A Study to Assess the Safety, Reactogenicity, and Immunogenicity of SK Japanese Encephalitis Messenger Ribonucleic Acid (mRNA) Vaccines (GBP560) in Healthy Adults

NCT06680128 | Recruiting Phase 1 DMC

• 1 other identifier: GBP560_001
• Study Type: interventional
• Target: 402
• Locations: 2 countries
• Sites: 3

Brief Summary

This is a 2-Stage, Phase I/II Study to Assess the Safety, Reactogenicity, and Immunogenicity of SK Japanese Encephalitis mRNA Vaccines (GBP560) in Healthy Adults (Aged 18 Years and Older)

Conditions

Japanese Encephalitis Virus Disease

Outcome Measures

Primary Outcomes (11)

• Percentage of participants experiencing any immediate reactions

  For all cohort

  30 minutes (2 hours for the sentinel participants in stage 1) post each vaccination

• Percentage of participants reporting any solicited local Adverse Event (AE)

  For all cohort

  during the 7 days following each study vaccination

• Percentage of participants reporting any solicited systemic Adverse Event (AE)

  For all cohort

  during the 7 days following each study vaccination

• Percentage of participants experiencing any unsolicited Adverse Event (AE)

  For all cohort

  during the 28 days following each study vaccination

• Percentage of participants with any Medically Attended Adverse Event (MAAE)

  For all cohort

  until 6 months following the last study vaccination

• Percentage of participants experiencing any Adverse Event of Special Interest (AESI)s, AEs leading to study withdrawal and Serious Adverse Event (SAE)s during the entire study period

  For all cohort

  up to 12 months for stage 1 and up to 24 months for stage 2

• Seroprotection rate for both the respective and cross Japanese encephalitis virus (JEV) strains of each vaccine (SA14-14-2 and Beijing-1 strain) in live-virus neutralizing antibody titers at each time point

  For stage 2

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months following the 2nd study vaccination.

• Seroresponse rate for both the respective and cross JEV strains of each vaccine (SA14-14-2 and Beijing-1 strain) in live-virus neutralizing antibody titers, from baseline to each subsequent time point

  For Stage 2

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months following the 2nd study vaccination

• Geometric Mean Titer (GMT) of neutralizing antibody against both the respective and cross JEV strains of each vaccine (SA14-14-2 and Beijing-1 strain) measured by a live-virus neutralization assay (PRNT) at each time point

  For stage 2

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months following the 2nd study vaccination.

• Geometric mean fold rise of neutralizing antibody against both the respective and cross JEV strains of each vaccine (SA14-14-2,Beijing-1 strain), measured by a live-virus neutralization assay(PRNT), from each pre-vaccination to each subsequent timepoint

  For Stage 2

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months following the 2nd study vaccination

• Geometric mean fold reduction of neutralizing antibody against both respective and cross JEV strains of each vaccine (SA-14-14-2,Beijing-1 strain), measured by live-virus neutralization assay (PRNT) from persistence baseline to each subsequent timepoint

  For Stage 2

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, 12 months, and 24 months following the 2nd study vaccination.

Secondary Outcomes (6)

• Seroprotection rate for both the respective and cross JEV strains of each vaccine (SA14-14-2 and Beijing-1 strain) in live-virus neutralizing antibody titers at each time point

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination

• Seroresponse rate for both the respective and cross JEV strains of each vaccine (SA14-14-2 and Beijing-1 strain) in live-virus neutralizing antibody titers, from baseline to each subsequent time point.

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination

• GMT of neutralizing antibody against both the respective and cross JEV strains of each vaccine (SA14-14-2 and Beijing-1 strain) measured by a live-virus neutralization assay (PRNT) at each time point

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination

• Geometric mean fold rise of neutralizing antibody against both the respective and cross JEV strains of each vaccine (SA14-14-2,Beijing-1 strain), measured by live-virus neutralization assay(PRNT), from each pre-vaccination to each subsequent timepoint

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.

• Geometric mean fold reduction of neutralizing antibody against both respective and cross JEV strains of each vaccine (SA-14-14-2,Beijing-1 strain),measured by live-virus neutralization assay(PRNT) from persistence baseline to each subsequent timepoint

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.

Other Outcomes (4)

• Seroprotection rate for the heterologous JEV strains of each vaccine (including, but not limited to K95A07, Bennett, JKT 6468, Sangju-v1 strains) in live-virus neutralizing antibody titers at each timepoint.

