Patent: 10,815,455

Summary for Patent: 10,815,455

Title:	Salmonella-based vectors for cancer immunotherapy targeting Wilms\' tumor gene WT1
Abstract:	The present invention relates to an attenuated mutant strain of Salmonella comprising a recombinant DNA molecule encoding Wilms\' tumor Protein I. In particular, the present invention relates to the use of said attenuated mutant strain of Salmonella in cancer immunotherapy.
Inventor(s):	Lubenau; Heinz (Neustadt an der Weinstrasse, DE), Springer; Marco (Wendlingen, DE)
Assignee:	Vaximm AG (CH)
Application Number:	15/872,750
Patent Claims:	see list of patent claims

US Patent 10,815,455 Landscape Analysis: WT1-Expressing, Non-HLA-Restricted Oral Salmonella Ty21a DNA Vaccines for Wilms’ Tumor Protein Cancers

Executive summary

US Patent 10,815,455 claims methods of treating WT1-expressing cancers using an orally administered DNA vaccine made from an attenuated mutant Salmonella enterica serovar Typhi Ty21a strain that carries a recombinant DNA molecule with a eukaryotic expression cassette encoding WT1. The independent claim is constrained by (i) WT1 antigen expression, (ii) an oral administration regimen using attenuated mutant Ty21a, (iii) a vaccine “not HLA-restricted,” and (iv) a cancer immunotherapy context that can optionally add co-administered attenuated Salmonella strains carrying other tumor antigens/stroma antigens. Dependent claims further specify human WT1, CMV promoter-controlled expression, vector elements (kanamycin resistance gene, pMB1 ori), truncated WT1 sequences, individualized antigen pattern assessment, dose CFU ranges, and broad tumor-type coverage including AML/ALL and multiple solid tumors.

The patent’s enforceability and practical value hinge on whether competitors can avoid each of the claim’s core limitations: Ty21a carrier, oral route, eukaryotic expression cassette architecture (including CMV promoter and/or WT1 truncation), and especially the “not HLA-restricted” requirement.

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What exactly does US 10,815,455 claim for WT1 cancer treatment using oral Ty21a DNA vaccines?

Core claim (Claim 1) is a method claim for treating a WT1-expressing cancer by administering orally a DNA vaccine comprising an attenuated mutant Salmonella enterica typhi Ty21a strain carrying at least one recombinant DNA molecule with a eukaryotic expression cassette encoding WT1, under a condition that the vaccine is “not HLA-restricted.”

Key claim elements that define infringement risk

1. Target biology

   • Patient selection is tied to WT1-expressing cancer.
   • This implies that infringement analysis depends on whether a treated subject has WT1 expression meeting whatever standard is used in practice and/or as taught in the patent family.

2. Delivery platform

   • The claim requires an attenuated mutant Salmonella enterica typhi Ty21a carrier.
   • Substitution with other attenuated Salmonella strains (even closely related) changes the carrier and creates a potential non-infringement design-around.

3. Molecular cargo

   • The recombinant DNA molecule must include a eukaryotic expression cassette encoding WT1.
   • Any competitor using a different expression construct type (prokaryotic-only expression, non-eukaryotic cassette architecture, or lack of a eukaryotic expression cassette) creates risk dilution.

4. Route

   • The method is expressly oral.

5. Immunologic claim limitation

   • “Vaccine is not HLA-restricted.”
   • This is the most litigation-sensitive limitation because it usually maps to an immunological mechanism: either broadly presented epitopes independent of specific HLA types, or evidence that immune recognition does not depend on a limited set of HLA class I alleles.

Claim 2 and Claim 3 narrow what can be used as “WT1” and how it is expressed

• Claim 2 limits to human WT1.
• Claim 3 specifies the recombinant DNA molecule comprises:
  • a kanamycin antibiotic resistance gene
  • pMB1 ori
  • a CMV promoter driving a eukaryotic expression cassette encoding human WT1

This combination becomes a high-specificity “lock” if a competitor does not use those vector elements or the CMV promoter.

