Vesicular Stomatitis Virus-Based Oncolytic Virotherapy: Recent Progress and Emerging Trends

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This review paper meticulously summarizes all of the relevant aspects surrounding the use and advancements of vesicular stomatitis virus (VSV) as an oncolytic virus. This is a comprehensive update on the progress of the last 8 years of research since the last review published by Grdzelishvili and colleagues. This manuscript comprises an exhaustive review of the many advancements, including genetic modifications, chimeric vectors, novel payloads, combination therapies, and clinical development. There are a few minor comments to address prior to publication:

 

• There are numerous grammatical errors, including incomplete sentences, such as in lines 130-140 and 163.
• In line 71, teserpaturev (G47D) is mistakenly referred to as an adenovirus, when in fact, it is a herpes simplex virus vector.
• Gendicine (line 72) is arguably a gene therapy, not an oncolytic virus.
• The paragraph on directed evolution/virus adaptation seems to appear twice (lines 181-200 and 304-323). I think the paragraph fits best at its second appearance.
• Naik et al was seemingly mis-cited regarding work on VSV-GP. I believe the proper citation should be Muik et al (PMID 21450833).
• Table 1 is titled “Recombinant VSVs with a pseudotyped or chimeric foreign component”; however, to my knowledge, all of the vectors listed are chimeric. If there are in fact pseudotyped and chimeric vectors in the table, it should be indicated which are which. Furthermore, the last entry in the table (VSV for dual-specific CAR T), and also described in lines 293-300, does not seem to relate to either a chimeric or pseudotyped vector.
• There are occasionally formatting issues with the citations, for example in line 389.
• Line 482, the first line of a new section starts with “Some types exhibit…”. Some types of what? Tumor?
• Lines 673-674: “3.1.1. Subsubsection” should be deleted.
• In general, the citations should be double-checked. For example, reference 126 should refer to the section on T cell carriers, not clinical studies.
• Lines 964-966: expression of immune-evasive proteins is mentioned but not elaborated upon. Which immune-evasive proteins? The citations do not seem to reference this.
• Lines 121-123: anti-CTLA4 was used in this study, not anti-PD1 as described.
• Line 122: pre-existing immunity is described as a challenge in VSV-based virotherapy. This contradicts lines 80-81 and the widespread understanding that VSV is not a human pathogen and few humans have been exposed to this virus.

 

In general, this paper is very long, and there are many redundancies that can be eliminated. The authors should also consider removing parts that do not directly relate to oncolytic VSV (for example, references to the use of VSV-G in other virus pseudotypes). In some sections, for example the one describing the combination of VSV with embolization, there does not seem to be anything new since the previous review, and the description here is mostly hypothetical and could perhaps be removed. Most of the section on combination with chemotherapy refers to older research which therefore does not fit to this manuscript focusing on recent advancements. These would all be opportunities to cut down some of the text.

Author Response

Reviewer 1 (R1) Comments (C)

R1C1: There are numerous grammatical errors, including incomplete sentences, such as in lines 130-140 and 163.
Our Response: We carefully reviewed the entire manuscript and corrected all grammatical errors and sentence fragments, including those identified in the original submission’s lines 130–140 and 163.

R1C2: In line 71, teserpaturev (G47D) is mistakenly referred to as an adenovirus, when in fact, it is a herpes simplex virus vector.
Our Response:  Corrected. The text now accurately identifies teserpaturev (G47Δ) as a herpes simplex virus vector.

R1C3: Gendicine (line 72) is arguably a gene therapy, not an oncolytic virus.
Our Response:  We revised this section and removed Gendicine.

R1C4: The paragraph on directed evolution/virus adaptation seems to appear twice (lines 181-200 and 304-323). I think the paragraph fits best at its second appearance.
Our Response:  We removed the redundant paragraph and retained the version in its more appropriate position at lines 304–323, as suggested.

