MMV and GlaxoSmithKline (GSK) are developing tafenoquine as a potential medicine to prevent Plasmodium. vivax relapse by eliminating hypnozoites from the livers of infected patients with a single dose.
Tafenoquine is an investigational medicine that has completed phase III studies. If approved, it would be the first new medicine for relapsing malaria in over 60 years. Tafenoquine will potentially offer a single-dose cure for the liver-stage of P. vivax infections and will be administered alongside a standard 3-day chloroquine or potentially an ACT treatment regimen.
Tafenoquine is a member of the same chemical family as primaquine; both are associated with a risk of haemolytic side-effects in a subset of patients lacking adequate levels of the enzyme glucose-6-phosphate dehydrogenase (G6PD) (on average 8% of people in malaria-endemic countries).1 To reduce the risk of haemolysis, GSK is working with PATH on the development of a quantitative G6PD point-of-care diagnostic test so that patients’ G6PD status can be tested to determine if tafenoquine or primaquine can be safely administered. The goal is for this field-ready diagnostic test to be available at the same time as the potential launch of tafenoquine in malaria-endemic countries.
About plasmodium vivax
The Plasmodium vivax malaria parasite is estimated to cause around 8.5 million clinical infections every year.2 It has the ability to lie dormant in the liver as hypnozoites, which periodically reactivate, leading to a relapse of malaria in the absence of a new infective mosquito bite. Each of the multiple episodes of relapsing malaria keeps a child or adult from school or work for at least 3 days.3 Studies have shown that beyond lost time, malaria can also have adverse effects on cognitive ability.4,5 Primaquine is currently the only treatment available to kill the dormant parasites and stop the relapses. WHO recommends its administration once daily for up to 14 days – a regimen that is typically associated with poor compliance.6
Updated July 2017
1. Howes RE et al. “G6PD deficiency prevalence and estimates of affected populations in malaria endemic countries: a geostatistical modelbased map.” PLoS Med. 9(11):e1001339 (2012).
2. World Health Organization. World Malaria Report 2016 (2016).
3. Price RN et al. “Vivax malaria: neglected and not benign.” Am J Trop Med Hyg 77:79–87 (2007).
4. Vitor-Silva S et al. “Malaria is associated with poor school performance in an endemic area of the Brazilian Amazon.” Malar J. 8:230 (2009).
5. Fernando SD et al. “The impact of repeated malaria attacks on the school performance of children.” Am J Trop Med Hyg. 69(6):582−8 (2003).
6. Baird JK et al. “Diagnosis and Treatment of Plasmodium vivax Malaria.” Am J Trop Med Hyg. 28;95(6 Suppl):35-51 (2016).