Single dose Tafenoquine prevents relapse of P. vivax Malaria: NEJM

In a major treatment breakthrough, single-dose tafenoquine resulted in a significantly lower risk of P. vivax recurrence than placebo in malaria patients with phenotypically normal G6PD activity. The study was published in NEJM.

Treatment of Plasmodium vivax malaria requires the clearing of asexual parasites, but relapse can be prevented only if dormant hypnozoites are cleared from the liver (a treatment termed “radical cure”).

Tafenoquine, a single-dose 8-aminoquinoline therapy for Plasmodium vivax malaria, has been associated with relapse prevention through the clearance of P. vivax parasitemia and hypnozoites.

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Alejandro Llanos-Cuentas and associates conducted a multicentered, double-blind, double-dummy, parallel group, randomized, placebo-controlled trial in Ethiopia, Peru, Brazil, Cambodia, Thailand, and the Philippines.

The study involved patients with microscopically confirmed P. vivax infection (>100 to <100,000 parasites per microliter) and normal glucose-6-phosphate dehydrogenase (G6PD) activity (with normal activity defined as ≥70% of the median value determined at each trial site among 36 healthy male volunteers who were otherwise not involved in the trial).

The patients were assigned to receive a single 300-mg dose of tafenoquine on day 1 or 2 (260 patients), placebo (133 patients), or a 15-mg dose of primaquine once daily for 14 days (129 patients).In addition, all patients received a 3-day course of chloroquine (total dose of 1500 mg) and were followed for 180 days.

The study found that the percentage of patients who were free from recurrence at 6 months was 62.4% in the tafenoquine group, 27.7% in the placebo group, and 69.6% in the primaquine group.

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The hazard ratio for the risk of recurrence was 0.30 with tafenoquine as compared with placebo and 0.26 with primaquine as compared with placebo. Tafenoquine was associated with an asymptomatic decline in hemoglobin levels, which resolved without intervention.

The study concluded that tafenoquine showed efficacy for the radical cure of P. vivax malaria and tafenoquine was not shown to be non-inferior to primaquine.

According to WHO, in 2017, there were an estimated 219 million cases of malaria in 90 countries and malaria deaths reached 435 000 in 2017. The WHO African Region carries a disproportionately high share of the global malaria burden. In 2017, the region was home to 92% of malaria cases and 93% of malaria deaths.