R1C5: Naik et al was seemingly mis-cited regarding work on VSV-GP. I believe the proper citation should be Muik et al (PMID 21450833).
Our Response:  Corrected. The Naik et al citation was replaced with the appropriate reference to Muik et al. (PMID 21450833).

R1C6: Table 1 is titled “Recombinant VSVs with a pseudotyped or chimeric foreign component”; however, to my knowledge, all of the vectors listed are chimeric. If there are in fact pseudotyped and chimeric vectors in the table, it should be indicated which are which. Furthermore, the last entry in the table (VSV for dual-specific CAR T), and also described in lines 293-300, does not seem to relate to either a chimeric or pseudotyped vector.
Our Response:  We revised Table 1 to only include chimeric vectors. The VSV-CAR T entry has been removed from this section.

R1C7: There are occasionally formatting issues with the citations, for example in line 389.
Our Response:  All references were rechecked and reformatted for consistency according to journal style guidelines.

R1C8: Line 482, the first line of a new section starts with “Some types exhibit…”. Some types of what? Tumor?
Our Response:  Revised to specify “Some tumor types exhibit…” for clarity.

R1C9: Lines 673-674: “3.1.1. Subsubsection” should be deleted.
Our Response:  Deleted as suggested.

R1C10: In general, the citations should be double-checked. For example, reference 126 should refer to the section on T cell carriers, not clinical studies.
Our Response:  All references were verified and corrected. Reference 126 now appears in the appropriate section.

R1C11: Lines 964-966: expression of immune-evasive proteins is mentioned but not elaborated upon. Which immune-evasive proteins? The citations do not seem to reference this.
Our Response:  We removed this text as an effort to condense the manuscript.

R1C12: Lines 121-123: anti-CTLA4 was used in this study, not anti-PD1 as described.
Our Response:  Corrected. The text now specifies “anti-CTLA4.”

R1C13: Line 122: pre-existing immunity is described as a challenge in VSV-based virotherapy. This contradicts lines 80-81 and the widespread understanding that VSV is not a human pathogen and few humans have been exposed to this virus.
Our Response:  We agree, and removed this statement about “pre-existing immunity is described as a challenge in VSV-based virotherapy”.

R1C14: In general, this paper is very long, and there are many redundancies that can be eliminated. The authors should also consider removing parts that do not directly relate to oncolytic VSV (for example, references to the use of VSV-G in other virus pseudotypes). In some sections, for example the one describing the combination of VSV with embolization, there does not seem to be anything new since the previous review, and the description here is mostly hypothetical and could perhaps be removed. Most of the section on combination with chemotherapy refers to older research which therefore does not fit to this manuscript focusing on recent advancements. These would all be opportunities to cut down some of the text.
Our Response: Thank you for these suggestions! We carefully condensed redundant content, removed outdated or tangential examples (e.g., embolization and pseudotypes).

Reviewer 2 Report

Comments and Suggestions for Authors

This is a very well-written, clear and comprehensive review. Inclusion of Maraba, Morreton, and Jurona viruses is very useful.

Reviewer Comments: Vesicular stomatitis virus as an oncolytic platform: recent advances in safety, selectivity, and therapeutic application

Comments on Introduction -The introduction is clear and informative but reads more like a historical overview of oncolytic virotherapy rather than a focused entry point into the unique biology of VSV. Consider tightening the background on general OV therapy (lines 41–76) to reduce redundancy with other recent reviews. The space could instead emphasize why VSV, in particular, continues to stand out, e.g., its cytoplasmic replication, modular genome, and capacity for immune reprogramming.

Minor Comments

• Line 61: “can also elicits” to “can also elicit.”
• Line 66: Remove oncolytic viruses and use OVs instead. This was defined in line 56.
• Line 83: “cytoplasmic replication and cell lysis without risk of genome integration or cell transformation” could be simplified for clarity.

