US Patent 9,730,888 (Plasmin + Nucleic Acid Opsin Expression Vectors for Intravitreal Gene Delivery): Claim Construction, Validity Risks, and US Patent Estate Strength
US Patent 9,730,888 claims intravitreal delivery of a plasmin (or derivative) together with a nucleic acid expression vector encoding an opsin to enhance ocular delivery and restore/increase light sensitivity. Claim scope is concentrated on (i) the delivery system (intravitreal injection; plasmin/miniplasmin/microplasmin/ocriplasmin), (ii) the therapeutic payload (nucleic acid expression vectors, often viral vectors), and (iii) the therapeutic gene (opsins under defined gene and promoter constraints), with optional formulation and cell-type targeting.
The key business implication is that the effective US exclusivity value is driven less by the “opsin” concept broadly and more by the specific combination of an ocular plasmin proteolytic agent with an intravitreal nucleic acid expression vector, including timing (concurrent/sequential) and directed delivery to retinal target cells.
What claims are in US Patent 9,730,888 and how broad are they?
Core independent claim structure
- Claim 1: Method “enhancing the delivery of a therapeutic agent to an eye” via intravitreal injection of plasmin or derivative + therapeutic agent comprising a nucleic acid expression vector.
- Claim 12: Method to increase light sensitivity/improve or restore vision via intravitreal administration of plasmin or derivative + nucleic acid expression vector encoding an opsin.
Built-in claim levers
- Delivery route: intravitreal injection (narrows to a specific administration route).
- Protease: plasmin or derivatives (narrows to proteolytic agents with specific identity).
- Payload class: nucleic acid expression vectors (encompasses plasmids and viral vectors, but dependent claims steer heavily to viral).
- Gene specificity: opsin family plus functional variants; additional dependent claims constrain promoters.
- Target cells: enumerated retinal cell types (dependent).
- Co-administration: concurrently or sequentially (dependent).
- Formulations: optional encapsulation in nanoparticle/polymer/liposome (dependent).
- Therapeutic indication: “ocular disease or disorder” (dependent).
Claim 1 (delivery enhancement) elements
Claim 1 requires all of:
- An enhancing objective (“enhancing delivery of a therapeutic agent to an eye of a subject”).
- Intravitreal injection.
- Plasmin or derivative.
- Therapeutic agent comprises a nucleic acid expression vector.
Scope impacts
- The claim is not limited to opsins for Claim 1. It is broader: any nucleic acid expression vector qualifies as the “therapeutic agent.”
- The claim is still limited by the requirement that the therapeutic agent “compris[es] a nucleic acid expression vector.” If a competitor uses an mRNA therapy, a protein therapy, or non-expression vectors, Claim 1 may not read.
- If a competitor uses intravitreal injection of a non-plasmin protease or a plasmin delivered by another route, the literal scope narrows.
Claim 12 (vision restoration / opsin encoding) elements
Claim 12 requires all of:
- Increasing light sensitivity or improving/restoring vision.
- Intravitreal delivery.
- Plasmin or derivative.
- Nucleic acid expression vector encoding an opsin.
- “Opsin” is limited to a defined group in dependent claims.
Scope impacts
- Claim 12 is a functional-medical outcome claim combined with a payload identity requirement (opsin gene). It has narrower breadth than Claim 1, but likely stronger enforcement leverage because it ties directly to a common therapeutic goal in retinal gene therapy for blindness.
Dependent claims constrain scope in predictable ways
- Claim 2: miniplasmin or microplasmin (ocriplasmin).
- Claim 3: viral vector comprising a transgene.
- Claim 4-5: opsin defined list (channelrhodopsin, halorhodopsin, melanopsin, pineal opsin, bacteriorhodopsin, proteorhodopsin) or functional variant.
- Claim 6: operably linked to a cell-specific promoter.
- Claim 7: encapsulated in nanoparticle/polymer/liposome.
- Claim 8: subject has ocular disease/disorder (generic indication).
- Claim 9: concurrent or sequential delivery.
- Claim 10-11: delivered to retinal cell types enumerated (including RGC, bipolar, horizontal, amacrine, photoreceptor, Müller glia, RPE).
- Claim 13: opsin list repeated for Claim 12.
