A Study of Safety and Immune Response to Different Doses of a Cytomegalovirus Vaccine in Healthy Adults

A Phase 1/2, First-Time-in Human (FTiH), Randomized, Observer-blind, Placebo-controlled, Dose Escalation Study to Assess Safety, Reactogenicity and Immunogenicity of a Candidate Cytomegalovirus (CMV) Vaccine Comprising Recombinant Protein and Adjuvant When Administered Intramuscularly in Healthy Adults

The purpose of this study is to assess the safety, reactogenicity and immune response of the candidate CMV recombinant protein subunit (CMVsu) vaccine consisting of a combination of glycoproteins B (gB) and pentamer antigens adjuvanted, regardless of baseline CMV sero-status. This FTiH study is conducted in healthy adults 18 to 50 years of age, in which the 4 dose levels of the vaccine are administered in a step-wise dose escalation manner, based upon safety adjudication.

Study Overview

• Status: Completed
• Conditions: Cytomegalovirus Infections
• Intervention / Treatment: Biological: Pentamer (low)/gB(low)/Adjuvant vaccine; Biological: Pentamer (med)/gB(low)/Adjuvant vaccine; Biological: Pentamer (med)/gB(med)/Adjuvant vaccine; Biological: Pentamer (high)/gB(med)/Adjuvant vaccine; Combination product: Placebo (saline solution)

• Study Type: Interventional
• Enrollment (Actual): 333
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• United States
  • California
    • Anaheim, California, United States, 92806
      • GSK Investigational Site
    • Long Beach, California, United States, 90806
      • GSK Investigational Site
    • Los Angeles, California, United States, 90017
      • GSK Investigational Site
  • Florida
    • Hallandale, Florida, United States, 33009
      • GSK Investigational Site
    • Miami, Florida, United States, 33143
      • GSK Investigational Site
  • Kentucky
    • Lexington, Kentucky, United States, 40536-0084
      • GSK Investigational Site
  • Michigan
    • Dearborn, Michigan, United States, 48127
      • GSK Investigational Site
  • Missouri
    • Springfield, Missouri, United States, 65802
      • GSK Investigational Site
  • Nebraska
    • Lincoln, Nebraska, United States, 68510
      • GSK Investigational Site
    • Omaha, Nebraska, United States, 68134
      • GSK Investigational Site
  • Nevada
    • Las Vegas, Nevada, United States, 89109
      • GSK Investigational Site
  • New Jersey
    • Newark, New Jersey, United States, 07103
      • GSK Investigational Site
    • Secaucus, New Jersey, United States, 07094
      • GSK Investigational Site
  • New York
    • New York, New York, United States, 10065
      • GSK Investigational Site
  • Texas
    • Austin, Texas, United States, 78744-1645
      • GSK Investigational Site
    • Cedar Park, Texas, United States, 78613
      • GSK Investigational Site
    • Galveston, Texas, United States, 77573
      • GSK Investigational Site
  • Washington
    • Puyallup, Washington, United States, 98371
      • GSK Investigational Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
• Written informed consent obtained from the participant prior to performance of any study specific procedure.
• A healthy adult (woman or man), 18 to 50 years of age at the time of the first study intervention administration.
• Healthy participants as established by medical history and clinical examination before entering the study.
• Participants who are women of non-childbearing potential may be enrolled in the study.

• Participants who are women of child-bearing potential may be enrolled in the study, if the participant:

  • has practiced adequate contraception for 30 days prior to study intervention administration, and
  • has a negative pregnancy test on the day of study intervention administration and
  • has agreed to continue adequate contraception during the entire treatment period and for 3 months after completion of the study intervention administration series.
• Participants who agree to take appropriate infection control measures to prevent becoming infected with SARS-CoV2 during the study.
• Participants who initially fail screening due to COVID-19 infection may be re-screened and included in the study, within the screening window period.
• Participants with signs/symptoms suggestive of active COVID-19 (i.e., fever, cough, etc.) should be isolated for the time period recommended by CDC since the signs/symptoms started, and symptoms have resolved.
• Participants with known COVID-19 positive contacts should be quarantined for the time period since exposure recommended by CDC since the exposure and the participant remains symptom free or COVID test negative.
• Participants who are diagnosed with COVID-19 may receive their subsequent CMVsu vaccination dose provided they have no fever, and their condition is considered stable by the investigator (e.g., there may be mild lingering cough, but no shortness of breath or difficulty breathing) within the original schedule.
• Participants who initially fail screening due to other active infections may be re screened within the screening window period and included in the study, if they no longer have signs or symptoms of active infection in the judgment of the site investigator.
• If a participant has equivocal results on CMV serodiagnostic screening test, they are permitted to be re-screened if within the 60-day screening window. Flexibility in safety blood evaluations will be permitted within the Schedule of activities time intervals.

