Scope, Claim Architecture, and US Patent Landscape for US 7,247,316
What is US 7,247,316 claiming in operational terms?
US 7,247,316 claims a multivial formulation kit used to prepare a vincristine-loaded liposomal composition for treatment of neoplasia in a mammal, where the liposomes are made from sphingomyelin and cholesterol with defined molar ratios, and where the pH of the liposome interior/exterior is engineered via buffered mixing (acidic citrate conditions followed by an alkaline phosphate buffer to neutralize exterior pH).
From the claim set you provided, the commercially and legally relevant claim scope concentrates on three levers:
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Drug payload solution
- Vincristine sulfate (claim 1) at about 1 mg/mL, mannitol ~100 mg/mL, pH 3.5 to 5.5.
- Vincristine solution alternative range 1 to 5 mg/mL, same pH 3.5 to 5.5 (claim 2).
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Liposome lipid composition and buffer environment
- Liposomes comprising sphingomyelin and cholesterol at specified molar ratios spanning:
- 75/25 to 50/50 (mol% sphingomyelin/mol% cholesterol) (claims 1 and 2).
- The liposome suspension is citrate-buffered, and in claim 2 the interior and exterior pH is acidic.
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Third buffer step to tune exterior pH
- A dibasic sodium phosphate heptahydrate buffer solution at ~14.2 mg/mL (claim 1 and 3), used to combine with the citrate-liposome solution.
- In claim 2: the alkaline phosphate buffer has a pH higher than the second vial, such that mixing yields neutral exterior pH of the liposomes.
Dependent claim coverage further narrows to target indication and specific parameter points:
- Relapsed lymphoma or leukemia (claim 4).
- Liposome interior and exterior pH approximately 4.0 (claim 5).
- Sphingomyelin/cholesterol ratio about 55/45 (claim 6).
- Alkaline phosphate buffer pH approximately 9.0 (claim 7).
How do the independent claims differ (1 vs 2 vs 3)?
Claim 1 (fixed vincristine sulfate + mannitol)
- First vial: vincristine sulfate ~1 mg/mL + mannitol ~100 mg/mL, pH 3.5 to 5.5
- Second vial: citrate-buffered liposomes with sphingomyelin/cholesterol 75/25 to 50/50
- Third vial: dibasic sodium phosphate heptahydrate ~14.2 mg/mL
- Output: instructions to prepare a liposomal composition for neoplasia.
Claim 2 (vincristine concentration range + explicit pH-engineering)
- First vial: vincristine 1 to 5 mg/mL, pH 3.5 to 5.5 (mannitol not required here)
- Second vial: liposomes in citrate-buffered solution with:
- sphingomyelin/cholesterol 75/25 to 50/50
- acidic pH in both interior and exterior
- Third vial: alkaline phosphate buffer at pH higher than the second vial so that after combining, exterior becomes neutral
- Output: instructions for treating neoplasia.
Claim 3 (mirrors claim 1 on the key formulation points)
- Same as claim 1 in the text you provided:
- vincristine ~1 mg/mL + mannitol ~100 mg/mL, pH 3.5 to 5.5
- citrate-buffered sphingomyelin/cholesterol liposomes 75/25 to 50/50
- dibasic sodium phosphate heptahydrate ~14.2 mg/mL
- instructions to prepare a liposomal composition for neoplasia.
Practical implication for scope: claim 2 is broader on vincristine concentration (1-5 mg/mL) and adds a functional pH outcome (neutral exterior after mixing). Claims 1 and 3 are narrower by reciting mannitol presence and fixed vincristine ~1 mg/mL.