Comments on Section 2  -This section provides a comprehensive overview of the strategies used to enhance VSV safety and tumor selectivity. The section is logically structured.

• The first few paragraphs (lines 114–134) repeatedly explain the concepts of safety and oncoselectivity. While these are foundational, the discussion could be condensed to avoid redundancy. For instance, lines 128–133 reiterate points already made in lines 116–123.
• Consider reorganizing so that each principle (safety, oncoselectivity) is explained concisely, followed immediately by the VSV-specific examples.
• Including a small table summarizing strategies, mechanistic rationale, and clinical status could improve readability and impact.

Minor Errors

• Line 137–139: “Because LDL-R is expressed on nearly all nucleated cells, including the vast majority of tumor cells.” is a sentence fragment, consider combining with the previous sentence.
• Line 157: “Stojdl et al. 2003)” incorrect placement of parentheses.
• Line 163: 162: Repeated “VSV-IFNβ-NIS.” should be removed.
• Lines 174–175: The phrase “Most of which will be discussed in greater detail” could be reworded for smoother readability.

Comments on Section3 - While comprehensive, the section is dense and could benefit from clearer subsection headings. For example:

• “Directed Viral Evolution of VSV” (lines 180–200)
• “Chimeric and Pseudotyped VSV Approaches” (lines 201–300)
• “Clinical Translation and Immunomodulation” (lines 227–300)

• Line 246: “CD8⁺ T cell were shown” should be “CD8⁺ T cells were shown”
• Line 276: “in which replacing VSV-G was replaced with Lassa virus glycoprotein” needs to be reworded for clarity.
• Table 1 is excellent but could be enhanced by adding a column noting “Stage of Development” (preclinical vs. early clinical).

Comments on Section 4 -This section is clear and informative.

• The opening paragraph (lines 303–322) largely repeats concepts already introduced in Section 3 regarding viral adaptation and improved attachment. Consider a brief cross-reference instead of repeating methodology and outcomes. For instance, the principle of serial passaging could be summarized in 1–2 sentences with citation to previous sections.
• Some phrases are slightly repetitive, e.g., “improved replication in SUIT-2 and AsPC-1… remaining highly attenuated in non-malignant cells” and “adapted viruses maintained oncolytic selectivity” (lines 315, 329). Condensing these would improve flow.

Minor Suggestions

• Line 303: Consider rephrasing the section title to “Enhancing VSV Tumor Tropism via Experimental Adaptation” for clarity and alignment with standard virology terminology.
• Line 306: “select viral variants with enhanced replication and cytotoxicity” could be shortened to “select variants with improved oncolytic potency.”
• Line 338–340: Minor typo – “Ovs” should be “OVs.”

Comments on Section 5 -This section is comprehensive and provides an overview of strategies to enhance the tumor-selective replication of VSV.

• While subsections (5.1–5.8) are logical, some are very dense and may overwhelm readers. For example, 5.3 (VSV recombinants encoding IFN transgenes) is very long with multiple
• Line 594–596: “VSV-M protein directly targets mitochondria…” could benefit from specifying whether this is direct binding or indirect modulation.
• Subsection 5.7 (vaccinia virus genes) describes IFN evasion strategies, but could clarify the distinction between co-administration with vaccinia virus versus engineering VSV to express E3L/B18R.
• References to studies are sometimes inconsistent in formatting. For example:
  • Line 388: “Stojdl et al. 2003; Bischoff et al. 1996)” – mismatched parentheses.
  • Lines 494–499: Some studies are cited parenthetically, others inline with text.

Minor Suggestions

• Line 344: “alternative approaches to enhance the oncoselectivity” could be simplified to “strategies to improve tumor-selective replication.”
• Lines 670–674: The sentence “Another major limitation to OV is a complex tumor microenvironment…” could be edited for grammar and clarity “Another major limitation for OV therapy is the complex tumor microenvironment…”.

Comments on Section 6 - This section provides a overview nof strategies to enhance direct oncolysis by VSV.

