GlaxoSmithKline (GSK) and Swiss-based Medicines for Malaria Venture (MMV) have reported positive headline results from two Phase III clinical trials of tafenoquine to prevent a relapse of malaria caused by Plasmodium vivax (P. vivax).
Discovered in 1978 by scientists at the Walter Reed Army Institute of Research, tafenoquine is an investigational 8-aminoquinoline derivative that shows activity against the lifecycle of P. Vivax.
The results indicated that a single dose of tafenoquine combined with a three-day, blood-stage chloroquine treatment minimised the risk of relapse when compared to placebo and chloroquine.
Conducted in malaria-endemic countries across South America, Asia and Africa, the Phase III DETECTIVE and GATHER trials evaluated single doses of 300mg of tafenoquine.
GSK R&D president Patrick Vallance said: “Being able to treat patients with a single dose of medicine would be an important step forward in ensuring efficacious treatment, thereby reducing the risk of relapse, particularly in areas with very limited healthcare infrastructure.”
The double-blind, double-dummy DETECTIVE trial assessed the efficacy, safety and tolerability of tafenoquine in 522 patients also administered with chloroquine for treating the acute blood stage of the infection.
The primary endpoint of a statistically significant proportion of patients being relapse-free during the six-month follow-up period was met during the trial.
Patients who were given a 14-day course of 15mg of primaquine were also found to be relapse-free over the six-month follow-up period.
Designed to evaluate the effect of tafenoquine on levels of haemoglobin, the GATHER trial compared the product with a 14-day course of 15mg of primaquine in 251 patients on standard course chloroquine.
The trial’s primary endpoint of a decrease in haemoglobin was found to be similar in the case of both tafenoquine and primaquine treatment groups.
GSK and MMV have been collaborating since 2008 to develop single-dose tafenoquine as an alternative to the primaquine, which must be taken for 14 days for patients with a relapsing form of the disease.
Image: A technician at work in a lab focused on malaria research. Photo: courtesy of Flickr / GSK.