Healthy ParticipantsPhase 1/2NCT07280858
A Phase I/II, Dose-finding Study to Assess the Safety, Reactogenicity, and Immunogenicity of a Broadly Protective Sarbecovirus Vaccine (GBP511) in Healthy Adults.
A Phase 1/2 study testing Test Drug 1-1 (GBP511 low dose), Test Drug 1-2 (GBP511 mid dose) and Test Drug 1-3 (GBP511 high dose) in people with Healthy Participants and Sarbecovirus, run by SK Bioscience Co., Ltd. at 3 sites in Australia.
Trial summary
The purpose of this research study is to evaluate the safety of and the body's immune response to single and multiple vaccinations in healthy men and women. We want to find out what effects GBP511 has on you and your health. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Healthy Participants, Sarbecovirus
- What is being tested?
- Test Drug 1-1 (GBP511 low dose), Test Drug 1-2 (GBP511 mid dose) and Test Drug 1-3 (GBP511 high dose)
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 368 participants
- Where
- 3 sitesAustralia
- Study dates
- 28 Jan 2026to 12 Sep 2028
- Phase
- Phase 1/2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 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.
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- Body mass index (BMI) within the range of 18.5-32.0 kg/m2 (revised) at screening
- Participants who received a primary series and at least one booster dose of an authorized COVID-19 vaccine at least 24 weeks prior to the 1st study vaccination.
- Sex and Contraceptive/Barrier Requirements
- All participants must agree to be abstinent from heterosexual intercourse 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 (See Appendix 10.4 for detailed contraceptive methods).
- Women of childbearing potential (WOCBP) 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 at least 12 months amenorrhoea not considered to be caused by any other medical condition, 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.
Who cannot join
- 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.
- Concurrent or a history of virologically or serologically confirmed SARS-CoV-2 infection, or suspected SARS-CoV-2 infection as determined by the investigator, within 24 weeks prior to the 1st study vaccination.
- History of virologically or serologically confirmed SARS-CoV-1, or MERS disease.
- 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.
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- 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) to any vaccines or components of the study intervention.
- History of neurologic diseases (e.g., Guillain-Barre syndrome, myelitis, or encephalomyelitis).
- History of myocarditis, pericarditis or myopericarditis, 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 malignancy within 1 year prior to first study vaccination, except for cutaneous non-melanoma malignancy, melanoma-in-situ, or cervical carcinoma in situ that have been fully treated with completed follow-up prior to screening. Malignancy considered to carry minimal risk of recurrence may also be permitted 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.
- 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.
- Prior/Concomitant therapy
- Receipt of any COVID-19 vaccination including investigational vaccines within 24 weeks prior to the 1st study vaccination or planned receipt at any time during the study period.
- Receipt of any vaccinations intended to prevent SARS-CoV-1 or MERS, including investigational vaccines.
- Receipt of any vaccine within 4 weeks prior to the 1st study vaccination or planned receipt of any vaccine through 4 weeks after the last study vaccination, except for influenza vaccination, which may be received at least 2 weeks prior to the 1st study vaccination.
- Receipt of any immunoglobulins and/or blood-derived products within 12 weeks prior to the 1st study vaccination or planned receipt at any time during the study period.
- Receipt of immunosuppressive therapy, such as any use of anti-cancer chemotherapy or radiation therapy; or chronic use of systemic corticosteroid (≥10 mg prednisone/day or equivalent more than 14 consecutive days) within 12 weeks prior to the 1st study vaccination and throughout the entire study period. The use of intranasal, inhaled, topical, or intra-articular corticosteroid is permitted.
- Prior/Concurrent Clinical Study Experience
- Participation in another clinical study and receipt of study intervention within 4 weeks prior to the 1st study vaccination, or concurrent, planned participation in another clinical study with study intervention during this study period.
- Other Exclusions
- Investigators, or study staff who are directly involved in the conduct of this study or supervised by the investigator, and their respective family members.
- Donation of ≥450mL of blood product within 4 weeks prior to screening, or planned donation of blood product from enrollment through 12 weeks after the last study vaccination.
Trial locations and contacts
3 sites in 1 country.
