SARS-CoV-2 DNA Vaccine INO-4800 Induces Durable Immune Responses Capable of Being Boosted in a Phase 1 Open-Label Trial

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Abstract

Background: Additional SARS-CoV-2 vaccines that are safe and effective as primary vaccines and boosters remain urgently needed to combat the COVID-19 pandemic. We describe the safety and durability of the immune responses following two primary doses and a homologous booster dose of an investigational DNA vaccine (INO-4800) targeting the full-length spike antigen. Methods: Three dosage strengths of INO-4800 (0.5 mg, 1.0 mg, and 2.0 mg) were evaluated in 120 age-stratified healthy adults. Intradermal injection of INO-4800 followed by electroporation at 0 and 4 weeks preceded an optional booster 6-10.5 months after the second dose. Results: INO-4800 appeared well tolerated, with no treatment-related serious adverse events. Most adverse events were mild and did not increase in frequency with age and subsequent dosing. A durable antibody response was observed 6 months following the second dose; a homologous booster dose significantly increased immune responses. Cytokine producing T cells and activated CD8+ T cells with lytic potential were significantly increased in the 2.0 mg dose group. Conclusion: INO-4800 was well tolerated in a 2-dose primary series and as a homologous booster in all adults, including the elderly. These results support further development of INO-4800 for use as a primary vaccine and as a booster. Keywords: SARS-CoV-2; Clinical trial; DNA Vaccine; INO-4800; COVID-19; Safety; Immunogenicity; Booster

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  1. SciScore for 10.1101/2021.10.06.21264584: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: The trial was approved by the institutional review board of each clinical site and all participants provided written informed consent prior to enrollment.
    Consent: The trial was approved by the institutional review board of each clinical site and all participants provided written informed consent prior to enrollment.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power AnalysisStatistical Analysis: No formal power analysis was applicable to this trial.

    Table 2: Resources

    Antibodies
    SentencesResources
    Primary immunological endpoints included the measurement of SARS-CoV-2 Spike glycoprotein antigen-specific binding antibodies as well as the measurement of antigen-specific cellular immune responses by IFN-γ, ELISPOT and flow cytometry assays.
    antigen-specific binding
    suggested: (GeneTex Cat# GTX72515, RRID:AB_383651)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    We acknowledge limitations to this trial that include the relatively small study population and the limited number of PBMCs available for testing across more than one assay. This trial was not powered to formally compare immune responses between dose groups or age stratifications. The immune responses observed in the current trial and in our larger Phase 2 trial [4] support advancing the 2.0 mg dose of INO-4800 to a Phase 3 efficacy evaluation. This dose has elicited the highest binding and neutralizing antibody titers, the highest T cell cytokine production from both CD4+ and CD8+ T cells and the highest expression of markers associated with attenuation of severe COVID-19 on CD8+ T cells (which could be critically important for vaccine efficacy in preventing hospitalization and death in the context of the circulating Delta variant). Our demonstration in this trial that the immune responses, both antibody as well as T cell responses, elicited by a 2-dose primary series of INO-4800 could be further boosted with a third dose without safety or tolerability concerns positions INO-4800 as an important candidate for continued development as a stand-alone SARS-CoV-2 vaccine, as well as for continued examination in combination approaches. The potential ability to administer INO-4800 multiple times, with high tolerability, along with its ease of scalability and thermostability, contribute to its potential value in combatting the COVID-19 pandemic and addressing the persistence of SARS...

    Results from TrialIdentifier: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    NCT04336410Active, not recruitingSafety, Tolerability and Immunogenicity of INO-4800 for COVI…


    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a protocol registration statement.

    Results from scite Reference Check: We found no unreliable references.


    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.