- Claim 15-20: miniplasmin/microplasmin, promoter, timing, viral vector, and retinal cell targeting.
Enforcement posture by claim layer
- Broadest literal hook: Claim 1 (delivery enhancement with any nucleic acid expression vector).
- Strongest “therapeutic intent + gene” hook: Claim 12 + dependent opsin/promoter/cell-type constraints.
Which parts of the claim language are most likely to be litigated?
1) “Enhancing the delivery” and proof burden
Method claims with enhancement language often generate disputes over:
- What constitutes “enhancing” (statistical threshold, assay type).
- Whether baseline delivery must be compared.
- Whether “delivery enhancement” must be to the “eye” generally or to a particular retinal compartment.
A competitor’s defense path typically targets causation and measurable effect rather than identity of components.
2) “Intravitreal injection”
This can be litigated when companies use:
- Suprachoroidal, subretinal, intravitreal infusion, or device-mediated delivery.
- Different injection volumes, schedules, or routes via catheters.
Even when the drug ultimately reaches ocular tissue, the claim’s method requires intravitreal injection.
3) “Plasmin or derivative thereof” identity
Dependent claim 2 lists miniplasmin and microplasmin/ocriplasmin. Claim 1 covers “plasmin or derivative thereof,” which can broaden beyond the named derivatives depending on the patent specification’s definitions.
Core litigation question in practice: does a competitor’s protease fall within “derivative thereof,” or is it excluded by how “derivative” is construed in the patent?
4) “Nucleic acid expression vector” and vector class boundaries
This term can be contested between:
- DNA plasmids vs viral vectors vs hybrid systems.
- Replicating vs non-replicating vectors.
- Use of episomal delivery, transposons, or lentiviral variants.
Dependent claim 3 narrows to viral vectors, but independent claim 1 is not so limited.
5) “Opsin” list and “functional variant”
The opsin family list in claims 4-5 and 13 defines the gene identity. “Functional variant” is a litigation magnet:
- What degree of sequence identity triggers inclusion.
- What functional assay defines “functional.”
- Whether codon variants, truncated opsins, or chimeras qualify.
How do these claims compare to prior art in retinal gene therapy and plasmin delivery?
The claims sit at the intersection of two prior-art clusters:
- Retinal gene therapy using nucleic acid expression vectors, including viral delivery systems encoding opsins.
- Use of plasmin/miniplasmin/microplasmin (ocriplasmin) to alter ocular barriers or extracellular matrix properties to improve delivery.
A validity challenge would typically combine:
- References disclosing intravitreal nucleic acid expression with retinal targeting and opsin genes.
- References disclosing plasmin or derivatives administered intravitreally to enhance delivery or reduce barriers.
- Rationale-based combinations under obviousness, where the question becomes whether a skilled artisan would have had a clear path to combine plasmin derivatives with nucleic acid expression vectors for intravitreal delivery and obtain enhanced gene delivery and visual function outcomes.
Because Claim 1 is framed as delivery enhancement plus intravitreal plasmid/viral vector payload, the strongest prior art alignment is any pre-existing disclosure that uses plasmin/miniplasmin to enhance delivery for macromolecules and any pre-existing disclosure of intravitreal viral vectors expressing opsins or other retinal transgenes.
Business risk: even if opsin gene therapy was known, the combination claim can still be invalid if the plasmin co-administration is found to be an expected optimization. Conversely, if prior art teaches away from combining proteases with nucleic acid vectors or if dosing, timing, or stability constraints are not taught, the claims have better standing.
What is the US patent landscape around US 9,730,888 for plasmin-augmented ocular gene delivery?
Where the estate value is concentrated
Even without reproducing the full patent family map here, the enforceable value for US 9,730,888 is concentrated in:
- The combination method (plasmin derivative + nucleic acid expression vector) delivered intravitreally.
- Opsin-specific implementations (channelrhodopsin/halorhodopsin/etc., functional variants, cell-specific promoters).
- Retinal cell targeting enumerations (RGC, bipolar, horizontal, amacrine, photoreceptors, Müller glia, RPE).
- Timing and co-delivery sequences.
This configuration positions the patent for coverage of:
- Licensing discussions with gene therapy developers focused on optogenetics in retinal disease.
