Patent 9,341,629 Landscape: Scope, Claim Coverage, and US Enforcement Risks for NIR Fluorescent Amino-Acid Conjugate Kits

US Drug Patent 9,341,629 claims a diagnostic/profiling kit built around a near-infrared (NIR) fluorescent dye whose fluorescence is maintained or enhanced when conjugated to, or associated with, a single amino acid (or amino-acid derivative) containing one primary functional handle (–OH, –NH2, or –SH). The protected subject matter centers on: (1) a compound defined by a constrained dye scaffold plus amino-acid-dependent connectivity variables (X and X′); (2) kit-level inclusion (fluorescence-capable dye-amino-acid compound plus excipients/carriers); and (3) use-enabling properties such as NIR absorption/emission maxima (600–800 nm), cellular fluorescence after distribution, and tumor-cell selectivity.

Because the provided claim text is partially redacted (several formula components are omitted), the analysis below focuses on what can be established with high precision from the claim elements you supplied: kit composition scope, structural constraints at the variable level (X, X′, R′), and the narrowing dependent claims (amino-acid identities, isotopic labeling, specific salt forms, and target-selective behavior). No other conclusions are produced without the missing formula content.

What does US Patent 9,341,629 claim: kit composition scope for NIR fluorescent amino-acid conjugates?

Core independent claim (Claim 1) protects a “kit comprising a compound” that includes:

A compound defined by a general formula (redacted in the claim text you provided), said compound including:
- A variable X: “a single amino acid or a single amino acid derivative thereof”
- The amino acid/derivative contains a single functional group selected from –OH, –NH2, or –SH
- A dye Y: fluorescence excitation and emission are in the near-infrared range
- Dye Y is represented by a second general formula with:
  - X′ independently selected from O, S, N, and C
  - R′ independently selected from CH2 and CH2CH2
- A functional relationship: the compound maintains or enhances the fluorescence of the dye
Kit-level inclusion
- A “kit” implies at least one container/formulation plus the compound (and, in dependent claims, excipients/carriers).

Claim 1 structural “hinges” that define protected coverage

The claim’s novelty is not the idea of NIR dyes or amino-acid targeting by itself, but the specific combination of variable definitions:

X is limited to a single amino acid (or derivative) with only one of three functional groups (–OH/–NH2/–SH) as the relevant handle.
Y is limited to an NIR dye scaffold with variable atoms X′ = O/S/N/C and linking chain units R′ = CH2 or CH2CH2.
Fluorescence performance is part of the claim: maintains or enhances fluorescence after conjugation/association.

Practical effect for freedom-to-operate (FTO)

A generic “near-infrared fluorescent amino-acid conjugate kit” is not automatically within scope. For infringement risk, a product must satisfy all of the following simultaneously:

NIR excitation/emission (not just visible)
Dye scaffold consistent with X′ ∈ {O,S,N,C} and R′ ∈ {CH2, CH2CH2}
Amino-acid component is one amino acid (or one derivative) with a single handle functional group of the claimed type
The compound maintains or enhances dye fluorescence

How narrow are Claim 2–11: which amino acids, isotopes, salts, and performance limits narrow the patent?

Dependent claim 2: which amino acids are explicitly covered?

Claim 2 narrows X to:

tyrosine
cysteine
lysine
serine
or derivatives of tyrosine or cysteine

This is an explicit “listed-members” narrowing of the amino-acid identity.

Dependent claim 3: isotopic tyrosine coverage

Claim 3 narrows X to:

tyrosine, with the aromatic ring containing a carbon isotope and/or a hydrogen isotope

This covers labeled tyrosine variants (e.g., ^13C and/or ^2H) when used to build the kit compound.

Dependent claim 4: tyrosine derivatives and racemates

Claim 4 adds:

amino-acid derivative is a derivative of tyrosine
including racemic mixtures

This expands coverage across stereochemical identity while remaining tethered to tyrosine-derivative chemistry.

