A Clinical Study to Evaluate the Safety, Tolerability, and Immunogenicity of VAX-A1 in Healthy Young Adults

NCT07616934 | Recruiting Phase 1 DMC

• 1 other identifier: VAXA1-101
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

This is a phase 1, first-in-human, randomized, double-blind, placebo-controlled, dose-escalation study to evaluate the safety, tolerability, and immunogenicity of VAX-A1 in healthy adults 18-40 years of age.

Conditions

Group A Streptococcal Infection

Keywords

Strep A; Streptococcus pyogenes; Safety; Reactogenicity; Immunogenicity; Healthy Adults; Australia

Outcome Measures

Primary Outcomes (8)

• Frequency of solicited local reactions (redness, swelling, and pain at injection site)

  up to 7 days after each vaccination

• Frequency of solicited systemic adverse events (AE) (fever, headache, fatigue, muscle pain, rash, joint pain, nausea/vomiting, diarrhea)

  up to 7 days after each vaccination

• Frequency of laboratory abnormalities identified from protocol-scheduled safety laboratory assessments at 7 days after each vaccination and reported as AE

  7 days after each vaccination

• Frequency of unsolicited AE

  up to 30 days after each vaccination

• Frequency of medically attended AE (MAAE)

  Up to 8 months after first vaccination

• Frequency of new onset chronic illness (NOCI)

  up to 8 months after the first vaccination

• Frequency of serious adverse events (SAE)

  from screening through up to 8 months after first vaccination

• Occurrence of AE of special interest (AESI) (acute rheumatic fever [ARF], acute carditis [AC], and acute glomerulonephritis [AGN])

  up to 8 months after the first vaccination

Secondary Outcomes (6)

• Median value of each safety laboratory parameter assessed 7 days after each vaccination

  7 days after each vaccination

• Median change from baseline to 7 days after each vaccination for each safety laboratory parameter

  7 days after each vaccination

• Serum IgG geometric mean titer (GMT) at each scheduled immunogenicity sample collection visit for each vaccine antigen (SLO, C5a pep, SpyAD, GAC)

  Prior to each vaccination, 1 month after each vaccination and Month 8

• Serum IgG geometric mean fold rise (GMFR) from baseline to each scheduled post-vaccination immunogenicity sample collection visit for each vaccine antigen (SLO, C5a pep, SpyAD, GAC)

  Prior to each vaccination, 1 month after each vaccination and Month 8

• Percentage of participants achieving serum IgG ≥2-fold increase from baseline at each scheduled post-vaccination immunogenicity sample collection visit for each vaccine antigen (SLO, C5a pep, SpyAD, GAC)

  1 month after each vaccination and Month 8

Study Arms (4)

VAX-A1 Low

EXPERIMENTAL

Participants will receive 2 doses of VAX-A1 administered via intramuscular injection at Day 1 and Month 2

Biological: VAX-A1 Low

VAX-A1 Mid

EXPERIMENTAL

Participants will receive 2 doses of VAX-A1 administered via intramuscular injection at Day 1 and Month 2

Biological: VAX-A1 Mid

VAX-A1 High

EXPERIMENTAL

Participants will receive 2 doses of VAX-A1 administered via intramuscular injection at Day 1 and Month 2

Biological: VAX-A1 High

Placebo

PLACEBO COMPARATOR

Participants will receive 2 doses of placebo administered via intramuscular injection at Day 1 and Month 2

Biological: Placebo

Interventions

Placebo BIOLOGICAL

0.5mL of placebo (normal saline) will be administered into the deltoid muscle

Placebo

VAX-A1 Low BIOLOGICAL

0.5mL of the low dose VAX-A1 will be administered into the deltoid muscle

VAX-A1 Low

VAX-A1 High BIOLOGICAL

0.5mL of the high dose VAX-A1 will be administered into the deltoid muscle

VAX-A1 High

VAX-A1 Mid BIOLOGICAL

0.5mL of the mid dose VAX-A1 will be administered into the deltoid muscle

VAX-A1 Mid

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Individuals 18-40 years of age (inclusive) at the time of randomization into the study
• Able and willing to complete the informed consent process
• Available for clinical follow-up through the last study visit at 6 months post-Dose 2
• Willing to have blood samples collected, stored indefinitely, and be used for research purposes
• Able to provide proof of identity to the satisfaction of the study staff completing the enrollment process
• Healthy, as defined by absence of clinically significant medical condition, either acute or chronic, as determined by medical history, vital signs, physical examination, screening laboratory test results, TTE and ECG results, and clinical assessment by the Investigator
• For applicable individuals, postmenopausal (as confirmed by follicle-stimulating hormone \[FSH\] level at Screening) for at least 1 year, or surgically sterile for at least 6 months prior to dosing
• Individuals of childbearing potential must be not pregnant and not lactating, must have negative urine and serum pregnancy tests at Screening and a negative urine pregnancy test immediately prior to randomization, and agree to use acceptable contraception if heterosexually active. Participants must agree to consistently practice contraception if sexually active at least 7 days prior to enrollment and throughout the duration of the study
• Able to access and use a smartphone, tablet, computer, or other device connected to Wi-Fi or cellular network for completion of an eDiary

You may not qualify if:

• History of any clinically important cardiac, rheumatologic, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal, or other disease as determined by the Investigator. This includes a history of polyarthritis, nephropathy, pericarditis, myocarditis, or hypertension requiring current pharmacologic treatment.
• History of invasive GAS infection (such as toxic shock syndrome, necrotizing fasciitis, bloodstream infection, pleural empyema, meningitis) or poststreptococcal immune mediated disease (such as RHD, ARF, or APSGN)
• Known or suspected autoimmune disease, collagen vascular disease, or impairment/alteration of immune function (e.g., congenital or acquired immunodeficiency)
• Previous or existing diagnosis of human immunodeficiency virus, Hepatitis B virus, or Hepatitis C virus, or a positive serologic test at Screening
• History of malignancy or neoplasm, except for adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer
• Bleeding disorder diagnosed by a physician (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) resulting in clinically significant bruising or bleeding difficulties with IM injections or blood draws
• History of severe allergic reaction with generalized urticaria, angioedema, or anaphylaxis to any previous vaccination
• Oral temperature \>38.0°C (\>100.4°F) or acute illness within 3 days prior to study vaccination (subject may be rescreened)
• Confirmed elevated BP at Screening, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg measured seated after ≥5 minutes rest and confirmed by repeat measurement
• Physical examination indicating any clinically significant medical condition or inadequate venous access
• Any Grade ≥2 abnormal safety laboratory test at Screening
• Abnormal ESR, or CRP or C3 levels at Screening
• Evidence of antecedent/recent GAS infection based on anti-DNase B titer ≥ the laboratory reported upper limit of normal (ULN) for the assay used at Screening. Participants with anti-DNase B titer ≥0.8×ULN and \<ULN at the initial Screening visit are temporarily ineligible and may be re-screened with repeat anti-DNase B testing 7-21 days after the initial sample; participants will be excluded if the repeat anti-DNase B titer is ≥ULN or demonstrates a clinically meaningful increase of ≥20% relative to the initial screening value, in the absence of an alternative explanation.
• Positive GAS rapid NAAT at Screening or Day 1
• Any finding based on comprehensive TTE at Screening indicative of possible cardiac pathology, including valvular abnormalities defined as mild stenosis or regurgitation.

Sponsors & Collaborators

• Vaxcyte, Inc.: lead

Study Sites (1)

Fusion Clinical Research

Adelaide, South Australia, 5067, Australia

RECRUITING

MeSH Terms

Conditions

Streptococcal Infections

Condition Hierarchy (Ancestors)

Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Infections

Central Study Contacts

Clinical Development

CONTACT

650-837-0111; Clinicaltrialsgov@vaxcyte.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: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 18, 2026
• First Posted: June 1, 2026
• Study Start: June 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: June 16, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will share
• Access Criteria: Criteria will depend on the specific proposal received and may include qualification of the scientific researchers, potential contribution to the research field, scientific rigor of statistical and analytical methods, and other criteria appropriate for the proposal.

Locations

AU (1)