A Study on the Immune Response and Safety of a Combined Vaccine Against Diphtheria, Tetanus and Acellular Pertussis (dTpa) in Healthy Japanese Adolescents Aged 11 Years to <13 Years

NCT07596173 | Not Yet Recruiting Phase 3

• 1 other identifier: 308734
• Study Type: interventional
• Target: 85
• Locations: 0 countries
• Sites: N/A

Brief Summary

The purpose of the study is to assess the immune response, reactogenicity and safety of a booster dose of dTpa vaccine 1 month after vaccination in healthy Japanese participants aged 11 to \<13 years.

Conditions

Diphtheria-Tetanus-acellular Pertussis Vaccines

Keywords

Diphtheria tetanus and acellular pertussis (dTpa) vaccine; Adolescent; Immune response; Reactogenicity; Safety

Outcome Measures

Primary Outcomes (2)

• Number of seropositive participants for anti-pertussis toxin (anti-PT), anti-filamentous hemagglutinin (FHA) and anti-pertactin (PRN) antibodies

  Seropositivity is defined as antibody concentrations (anti-PT, anti-FHA and anti-PRN) are greater than or equal to the assessed assay cut-offs. The considered cut-off values are: anti-PT: 2.693 International Units per milliliter (IU/mL), anti-FHA: 2.046 IU/mL, anti-PRN: 2.187 IU/mL, as measured by Enzyme-Linked Immunosorbent assay (ELISA).

  1 month after vaccination

• Number of seroprotected participants for anti-diphteria and anti-tetanus antibodies

  Seroprotection is defined as anti-diphtheria and anti- tetanus antibody concentrations being \>=0.1 IU/mL as measured by ELISA.

  1 month after vaccination

Secondary Outcomes (8)

• Number of participants with booster-response to pertussis (PT, FHA and PRN) antigens

  1 month after vaccination

• Antibody concentration against pertussis (PT, FHA, PRN) antigens

  At baseline (Day 1) and 1 month after vaccination

• Antibody concentration for anti-diphtheria and anti-tetanus antibodies

  At baseline (Day 1) and 1 month after vaccination

• Number of participants with solicited local adverse events (AEs)

  From Day 1 (day of vaccination) to Day 7 post-vaccination

• Number of participants with solicited systemic AEs

  From Day 1 (day of vaccination) to Day 7 post-vaccination

Study Arms (1)

dTpa Group

EXPERIMENTAL

Participants aged 11 to less than (\<) 13 years receive the dTpa vaccine at Day 1.

Biological: dTpa vaccine

Interventions

dTpa vaccine BIOLOGICAL

Combined reduced antigen content diphtheria, tetanus and acellular pertussis (dTpa) vaccine administered at Day 1.

dTpa Group

Eligibility Criteria

• Age: 11 Years - 12 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• Participants and/or participants' parent(s)/ Legally acceptable representative(s) \[LAR(s)\], who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
• Physical or digital informed assent obtained from the participant prior to performance of any study-specific procedure.
• Physical or digital informed consent obtained from the parent(s)/LAR(s) of the participant prior to performance of any study-specific procedure.
• Healthy participants as established by medical history and clinical examination at screening.
• Male/female participant between and including 11 and \<13 years of age at the time of the study intervention administration (Visit 1/Day 1).
• Previously completed all routine childhood vaccinations to the best knowledge of the participant's parent(s)/LAR(s). Participants with documented previous diphtheria, tetanus and pertussis vaccination (primary series and first booster) as per routine vaccination in Japan prior to study enrolment.
• Participants did not receive an additional diphtheria, tetanus with or without pertussis vaccination within 5 years prior to enrolment in the study.
• Japanese ethnic origin.
• Participants of non-childbearing potential may be enrolled in the clinical study.
• Participant of childbearing potential may be enrolled in the study if the participant:
• has practiced adequate contraception for at least 30 days prior to study intervention administration, and
• has a negative pregnancy test within 24 hours prior to the study intervention administration, and
• has agreed to continue adequate contraception during the entire treatment period and for 8 weeks after completion of the study intervention administration series.

You may not qualify if:

• Medical conditions
• History of physician-diagnosed or laboratory-confirmed diphtheria, tetanus or pertussis diseases within the past 5 years.
• History of encephalopathy after administration of a previous dose of pertussis vaccine that could not be attributed to another identifiable cause, progressive neurologic disorder, uncontrolled epilepsy or progressive encephalopathy: pertussis vaccine should not be administered to individuals with these conditions until a treatment regimen has been established and the condition has stabilized.
• History of transient thrombocytopenia or neurological complications following an earlier immunization against diphtheria and/or tetanus.
• History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention(s) or having shown signs of hypersensitivity after previous administration of diphtheria, tetanus or pertussis vaccines.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination
• Acute or unstable chronic conditions clinically significant pulmonary, cardiovascular, hepatic, or renal functional abnormality, as determined by physical examination and/or laboratory screening tests.
• Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the clinical study.
• Condition that in the judgment of the investigator would make intramuscular injection unsafe.
• Prior/Concomitant therapy
• Use of any investigational or non-registered product other than the study intervention(s) during the period beginning 30 days before the dose of study intervention(s), or their planned use during the study period.
• Administration of immunoglobulins or other blood products or plasma derivatives during the period starting 90 days before the study intervention or planned administration during the study period.
• Chronic administration of immune-modifying drugs and/or planned use of long-acting immune-modifying treatments at any time up to the end of the study.
• Up to 6 months prior to the study intervention administration:
• For corticosteroids, this will mean prednisone equivalent ³0.5 mg/kg/day with maximum of 20 mg/day. Inhaled, intra-articular/intra-bursal and topical steroids are allowed.

Sponsors & Collaborators

• GlaxoSmithKline: lead

Central Study Contacts

US GSK Clinical Trials Call Center

CONTACT

877-379-3718; GSKClinicalSupportHD@gsk.com

EU GSK Clinical Trials Call Center

CONTACT

+44 (0) 20 89904466; GSKClinicalSupportHD@gsk.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NON RANDOMIZED
• Masking: NONE
• Masking Details: Open-label study.
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 13, 2026
• First Posted: May 19, 2026
• Study Start (Estimated): June 29, 2026
• Primary Completion (Estimated): October 14, 2026
• Study Completion (Estimated): October 14, 2026
• Last Updated: May 19, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR
• 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.
• 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.