• Some points, especially regarding VSV-S and its immune modulation (e.g., reducing MDSCs/TAMs and increasing CD8⁺ T cells), are repeated multiple times across paragraphs (lines 765–770 vs. 768–770).
• inconsistent use of terms. For example “wt VSV” vs. “wild-type VSV,” “PDAC” vs. “pancreatic cancer”) and could be standardized.

Minor Points

• Some sentences could be shortened for clarity.

Comments on Section 7 - This section addresses improving delivery and preventing premature immune clearance. The section is informative and cites relevant preclinical studies.

• Lines 933–936 and 938–939 repeat similar points. Consider consolidating
• T cell delivery is described in multiple sentences with overlapping content (lines 940–954).
• Consider subheadings or clearer transitions between:
  • Physical/chemical carriers
  • Cellular carriers
  • Viral engineering modifications

Minor Points

• Line 928: “even in absence of pre-existing immunity” should be “even in the absence…”

Comments on Section 8 - This section details ways to enhance tumor-specific immunity. The tables summarizing VSV variants and transgenes are very helpful.

• Lines 970–986 largely repeat the principle that VSV can induce tumor-specific immunity and synergize with ICIs.
• Cytokine arming is discussed repeatedly. a subsection summarizing all cytokine-based strategies could reduce repetition.
• Consider reorganizing section 8.1:
  • Cytokine/immune modulator arming of VSV
  • Combo with ICIs
  • VSV-based vaccines
  • Enhancement of CAR T therapy
• Acronyms are sometimes inconsistently used (e.g., “OVs,” “oVSV,” “VSV-based oncolytic virotherapy”).

Comments on Section 9 - This section provides an overview of other vesiculoviruses as OVs.

• Several paragraphs repeat similar points:
  • Maraba virus prime-boost strategies and T cell activation are discussed multiple times.
  • Safety and low seroprevalence are mentioned for each virus, which could be consolidated into a comparative table or summary paragraph.
• Restructuring based on virus type may help with flow:
  • 1 Maraba virus: efficacy, prime-boost, immune activation, translational studies
  • 2 Morreton virus: oncolytic activity, safety, glycoprotein engineering, limitations
  • 3 Jurona virus: efficacy, immune remodeling, translational potential
  • 4 Comparative summary of vesiculoviruses relative to VSV (safety, tropism, immunogenicity, clinical potential)

Minor Issues

• “A potent platform for a ‘oncolytic vaccine vector’” (line 1129) should be “an oncolytic vaccine vector’
• : consistent use of virus abbreviations (MG1, MORV, JURV) would improve clarity.

Comments on Conclusion section - The section summarizes the current state of VSV-based oncolytic virotherapy and highlights key challenges and future directions.

• Consider organizing conclusions into subsections or perhaps bullet points:
  • 1 Field evolution and current scope
  • 2 Divergent therapeutic visions for VSV
  • 3 Systemic delivery challenges and strategies
  • 4 Future directions and translational priorities

Author Response

Reviewer 2 (R2) Comments (C)

R2C1: The introduction is clear and informative but reads more like a historical overview of oncolytic virotherapy rather than a focused entry point into the unique biology of VSV. Consider tightening the background on general OV therapy (lines 41–76) to reduce redundancy with other recent reviews.
Our Response:  We revised the introduction to reduce general OV background and emphasize unique aspects of VSV biology, such as cytoplasmic replication, modular genome, and immune modulation capacity.

R2C2: Line 61: “can also elicits” to “can also elicit.”
Our Response:  Corrected.

R2C3: Line 66: Remove oncolytic viruses and use OVs instead.
Our Response:  Updated throughout the text for consistency.

R2C4: Line 83: “cytoplasmic replication and cell lysis without risk of genome integration or cell transformation” could be simplified for clarity.
Our Response:  Simplified!

