The WHO Standard Treatment Guildelines and national treatment guidelines recommend treating both the blood-and liver-stages of P. vivax (relapsing) malaria. Until recently, primaquine was the only approved treatment for the relapsing, liver-stage, of the P. vivax life cycle. However, physicians do not always prescribe primaquine to prevent relapse, due to concerns about possible haemolysis in patients deficient in the glucose-6-phosphate dehydrogenase (G6PD) enzyme, limited access to G6PD tests, and poor compliance with the 14-day course of treatment.
Tafenoquine, a single-dose treatment developed by GSK and MMV for the radical cure of P. vivax malaria, was approved by the US Food and Drug Administration and the Australian Therapeutic Goods Administration in July and September 2018, under the names of Krintafel and Kozenis,1 respectively.
With these approvals, tafenoquine became the first new medicine for this indication in more than 60 years, marking a major milestone on the road to malaria eradication. Following these stringent regulatory approvals, dossiers have already been submitted to regulatory agencies in priority malaria endemic countries and additional submissions are planned for 2019.
Tafenoquine shares similar limitations with primaquine regarding use in G6PD-deficient patients and its simplified dosing regimen with a single dose should improve real-life treatment compliance and drug effectiveness.
The development of a paediatric formulation of tafenoquine is ongoing. The first two cohorts of a paediatric PK bridging study is complete; recruitment of the third cohort is anticipated to be completed by the end of 2019.
A study is also on-going in Indonesia to assess the safety and efficacy of tafenoquine co-administered with an ACT, DHA-PQP.
In parallel, PATH in collaboration with industry partners, has developed a quantitative, point-of-care G6PD test to ensure that only patients with adequate levels of G6PD enzymatic activity will receive tafenoquine.
1. Trademarks owned or licensed by GSK