From the Journals

Single-dose tafenoquine appears to prevent malaria relapse

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Too soon to conclude radical progress

The studies show that tafenoquine reduces the risk of Plasmodium vivax recurrence in patients with quantitatively confirmed normal glucose-6-phosphate dehydrogenase (G6PD) activity, Nicholas J. White, FRS, wrote in an accompanying editorial.

But the need for this test and current prescribing restrictions will “limit the potential deployment of tafenoquine, at least in the immediate future,” he said. He praised the developers of tafenoquine “for persevering with this potentially valuable antimalarial drug, despite the difficulties,” but cautioned that it’s too soon to conclude that tafenoquine can be used safely and routinely on a large scale “and thus fulfill its promise as a radical improvement in the treatment of malaria.”

Currently, tafenoquine may not be used during pregnancy, lactation, or in patients younger than 16 years, Dr. White noted. Tafenoquine, like primaquine, causes dose-dependent hemolysis in patients with G6PD deficiency, but unlike primaquine, it is given as a single large dose. Hence, pretreatment quantitative G6PD testing is necessary. Point-of-care quantitative G6PD tests have been developed but await extensive field testing, Dr. White said.

Dr. White is with Mahidol University, Bangkok, Thailand, and University of Oxford, England. He reported having no financial disclosures. These comments are from his accompanying editorial ( N Engl J Med. 2019;380:285-6 ).


 

FROM NEW ENGLAND JOURNAL OF MEDICINE

Single-dose tafenoquine therapy safely reduces the risk of Plasmodium vivax relapse in patients with normal glucose-6-phosphate dehydrogenase (G6PD) activity, according to the results of two phase 3, double-blind, randomized controlled trials.

This image shows a malaria-infected red blood cell. Courtesy NIAID

This image shows a malaria-infected red blood cell.

Findings from both studies were published in two separate reports in the New England Journal of Medicine.

In the first study, the Dose and Efficacy Trial Evaluating Chloroquine and Tafenoquine in Vivax Elimination (DETECTIVE), the risk of P. vivax recurrence was approximately 70% lower with tafenoquine versus placebo, wrote Marcus V.G. Lacerda, MD, of Fundação de Medicina Tropical Doutor Heitor Vieira Dourado in Manaus, Brazil, and his colleagues.

The study included 522 patients with confirmed P. vivax infection from Peru, Brazil, Ethiopia, Cambodia, Thailand, and the Philippines. Patients received 3 days of chloroquine therapy (600 mg on days 1 and 2, and 300 mg on day 3) and were randomly assigned on a 2:1:1 basis to receive a single 300-mg dose of tafenoquine on day 1 or 2, primaquine once daily for 14 days, or placebo.

Since primaquine and tafenoquine can cause clinically significant hemolysis in individuals with G6PD deficiency, the study included only patients with normal G6PD activity.

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