Claims 4 and 5 add multi-antigen strategy via co-administration

• Claim 4 allows the cancer immunotherapy to include one or more further attenuated mutant Salmonella strains, each carrying a recombinant DNA molecule encoding a tumor antigen and/or tumor stroma antigen.
• Claim 5 requires co-administration of those further attenuated Salmonella strains.

Claims 6 to 9 build treatment context, dosing, and personalization

• Claim 6: method can be accompanied by chemotherapy, radiotherapy, or biological cancer therapy.
• Claim 7: cancer selection includes leukemia and solid tumors.
• Claim 8: the attenuated mutant strain is administered as a single dose of about 10^5 to 10^11 CFU.
• Claim 9: “individualized” approach includes a step of assessing tumor antigen/stroma antigen expression pattern.

Claims 10 to 14 add WT1 truncation, specific additional antigen constructs, and an extensive tumor panel

• Claim 10: WT1 can be truncated, and the truncated WT1 must have the amino acid sequence in SEQ ID NO 1.
• Claim 11: further Salmonella strains (if used) can also be Salmonella typhi Ty21a carrying a eukaryotic cassette.
• Claim 12: a further strain can encode human VEGFR-2.
• Claim 13: leukemia subtypes include AML and ALL.
• Claim 14: broad list of solid tumors, including lung, breast, esophageal, colon/colorectal, gastric, cholangi(o)ductal, pancreatic, glioblastoma, head and neck, synovial sarcoma, angiosarcoma, osteosarcoma, thyroid, cervical, endometrial, ovarian, neuroblastoma, rhabdomyosarcoma, and prostate.

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How strong are the “core” claim limitations likely to be against generic design-arounds?

The claim set is structured so that several dependent claims create narrower “gates” but Claim 1 remains broad on many axes. Practical enforceability often turns on whether Claim 1’s gates are satisfied.

Most defensible (hard to design around)

1. Ty21a carrier + oral administration + eukaryotic cassette encoding WT1

   • Many Salmonella DNA vaccine programs differ in strain, route, or cassette design. If the accused product uses Ty21a and delivers WT1 via a eukaryotic cassette, these elements are difficult to avoid simultaneously.

2. WT1-expressing cancer

   • If the competitor’s clinical protocol uses WT1 biomarker-based inclusion, the record can map directly to this element.

Most attackable (litigation hinge)

1. “Not HLA-restricted”

   • If the accused program is positioned as HLA-dependent, or if immune responses are evidenced as restricted to certain HLA alleles, an accused party can attempt to argue lack of the “not HLA-restricted” limitation.
   • Conversely, if “not HLA-restricted” is interpreted broadly based on polyclonal responses or MHC promiscuity, it can be hard to defeat.

2. “WT1” definition and truncated WT1 mapping

   • Claim 1 is for WT1 generally. Claim 10 narrows to truncated WT1 with a specific SEQ ID. Competitors using non-matching truncations can attempt to avoid Claim 10 but still risk Claim 1 unless they also change WT1 sequence architecture.

3. Recombinant DNA molecule composition

   • Claim 3’s vector component specificity is easier to design around than Claim 1’s broader requirement for a eukaryotic cassette encoding WT1.

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Which claim-dependent features create the highest infringement leverage in practice?

A target product that matches Claim 1 but diverges from dependent claims can still infringe Claim 1. But for litigation leverage, counsel typically anchors on the set of features most likely to be used in development and manufacturing.

High-leverage dependent claims

• Claim 3 (kanamycin resistance gene + pMB1 ori + CMV promoter)
  • Many plasmid constructs in academia and industry use CMV promoters; many also include bacterial selection elements like kanamycin and ori elements like pMB1.
• Claim 8 (single dose 10^5–10^11 CFU)
  • Dosing ranges are often protocol-defined and thus evidentiary. If the accused product uses this interval, it strengthens enforceability.
• Claim 10 (truncated WT1 sequence = SEQ ID NO 1)
  • If the accused construct uses this exact truncation, Claim 10 can provide a crisp “sequence match” argument.
• Claim 12 (co-delivery of attenuated Salmonella encoding human VEGFR-2)
  • Programs combining WT1 and VEGFR-2 can map closely to a multi-antigen platform.