Australia3 sites
Linear
Joondalup, Western Australia, 6027
Linear
Nedlands, Western Australia, 6009
Momentum Clinical Research Darlinghurst
Sydney, Kent Street, 309, Level 9
About this study
Official title: A 2-Stage, Phase I/II, Active-controlled, Randomized, Observer-blinded, Dose-finding Study to Assess the Safety, Reactogenicity, and Immunogenicity of a Broadly Protective Sarbecovirus Vaccine (GBP511) in Healthy Adults (Aged 18 Years and Older)
The purpose of this research study is to evaluate the safety of and the body's immune response to single and multiple vaccinations in healthy men and women. We want to find out what effects GBP511 has on you and your health. We are doing this study to find out:
If the study drug has any side effects when given as single and multiple vaccinations.
Read more
If reactogenicity, an indication that the immune systems is working and is preparing to protect the body against future infection, occurs. This is a normal physical inflammatory response that occurs after vaccination, manifesting as localised reactions that may include pain or redness at the injection site, or systemic symptoms such as headache or fever.
If immunogenicity which is when GBP511 causes your body to make antibodies against the non-harmful viral proteins contained within GBP511, called 'neutralising antibodies (Nab),' occurs. And if GBP511 will cause the specialised cells of the body's immune system to mount a defence against the non-harmful viral proteins contained within GBP511, called 'cell-mediated immunity (CMI)'.
In this study, GBP511 will be administered with and without adjuvant, CAS-1. An adjuvant is an ingredient used in some vaccines that help produce a stronger immune response in the people receiving the vaccine and thus helps the vaccine work better.
This study will recruit approximately 368 participants in total and will be conducted in two stages:
Stage 1 will look at two vaccinations with GBP511 when given with and without the CAS-1 adjuvant; and Stage 2 will look at either one or two vaccinations with two candidate GBP511 vaccines chosen from Stage 1 of the study.
Participants will be required to attend Linear's clinical unit on two separate occasions to receive their two vaccinations. On the first day of dosing (Visit 2/Day 1) and second day of dosing (Visit 5/Day 29), we will be testing a single dose of the study drug in up to 168 healthy volunteers who will be divided into 3 groups. Group 1, Groups 2 and 3 will have 56 people each. These 3 groups will be divided into treatment subgroups, with a total of 6 test subgroups and 3 control subgroups. In all groups, neither you or the study doctor will know what subgroup you are part of, and therefore what treatment (GBP511 or Comirnaty+ placebo) you will receive.
- Conditions
- Healthy Participants, Sarbecovirus
- Being tested
- Test Drug 1-1 (GBP511 low dose), Test Drug 1-2 (GBP511 mid dose), Test Drug 1-3 (GBP511 high dose), Test Drug 2-1 (GBP511 low dose + CAS-1), Test Drug 2-2 (GBP511 mid dose + CAS-1)
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Test Drug 1-1 (GBP511 low dose)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
Test Drug 1-2 (GBP511 mid dose)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
Test Drug 1-3 (GBP511 high dose)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
Test Drug 2-1 (GBP511 low dose + CAS-1)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
Test Drug 2-2 (GBP511 mid dose + CAS-1)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
Test Drug 2-3 (GBP511 high dose + CAS-1)Biological
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2.
GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
Comparator (Comirnaty)Biological
injection volume of 0.3mililiter (mL) with single-dose at visit 2.
30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA per 0.3mL
Placebo (Normal Saline)Biological
injection volume of 0.5mililiter (mL) with single-dose at visit 5.
Test Drug 13 (Stage 2, GBP511-A or B)Biological
Participants will receive 2 intramuscular injections of the test vaccine in stage 2.
Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
Test Drug 14 (Stage 2, GBP511-A or B)Biological
Participants will receive 2 intramuscular injections of the test vaccine in stage 2.
Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
| Study group | Role | What they receive |
|---|---|---|
| Test Group 1-1 (GBP511) | Experimental | Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain); a total injection volume of 0.5mL
IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 1-1 (GBP511 low dose) |
| Test Group 1-2 (GBP511+CAS-1) | Experimental | Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL
IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 2-1 (GBP511 low dose + CAS-1) |
| Control Group | Active comparator | Comirnaty (2025-26 or subsequent seasonal formulation, 30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA); a total injection volume of 0.3mL Normal saline; a total injection volume of 0.5mL
Comirnaty: IM injection on Day 1 (Visit 2) Normal Saline: IM injection on Day 29 (Visit 5) Receives: Biological: Comparator (Comirnaty); Biological: Placebo (Normal Saline) |
| Test group 1-3 (GBP511) | Experimental | Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 1-2 (GBP511 mid dose) |
| Test group 1-4 (GBP511+CAS-1) | Experimental | Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 2-2 (GBP511 mid dose + CAS-1) |
| Test Group 1-5 (GBP511) | Experimental | High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 1-3 (GBP511 high dose) |
| Test Group 1-6 (GBP511+CAS-1) | Experimental | High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) Receives: Biological: Test Drug 2-3 (GBP511 high dose + CAS-1) |
| Test Group 2-1 (Stage 2) | Experimental | Participants will receive 2 intramuscular injections of the test vaccine in stage 2.
Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. Receives: Biological: Test Drug 13 (Stage 2, GBP511-A or B) |
| Test Group 2-2 (Stage 2) | Experimental | Participants will receive 2 intramuscular injections of the test vaccine in stage 2.
Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. Receives: Biological: Test Drug 14 (Stage 2, GBP511-A or B) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage of participants experiencing any immediate reactions
For stage 1
Measured: 30 minutes (2 hours for sentinel participants) following each study vaccination
Percentage of participants reporting any solicited local AEs
For stage 1
Measured: during the 7 days following each study vaccination
Percentage of participants reporting any solicited systemic AEs
For stage 1
Measured: during the 7 days following each study vaccination
Percentage of participants experiencing any unsolicited AEs
For stage 1
Measured: during the 28 days following each study vaccination
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
For stage 1
Measured: 1st Vaccination date, 1 week, 2 weeks, 4 weeks following the 1st study vaccination, and 2nd vaccination date, 1 week, 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
GMT of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay at each time point.
For stage 2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
GMR of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
For stage 2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point
For stage 2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Secondary outcomes (15)
Geometric mean titer (GMT) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
For stage 1
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Geometric mean ratio (GMR) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
For stage 1
Measured: From pre-vaccination to baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer
For stage 1
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
GMT of RBD-binding IgG antibody against each matched strain measured by ECL assay at each time point.
For stage 1,2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2)
GMR of RBD-binding IgG antibody against each matched strain measured by ECL assay, from each pre-vaccination to subsequent time point.
For stage 1,2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises in RBD-binding IgG titer against each matched strain, measured by ECL assay, from baseline to each subsequent time point.
For stage 1,2
Measured: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
GMT of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay at each time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Measured: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
GMR of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Measured: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises against each mismatched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points:
baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Measured: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Cell-mediated response for both Th1 and Th2 cytokines (including but not limited to IFN-γ, IL-2, and IL-4 produced by T lymphocytes) measured by FluoroSpot
For Stage 1, The following endpoint will be evaluated exclusively in sentinel participants at the following time points:
baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the 2nd study vaccination.
For Stage 2, The following endpoints will be evaluated exclusively in a subset of approximately the first 20% of participants at the following time points:
baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the last study vaccination.
Measured: baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants experiencing any immediate reactions
For stage 2
Measured: within 30 minutes following each study vaccination
Percentage of participants reporting any solicited local AEs
For stage 2
Measured: during the 7 days following each study vaccination
Percentage of participants reporting any solicited systemic AEs
For stage 2
Measured: during the 7 days following each study vaccination
Percentage of participants experiencing any unsolicited AEs
For stage 2
Measured: during the 28 days following each study vaccination
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
For stage 2
Measured: during the entire study period
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Dec 2025
- Study start28 Jan 2026
- Primary completion9 Dec 2026 (estimated)
- Study completion12 Sep 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy ParticipantsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1/2
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Model description
- Stage 1: sequential, Stage 2 : parallel
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 368 participants (estimated)
Sponsor and investigators
- Lead sponsor
- SK Bioscience Co., Ltd.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07280858
- Sponsor's protocol ID
- GBP511_001
- Status last verified
- Sep 2026
- First submitted
- 26 Nov 2025
- Last updated
- 9 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A 2-Stage, Phase I/II, Active-controlled, Randomized, Observer-blinded, Dose-finding Study to Assess the Safety, Reactogenicity, and Immunogenicity of a Broadly Protective Sarbecovirus Vaccine (GBP511) in Healthy Adults (Aged 18 Years and Older)
- ClinicalTrials.gov ID
- NCT07280858
- Acronym / sponsor ID
- GBP511_001
- Conditions
- Healthy Participants, Sarbecovirus
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 368 participants (estimated)
- Lead sponsor
- SK Bioscience Co., Ltd.Industry (pharma, biotech, devices)
- Study start
- 28 Jan 2026 (actual)
- Primary completion
- 9 Dec 2026 (estimated)
- Study completion
- 12 Sep 2028 (estimated)
- First posted
- 12 Dec 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this research study is to evaluate the safety of and the body's immune response to single and multiple vaccinations in healthy men and women. We want to find out what effects GBP511 has on you and your health. We are doing this study to find out:
If the study drug has any side effects when given as single and multiple vaccinations.
