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BACKGROUND:Tafenoquine, a single-dose therapy for Plasmodium vivax malaria, has been associated with relapse prevention through the clearance of P. vivax parasitemia and hypnozoites, termed "radical cure." METHODS:We performed a phase 3, prospective, double-blind, double-dummy, randomized, controlled trial to compare tafenoquine with primaquine in terms of safety and efficacy. The trial was conducted at seven hospitals or clinics in Peru, Brazil, Colombia, Vietnam, and Thailand and involved patients with normal glucose-6-phosphate dehydrogenase (G6PD) enzyme activity and female patients with moderate G6PD enzyme deficiency; all patients had confirmed P. vivax parasitemia. The patients were randomly assigned, in a 2:1 ratio, to receive a single 300-mg dose of tafenoquine or 15 mg of primaquine once daily for 14 days (administered under supervision); all patients received a 3-day course of chloroquine and were followed for 180 days. The primary safety outcome was a protocol-defined decrease in the hemoglobin level (>3.0 g per deciliter or ≥30% from baseline or to a level of <6.0 g per deciliter). Freedom from recurrence of P. vivax parasitemia at 6 months was the primary efficacy outcome in a planned patient-level meta-analysis of the current trial and another phase 3 trial of tafenoquine and primaquine (per-protocol populations), and an odds ratio for recurrence of 1.45 (tafenoquine vs. primaquine) was used as a noninferiority margin. RESULTS:A protocol-defined decrease in the hemoglobin level occurred in 4 of 166 patients (2.4%; 95% confidence interval [CI], 0.9 to 6.0) in the tafenoquine group and in 1 of 85 patients (1.2%; 95% CI, 0.2 to 6.4) in the primaquine group, for a between-group difference of 1.2 percentage points (95% CI, -4.2 to 5.0). In the patient-level meta-analysis, the percentage of patients who were free from recurrence at 6 months was 67.0% (95% CI, 61.0 to 72.3) among the 426 patients in the tafenoquine group and 72.8% (95% CI, 65.6 to 78.8) among the 214 patients in the primaquine group. The efficacy of tafenoquine was not shown to be noninferior to that of primaquine (odds ratio for recurrence, 1.81; 95% CI, 0.82 to 3.96). CONCLUSIONS:Among patients with normal G6PD enzyme activity, the decline in hemoglobin level with tafenoquine did not differ significantly from that with primaquine. Tafenoquine showed efficacy for the radical cure of P. vivax malaria, although tafenoquine was not shown to be noninferior to primaquine. (Funded by GlaxoSmithKline and Medicines for Malaria Venture; GATHER ClinicalTrials.gov number, NCT02216123 .).

Original publication

DOI

10.1056/nejmoa1802537

Type

Journal article

Journal

The New England journal of medicine

Publication Date

01/2019

Volume

380

Pages

229 - 241

Addresses

From Universidad Peruana Cayetano Heredia, Lima, Peru (A.L.-C., R.C., M.C.); Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus (M.V.G.L., F.V., W.M.M., M.A.M.B., M.R.F.C.), and Fundação Oswaldo Cruz, Manguinhos, Rio de Janeiro (M.V.G.L.) - both in Brazil; Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (T.T.H., C.H.N.); Universidad de Antioquia, Medellin (I.D.V.), Centro de Investigaciones Clinicas S.A.S de Cali, Cali (M.F.V.), and IMAT Oncomedica, Monteria (S.A.) - all in Colombia; Umphang Hospital, Tak (C.N.-l., R.P.), and Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot (C.S.C., F.H.N., G.B.) - both in Thailand; the Centre for Tropical Medicine and Global Health (C.S.C., F.H.N., G.B.) and the Oxford Centre for Clinical Tropical Medicine (B.A.), Nuffield Department of Medicine, University of Oxford, Oxford, GlaxoSmithKline, Stockley Park West (G.C., V.M.R., S.W.J., E.H., D.D.C., K.M., G.C.K.W.K., J.A.G.), and GlaxoSmithKline, Stevenage (L.K.) - all in the United Kingdom; Medicines for Malaria Venture, Geneva (S.D.); and GlaxoSmithKline, Collegeville, PA (V.M.W., J.J.B.).

Keywords

Humans, Plasmodium vivax, Parasitemia, Malaria, Vivax, Glucosephosphate Dehydrogenase Deficiency, Aminoquinolines, Chloroquine, Primaquine, Glucosephosphate Dehydrogenase, Hemoglobins, Antimalarials, Disease-Free Survival, Drug Therapy, Combination, Prospective Studies, Double-Blind Method, Adolescent, Adult, Female, Male, Secondary Prevention, Kaplan-Meier Estimate