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. and 24 months following the 2nd study vaccination (for stage2 only)

• GMT of neutralizing antibody against the heterologous JEV strains of each vaccine (including, but not limited to K95A07, Bennett, JKT 6468, Sangju-v1 strains) measured by a live-virus neutralization assay (PRNT) at each timepoint

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. and 24 months following the 2nd study vaccination (for stage2 only)

• Seroresponse rate for the heterologous JEV strains of each vaccine (including, but not limited to K95A07, Bennett, JKT 6468, Sangju-v1 strains) in live-virus neutralizing antibody titers, from baseline to each subsequent time point

  At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. and 24 months following the 2nd study vaccination (for stage2 only)

Study Arms (10)

Test group 1-1 (GBP560-A)

EXPERIMENTAL

Low dose level(3µg) for GBP560-A in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-A

Test group 1-2 (GBP560-B)

EXPERIMENTAL

Low dose level (3µg) for GBP560-B in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-B

Test group1-3 (GBP560-A)

EXPERIMENTAL

Mid dose level (15µg) for GBP560-A in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-A

Test group1-4 (GBP560-B)

EXPERIMENTAL

Mid dose level (15µg) for GBP560-B in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-B

Test group1-5 (GBP560-A)

EXPERIMENTAL

High dose level (50µg) for GBP560-A in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-A

Test group1-6 (GBP560-B)

EXPERIMENTAL

High dose level (50µg) for GBP560-B in stage 1. Participants will receive 2 doses of one of the test vaccines at 4-week intervals, respectively.

Biological: GBP560-B

Control group1 (IXIARO®)

ACTIVE COMPARATOR

Participants will receive 2 doses of one of the active comparators (IXIARO®, 6 Antigen Unit, corresponding to a potency of ≤ 460 ng ED) at 4-week intervals, respectively in Stage 1 and Stage 2.

Biological: IXIARO

Control group2 (IMOJEV®)

ACTIVE COMPARATOR

Participants will receive 1 dose of placebo saline and 1 dose of another active comparator (IMOJEV®, 4.0 - 5.8 log PFU) at 4-week intervals, respectively in Stage 1 and Stage 2.

Biological: IMOJEV; Biological: Normal Saline (Placebo)

Test group 2-1 (GBP560-A or B)

EXPERIMENTAL

Participants will receive 2 intramuscular injections of the test vaccines in stage 2. 1st will be on Visit 2 and 2nd will be on Visit 5, in line with the selected dose regimen in stage 1.

Biological: GBP560-A; Biological: GBP560-B

Test group 2-2 (GBP560-A or B)

EXPERIMENTAL

Participants will receive 2 intramuscular injections of the test vaccines in stage 2. 1st will be on Visit 2 and 2nd will be on Visit 5, in line with the selected dose regimen in stage 1.

Biological: GBP560-A; Biological: GBP560-B

Interventions

GBP560-A BIOLOGICAL

injection volume of 0.5mililiter (mL) with each dose on V2(1day) and V5 (29day) in stage1 and stage2. Low dose: 3μg Mid dose: 15μg High dose: 50μg

Test group 1-1 (GBP560-A); Test group 2-1 (GBP560-A or B); Test group 2-2 (GBP560-A or B); Test group1-3 (GBP560-A); Test group1-5 (GBP560-A)

GBP560-B BIOLOGICAL

injection volume of 0.5mL with each dose on V2(1day) and V5 (29day) in stage1 and stage2. Low dose: 3μg Mid dose: 15μg High dose: 50μg

Test group 1-2 (GBP560-B); Test group 2-1 (GBP560-A or B); Test group 2-2 (GBP560-A or B); Test group1-4 (GBP560-B); Test group1-6 (GBP560-B)

IXIARO BIOLOGICAL

injection volume of 0.5mL on V2(1day) and V5 (29day) in stage1 and stage2

Control group1 (IXIARO®)

IMOJEV BIOLOGICAL

injection volume of 0.5mL on V5 (29day) in stage1 and stage2

Control group2 (IMOJEV®)

Normal Saline (Placebo) BIOLOGICAL

injection volume of 0.5mL on V2 (1day) in stage1 and stage2 (This is for IMOJEV placebo)