If reactogenicity, an indication that the immune systems is working and is preparing to protect the body against future infection, occurs. This is a normal physical inflammatory response that occurs after vaccination, manifesting as localised reactions that may include pain or redness at the injection site, or systemic symptoms such as headache or fever.
If immunogenicity which is when GBP511 causes your body to make antibodies against the non-harmful viral proteins contained within GBP511, called 'neutralising antibodies (Nab),' occurs. And if GBP511 will cause the specialised cells of the body's immune system to mount a defence against the non-harmful viral proteins contained within GBP511, called 'cell-mediated immunity (CMI)'.
In this study, GBP511 will be administered with and without adjuvant, CAS-1. An adjuvant is an ingredient used in some vaccines that help produce a stronger immune response in the people receiving the vaccine and thus helps the vaccine work better.
This study will recruit approximately 368 participants in total and will be conducted in two stages:
Stage 1 will look at two vaccinations with GBP511 when given with and without the CAS-1 adjuvant; and Stage 2 will look at either one or two vaccinations with two candidate GBP511 vaccines chosen from Stage 1 of the study.
Participants will be required to attend Linear's clinical unit on two separate occasions to receive their two vaccinations. On the first day of dosing (Visit 2/Day 1) and second day of dosing (Visit 5/Day 29), we will be testing a single dose of the study drug in up to 168 healthy volunteers who will be divided into 3 groups. Group 1, Groups 2 and 3 will have 56 people each. These 3 groups will be divided into treatment subgroups, with a total of 6 test subgroups and 3 control subgroups. In all groups, neither you or the study doctor will know what subgroup you are part of, and therefore what treatment (GBP511 or Comirnaty+ placebo) you will receive.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 9
- Model description
- Stage 1: sequential, Stage 2 : parallel
| Arm | Type | Receives |
|---|---|---|
| Test Group 1-1 (GBP511) | Experimental | Biological: Test Drug 1-1 (GBP511 low dose)Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Test Group 1-2 (GBP511+CAS-1) | Experimental | Biological: Test Drug 2-1 (GBP511 low dose + CAS-1)Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Control Group | Active comparator | Biological: Comparator (Comirnaty), Biological: Placebo (Normal Saline)Comirnaty (2025-26 or subsequent seasonal formulation, 30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA); a total injection volume of 0.3mL Normal saline; a total injection volume of 0.5mL Comirnaty: IM injection on Day 1 (Visit 2) Normal Saline: IM injection on Day 29 (Visit 5) |
| Test group 1-3 (GBP511) | Experimental | Biological: Test Drug 1-2 (GBP511 mid dose)Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Test group 1-4 (GBP511+CAS-1) | Experimental | Biological: Test Drug 2-2 (GBP511 mid dose + CAS-1)Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Test Group 1-5 (GBP511) | Experimental | Biological: Test Drug 1-3 (GBP511 high dose)High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Test Group 1-6 (GBP511+CAS-1) | Experimental | Biological: Test Drug 2-3 (GBP511 high dose + CAS-1)High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5) |
| Test Group 2-1 (Stage 2) | Experimental | Biological: Test Drug 13 (Stage 2, GBP511-A or B)Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. |
| Test Group 2-2 (Stage 2) | Experimental | Biological: Test Drug 14 (Stage 2, GBP511-A or B)Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (14 listed)
- 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.
