Efficacy of DB289 in Thai patients with Plasmodium vivax or acute, uncomplicated Plasmodium falciparum infections

Background. DB289 is the orally active prodrug of the diamidine DB75, which was developed for the treatment of human African trypanosomiasis. Methods. We tested the safety and efficacy of DB289 for the treatment of Plasmodium vivax and acute, uncomplicated P. falciparum infections in an open-label pilot study at the Hospital for Tropical Diseases in Bangkok. Nine patients with P. vivax infections and 23 patients with P. falciparum infections were admitted and treated with 100 mg of DB289 given orally twice a day for 5 days and were followed for 28 days. Patients with P. vivax infections were also treated with primaquine on days 10-23. Results. All patients cleared parasites by day 7, with a mean +/- SD clearance time of 43 +/- 41 h. One patient with a P. vivax infection had a recurrence of parasitemia on day 9. Of the 23 patients with P. falciparum infections, 3 had recurrences of parasitemia caused by P. vivax and 2 had recurrences of parasitemia caused by P. falciparum. In only 1 of 2 recurrences of parasitemia caused by P. falciparum were the parasites genotypically distinct from the infecting parasites the patient had at enrollment, which means there was a 96% cure rate. Conclusions. DB289 is a promising new antimalarial compound that could become an important component of new antimalarial combinations.