Lower-leverage dependent claims

• Claim 6 (combination with chemo/radiotherapy/biological therapy)
  • This is often flexible in clinical practice. If an accused method is used alone, it can avoid Claim 6 specifically while still risking Claim 1.
• Claim 14 (long tumor panel)
  • A broad list can support coverage across many indications, but infringement still depends on the treated cancer being WT1-expressing.

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What does it mean that the vaccine is “not HLA-restricted” and why does it matter legally?

The limitation functions as an immunologic constraint. In patent litigation, that means the claim construction and evidentiary record can become central.

Two practical interpretations competitors fight over

• Broad “not HLA-restricted” interpretation

  • Immune responses are elicited in a way that does not depend on specific HLA allele presentation.
  • This can include polyclonal CD4/CD8 responses with sufficiently diverse epitope recognition.

• Narrow “functional non-restriction” interpretation

  • The patent may require empirical evidence (in the spec) that responses are not limited to a subset of HLA types.
  • If a competitor shows allele-specific responses, it can argue the limitation is not met.

Design-around levers

• Use an antigen processing strategy that yields more allele-sensitive epitopes.
• Adopt an alternative carrier or expression format that changes epitope processing and presentation in a way that yields HLA-dependent recognition.
• Avoid the “not HLA-restricted” positioning, though legally the question is claim satisfaction during treatment, not marketing language.

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How do the claim’s WT1 construct requirements shape the patent landscape for competitors?

US 10,815,455’s protection is not just “WT1 immunotherapy.” It is “WT1 delivered via eukaryotic cassette in attenuated Ty21a DNA vaccine, orally, in a non-HLA-restricted manner.”

Construct-level elements that matter

• Eukaryotic expression cassette:
  • Requires eukaryotic transcription/translation elements, not just plasmid DNA presence.
• Promoter choice (CMV)
  • Explicit in Claim 3, but not required in Claim 1.
• Truncation (SEQ ID NO 1)
  • Explicit in Claim 10; not required in Claim 1.

Implication for competitor portfolios

Programs using Ty21a to express other antigens can still be pushed into the WT1 territory if they add WT1 and an appropriate cassette. Conversely, programs that already use Ty21a but with non-eukaryotic expression approaches may avoid certain claim elements.

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How do co-administered multi-antigen Salmonella strategies affect freedom to operate?

Claims 4 and 5 let the therapy include additional attenuated mutant Salmonella strains encoding tumor antigens and/or stroma antigens, and require co-administration when such further strains are used.

VEGFR-2 is explicitly named

• Claim 12 highlights a further strain encoding human VEGFR-2.
• If a competitor’s regimen includes a second attenuated Salmonella with VEGFR-2, the patent landscape concentrates around WT1 plus that specific second antigen.

Practical risk

Even if a competitor does not use VEGFR-2, it can still infringe Claim 1 if it uses the WT1 Ty21a oral DNA vaccine satisfying Claim 1’s other limitations.

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What is the potential relationship between this method patent and typical vaccine platform IP (vector, carrier, attenuation, oral delivery)?

US 10,815,455 is a method claim anchored on administration and construct content. The carrier and vaccine platform are likely also the subject of earlier patents in the Ty21a DNA vaccine space (attenuation methodology, oral delivery systems, Ty21a engineering, and immune modulation). While those platform patents are not enumerated in the prompt, the litigation pattern in this area typically features:

• platform patents for the attenuated Salmonella chassis and oral dosing,
• construct patents for WT1 expression cassettes and sequence-defined variants,
• method patents like 10,815,455 covering specific antigen and immunologic constraints.

For freedom-to-operate, even if Claim 1 is avoided by changing a single parameter, other patents in the ecosystem can still present barriers.

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What patent expiry and exclusivity timing matters for US 10,815,455?

No filing dates, priority dates, prosecution history, terminal disclaimers, or maintenance/expiration status were provided with the prompt. Without those data, an exclusivity timeline can’t be stated accurately.

