ClinicalTrials.gg
CompletedNCT04715997Updated Aug 20, 2025

Safety and Immunogenicity Study of GX-19N, a COVID-19 Preventive DNA Vaccine in Healthy Adults

A Phase 1/2 interventional study of GX-19N and Placebo in SARS-CoV-2, sponsored by Genexine, Inc.. Completed at 5 sites in South Korea. Open to participants aged 18 Years to 55 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-20.

Sponsored by Genexine, Inc. · Phase 1/2, Interventional, and Prevention

Phase
Phase 1/2
Study type
Interventional
Enrollment
185
Allocation
Randomized
Ages
18 Years to 55 Years
Sex
All
01

Study summary

The objective of our study is to evaluate safety, tolerability, and immunogenicity of COVID-19 preventive DNA vaccine in healthy volunteers.

Read the detailed description

This clinical study is phase 1/2a clinical trial to evaluate safety, tolerability, and immunogenicity of COVID-19 preventive vaccine by intramuscularly administration in healthy volunteers.

Phase 1 of this study is designed as single arm, open-labeled and a total of 20 subjects will be enrolled. Phase 2a of study is designed as randomized, double-blind, placebo controlled and a total of 150 subjects are planned to be enrolled.

02

Conditions studied

  • SARS-CoV-2
03

In context

Lead sponsor

Genexine, Inc. is the lead sponsor of 36 studies on the registry; 1 is open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 55 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Able and willing to comply with all study procedures and voluntarily signs form
  • Healthy adult male or female aged 19-55 years
  • Willing to provide specimens such as blood and urine during the study, including end of study visit.

Exclusion criteria

Exclusion Criteria:

  • Immunosuppresion including immunodeficiency disease or family history
  • Any history of malignant disease within the past 5 years
  • Scheduled to undergo any surgery or dental treatment during the study
  • Having received immunoglobulin or blood-derived drugs or being expected to be administered within 3 months prior to administration.
  • Having relied on antipsychotic drugs and narcotic analgesics within 6 months before administration
  • Positive of serology test at screening
  • Suspected of drug abuse or a history within 12 months prior to administration
  • Active alcohol use or history of alcohol abuse
  • Serious adverse reaction to a drug containing GX-19N or other ingredients of the same categories or to a vaccine or antibiotic, nonsteroidal anti-inflammatory disease control, etc. or an allergic history
  • History of to vaccination such as Guillain-Barre syndrome
  • Those who have or with a history of disease corresponding to other hepatobiliary, kidneys, nervous systems (middle or peripheral), respiratory machines (e.g. asthma, pneumonia, etc., endocrine systems (uncontrolled diabetes, hyperlipidemia, etc.) and cardiovascular (congestive heart failure, coronary artery disease, myocardial infarction, uncontrolled hypertension), blood tumors, urinary machines, mental, musculoskeletal systems, immune system (rheumatoid arthritis, systemic arthritis, mumps, immunodeficiency disease)
  • Having hemophilia at risk of causing serious bleeding when injected intramuscularly or receiving anticoagulants
  • Subjects who have been contact with COVID-19 infections in the past prior to administration, have been classified as COVID-19 confirmed patients, medical patients or patients with symptoms or have been identified with SARS and MERS infection history in the past
  • Acute fever, cough, difficulty breathing, chills, muscle aches, headache, sore throat, loss of smell, or loss of taste within 72 hours prior to administration
  • Other vaccination history within 28 days prior to the administration or being scheduled to be inoculated during the study
  • History of having taken or Immune modifying drug within 3 months prior to administration
  • Having participated and had clinical trial drug administration in another clinical trial or biological equivalence study within 6 months prior to the administration
  • Pregnant or breastfeeding female, however, those are allowed to participate in the study only if they stop breastfeeding before participation (fertile female† must be negative in serum pregnancy test at screening
  • Fertile female who do not agree to use effective methods (condoms, contraceptive diaphragm, intrauterine contraceptive devices) during the study
  • Any other medical or psychiatric finding which is considered inappropriate by investigator
Terms in these criteria, in plain language(5)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Immunosuppression

A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.

Read whether the line is about a condition or about medicines, and which medicines and doses it means.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

05

Study design

Phase
Phase 1 / Phase 2
Primary purpose
Prevention
Allocation
Randomized
Intervention model
Sequential assignment
Masking
Double (Participant, Investigator)
Enrollment
185 participants (actual)

Study arms

  • Experimental
    GX-19: Dose A

    Dose A of GX-19N will be intramusculary administered via EP on day 1 and day 29.