Control group2 (IMOJEV®)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• \[Age\]
• For Stage 1, participant must be 18 to 55 years of age inclusive, at the time of signing the informed consent.
• For Stage 2, participant must be 18 years of age and older, at the time of signing the informed consent.
• \[Type of Participant and Disease Characteristics\]
• Participants who are healthy as determined by medical evaluation including medical history, vital signs, physical examination, clinical laboratory tests and medical judgement of the investigator.
• Participants who are willing and able to attend all scheduled visits and comply with all study procedures.
• Body mass index (BMI) within the range of 18.5-29.9 kg/m2 (inclusive) at screening
• \[Sex and Contraceptive/Barrier Requirements\]
• All participants must agree to be heterosexually inactive or agree to consistently use at least one acceptable method of contraception from at least 4 weeks prior to the 1st study vaccination to 12 weeks after the last study vaccination (Visit 9) (See Appendix 10.4 for detailed contraceptive methods).
• Female participants with a negative urine or serum pregnancy test at screening.
• \* Female participants who are surgically sterile (e.g., having undergone a full hysterectomy, bilateral salpingectomy, or bilateral oophorectomy) or postmenopausal with amenorrhea for at least 12 months are not subject to a pregnancy test.
• \[Informed Consent\]
• Participants who are capable of giving signed informed consent as described in Appendix 10.1.3 which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol before initiation of any trial-specific procedures.

You may not qualify if:

• \[Medical Conditions\]
• Any clinically significant respiratory symptoms (e.g., cough, sore throat), febrile illness (tympanic temperature \>38°C), or acute illness within 24 hours prior to the 1st study vaccination. Prospective participants with these conditions cannot be included until 24 hours after resolution.
• History of congenital, hereditary, acquired immunodeficiency, or autoimmune disease.
• Any positive test results for hepatitis B surface antigen, hepatitis C antibody, or human immunodeficiency virus (HIV) at screening.
• History of bleeding disorder or thrombocytopenia which is contraindicating intramuscular vaccination in the investigator's opinion.
• History of hypersensitivity and severe allergic reaction (e.g., anaphylaxis, Guillain-Barre syndrome) to any vaccines or components of the study intervention.
• History of myocarditis, pericarditis or myopericarditis (including the screening 12-lead ECG results from Stage 1 participants), as assessed by the investigator, indicating probable or possible myocarditis, pericarditis, or myopericarditis, or demonstrating clinically significant abnormalities that could affect participant safety or the interpretation of study findings.
• History of JEV infection/other flaviviruses infection (e.g., Dengue, West Nile, Zika, St. Louis Encephalitis, Yellow fever).
• History of malignancy within 1 year prior to the 1st study vaccination (with the exception of malignancy with minimal risk of recurrence at the discretion of the investigator).
• Significant unstable chronic or acute illness that, in the opinion of the investigator, might pose a health risk to the participant if enrolled, or could interfere with the protocol-specified activities, or interpretation of study results.
• \* The AESIs as outlined in Section 8.1.4 should be considered for evaluating the participant
• Any other conditions which, in the opinion of the investigator, might interfere with the evaluation of the study objectives (e.g., alcohol or drug abuse, neurologic or psychiatric conditions).
• Female participants who are pregnant or breastfeeding.
• (Only for Stage 1) Current smoker or a recent smoking history within 12 weeks prior to screening. Occasional smoker who smokes up to 10 cigarettes per month may be allowed to participate at the investigator's discretion.
• \[Prior/Concomitant medication\]

Sponsors & Collaborators

• SK Bioscience Co., Ltd.: lead

Study Sites (3)

Nucleus Network - Brisbane (Q Pharm)

Brisbane, Australia

RECRUITING

Nucleus Network - Melbourne

Melbourne, Australia

RECRUITING

New Zealand Clinical Research

Christchurch, Central City, 8011, New Zealand

NOT YET RECRUITING

MeSH Terms

Conditions

Encephalitis, Japanese

Interventions

Saline Solution

Condition Hierarchy (Ancestors)

Encephalitis, Arbovirus; Encephalitis, Viral; Central Nervous System Viral Diseases; Central Nervous System Infections; Infections; Infectious Encephalitis; Arbovirus Infections; Vector Borne Diseases; Mosquito-Borne Diseases; Virus Diseases; RNA Virus Infections; Flavivirus Infections; Flaviviridae Infections; Encephalitis; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neuroinflammatory Diseases

Intervention Hierarchy (Ancestors)

Crystalloid Solutions; Isotonic Solutions; Solutions; Pharmaceutical Preparations

Central Study Contacts

Sejun Oh

CONTACT

82-2-2008-2200; sejunoh@sk.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Stage 1: sequential, Stage 2 : parallel

Study Record Dates

• First Submitted: October 28, 2024
• First Posted: November 8, 2024
• Study Start: February 24, 2025
• Primary Completion (Estimated): June 26, 2026
• Study Completion (Estimated): March 19, 2028
• Last Updated: December 23, 2025

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

AU (2); NZ (1)