- Barrier-enhancement strategies that use proteases to improve transduction or expression.
Typical design-around pathways implied by the claims
A generic “avoid infringement” approach must attack at least one required claim element:
- Route: do not use intravitreal injection (or argue not an “intravitreal injection”).
- Protease: use a non-plasmin protease or a delivery strategy that does not constitute “plasmin or derivative.”
- Payload: deliver non-expression modalities (protein, mRNA if it is argued not to be “expression vector,” though mRNA generally supports expression).
- Gene restriction: avoid opsin genes or avoid the claimed opsin list/functional variants.
- Timing: if timing is central in dependent claims, avoid concurrent/sequential delivery as claimed.
Because Claim 1 is broad on the payload (any nucleic acid expression vector), design-around is most likely to hinge on (i) protease identity or (ii) delivery route.
What do claims 1 and 12 suggest about the likely infringement theory in US court?
Infringement theory for a contender
Plaintiff infringement theory typically proceeds in three steps:
- Identify the product method: intravitreal injection of plasmin/miniplasmin/microplasmin (including OCRiPlasmin) plus a gene therapy vector.
- Prove the therapeutic agent is a nucleic acid expression vector.
- Map the delivered vector’s gene payload to opsin genes for Claim 12 (if using Claim 12) and map to retinal targeting outcomes/cell types for dependent claim support.
Infringement evidence likely to matter
- Labeling and IFU describing intravitreal administration.
- Product composition documents for the protease and vector.
- Dosing protocols proving concurrent or sequential schedules.
- Histology/transduction assays showing which retinal cells are transduced.
What patent strength signals are embedded in the claim drafting?
Strength indicators
- Clear conjunction of components: intravitreal plasmin derivative + nucleic acid expression vector.
- Multiple dependent claims that narrow to widely used embodiments (viral vectors, opsin genes, cell-specific promoters).
- Inclusion of cell-type targeting supports argument that therapeutic intent is cellularly specific and not purely systemic.
Weakness indicators
- The “enhancing delivery” and functional vision restoration language can invite arguments that the claimed method lacks a specific measurable parameter in the claims.
- Broadness in Claim 1 across any nucleic acid expression vector increases the need to distinguish prior art combinations. If prior art has plasmin used with other biologics and separate gene therapy disclosures, obviousness risk increases.
- “Functional variant” for opsins expands interpretation disputes.
How does US 9,730,888 likely perform against common US patent validity challenges?
1) 35 U.S.C. § 102 (novelty)
A strict novelty attack requires:
- A single prior art reference disclosing intravitreal administration of plasmin/miniplasmin/microplasmin (or derivatives) with a nucleic acid expression vector.
- If targeting Claim 12, the same reference must disclose opsin-encoding nucleic acids in that combination.
This is a higher bar than obviousness because the combination must be in one document.
2) 35 U.S.C. § 103 (obviousness)
Most likely validity strategy:
- Combine references showing plasmin derivative enhances ocular delivery with references showing intravitreal opsin-encoding gene therapy vectors.
- Argue predictable results: increased transduction/expression leading to improved light sensitivity.
The defense counter typically centers on:
- Lack of motivation to combine.
- Technical hurdles (stability of vectors, activity of protease, dosing tolerability).
- Non-predictable results on functional vision metrics.
3) § 112 issues (written description/enablement/indefiniteness)
Potential § 112 attack surfaces:
- Breadth: “plasmin or derivative thereof” and “functional variant” may be argued as indefinite if the patent fails to define boundaries.
- Enablement: if multiple opsin variants and cell-specific promoters are claimed, the specification must enable those embodiments.
What competitor product patterns are most at risk?
US 9,730,888 is most exposed to products that combine:
- An ocular barrier-enhancing plasmin derivative (including miniplasmin and microplasmin/OCRiPlasmin) with
- Viral or other nucleic acid expression vectors encoding opsins used for optogenetics.
Risk rises when:
- The route is intravitreal injection.
- The therapy delivers to retinal cells (RGC, bipolar, etc.) in ways consistent with the claimed enumerations.
- The regimen uses concurrent or sequential delivery of the protease and vector.
Lower risk patterns:
- Non-intravitreal routes.
- Non-plasmin protease barrier tools.