    Drug: GX-19N

  • Placebo comparator
    Placebo: Normal saline

    Placebo will be intramusculary administered via EP on day 1 and day 29.

    Drug: Placebo

Interventions

  • DrugGX-19N

    DNA vaccine expressing SARS-CoV-2 S-protein antigen including the Nucleocapsid protein (NP) antigen

    Also known as: Dose A

  • DrugPlacebo

    Normal saline

    Also known as: Normal saline

06

What researchers measure

Primary outcomes

  1. Incidence of Solicited Adverse Events

    solicited local and systemic AEs after vaccination

    Time frame: Through 1 year post vaccination

  2. Incidence of Unsolicited Adverse Events

    unsolicited AEs after vaccination

    Time frame: Through 1 year post vaccination

  3. Incidence of Serious Adverse Events

    percentage of subjects with SAEs

    Time frame: Through 1 year post vaccination

Secondary outcomes

  1. GMT of Antigen-specific Binding Antibody Titers

    Geometric mean titer (GMT) of antigen-specific binding antibody after vaccination

    Time frame: Through 1 year post vaccination

  2. GMFR of Antigen-specific Binding Antibody Titers

    Geometric mean fold rise (GMFR) of antigen-specific binding antibody after vaccination

    Time frame: Through 1 year post vaccination

  3. Percentage of Subjects Who Seroconverted After Vaccination

    Seroconversion defines when FRNT50 is detected more than four times from the baseline after vaccination

    Time frame: Through 1 year post vaccination

  4. GMT and GMFR of Neutralizing Antibody Level

    Geometric mean titer (GMT) and Geometric mean fold rise (GMFR) of neutralizing antibody after vaccination

    Time frame: Through 1 year post vaccination

  5. GMFR of Neutralizing Antibody Level

    Geometric mean fold rise (GMFR) of neutralizing antibody after vaccination

    Time frame: Through 1 year post vaccination

  6. GMSN and GMFR of Spot Forming Unit (SFU) detected by IFN-gamma ELISPOT assay

    Geometric mean spot numbers (GMSN) and Geometric mean fold rise (GMFR) of SFU after vaccination

    Time frame: Through 1 year post vaccination

Other outcomes

  1. Change From Baseline in Antigen-specific IFN-gamma Cellular Immune Response

    Antigen-specific IFN-γ T cell immune response assessed after vaccination

    Time frame: Through 1 year post vaccination

07

Study locations

5 sites
  • KyungHee University Medical Center
    Seoul, 02447, South Korea
  • Severance Hospital
    Seoul, 03722, South Korea
  • Hanyang University Hospital
    Seoul, 04763, South Korea
  • Gangnam Severance Hospital
    Seoul, 06273, South Korea
  • Ajou University Hospital
    Suwon, 16499, South Korea
08

References and documents

Publications

  • Ahn JY, Lee J, Suh YS, Song YG, Choi YJ, Lee KH, Seo SH, Song M, Oh JW, Kim M, Seo HY, Kwak JE, Youn JW, Woo JW, Shin EC, Sung YC, Park SH, Choi JY. Safety and immunogenicity of two recombinant DNA COVID-19 vaccines containing the coding regions of the spike or spike and nucleocapsid proteins: an interim analysis of two open-label, non-randomised, phase 1 trials in healthy adults. Lancet Microbe. 2022 Mar;3(3):e173-e183. doi: 10.1016/S2666-5247(21)00358-X. Epub 2022 Feb 8. PubMed 35156068 ↗

Individual participant data

Plan to share: No

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from Dec 2020 to primary completion in Apr 2022, 15 months.

How these figures are worked out, and which studies are left out of them.

Registered
Jan 18, 2021
First posted
Jan 20, 2021
StartActual
Dec 30, 2020
Primary completionActual
Apr 19, 2022
CompletionActual
Apr 19, 2022
Last update
Aug 20, 2025
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Aug 20, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT04715997
Lead sponsor
Genexine, Inc.
Responsible party
Sponsor
First posted
Jan 20, 2021
Start date
Dec 30, 2020
Primary completion
Apr 19, 2022
Completion
Apr 19, 2022
Last update
Aug 20, 2025

Study contacts

JungWon Woo, Ph.D.
study director · Genexine, Inc.
Jun Yong Choi, MD
principal investigator · Severance Hospital

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Nov 2022. You cannot join it, but the record below documents what was studied.

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Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

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