Background 

Plasmodium vivax is a type of malaria that caused an estimated 14.3 million symptomatic illnesses globally in 2017, with over half of these cases occurring in Southeast Asia. A major challenge with this type of malaria is that the parasite can hide in the liver and cause the illness to return (relapse) weeks or months later. While a 14-day treatment of a medicine called primaquine can prevent these relapses, it is difficult for many patients to finish the entire course. 

A newer drug called tafenoquine is much easier to take because it only requires a single dose. However, recent studies have shown that the currently approved dose of 300 milligrammes is not effective enough for patients in Southeast Asia, where higher doses are generally needed to completely clear the parasites. As a result, researchers believe a 50% higher dose of tafenoquine is necessary to effectively cure patients and prevent the disease from coming back with just a single dose. 

Study Goals

The primary goal of this clinical trial is to determine if increasing the standard dose of tafenoquine by 50% will be more effective at stopping the malaria from returning within a four-month period. 

In addition to checking how well the drug works, we also want to ensure that the higher dose is safe and well-tolerated by patients. Other secondary aims include understanding how the body processes the drug, identifying the best ways to predict if a relapse will occur, and observing how the drug affects the malaria parasites at a microscopic level. 

Study Design

The study will enrol a total of 700 adults and children with Plasmodium vivax malaria across clinics in Cambodia, Laos, Thailand, Vietnam, and Indonesia. Participants will be randomly assigned to receive either the currently recommended dose of tafenoquine or a 50% higher dose, alongside their standard malaria treatment. Neither the patients nor the doctors will know which dose is being given, to ensure the results are fair and unbiased. In Indonesia, an extra 120 participants will be enrolled to receive the national standard treatment (a 7-day course of primaquine) to serve as a comparison group. 

Following their treatment, participants will be closely monitored with clinical visits and blood tests for four months to see if the malaria returns. To ensure safety, all patients will be tested before the study begins to make sure they do not have a specific genetic condition (G6PD deficiency) that can cause severe side effects with these types of medicines. 

Read the details of the clinical trial here.

Status

This study is still at the start up phase and aims to start recruiting later in the year.