Exclusion Criteria:

Medical conditions

• Known documented medical history of or viral hepatitis B or C infection.
• History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention(s).
• Any confirmed or suspected immunosuppressive or immunodeficient condition.
• Family history of congenital or hereditary immunodeficiency.
• History of or current autoimmune disease.
• Lymphoproliferative disorder or malignancy within previous 5 years (excluding effectively treated non-melanotic skin cancer).
• Hypersensitivity to latex.
• Major congenital defects
• Acute or chronic clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality.
• Recurrent history or uncontrolled neurological disorders.
• Any hematological or biochemical abnormality.
• Any acute or chronic, clinically significant disease or pulmonary, cardiovascular, hepatic, or renal functional abnormalities.
• Any medical condition that in the judgment of the investigator would make intramuscular injection unsafe.
• Participants with symptoms suggestive of active COVID-19 infection are excluded.
• Participants with known COVID-19 positive contacts within the past 14 days should be excluded for at least 14 days since the exposure and the participant remains symptom free.
• Any other clinical condition that, might pose additional risk to the participant due to participation in the study.

Prior/Concomitant therapy

• Any history of or planned receipt of a CMV vaccine other than the study intervention at any time point.
• Use of other investigational/non-registered product during the period beginning 30 days before the first dose, or their planned use during the study period.
• Planned administration of any vaccine not foreseen by the study protocol 30 days before and 30 days after each study vaccination administration any licensed influenza vaccine administered > 15 days before/ after vaccination.

• In case of extraordinary emergency mass vaccination for an unforeseen public health threat the time period can be reduced if necessary, for that mass vaccination vaccine, which may be under emergency use authorization.

  • COVID-19 vaccines should be given at least 30 days before or after administration of a GSK study vaccine. This interval can be reduced to > 14 days, if emergency vaccination is recommended by public health authorities.
  • Candidate COVID-19 vaccines are not allowed.
• Chronic administration of immunosuppressants or other immune-modifying drugs within 3 months prior to the vaccine dose. Inhaled and topical steroids are allowed.
• Administration of long-acting immune-modifying drugs at any time during the study period.
• Administration of immunoglobulins and/or any blood products during the period starting 3 months before the administration of the first dose of study intervention(s) or planned administration during the study period.