- Gene therapies not using opsins (for Claim 12), though Claim 1 could still capture non-opsin transgenes.
What is the “Orange Book” status of US 9,730,888 and does it matter?
US 9,730,888 is directed to method claims using a combination (plasmin/derivative + nucleic acid expression vector). Method patents for biologics and gene therapies are not necessarily Orange Book-listed in the way that small-molecule drug product patents are. Orange Book listing is product/NDA-context dependent, and method patents for biologics often appear under the “Patent” listing framework in other FDA mechanisms rather than the Orange Book model.
From a business perspective, the practical enforceability question is less about Orange Book and more about:
- FDA listing (where applicable),
- enforcement via infringement actions,
- and whether the assignee has a coordinated patent strategy around the clinical program.
How does US 9,730,888 compare to other patent estates in retinal gene delivery?
Within retinal gene therapy, estates typically bifurcate into:
- Vector and promoter/control elements.
- Delivery route and method-of-administration.
- Therapeutic gene constructs and variants (opsin-specific claims).
- Barrier modulation approaches.
US 9,730,888 is positioned as a barrier modulation + delivery enhancement combination patent. It can become an “anchor” patent in negotiations if the clinical program’s differentiator is precisely plasmin-augmented intravitreal gene delivery.
Competitor estates that focus only on opsin constructs without barrier modulation are more vulnerable to being displaced in a settlement by a combination claim like this. Conversely, if competitors have robust independent patents on their vector systems and promoters, they can settle licensing in a narrower field-of-use while avoiding a broader “combination” license.
What are the likely licensing and settlement dynamics for a combination patent like this?
Business dynamics typically include:
- Field-of-use carveouts: licenses that permit intravitreal plasmin-augmented delivery for defined opsins or defined retinal cell targeting.
- Platform cross-licenses: if multiple plasmid/viral payloads share the same barrier modulation.
- Royalty stacking management: if both a vector/payload patent estate and this plasmin enhancement estate are asserted, parties may agree on caps or allocation by use-case.
The dependent claim structure supports narrower settlement scopes:
- An agreement may cover only viral vectors (Claim 3) and only the opsin list (Claims 4-5 and 13) rather than all nucleic acid vectors.
Key Takeaways
- US 9,730,888 claims intravitreal delivery methods combining a plasmin (or derivative) with nucleic acid expression vectors, with a narrower but commercially salient subset covering opsin-encoding vectors for vision restoration/light sensitivity.
- The enforceable leverage is strongest where an accused therapy matches the combination (plasmin derivative + intravitreal gene vector) and, for vision restoration claims, matches the opsin family and promoter/cell targeting constraints.
- Main validity risk pathways are obviousness combinations that pair known plasmin delivery enhancement with known intravitreal retinal gene therapy, including optogenetic/opsin constructs.
- The most straightforward design-around strategy implied by the claim set is to avoid intravitreal plasmin-derivative co-administration while maintaining gene therapy delivery through other routes or protease modalities.
FAQs
1) Can a therapy that uses subretinal injection avoid infringement of US 9,730,888?
Claim 1 and Claim 12 require “administering, by intravitreous injection.” A subretinal route avoids an essential claim element.
2) Does US 9,730,888 cover non-viral nucleic acid therapies under Claim 1?
Yes. Claim 1 requires a “nucleic acid expression vector” but does not require viral vectors. Viral vectors are constrained in dependent Claim 3.
3) If a gene therapy encodes an opsin outside the listed set, is it automatically outside Claim 12?
Dependent Claims 4-5 and 13 list specific opsins and “functional variant[s].” Genes outside the list may still be argued as “functional variants,” depending on claim construction.
4) What role does concurrent vs sequential delivery play?
Timing is a dependent limitation (Claim 9 for Claim 1; Claim 17 for Claim 12). If an accused regimen avoids the claimed concurrent/sequential relationship, it may reduce infringement for those dependent claims.
5) Are nanoparticle/liposome formulations required for infringement?
No. Encapsulation in nanoparticles/polymers/liposomes is in dependent Claim 7, so it is optional for Claim 1 and Claim 12.
References (APA)
No external sources were provided in the prompt to cite for claim text verification, prosecution history, family members, assignment, FDA listings, litigation, or prior art.
