Safety and Immunogenicity of Pvs25-IMX313/Matrix-M1 Vaccine

A Phase Ia Study to Assess Safety and Immunogenicity of the Plasmodium Vivax Malaria Vaccine Candidate Pvs25-IMX313 in Matrix-M1 Adjuvant in Healthy Adults Living in the UK

This is an open-label, single-centre, non-randomised, first-in-human Phase Ia study to assess the safety and immunogenicity of the Pvs25-IMX313 vaccine, administered in Matrix-M1 adjuvant.

Study Overview

• Status: Terminated
• Conditions: Malaria, Vivax
• Intervention / Treatment: Biological: Pvs25-IMX313/Matrix-M1

Detailed Description

Volunteers will be recruited into one of three groups (n=8-10 per group) at the Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Oxford over approximately 18 months. All volunteers will receive three doses of Pvs25-IMX313 in Matrix-M1, administered intramuscularly and given four weeks apart. Enrolment will be staggered with clinical and safety reviews, follow-up visits and monitoring via a diary card.

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• United Kingdom
  • Oxford, United Kingdom, OX3 7LE
    • CCVTM, University of Oxford, Churchill Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 45 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy adult aged 18 to 45 years.
• Able and willing (in the Investigator's opinion) to comply with all study requirements.
• Willing to allow the Investigators to discuss the volunteer's medical history with their GP.
• Volunteers with the potential to become pregnant only: must practice continuous effective contraception for the duration of the study. Acceptable forms of contraception for volunteers of child-bearing potential are: Established use of oral, injected or implanted hormonal methods of contraception, Placement of an intrauterine device or intrauterine system, Male sterilization (if the vasectomised partner is the sole partner for the participant), True abstinence from sex with sperm-producing partners, when this is in line with the preferred and usual lifestyle of the participant (periodic abstinence and withdrawal are not acceptable methods of contraception).
• Agreement to refrain from blood donation for the duration of the study.
• Able and willing to provide written informed consent to participate in the trial.

Exclusion Criteria:

• History of clinical malaria (any species).
• Travel to a clearly malaria endemic locality during the study period or within the preceding six months.
• Use of immunoglobulins or blood products (e.g., blood transfusion) in the last three months.
• Receipt of any vaccine in the 30 days preceding enrolment, or planned receipt of any other vaccine within 30 days following each study vaccination, with the exception of --COVID-19 vaccines, which should not be received between 14 days before to 7 days after any study vaccination.
• Receipt of an investigational product in the 30 days preceding enrolment, or planned receipt during the study period.
• Concurrent involvement in another clinical trial or planned involvement during the study period.
• Prior receipt of an investigational vaccine likely to impact on interpretation of the trial data, as assessed by the Investigator.
• Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection; asplenia; recurrent, severe infections and chronic (more than 14 days) immunosuppressant medication within the past 6 months (inhaled and topical steroids are allowed).
• History of allergic disease or reactions likely to be exacerbated by any component of the -vaccine.
• Any history of anaphylaxis in reaction to vaccinations.
• Pregnancy, lactation or intention to become pregnant during the study.
• History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ).
• History of serious psychiatric condition that may affect participation in the study.
• Any other serious chronic illness requiring hospital specialist supervision.
• Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 25 standard UK units every week.
• Suspected or known injecting drug abuse in the 5 years preceding enrolment.
• Hepatitis B surface antigen (HBsAg) detected in serum.
• Seropositive for hepatitis C virus (antibodies to HCV) at screening (unless volunteer has taken part in a prior hepatitis C vaccine study with confirmed negative HCV antibodies prior to participation in that study, and negative HCV ribonucleic acid (RNA) PCR at screening for this study).
• Volunteers unable to be closely followed for social, geographic or psychological reasons.
• Any clinically significant abnormal finding on biochemistry or haematology blood tests, urinalysis or clinical examination. In the event of abnormal test results, confirmatory repeat tests will be requested. Procedures for identifying laboratory values meeting exclusion criteria are shown in SOP VC027.
• Any other significant disease, disorder, or finding which may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study or impair interpretation of the study data.
• Inability of the study team to contact the volunteer's GP to confirm medical history and safety to participate.

Vaccination and re-vaccination exclusion criteria:

Absolute contraindications:

• Anaphylactic reaction following administration of vaccine
• Pregnancy

Contraindications at that point in time (may be rescheduled):

• Acute disease (moderate/severe illness with or without fever)
• T>37.5C
• Current COVID-19 infection, defined as ongoing symptoms with positive COVID-19 PCR swab test taken during current illness or positive COVID-19 PCR swab or rapid antigen test within preceding 7 days without symptoms. Vaccinations will be delayed by a minimum of 7 days from the date of the first positive COVID-19 PCR swab or rapid antigen test, as long as symptoms are improving or resolved. It will be at the discretion of the Investigator to withdraw a participant if they develop severe COVID-19 disease.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group 1 (low dose); 8-10 volunteers receiving three doses of 10 µg Pvs25-IMX313 in 50 µg Matrix-M1 on days 0, 28 and 56 via intramuscular injection (IM) in the deltoid region of the arm	Biological: Pvs25-IMX313/Matrix-M1; Three doses of Pvs25-IMX313 in Matrix-M1 at different concentrations
Experimental: Group 2 (standard dose); 8-10 volunteers receiving three doses of 50 µg Pvs25-IMX313 in 50 µg Matrix-M1 on days 0, 28 and 56 via intramuscular injection (IM) in the deltoid region of the arm	Biological: Pvs25-IMX313/Matrix-M1; Three doses of Pvs25-IMX313 in Matrix-M1 at different concentrations
Experimental: Group 3 (fractional dose); 8-10 volunteers receiving two doses of 50 µg Pvs25-IMX313 in 50 µg Matrix-M1 on days 0 and 28, followed by one dose of 10 µg Pvs25-IMX313 in 50 µg Matrix-M1 on day 56 via intramuscular injection (IM) in the deltoid region of the arm	Biological: Pvs25-IMX313/Matrix-M1; Three doses of Pvs25-IMX313 in Matrix-M1 at different concentrations

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety and Tolerability of the Pvs25-IMX313/Matrix-M1 Vaccine in Healthy Adult Volunteers: Number of Participants Reporting Solicited Local Reactogenicity Signs and Symptoms	Number of participants in each group who reported solicited local reactogenicity signs and symptoms in the 7 days following each vaccination. Solicited local reactogenicity signs and symptoms are collected through participant-reported e-diaries.	7 days following each vaccination
Safety and Tolerability of the Pvs25-IMX313/Matrix-M1 Vaccine in Healthy Adult Volunteers: Number of Participants Reporting Solicited Systemic Reactogenicity Signs and Symptoms.	Number of participants in each group who reported solicited systemic reactogenicity signs and symptoms in the 7 days following each vaccination. Solicited systemic reactogenicity signs and symptoms are collected through participant-reported e-diaries.	7 days following each vaccination
Safety and Tolerability of the Pvs25-IMX313/Matrix-M1 Vaccine in Healthy Adult Volunteers: Number of Unsolicited Adverse Events.	Unsolicited adverse events were collected for 28 days following each vaccination through participant-reported e-diaries.	28 days following each vaccination
Safety of the Pvs25-IMX313/Matrix-M1 Vaccine in Healthy Adult Volunteers: Occurrence of Abnormal Laboratory Test Results	Occurrence of change from baseline laboratory test results	28 days following vaccination
Safety and Tolerability of the Pvs25-IMx313/Matrix-M1 Vaccine in Healthy Adult Volunteers: Number of Serious Adverse Events	Number of serious adverse events reported per group throughout the study period.	Whole duration of the study period (8 months following enrolment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Humoral Immunogenicity of the Pvs25-IMX313/Matrix-M1 Vaccine When Administered to Healthy Adult Volunteers: Humoral Responses to the Pvs25 Protein	Antibody responses to the Pvs25 protein will be assessed through total IgG isotypes and avidity	Days 1, 29, 57, 140 and 240.
Cellular Immunogenicity of the Pvs25-IMX313/Matrix-M1 Vaccine When Administered to Healthy Adult Volunteers: Cellular Responses to the Pvs25 Protein.	T cell responses to Pvs25 will be assessed by ex vivo enzyme-linked immunospot assays (ELISpot) and flow cytometry assays.	Days 1, 29, 57, 140 and 240.
Ex Vivo Efficacy of the Pvs25-IMX313/Matrix-M1 Vaccine When Administered to Healthy Adult Volunteers: Transmission-Reducing Activity	Transmission-reducing activity will be assessed through direct membrane feeding assays (DMFA).	Days 1, 29, 57, 140 and 240.
Ex Vivo Efficacy of the Pvs25-IMX313/Matrix-M1 Vaccine When Administered to Healthy Adult Volunteers: Transmission-Blocking Activity	Transmission-blocking activity will be assessed through direct membrane feeding assays (DMFA).	Days 1, 29, 57, 140 and 240.

Collaborators and Investigators

• Sponsor: University of Oxford
• Investigators: Principal Investigator: Angela M Minassian, DPhil FRCP, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United

Study record dates

Study Major Dates

• Study Start (Actual): February 9, 2022
• Primary Completion (Actual): July 31, 2023
• Study Completion (Actual): July 31, 2023

Study Registration Dates

• First Submitted: January 28, 2022
• First Submitted That Met QC Criteria: March 7, 2022
• First Posted (Actual): March 8, 2022

Study Record Updates

• Last Update Posted (Actual): January 15, 2026
• Last Update Submitted That Met QC Criteria: January 13, 2026
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Keywords: Pvs25-IMX313; Matrix-M1
• Additional Relevant MeSH Terms: Vector Borne Diseases; Mosquito-Borne Diseases; Infections; Protozoan Infections; Parasitic Diseases; Malaria; Malaria, Vivax; Matrix-M
• Other Study ID Numbers: VAC084

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No