Scope and Claim Analysis of US Patent 7,745,409 (SEQ ID NO:125 Polypeptide Activating Guanylate Cyclase C)
US 7,745,409 is narrowly anchored to a single, explicitly defined polypeptide sequence (SEQ ID NO:125; Cys Cys Glu Tyr Cys Cys Asn Pro Ala Cys Thr Gly Cys) and claims compositions and receptor-activation utility around that specific peptide. The patent estate is claim-type-light (sequence, composition, and a guanylate cyclase C activation use), so enforceable scope is driven by (1) whether an accused product includes the identical sequence (or a salt of it), and (2) whether it uses that sequence in a way that meets the claimed functional limitation (GC-C activation).
What exactly does US 7,745,409 claim: a sequence-only peptide or broader analogs?
Core answer: The independent concept is a polypeptide defined by an exact amino acid sequence (SEQ ID NO:125), not a class of variants. The claims read like they are built for sequence-infringement and carrier/composition infringement, with a single utility anchor for guanylate cyclase C (GC-C) receptor activation.
Claim 1: “A polypeptide comprising” the exact SEQ ID NO:125 sequence
Claim 1 recites:
- “A polypeptide comprising the amino acid sequence” corresponding to Cys Cys Glu Tyr Cys Cys Asn Pro Ala Cys Thr Gly Cys (SEQ ID NO:125), “or a pharmaceutically acceptable salt thereof.”
Legal scope implications
- “Comprising” typically includes the defined sequence as part of a larger construct. This can expand infringement risk beyond a peptide that is exactly SEQ ID NO:125 end-to-end, because a larger polypeptide that contains the full SEQ ID NO:125 as a sub-sequence could still fall within “comprising” language.
- The claim still requires that the accused polypeptide “compris[es]” the defined sequence. If an accused product uses a modified sequence that changes any residue in SEQ ID NO:125, it should not satisfy the “comprising” requirement (absent an interpretation that treats changes as non-material or captured by construction, which is unlikely where the sequence is explicit).
- “Pharmaceutically acceptable salt” is claim-adjacent; salt forms can be captured even if the free base/acid differs.
Practical scope
- Encompasses:
- The peptide as a standalone drug substance
- Salt forms of that peptide
- Potentially fusion or longer peptides that include the entire SEQ ID NO:125 segment as part of a larger polypeptide construct (only if the sequence is present exactly as recited)
Claim 2 and Claim 6: “consisting of” the exact sequence (sharper boundary)
Claim 2 recites a polypeptide “consisting of” the exact SEQ ID NO:125 sequence (or its salt). Claim 6 is the same but paired with a different dependent structure.
Legal scope implications
- “Consisting of” is restrictive. It requires that the polypeptide contains only the recited sequence (plus permitted salt considerations).
- This is a typical strategy to create a tighter claim for products that are exactly the peptide and not fusion constructs or other extended sequences.
Enforcement impact
- If an accused product is a peptide exactly matching SEQ ID NO:125, Claim 2/6 are directly implicated.
- If an accused product is a fusion construct that contains SEQ ID NO:125 but has additional amino acids outside the segment, Claim 1 may be implicated while Claim 2/6 should not.
What formulation and composition claims does US 7,745,409 include?
Core answer: It claims pharmaceutical compositions with the SEQ ID NO:125 polypeptide (or salt) plus a pharmaceutically acceptable carrier/excipient. The composition claims do not add formulation-specific constraints (no particle size, no stability system, no route, no dosage form) based on the claim set provided.
Claim 3 and Claim 5: compositions with “a pharmaceutically acceptable carrier or excipient”
- Claim 3: polypeptide of claim 1 + carrier/excipient
- Claim 5: polypeptide of claim 2 + carrier/excipient
Scope implications
- Covers a wide range of dosage forms to the extent the product is “a pharmaceutical composition” under claim interpretation.
- Without further limitations, the carrier/excipient language is broad: solutions, lyophilized powders with reconstitution media, standard injectables, and other conventional carriers could be implicated.
Claim 7: composition based on Claim 6 (consisting-of SEQ ID NO:125)
- Claim 7: polypeptide of claim 6 + carrier/excipient
Practical effect
- Creates a parallel composition claim for exactly-defined peptides, not just “comprising” variants.