Claim-by-claim scope map (legal “must-have” elements)
Independent claim scope elements
| Element |
Claim 1 |
Claim 2 |
Claim 3 |
| Intended use |
Treatment of neoplasia in a mammal |
Same |
Same |
| First vial (vincristine form) |
vincristine sulfate |
vincristine |
vincristine (as provided, but context reads as sulfate formulation) |
| First vial concentration |
~1 mg/mL |
1 to 5 mg/mL |
~1 mg/mL |
| Mannitol |
~100 mg/mL required |
Not required in text |
~100 mg/mL required |
| First vial pH |
3.5 to 5.5 |
3.5 to 5.5 |
3.5 to 5.5 |
| Second vial liposome buffer |
citrate-buffered |
citrate-buffered |
citrate-buffered |
| Liposome lipids |
sphingomyelin/cholesterol 75/25 to 50/50 |
Same |
Same |
| Liposome interior/exterior pH |
Not expressly recited in claim 1 |
acidic interior and exterior |
Not expressly recited in claim 3 |
| Third vial buffer type |
dibasic sodium phosphate heptahydrate |
alkaline phosphate buffer |
dibasic sodium phosphate heptahydrate |
| Third vial concentration |
~14.2 mg/mL |
Not specified as mg/mL in claim 2 |
~14.2 mg/mL |
| Third vial pH effect |
Not expressed as “neutralizing” in claim 1 |
neutral exterior after mixing |
Not expressed as “neutralizing” in claim 3 |
| Instructions |
Kit includes instructions to prepare liposomal composition |
Same |
Same |
Dependent narrowing claims
| Dependent claim |
Added limitation |
| Claim 4 |
Neoplasia is relapsed lymphoma or leukemia |
| Claim 5 |
Liposome interior and exterior pH ~4.0 |
| Claim 6 |
Lipid ratio ~55/45 (sphingomyelin/cholesterol) |
| Claim 7 |
Alkaline phosphate buffer pH ~9.0 |
Where does infringement risk concentrate?
Because the asserted claims are kit claims with parameter-defined components, product design-around success depends less on therapeutic intent and more on whether the physical formulation and mixing outcomes land inside the recited ranges.
High-risk “in-scope” design features
- Liposome membrane composition: sphingomyelin/cholesterol in the range 75/25 to 50/50 by mol%.
- Acid-base workflow:
- citrate-buffered acidic liposome suspension (explicitly in claim 2).
- mixing with alkaline phosphate to bring the exterior to neutral (claim 2).
- Drug solution pH: vincristine solution at pH 3.5 to 5.5.
- Specific formulation match:
- ~1 mg/mL vincristine plus mannitol ~100 mg/mL (claims 1 and 3).
- dibasic sodium phosphate heptahydrate ~14.2 mg/mL (claims 1 and 3).
- Indication narrowing: if marketed and used for relapsed lymphoma/leukemia, claim 4 becomes relevant (depending on asserted claim set).
“Easy” partial workarounds are limited
Swapping out one dimension (for example, changing the vincristine concentration) can remove coverage only if it takes the formulation outside all independent claim parameter envelopes. Under this set:
- Claim 2 captures vincristine 1 to 5 mg/mL.
- Claim 1 and 3 lock to ~1 mg/mL plus (in the provided text) mannitol ~100 mg/mL and pH 3.5-5.5.
To escape, a design must generally move at least one “core” element out of the claimed envelope:
- change lipid molar ratio so it is outside 75/25 to 50/50, or
- remove the citrate-buffered acidic liposome interior/exterior + alkaline phosphate neutralization relationship required for claim 2, or
- eliminate the specific phosphate salt/concentration and the mannitol/vincristine formulation points that define claims 1 and 3.
Claim interpretation pressure points (what a court is likely to focus on)
1. “Kit comprising” language
The kit must include each recited vial/component and instructions. A manufacturer distributing only the final mixed product could try to argue it is not a “kit,” but the claims are drafted to include instructions for preparing a liposomal composition. That pushes risk toward distribution of components packaged for use in a single workflow.
2. “Ratio of 75/25 to 50/50”
This is a range claim. Litigation will center on how lipid composition is measured and whether real-world formulation falls within the molar ratio bounds.
3. pH constraints
Two kinds appear:
- Vincristine solution pH 3.5 to 5.5 (claims 1-3)
- Functional exterior neutralization after combining second and third vials (claim 2)
A court will treat claim 2’s neutralization as a process outcome tied to the third vial’s pH being higher than the second vial and the resultant exterior pH being neutral.
4. Specific constants in dependent claims
- ~4.0 liposome interior/exterior pH (claim 5) and
- ~9.0 phosphate buffer pH (claim 7)
These dependent claims create narrower footholds if the accused product tracks those targets.
