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The study is designed to establish the best dose to safely infect healthy individuals with Plasmodium falciparum sporozoites (PfSPZ) by injection.
The goal of this study is to achieve infections in human volunteers with infection rates of 100% and pre-patent periods of less than 12 days.
Full description
This is an single center,open label, escalated and controlled human pilot study to optimize CHMI (controlled human malaria infection) administered by PfSPZ Challenge. The study was designed with an escalated dosing design in order to answer two questions:
Besides increasing the infectivity rate, we aim to reduce the pre-patent period to ~11 days.
In Part A of the trial, the volume of inoculation will vary in order to identify the optimal volume needed for a dose of 2,500 PfSPZ to induce the greatest infection rate (defined as highest percentage of infected volunteers and shortest pre-patent period.)
The outcome variables of part A are:
During Part A, an interim analysis will be performed in order to determine the optimal volume of inoculation that will be used during Part B. The variables that will be taken into account for this interim analysis will be: 1) number of volunteers infected per group and 2) pre-patent period by thick blood smear in individuals in each group.
Part B will assess the effect of the optimal volume of inoculation determined in part A when administered with different PfSPZ doses, compared to the dose of 25,000 PfSPZ in 50 µL
However, i) If the optimal volume in Part A is 10 µL, then Group 6 will receive 100,000 PfSPZ (2 inoculations of 50,000 PfSPZ) instead of 125,000 PfSPZ, as the PfSPZs are vialed at 100,000 PfSPZ in 20 µL.
ii) If the optimal volume in Part A is 50µL, then Group 5 will be modified to avoid duplication of regimens between groups 4 and 5. In this case, volunteers in group 5 will be administered a dose of 25,000 PfSPZ administered ID (intradermal) in four 10 µL injections. (Every volunteer will receive 4 ID injections of 6,250 PfSPZ in a volume of 10 µL each, with 2 injections in each arm respectively).
The outcome variables in this part of the study are:
All volunteers recruited will be healthy adults aged between 18 and 45 years. Safety and infectivity data will be collected for each of the regimens and dose-levels. Volunteers and clinical investigators will not be blinded to group allocation, however laboratory investigators processing blood films and samples for qPCR analysis will be blinded to group allocation.
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36 participants in 6 patient groups
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Data sourced from clinicaltrials.gov
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