What is not claimed in the provided claim set
- No explicit route (oral vs parenteral)
- No dosage amount or regimen
- No specific formulation excipients
- No delivery system (e.g., nanoparticles, enteric coating)
- No manufacturing method constraints
This matters because it pushes the enforceable scope toward the active ingredient identity and simple composition incorporation rather than complex formulation differentiation.
Which utility limitation exists: does the patent require guanylate cyclase C receptor activation?
Core answer: Yes. Claim 4 includes a functional limitation: the polypeptide “activates the guanylate cyclase C receptor.”
Claim 4: polypeptide activating GC-C receptor
Claim 4 recites:
- polypeptide of claim 1, where the polypeptide “activates the guanylate cyclase C receptor.”
Scope implications
- If an accused product contains a polypeptide that satisfies the sequence requirement, infringement of Claim 4 depends on meeting the GC-C activation functional limitation.
- For functional claims tied to biological activity, infringement can be established via product pharmacology data, sequence-function linkage, or comparative assays. Practically, litigations often pivot on whether the accused peptide, even if sequence-identical, is formulated, folded, glycosylated (if relevant), or otherwise delivered such that it performs the claimed function.
Interplay with sequence claims
- Claim 1 is sequence-only (plus salt).
- Claim 4 adds activity. That gives the patent at least two enforcement pathways: “ingredient identity” and “ingredient identity plus biological activity.”
Why Claim 4 can be strategically important
- A competitor could attempt to argue that even with an identical sequence, their product does not meet the “activates” threshold under relevant conditions. Whether that argument succeeds depends on claim construction, what “activates” means, and the prior art/test data context, none of which is provided in the prompt beyond the claims.
How does US 7,745,409 treat salts and polymorphs: does it cover all forms?
Core answer: The provided claims capture “pharmaceutically acceptable salts” of the SEQ ID NO:125 polypeptide. Polymorphs and other solid-state forms are not expressly claimed in the set shown.
- Claims 1–2 and dependent compositions include “or a pharmaceutically acceptable salt thereof.”
- No explicit mention of hydrates, solvates, polymorphs, or specific crystalline forms appears in the provided claim text.
Licensing and litigation impact
- If an accused product uses the same peptide sequence but in a different salt form, the claim language suggests coverage.
- If a product uses a substantially different chemical form not treated as a “pharmaceutically acceptable salt,” coverage may hinge on claim construction.
What is the patent’s infringement theory if a generic or competitor makes a similar GC-C peptide?
Core answer: The claims are engineered for sequence identity. The main risk for a competitor is designing around the specific SEQ ID NO:125 sequence without triggering “comprising” infringement.
Design-around map (sequence engineering)
- Changing any residue in SEQ ID NO:125: typically breaks both “comprising” and “consisting of” requirements, pushing infringement risk down.
- Maintaining the full SEQ ID NO:125 segment exactly:
- Exact peptide: high risk under Claim 2/6 and composition claims (3/5/7).
- Fusion constructs that include the SEQ ID NO:125 segment plus additional residues: possible risk under Claim 1 and its compositions (3, 5 depending on whether the “consisting of” limitation applies).
- Salt-form switching: likely still falls within “pharmaceutically acceptable salt.”
Design-around map (activity engineering)
Even if sequence identity is maintained, a competitor could attempt to argue non-activation of GC-C under the claimed conditions. But with an activity limitation in Claim 4, the “activates” element becomes a litigation focal point.
What formulations are protected by US 7,745,409?
Core answer: Based on the provided claims, protection is formula-agnostic except for requiring a “pharmaceutical carrier or excipient.”
Covered:
- Any “pharmaceutical composition” containing the claimed peptide (or salt) with a pharmaceutically acceptable carrier/excipient.
- Coverage likely extends across multiple dosage forms unless the rest of the patent specification narrows interpretation (not provided here).
Not covered (in claim text provided):
- Enteric coatings
- Specific stabilizers (e.g., mannitol, polysorbates)
- Route-specific formulations
- Sustained-release systems
- Targeted delivery systems
This is important for freedom-to-operate analysis: if competitors create different delivery systems but still include the identical SEQ ID NO:125 peptide, the claim set suggests they remain within scope.
What would a competitor’s “Paragraph IV” posture look like for this patent?