What is the likely technology context?
The claim structure matches a known development pattern: “remote loading” or pH-driven encapsulation strategies using liposomes prepared under acidic conditions, then buffered/adjusted to trap drug in the liposome lumen.
Key technology anchors in these claims:
- citrate buffer on the liposome preparation side
- phosphate neutralization step
- sphingomyelin/cholesterol liposomes with tuned molar ratios
- vincristine payload and controlled solution pH
US patent landscape: what can be concluded from the claim text you supplied?
What cannot be completed from the provided information
A complete patent landscape for US 7,247,316 requires:
- the full bibliographic record (assignee, filing date, priority chain),
- the complete claim set (beyond claim text provided),
- and the citation graph of related patents (including family members and forward citations).
None of that metadata is contained in the excerpt you provided, so an accurate, source-cited landscape (other than claim-scope inference) cannot be produced from the current inputs.
What can be extracted reliably from the claims
Even without external citations, the claim language itself defines a tight cluster of differentiators that other patents in this space tend to compete on:
- lipid composition (sphingomyelin/cholesterol ratio),
- buffer system pairing (citrate to phosphate),
- pH states (acidic interior/exterior; neutral exterior after mixing),
- and payload solution formulation constraints (vincristine concentration, pH, mannitol presence).
From an investment and FTO perspective, these claims indicate that the patent is most likely to collide with:
- other vincristine-in-liposome formulations that use sphingomyelin/cholesterol at similar ratios and similar citrate/phosphate pH adjustment,
- kits or drug manufacturing workflows that package these components as a defined preparation procedure.
Landscape mapping framework you can apply immediately (claim-driven competitor screening)
Use the following checklist to screen other US patent families and product/process disclosures for same-element hits.
Element match scoring (high relevance)
- Payload: vincristine (often vincristine sulfate) in acidic aqueous solution (pH 3.5-5.5).
- Lipids: sphingomyelin + cholesterol, molar ratio in or near 75/25 to 50/50.
- Buffer workflow:
- citrate-buffered liposomes with acidic pH in lumen and suspension (claim 2 explicitly),
- addition of alkaline phosphate buffer to neutralize exterior pH.
- Kit concept: components delivered in separate vials with instructions to mix at use.
Narrow claim “trapdoor” matches (medium relevance)
- inclusion of mannitol ~100 mg/mL
- dibasic sodium phosphate heptahydrate ~14.2 mg/mL
- liposome pH around 4.0
- phosphate buffer pH around 9.0
- indication restricted to relapsed lymphoma/leukemia
Key Takeaways
- US 7,247,316 claims a multivial kit for preparing a vincristine-loaded sphingomyelin/cholesterol liposomal composition for neoplasia.
- The independent claims are anchored on (i) vincristine solution pH 3.5 to 5.5, (ii) citrate-buffered sphingomyelin/cholesterol liposomes in 75/25 to 50/50 mol%, and (iii) an alkaline phosphate (phosphate heptahydrate at ~14.2 mg/mL in claims 1/3) to control liposome pH state, with claim 2 requiring acidic interior/exterior and neutralized exterior after mixing.
- Dependent claims further constrain to relapsed lymphoma/leukemia and to specific pH targets (~4.0 liposome pH, ~9.0 buffer pH) and specific lipid ratio (~55/45).
FAQs
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Does the patent cover the final mixed liposomal drug product or only the kit?
The claims are drafted as kits with specific vials and instructions to prepare the liposomal composition.
-
What is the most determinative parameter for claim 2?
The pH engineering outcome: acidic liposomes in citrate buffer and mixing with alkaline phosphate so the exterior pH becomes neutral.
-
How does mannitol matter legally?
In the provided claim text, mannitol (~100 mg/mL) is required in claims 1 and 3, while claim 2 does not recite mannitol.
-
Is the lipid ratio a hard cutoff?
Yes. The claims recite a defined molar range 75/25 to 50/50 and a dependent point at ~55/45, so formulations outside the range should avoid those elements.
-
What therapeutic indications are explicitly limited in the claims?
Claim 4 limits to relapsed lymphoma or leukemia.
References
[1] United States Patent US 7,247,316 (claim text as provided by user).
