker
- avoid intramuscular delivery to a targeted muscle for ALS treatment (e.g., alternate route or targeted delivery concept that does not meet claim construction)
How much does the patent rely on dependent claims
Dependent claims add constraints that can narrow real-world infringement:
- localized vs systemic effects (Claims 2–6, 17)
- ADCC/CDC suppression through IgG constant domain selection (Claims 10–11, 16)
- sequence identity for constructs (Claims 12–13 and 14–15, 26–27)
- linker identity (Claims 22–25)
- IgG1/IgG2 constant domain sequence identities (Claims 19, 21)
In practice, plaintiffs often assert the broadest claim first (Claim 1) and use dependents to tighten the narrative when the accused construct is close. A competitor that cannot avoid Claim 1’s architecture and delivery constraints can still try to create clearance by failing “localized effect” or “ADCC/CDC suppression” dependents, but those are not safety valves against Claim 1.
Key takeaways
- US 10,010,498 is a method patent: ALS treatment with intramuscular delivery to a targeted muscle using a follistatin fusion protein.
- Claim 1 is pinned to a specific fusion blueprint: follistatin sequence (SEQ ID 15 or 16) + IgG constant domain + direct 1–10 aa linker.
- The dependent layer heavily emphasizes local muscle effects and suppressed systemic and immunological effects (no substantial contralateral growth; no substantial systemic biomarkers; limited ADCC/CDC).
- The strongest design-around levers are sequence-level changes (follistatin and/or IgG constant domain to non-covered sequences) or delivery paradigm changes away from the claimed “IM targeted muscle” treatment model.
- The patent includes tight fallback sequence claims (SEQ ID 42 and 43, including terminal lysine variants) and linker identity (SEQ ID 46), narrowing the runway for “near-match” biologics.
FAQs
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What combinations of SEQ ID sequences in US 10,010,498 must be present to infringe Claim 1?
Need follistatin from SEQ ID 15 or 16, an IgG constant domain, and a directly connecting 1–10 aa linker.
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Does the patent require that ALS responders show contralateral muscle effects?
No. The claims require the opposite in a dependent limitation: contralateral muscle does not substantially increase.
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Can a competitor avoid ADCC/CDC limitations by using an Fc-silenced IgG variant?
That approach targets dependents (Claims 10–11, 16) but does not necessarily remove Claim 1 if the architecture and delivery remain within scope.
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How does linker identity (SEQ ID 46) affect infringement strategy?
It tightens coverage for specific constructs (Claims 22–25). Avoiding SEQ ID 46 can reduce dependent claim risk, but Claim 1 still covers any 1–10 aa linker if the core sequence architecture matches.
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Are “no substantial systemic effects” requirements absolute?
The dependents use “not substantial,” creating a measurable but non-zero tolerance that turns on assay and endpoint interpretation.
References (APA)
- United States Patent 10,010,498.