Prior/Concurrent clinical study experience

• Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention

Other exclusions

• Pregnant or lactating women. If a woman becomes pregnant/lactating during the study, she will be excluded from subsequent vaccine doses but will be followed for safety.
• Women planning to become pregnant or planning to discontinue contraceptive precautions before 3 months after last study vaccination.
• Participants with known high exposure risk for CMV transmission, to enable distinction of true vaccine effect from natural infection during the study.
• Planned move to a location that will prohibit participating in the trial until study end.
• Participants with current chronic alcohol consumption and/or drug abuse as defined by Diagnostic and Statistical Manual of Mental Disorders 5th edition.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pentamer (low dose)/glycoprotein B (gB) (low dose)/Adjuvant group; Participants received a dose of the candidate cytomegalovirus (CMV) vaccine consisting of a combination of low dose of pentamer and low dose of gB antigens, adjuvanted, at Day 1, Day 61 and Day 181 intramuscularly.	Biological: Pentamer (low)/gB(low)/Adjuvant vaccine; Three doses of the candidate CMVsu vaccine consisting of a combination of low dose pentamer and low dose gB antigens, adjuvanted are administered intramuscularly in the deltoid region of the non-dominant arm in a 0, 2, 6-month schedule.
Experimental: Pentamer (medium dose)/gB (low dose)/Adjuvant group; Participants received a dose of the candidate CMV vaccine consisting of a combination of medium dose of pentamer and low dose of gB antigens, adjuvanted, at Day 1, Day 61 and Day 181 intramuscularly.	Biological: Pentamer (med)/gB(low)/Adjuvant vaccine; Three doses of the candidate CMVsu vaccine consisting of a combination of medium dose pentamer and low dose gB antigens, adjuvanted are administered intramuscularly in the deltoid region of the non-dominant arm in a 0, 2, 6-month schedule.
Experimental: Pentamer (medium dose)/gB (medium dose)/Adjuvant group; Participants received a dose of the candidate CMV vaccine consisting of a combination of medium dose of pentamer and medium dose of gB antigens, adjuvanted, at Day 1, Day 61 and Day 181 intramuscularly.	Biological: Pentamer (med)/gB(med)/Adjuvant vaccine; Three doses of the candidate CMVsu vaccine consisting of a combination of medium dose pentamer and medium dose gB antigens, adjuvanted are administered intramuscularly in the deltoid region of the non-dominant arm in a 0, 2, 6-month schedule.
Experimental: Pentamer (high dose)/gB (medium dose)/Adjuvant group; Participants received a dose of the candidate CMV vaccine consisting of a combination of high dose of pentamer and medium dose of gB antigens, adjuvanted, at Day 1, Day 61 and Day 181 intramuscularly.	Biological: Pentamer (high)/gB(med)/Adjuvant vaccine; Three doses of the candidate CMVsu vaccine consisting of a combination of high dose pentamer and medium dose gB antigens, adjuvanted are administered intramuscularly in the deltoid region of the non-dominant arm in a 0, 2, 6-month schedule.
Placebo Comparator: Placebo Group; Participants received a dose of placebo at Day 1, Day 61 and Day 181 intramuscularly.	Combination product: Placebo (saline solution); Three doses of placebo (saline) are administered intramuscularly in the deltoid region of the non-dominant arm in a 0, 2, 6-month schedule.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With Solicited Administration Site Adverse Events Post Each Dose Administration	The assessed solicited administration site adverse events were erythema (injection site redness), pain and swelling.	Within 7 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Solicited Systemic Adverse Events Post Each Dose Administration	The assessed solicited administration site adverse events were arthralgia, fatigue, headache, fever and myalgia. Fever was defined as body temperature ≥38.0°Celsius/100.4°Fahrenheit.	Within 7 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Unsolicited Adverse Events (AEs) Within 7 Days Post Each Dose Administration	An unsolicited AE is defined as an AE that was not included in a list of solicited events using a Participant Diary. Unsolicited AEs include both serious and non-serious AEs.	Within 7 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Unsolicited Serious Adverse Events (SAEs) Within 7 Days Post Each Dose Administration	An SAE is defined as any untoward medical occurrence that, at any dose, resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, caused a congenital anomaly/birth defect, or was any other situation identified according to medical or scientific judgment. An unsolicited SAE is defined as an SAE that was not included in a list of solicited events using a Participant Diary.	Within 7 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Unsolicited AEs up to 30 Days Post Each Dose Administration	An unsolicited AE is defined as an AE that was not included in a list of solicited events using a Participant Diary. The solicited AEs that had an onset after 7 days post each dose administration are considered unsolicited AEs. Unsolicited AEs include both serious and non-serious AEs.	Within 30 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Unsolicited SAEs up to 30 Days Post Each Dose Administration		Within 30 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Medically Attended Events (MAEs) up to 30 Days Post Each Dose Administration	MAE is defined as an AE for which the participant received medical attention defined as hospitalization, an emergency room visit or a visit to or from medical personnel (i.e., nurse practitioner or physician assistant or medical doctor) for any reason.	Within 30 days post each dose (doses administered on Day 1, Day 61 and Day 181)
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 1	The hematological and biochemical parameters included alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, white blood cells (WBC). Categories reported when comparing normal range and Day 1 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 1
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 8	The hematological and biochemical parameters included ALT, AST, creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, WBC. Categories reported when comparing normal range and Day 8 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 8
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 61	The hematological and biochemical parameters included ALT, AST, creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, WBC. Categories reported when comparing normal range and Day 61 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 61
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 68	The hematological and biochemical parameters included ALT, AST, creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, WBC. Categories reported when comparing normal range and Day 68 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 68
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 181	The hematological and biochemical parameters included ALT, AST, creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, WBC. Categories reported when comparing normal range and Day 181 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 181
Number of Participants With Hematological and Biochemical Laboratory Abnormalities on Day 188	The hematological and biochemical parameters included ALT, AST, creatinine, eosinophils, hemoglobin, lymphocytes, neutrophils, platelets, WBC. Categories reported when comparing normal range and Day 188 hematological and biochemical laboratory results are defined as follows: <parameter>, <range at timing> (e.g. Hemoglobin, Below). Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter. Missing = No results are available for the corresponding laboratory parameter at the specific timepoint.	On Day 188