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What Orange Book status exists for US 10,815,455?

No FDA product mapping or Orange Book listing context was provided. This patent appears to be method/vaccine-therapy IP rather than a small-molecule NDA/BLA listed drug. Without an associated FDA approval and patent listing record, Orange Book status cannot be determined from the provided information.

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What Paragraph IV, Hatch-Waxman, or biosimilar-style challenges could apply?

This is not described as a biologic with biosimilar pathways nor as a drug with an Abbreviated NDA framework in the prompt. Without product identification (sponsor, BLA/NDA number, formulation type, and listing in the FDA patent clearinghouse), no Paragraph IV or biosimilar litigation pathway can be mapped to US 10,815,455.

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How do companies likely evaluate this patent in licensing, litigation, or R&D decisions?

Even without knowing the assignee(s), the claim structure informs typical business screening:

R&D stage screening checklist

• Is the carrier attenuated mutant Salmonella enterica Typhi Ty21a?
• Is the administration oral?
• Is WT1 expressed from a eukaryotic expression cassette?
• Is the immunologic profile designed to be not HLA-restricted?
• Does the dosing regimen fall within the claimed CFU range for single-dose protocols?
• Is WT1 human and is truncation used in the form of SEQ ID NO 1?
• Is there any co-administered attenuated Salmonella expressing VEGFR-2 or other tumor/stroma antigens?

Licensing and litigation posture

• If a competitor’s candidate matches Claim 1’s core elements, licensing leverage increases because dependent claims often align with common plasmid features (CMV, bacterial selection/origin) and common co-antigen expansion strategies.
• If the competitor can plausibly show HLA dependence, it targets the most distinctive limitation and may reduce Claim 1 risk even if Ty21a/oral/eukaryotic-WT1 is present.

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Key Takeaways

• US 10,815,455 is a method-of-treatment patent for WT1-expressing cancers using an oral, attenuated Ty21a DNA vaccine carrying a eukaryotic expression cassette encoding WT1.
• The claim set’s highest-risk elements are Ty21a as the carrier, oral administration, and the distinctive limitation that the vaccine is “not HLA-restricted.”
• Dependent claims add strong construct and protocol specificity: CMV promoter + kanamycin/pMB1, CFU single-dose range, truncated WT1 = SEQ ID NO 1, and named multi-antigen options including VEGFR-2.
• Design-around opportunities concentrate on changing the carrier, route, cassette architecture, or challenging the HLA-restriction element.
• Timelines, Orange Book status, and litigation/Paragraph IV pathways cannot be determined from the provided prompt because no FDA product or priority/filing data were included.

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FAQs

1) Does US 10,815,455 require a specific WT1 sequence for infringement of Claim 1?
Claim 1 requires WT1 in general via a eukaryotic expression cassette, while Claim 10 separately requires a specific truncated sequence (SEQ ID NO 1).

2) If a competitor uses a different Salmonella strain than Ty21a, does it avoid the patent?
It can avoid key carrier limitations because Claim 1 expressly requires attenuated mutant Salmonella enterica typhi Ty21a.

3) Can a competitor avoid the patent by changing the promoter from CMV?
Claim 3 specifically requires CMV promoter, but Claim 1 does not. Changing CMV may avoid Claim 3 while still risking Claim 1 if the eukaryotic expression cassette encoding WT1 remains.

4) Is co-administration of additional tumor antigen Salmonella required for infringement?
No. Co-administration appears in dependent Claims 4 and 5. Claim 1 can be infringed without the multi-strain expansion.

5) How does the “not HLA-restricted” limitation affect evidentiary strategy?
It shifts dispute toward immunology evidence about allele dependence, epitope presentation, and whether the immune response is restricted to certain HLA types during treatment.

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References

1. United States Patent 10,815,455. (Claims provided in prompt).

Details for Patent 10,815,455

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Bavarian Nordic A/s	VIVOTIF	typhoid vaccine live oral ty21a	Capsule	103123	15-Dec-89		2038-01-16