Dependent claim 5: cysteine with sulfur-side-chain

Claim 5 narrows X to:

cysteine
explicitly tied to the sulfur-containing side-chain group

Dependent claim 6 and 7: salt forms

Claim 6 limits salts to:

potassium
sodium
ammonium

Claim 7 is broader in wording (still within “pharmaceutically acceptable salt”), but claim 6 gives specific salt options.

Dependent claim 8: NIR spectral window

Claim 8 constrains performance:

absorption and emission maxima between about 600 nm and 800 nm

This is a measurable limitation. A product with maxima outside this range avoids literal infringement of Claim 8 and may affect doctrine-of-equivalents arguments depending on closeness.

Dependent claim 9: cellular fluorescence after distribution

Claim 9 adds a functional/biological behavior:

the compound is made to fluoresce after distribution in tissue cells

This narrows toward environment-activated or bio-distribution-triggered fluorescence mechanisms, not dyes that fluoresce immediately regardless of cellular context.

Dependent claim 10: tumor-cell selectivity

Claim 10 adds:

highly selective targeting to a tumor cell

This adds a specificity requirement related to biodistribution and binding/uptake selectivity.

Dependent claim 11: excipients/carriers

Claim 11 adds kit formulation elements:

a pharmaceutically acceptable carrier, excipient, or diluent

This is standard, but it confirms kit compositions rather than an isolated active alone.

What is the likely dye class and how do the X′ and R′ variables constrain the protected fluorescence scaffold?

Claim 1 defines dye Y via:

fluorescence excitation and emission in the near-infrared range
dye formula includes:
- X′ independently selected from O, S, N, C
- R′ independently selected from CH2 and CH2CH2

Even without the missing full dye formula, the combination of:

NIR fluorescence requirement and
constrained substituent atoms and chain units creates a practical boundary for infringement.

How the X′ and R′ constraints act

If an accused dye uses heteroatoms outside {O,S,N,C} at the positions corresponding to X′, it is more likely to avoid literal inclusion of the dye definition.
If chain units at R′ differ from CH2 or CH2CH2 (e.g., O-alkyl, longer alkyl, aromatic linker), it may fail the dye definition.

NIR gating versus “any fluorophore”

Many NIR fluorophores exist. Claim 1 does not protect “all NIR dyes.” It protects dye Y within the specified formula family plus amino-acid handle constraints.

What are the enforceable claim boundaries: kit vs compound, and performance limits vs structure?

Claim structure features (strong boundary):

X = single amino acid/derivative with one of –OH/–NH2/–SH
Y = NIR dye scaffold with X′ and R′ variable constraints
maintain/enhance fluorescence

These are definitional and likely to be the highest-friction for design-around because infringement will be assessed on whether an accused compound fits the claim formulas and definitions.

Performance features (important but sometimes easier to dispute):

absorption/emission maxima between 600 and 800 nm (Claim 8)
fluoresces after distribution into tissue cells (Claim 9)
highly selective targeting to tumor cells (Claim 10)

If accused products show spectral maxima outside 600–800 nm, or lack tissue-activated fluorescence, or lack tumor-cell selectivity, those dependent limitations are weaker points for infringement mapping.

Kit features (market relevance):

Claim 1 is “kit comprising a compound.”
Claim 11 includes carriers/excipients. If an accused product sells only the active compound without kit packaging or without the claimed kit form, infringement depends on kit claim construction in the jurisdiction.

How strong is the patent estate likely to be based on claim drafting breadth?

Strength indicators from your claim set

Claim 1 uses variable definitions that appear to cover multiple amino acids/derivatives (X) and multiple dye substitutions (X′, R′).
NIR fluorescence is built into claim language, increasing specificity and aligning with diagnostic use cases.

Strength detractors (based on provided text only)

Several components depend on missing redacted formula content, so actual scope could be broader or narrower than the excerpt suggests.
Dependent claims add measurable and functional limitations (spectral window, cellular fluorescence behavior, tumor selectivity). These can narrow infringement to specific product behaviors.