Core answer: A typical Paragraph IV strategy against sequence-based peptide patents is to challenge validity (anticipation/obviousness) or avoid infringement by changing the peptide sequence or removing GC-C activation. With the limited claim set provided, infringement avoidance is primarily sequence-based.
Likely non-infringement arguments
- The generic/competitor product uses a different amino acid sequence than SEQ ID NO:125.
- If a “comprising” claim is asserted, argue the accused polypeptide does not include the full SEQ ID NO:125 segment exactly.
- If Claim 4 is asserted, argue the product does not activate GC-C in a relevant manner.
Likely validity challenges
Without the full patent disclosure and prosecution history, the most common validity attack lines for sequence-defined claims are:
- anticipation by a prior art peptide with identical SEQ ID NO:125
- obviousness in view of known GC-C activators and routine optimization of a peptide sequence
Those lines are consistent with how courts evaluate explicit sequence claims, but the actual strength depends on the prior art cited in US 7,745,409 and related family members.
How strong is the patent estate for SEQ ID NO:125: what do these claims say about enforceability?
Core answer: The enforceability is concentrated in:
- Exact peptide-sequence coverage (Claim 2/6 “consisting of”)
- Broader segment inclusion coverage (Claim 1 “comprising”)
- Composition coverage (Claim 3/5/7)
- One functional utility hook for GC-C activation (Claim 4)
What reduces enforceability breadth
- No broad genus language (“variants,” “analogs,” “substantially similar” peptides) appears in the provided claim set.
- No formulation detail reduces the ability to argue that an alternative product is outside scope due to formulation differences. That cuts both ways: it expands coverage for any product using the same peptide, but it narrows the universe of covered actives to the exact sequence.
What improves enforceability clarity
- Sequence is explicit (SEQ ID NO:125).
- “Consisting of” claims create crisp boundaries.
What should be checked in US prosecution and claim construction for this patent?
Core answer: In litigation or licensing, the decisive interpretive questions will be:
- What “comprising” means for fusion constructs: does “comprising the amino acid sequence” require an exact contiguous subsequence equal to SEQ ID NO:125?
- Whether “pharmaceutically acceptable salt” includes the salt used by the accused product.
- What “activates the guanylate cyclase C receptor” means: does it require a specific potency, signaling pathway effect, or measurable activation relative to controls?
Those questions are claim-construction issues tied to the wording shown, not to extrinsic assumptions.
Key Takeaways
- US 7,745,409 is a sequence-centered peptide patent tied to SEQ ID NO:125 (Cys Cys Glu Tyr Cys Cys Asn Pro Ala Cys Thr Gly Cys).
- Claims cover:
- Polypeptides containing SEQ ID NO:125 (“comprising,” Claim 1) and polypeptides limited to SEQ ID NO:125 (“consisting of,” Claims 2 and 6)
- Pharmaceutical compositions with the peptide plus a carrier/excipient (Claims 3, 5, 7)
- A GC-C receptor activation utility limitation (Claim 4)
- Enforceable scope is driven by sequence identity and salt form, with fusion constructs potentially implicated under “comprising.”
- There are no formulation-specific constraints in the provided claims, so delivery system changes alone do not avoid coverage if the active peptide identity is unchanged.
FAQs
1) Does US 7,745,409 cover fusion peptides that include SEQ ID NO:125?
Potentially under Claim 1’s “comprising” language, if the fusion polypeptide includes the complete SEQ ID NO:125 sequence exactly as recited; not under “consisting of” claims (2/6).
2) If an accused product uses SEQ ID NO:125 but a different salt, is it still covered?
Yes, the claims explicitly include “a pharmaceutically acceptable salt thereof.”
3) What is the difference between Claim 1 and Claim 2 infringement coverage?
Claim 1 covers polypeptides that include the SEQ ID NO:125 sequence as part of a larger construct; Claim 2 requires the polypeptide to consist only of the SEQ ID NO:125 sequence (plus salt form).
4) Can a competitor avoid Claim 4 by altering GC-C activation while keeping the same sequence?
They would need to avoid meeting the “activates the guanylate cyclase C receptor” limitation. Sequence identity alone does not automatically resolve the utility limitation in Claim 4.
5) Do changes to excipients or dosage form avoid infringement?
Not based on the provided claim set. The composition claims require only a “pharmaceutically acceptable carrier or excipient,” which is broad.
References
- US Patent 7,745,409.