Key exclusion criteria (25 listed)
- 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.
- Concurrent or a history of virologically or serologically confirmed SARS-CoV-2 infection, or suspected SARS-CoV-2 infection as determined by the investigator, within 24 weeks prior to the 1st study vaccination.
- History of virologically or serologically confirmed SARS-CoV-1, or MERS disease.
- History of congenital, hereditary, acquired immunodeficiency, or autoimmune disease.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Test Drug 1-1 (GBP511 low dose)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain | Biological | Test Group 1-1 (GBP511) |
| Test Drug 1-2 (GBP511 mid dose)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain | Biological | Test group 1-3 (GBP511) |
| Test Drug 1-3 (GBP511 high dose)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain | Biological | Test Group 1-5 (GBP511) |
| Test Drug 2-1 (GBP511 low dose + CAS-1)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose | Biological | Test Group 1-2 (GBP511+CAS-1) |
| Test Drug 2-2 (GBP511 mid dose + CAS-1)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose | Biological | Test group 1-4 (GBP511+CAS-1) |
| Test Drug 2-3 (GBP511 high dose + CAS-1)injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose | Biological | Test Group 1-6 (GBP511+CAS-1) |
| Comparator (Comirnaty)injection volume of 0.3mililiter (mL) with single-dose at visit 2. 30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA per 0.3mL | Biological | Control Group |
| Placebo (Normal Saline)injection volume of 0.5mililiter (mL) with single-dose at visit 5. | Biological | Control Group |
| Test Drug 13 (Stage 2, GBP511-A or B)Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. | Biological | Test Group 2-1 (Stage 2) |
| Test Drug 14 (Stage 2, GBP511-A or B)Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1. | Biological | Test Group 2-2 (Stage 2) |
Primary outcome
Percentage of participants experiencing any immediate reactions
Time frame: 30 minutes (2 hours for sentinel participants) following each study vaccination
For stage 1
Percentage of participants reporting any solicited local AEs
Time frame: during the 7 days following each study vaccination
For stage 1
Percentage of participants reporting any solicited systemic AEs
Time frame: during the 7 days following each study vaccination
For stage 1
Percentage of participants experiencing any unsolicited AEs
Time frame: during the 28 days following each study vaccination
For stage 1
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
Time frame: 1st Vaccination date, 1 week, 2 weeks, 4 weeks following the 1st study vaccination, and 2nd vaccination date, 1 week, 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
For stage 1
GMT of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay at each time point.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
For stage 2
GMR of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
For stage 2
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
For stage 2
15 secondary outcomes
Geometric mean titer (GMT) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Geometric mean ratio (GMR) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
Time frame: From pre-vaccination to baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
GMT of RBD-binding IgG antibody against each matched strain measured by ECL assay at each time point.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2)
GMR of RBD-binding IgG antibody against each matched strain measured by ECL assay, from each pre-vaccination to subsequent time point.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises in RBD-binding IgG titer against each matched strain, measured by ECL assay, from baseline to each subsequent time point.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
GMT of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay at each time point.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
GMR of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises against each mismatched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Cell-mediated response for both Th1 and Th2 cytokines (including but not limited to IFN-γ, IL-2, and IL-4 produced by T lymphocytes) measured by FluoroSpot
Time frame: baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants experiencing any immediate reactions
Time frame: within 30 minutes following each study vaccination
Percentage of participants reporting any solicited local AEs
Time frame: during the 7 days following each study vaccination
Percentage of participants reporting any solicited systemic AEs
Time frame: during the 7 days following each study vaccination
Percentage of participants experiencing any unsolicited AEs
Time frame: during the 28 days following each study vaccination
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
Time frame: during the entire study period
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Sep 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Test Drug 1-1 (GBP511 low dose), Test Drug 1-2 (GBP511 mid dose) and Test Drug 1-3 (GBP511 high dose) in people with Healthy Participants and Sarbecovirus, run by SK Bioscience Co., Ltd. at 3 sites in Australia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 14 inclusion and 25 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 9 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Australia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Percentage of participants experiencing any immediate reactions (time frame: 30 minutes (2 hours for sentinel participants) following each study vaccination). The study lists 8 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Sep 2026.