Net assessment for enforcement strategy

Independent Claim 1 is the primary target for enforcement because dependent claims narrow the design space.
Enforcement leverage likely improves if the accused product’s dye scaffold and amino-acid handle match the constrained definitions and if spectral maxima align with 600–800 nm.
If the accused product uses different dye scaffolds or different amino-acid functional handles, infringement risk drops at Claim 1 itself.

What generic or biosimilar risks exist: is this a “drug” patent with substitution pathways?

This patent reads as a diagnostic fluorescent agent kit, not a classical small-molecule therapeutic with “generics” in the conventional sense. Nonetheless, the market risk profile is similar: competitors may sell alternative kits with overlapping clinical utility.

Design-around risk drivers:

Matching the NIR dye scaffold family and its defined variable positions (X′, R′)
Using a “single amino acid” handle meeting the –OH/–NH2/–SH constraint
Matching the claimed spectral range (600–800 nm) and cellular/tumor selectivity behavior if dependent claims are asserted

“Generic” concept in practice:

Replacing the dye scaffold or the amino-acid connector is the highest-leverage route to avoid claim 1 literal coverage.
Replacing or shifting spectral maxima can help avoid dependent Claim 8.
Removing tumor-selective targeting and using non-selective distribution can help avoid Claim 10.

What patent challenges could be mounted: where are the most litigation-sensitive claim elements?

Given only the excerpted claims, the litigation-sensitive zones are:

Validity attacks on novelty/non-obviousness for the combination of:
- NIR fluorescent dye scaffold family
- conjugation/association with a single amino acid (specific functional handle)
- kit packaging
Claim construction disputes on:
- how “single amino acid derivative contains an —OH, —NH2, or —SH functional group” is applied, especially if the derivative uses multiple functional groups
- the mapping of “maintains or enhances fluorescence” (is any retention enough, or must enhancement be shown?)
- whether Claim 1 requires the amino acid to be chemically conjugated versus simply part of the compound architecture
Infringement proof on:
- spectral maxima (Claim 8)
- cellular activation/distribution-triggered fluorescence (Claim 9)
- tumor-cell targeting selectivity level (Claim 10)
- structural match to dye Y variables (X′ and R′) and amino-acid identity constraints for dependent claims

Does the patent cover isotopic amino-acid versions, and how does that affect commercial strategy?

Yes. Claim 3 covers isotopically substituted tyrosine (carbon and/or hydrogen isotopes in the aromatic ring). For commercialization, this matters because isotopic labeling can:

change pharmacokinetics and cellular uptake
support distinct imaging readouts or internal standards
create a narrower but valuable lane of exclusivity

An accused product using non-isotopic tyrosine would avoid Claim 3 literal coverage but could still face risk under broader Claim 1 or Claim 2 depending on how X is satisfied and whether the dye scaffold matches.

Claim coverage matrix: which product attributes trigger infringement risk at each claim tier

Product attribute	Claim 1	Claim 2	Claim 3	Claim 4	Claim 5	Claim 6	Claim 8	Claim 9	Claim 10
NIR excitation/emission	Yes (required)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Dye scaffold with X′ ∈ {O,S,N,C}, R′ ∈ {CH2,CH2CH2}	Required	Required	Required	Required	Required	Required	Required	Required	Required
Amino acid X is single amino acid with –OH/–NH2/–SH handle	Required	Listed members	Tyrosine only	Tyrosine derivatives	Cysteine only	Required	Required	Required	Required
Amino acids covered: tyrosine/cysteine/lysine/serine	No explicit	Yes	Yes (tyrosine)	Yes (tyrosine derivatives)	Yes (cysteine)	Yes	Yes	Yes	Yes
Isotopic aromatic tyrosine	No	No	Yes	No	No	No	Yes	Yes	Yes
Racemic tyrosine derivatives	No	No	No	Yes	No	No	Yes	Yes	Yes
Cysteine sulfur-side-chain emphasis	No	No	No	No	Yes	No	Yes	Yes	Yes
Salt form: K/Na/NH4	No (generic salt)	No	No	No	No	Yes	Yes	Yes	Yes
Abs/em maxima 600–800 nm	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Yes	Yes	Yes
Fluorescence after tissue distribution	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not required	Yes	Yes
Tumor-cell selectivity	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not expressly limited	Not required	Not required	Yes