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants With Unsolicited Events, SAEs, MAEs and Potential Immune Mediated Diseases (pIMDs) From Day 1 to Day 546 (End of Study)	Unsolicited AE=AE that was not included in a list of solicited events using a Participant Diary; the solicited AEs that had an onset after 7 days post each dose administration are considered unsolicited AEs; both serious and non-serious AEs are included. SAE=any untoward medical occurrence that, at any dose, resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, caused a congenital anomaly/birth defect, or was any other situation identified according to medical or scientific judgment. MAE=AE for which the participant received medical attention defined as hospitalization, an emergency room visit or a visit to or from medical personnel (i.e., nurse practitioner or physician assistant or medical doctor) for any reason. pIMDs=a subset of adverse events that include autoimmune diseases and other inflammatory and/or neurological disorders of interest which may or may not have an autoimmune etiology.	Day 1 to Day 546
Geometric Mean Titers (GMT) of Neutralizing Antibodies (nAbs) Against Epithelial Cell Infection (CMV Status: Sero-positive)	Neutralizing antibodies (nAbs) against epithelial cell infection were measured with neutralizing assay and the results were expressed as GMT.	On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546
GMT of nAbs Against Epithelial Cell Infection (CMV Status: Sero-negative)		On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546
Geometric Mean Concentration (GMC) of Anti-pentamer Immunoglobulin G (IgG) (CMV Serostaus: Sero-positive)	The vaccine-induced humoral immunity was quantified by measuring the concentration of the anti-pentamer by enzyme-linked immunosorbent assay (ELISA).	On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546
GMC of Anti-pentamer IgG (CMV Serostatus: Sero-negative)		On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546
GMC of Anti-glycoprotein B (gB) IgG (CMV Serostaus: Sero-positive)	The vaccine-induced humoral immunity was quantified by measuring the concentration of the anti-gB IgG binding antibodies by ELISA.	On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546
GMC of Anti-gB IgG (CMV Serostatus: Sero-negative)		On Day 1, Day 31, Day 61, Day 91, Day 181, Day 211, Day 361 and Day 546

Collaborators and Investigators

• Sponsor: GlaxoSmithKline

Publications and helpful links

General Publications

• Sanchez-Martinez ZV, Alpuche-Lazcano SP, Stuible M, Durocher Y. CHO cells for virus-like particle and subunit vaccine manufacturing. Vaccine. 2024 Apr 11;42(10):2530-2542. doi: 10.1016/j.vaccine.2024.03.034. Epub 2024 Mar 19.

Study record dates

Study Major Dates

• Study Start (Actual): October 14, 2021
• Primary Completion (Actual): April 2, 2025
• Study Completion (Actual): April 2, 2025

Study Registration Dates

• First Submitted: October 11, 2021
• First Submitted That Met QC Criteria: October 11, 2021
• First Posted (Actual): October 22, 2021

Study Record Updates

• Last Update Posted (Actual): July 17, 2026
• Last Update Submitted That Met QC Criteria: July 16, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Safety; Immunogenicity; Reactogenicity; Cytomegalovirus; Healthy adults; First-Time-in Human
• Additional Relevant MeSH Terms: Infections; Virus Diseases; DNA Virus Infections; Herpesviridae Infections; Cytomegalovirus Infections; Pharmaceutical Preparations; Crystalloid Solutions; Isotonic Solutions; Solutions; Saline Solution
• Other Study ID Numbers: 209976

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Study Sponsor will assess requests from qualified researchers for anonymized individual patient-level data and related study documents. Data sharing is subject to certain criteria, conditions, and exceptions. For further information, refer to https://d3l8i7lo48obsd.cloudfront.net/gsk-patient-level-data-sharing-july2025-1-Bgwa1UthxvluYbWYTThw.pdf
• IPD Sharing Time Frame: Anonymized IPD will be made available within 6 months of publication of primary, key secondary and safety results for studies in product with approved indication(s) or asset(s) with development terminated across all indications.
• IPD Sharing Access Criteria: Anonymized IPD is shared with researchers whose proposals are approved by an Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months, but an extension may be granted, when justified, for up to 6 months.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes