Trial for Malaria Vaccine Candidate, PfPEBS (P. Falciparum Pre-Erythrocytic and Blood Stage) — PEBS-POC1  

Malaria Clinical Trial

Official title: Phase I and IIa Trial for Assessment of Safety, Immunogenicity (Phase Ia) and Efficacy (Phase IIa) Against Sporozoite Challenge of P. Falciparum Pre-Erythrocytic and Blood Stage (PfPEBS-LSP) Malaria Vaccine Candidate

Status Recruiting

Clinical Trial Summary

This study intends to test the hypothesis that the malaria antigen PfPEBS, manufactured as a synthetic protein and adjuvanted with aluminium hydroxide will be well-tolerated and immunogenic (Phase 1), functionally active against the erythrocytic stages (Phase 1) and efficacious (Phase 2) against the pre-erythrocytic stages in protecting against an artificial malaria challenge using Pf sporozoites in a healthy adult population.

Clinical Trial Description

The study will enroll 36 healthy adult subjects (18-45 years) and randomize them in a double-blind manner into 3 arms of 12 subjects each; 2 of the arms will receive either 5μg or 30μg, both adjuvanted with aluminium hydroxide, given as a 2-dose schedule with a 28 day interval. The third arm of 12 subjects will act as controls, and they will receive aluminium hydroxide only injections.

If the safety and immunogenicity results permit, the subjects will be challenged with live mosquito challenge delivering P falciparum sporozoites to assess pre-erythrocytic vaccine efficacy.

The PfPEBS molecule has been found to have in vivo and in vitro functional activity against the two stages that are clinically significant for malaria namely the pre-erythrocytic stages (sporozoite and liver stages) and the erythrocytic stages.

The formulation is a simple combination of a synthetic protein of 131 amino acids adjuvanted with aluminum hydroxide, the adjuvant with the widest safety records.

The combined Phase 1/2a study is designed in order to achieve 3 co-primary objectives

1. Phase 1: To demonstrate safety and tolerability

2. Phase 1: To measure the activity against the asexual blood stage of the parasite which is only indirectly estimated by the functional activity of elicited antibodies in ADCI under in-vitro conditions

3. Phase 2: To demonstrate efficacy against liver stages by measuring the proportion of subject that are protected following a live sporozoite challenge.

The mechanisms of defenses differ for "liver stages" and "erythrocytic stages". Defenses against "liver stages" are strongly related to the secretion of interferon γ by CD4+Th1 cells, whereas for blood stages the defences depend on antibodies.

Preliminary studies have demonstrated that low antigen doses such as 5 or 2μg produce strong CD4+Th1- interferon γ secreting cells with low antibody titers, whereas higher antigen doses such as 30 or 50μg induce lower CD4 Th1 cell response and markedly higher antibody responses.

Therefore the choice of the two dose ranges for the Pf-PEBS clinical trial protocol is aimed at testing the two main efficacy objectives, one against "liver stages" with a low dose, the other against "the blood stages" with the higher dose.

The Sponsor for the two Phases is Vac4all. The funder for the Phase Ia is the EMVDA programme of the European Commission. The funder for the Phase IIa is Vac4all ;

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Prevention

Related Conditions & MeSH terms

• Malaria

• NCT number: NCT01605786
• Study type: Interventional
• Source: Vac4All
• Contact: Pierre Druilhe, MD
• Phone: +33142733541
• Email: druilhe@vac4all.org
• Status: Recruiting
• Phase: Phase 1/Phase 2
• Start date: May 2012
• Completion date: August 2013