Note: Claim 1 sets the base scaffold and amino-acid functional handle. Dependent claims add specific identity/performance constraints.

What is the US Orange Book status and expiration timeline for 9,341,629?

None. The patent appears to be a US patent number, but no Orange Book listing, FDA product mapping, or expiration dates can be stated from the information provided. Without the associated FDA application and listed drug entry, a timeline cannot be produced.

Key Takeaways

US 9,341,629 protects a kit built from a compound combining an NIR fluorescent dye scaffold (Y) defined by variable constraints (X′ ∈ {O,S,N,C}, R′ ∈ {CH2,CH2CH2}) with a single amino acid or amino-acid derivative (X) containing one functional handle (–OH, –NH2, or –SH), and requiring fluorescence maintenance or enhancement.
Dependent claim coverage tightens materially around amino-acid identity (tyrosine, cysteine, lysine, serine; plus tyrosine derivatives; plus isotopic tyrosine), salt forms (K/Na/NH4), and performance constraints (600–800 nm spectral window, fluorescence after tissue distribution, and tumor-cell selectivity).
For design-around and litigation risk, the highest-leverage mapping is at Claim 1 dye scaffold and amino-acid functional-handle constraints; dependent claims become decisive if the product matches the base scaffold and amino-acid/derivative family but misses the performance or identity limits.
The patent’s market impact is for diagnostic fluorescent kits rather than classical therapeutic “generics,” with differentiation possible through substitution of the dye scaffold and/or amino-acid connector and by moving spectral or targeting behavior outside dependent claim limits.

FAQs

Does US 9,341,629 require a chemically conjugated amino acid or does it cover associated compounds?
The claim language targets a “compound” in a defined formula family that includes the amino acid variable X and dye variable Y while maintaining/enhancing fluorescence, indicating the protected item is structurally defined rather than merely co-administered.
Which dependent claim is most useful for avoiding infringement by changing spectral properties?
Claim 8, because it limits absorption and emission maxima to about 600–800 nm.
Can a competitor avoid isotopic tyrosine coverage while still falling under other claims?
Yes. Avoiding isotopic aromatic tyrosine avoids Claim 3, but does not necessarily avoid Claim 1 and Claim 2 if tyrosine (non-isotopic) or cysteine/other listed amino acids and the dye scaffold match.
What design-around is most effective against tumor-selectivity accusations?
Avoid approaches that create “highly selective targeting to a tumor cell,” which is required in Claim 10. General fluorescence without tumor selectivity weakens literal coverage under that dependent claim.
Are salt-form changes sufficient to avoid the patent?
Salt changes can avoid Claim 6 if the product is not in K/Na/ammonium forms, but Claim 1 still covers the base kit compound as a “pharmaceutically acceptable salt” in general terms (per Claim 7 language).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
On Target Labs	CYTALUX	pafolacianine sodium	SOLUTION;INTRAVENOUS	214907-001	Nov 29, 2021		RX	Yes	Yes	9,341,629	⤷ Start Trial	Y	Y			⤷ 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
Australia	2013381391	⤷ Start Trial
Australia	2013383382	⤷ Start Trial
Australia	2013383386	⤷ Start Trial
Australia	2017203340	⤷ Start Trial
Brazil	112015022810	⤷ Start Trial
Canada	2902205	⤷ Start Trial
Canada	2903727	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,341,629

Which drugs does patent 9,341,629 protect, and when does it expire?

Summary for Patent: 9,341,629