R2C5: The first few paragraphs (lines 114–134) repeatedly explain the concepts of safety and oncoselectivity. While these are foundational, the discussion could be condensed.
Our Response:  Condensed the section and directly linked concepts to VSV-specific examples.

R2C6: Including a small table summarizing strategies, mechanistic rationale, and clinical status could improve readability.
Our Response:  We have included a supplementary table with a section detailing oncoselectivity and safety.

R2C7: Several minor grammar and formatting corrections (Lines 137–139, 157, 163, 174–175).
Our Response:  All corrected.

R2C8: Table 1 is excellent but could be enhanced by adding a column noting “Stage of Development.”
Our Response:  Added “Stage of Development” (preclinical vs. clinical stage) to Table 1.

R2C9: The section on viral adaptation repeats concepts from Section 3.
Our Response:  Condensed and cross-referenced to eliminate repetition.

R2C10: Suggested structural improvements for Sections 5–9, reduction of redundancy, and clearer subheadings.
Our Response:  Implemented all organizational suggestions; added new subheadings and merged overlapping paragraphs for better readability.

R2C11: Consistent terminology (e.g., “wild-type VSV,” “OVs”) and minor typographical fixes.
Our Response:  Standardized terminology and corrected all inconsistencies. We use “OV” when making general statements that encapsulates all anti-cancer viruses and “VSV” when describing VSV in particular.

R2C12: Suggest reorganizing Section 8 to separate cytokine arming, ICIs, and CAR T therapy.
Our Response:  Reorganized Section 8 accordingly.

R2C13: Comments on Section 9 recommending consolidation of repeated points and a comparative table of vesiculoviruses.
Our Response:  Consolidated overlapping descriptions and added a new comparative summary table for Maraba, Morreton, and Jurona viruses.

R2C14: Suggested bullet-style or structured conclusion.
Our Response:  Revised conclusion into structured subsections: “Current Challenges” and “Future Directions.”

Reviewer 3 Report

Comments and Suggestions for Authors

Summary:

       The authors present a comprehensive and well-structured update on recent developments in VSV-based oncolytic virotherapy, highlighting advances in VSV safety, oncoselectivity, tumor-specific replication, direct oncolysis, and the induction of antitumor immunity. Moreover, the manuscript provides a systematic overview of several emerging oncolytic platforms currently under preclinical and clinical evaluation. Overall, this review is informative and timely, though minor clarifications or additional contextual details in a few sections could further enhance its clarity and impact. I recommend publication in Current Oncology, pending the following minor revisions.

Detailed comments as below:

1. Some sections lack proper literature support. For example, Section 3 (Lines 180–213) would benefit from adding references to the original studies.
2. The review is comprehensive, but a more selective presentation would improve readability. Try to reduce excessive experimental details from cited papers and focus on the main advances and concepts.
3. Consider dividing the Conclusion into two subsections: Future Directions and Current Challenges, to make the final section more structured and easier to follow.
4. The manuscript is generally well written but would benefit from professional language refinement to improve clarity and readability.

Author Response

Reviewer 3 (R3) Comments (C)

R3C1: Some sections lack proper literature support. For example, Section 3 (Lines 180–213) would benefit from adding references to the original studies.
Our Response:  Added primary citations to support all major statements in Section 3.

R3C2: The review is comprehensive, but a more selective presentation would improve readability.
Our Response:  Condensed excessive experimental details and emphasized overarching advances and concepts.

R3C3: Consider dividing the Conclusion into two subsections: Future Directions and Current Challenges.
Our Response:  Revised accordingly; the conclusion now has two clear subsections titled “Current Challenges” and “Future Directions.”

R3C4: The manuscript is generally well written but would benefit from professional language refinement.
Our Response:  The manuscript underwent full professional English editing for clarity and flow.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have addressed all of my concerns, and the revised manuscript is suitable for publication, in my opinion.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have revised the manuscript in accordance with my input. I have no additional comments.