In vitro and in vivo evaluation of 28DAP010, a novel diamidine for treatment of second-stage African sleeping sickness

Abstract

African sleeping sickness is a neglected tropical disease transmitted by tsetse flies. New and better drugs are still needed especially for its second stage, which is fatal if untreated. 28DAP010, a dipyridylbenzene analogue of DB829, is the second simple diamidine found to cure mice with central nervous system infections by a parenteral route of administration. 28DAP010 showed efficacy similar to that of DB829 in dose-response studies in mouse models of first- and second-stage African sleeping sickness. The in vitro time to kill, determined by microcalorimetry, and the parasite clearance time in mice were shorter for 28DAP010 than for DB829. No cross-resistance was observed between 28DAP010 and pentamidine on the tested Trypanosoma brucei gambiense isolates from melarsoprol-refractory patients. 28DAP010 is the second promising preclinical candidate among the diamidines for the treatment of second-stage African sleeping sickness.

FIG 1

Chemical structures of 28DAP010, its prodrug DB1244, and its analogues.

FIG 2

In vitro activities of pentamidine versus 28DAP010 against different T. b. gambiense strains. Symbols represent the average IC₅₀ of at least three independent determinations. The first number in each set of parentheses represents the IC₅₀ for pentamidine and the second number that for 28DAP010. No significant correlation was observed between pentamidine and 28DAP010 activities (r² = 0.019).

FIG 3

Microcalorimetry heat flow profiles of T. b. rhodesiense strain STIB900 (A) and T. b. gambiense strains STIB930 (B) and ITMAP141267 (C) in the presence of various concentrations of 28DAP010. Drug-free samples included parasites (5 × 10⁴/ml inoculum) without drug treatment, and trypanosome-free experiment did not include any parasites or drug. Each curve represents the mean of three samples.

FIG 4

Plasma (filled circles) and brain (open squares) concentration-time profiles of 28DAP010 following intravenous (A) and intraperitoneal (B) administration to uninfected mice. The doses were 7.5 μmol/kg (or 2.4 mg/kg) for i.v. administration and 65 μmol/kg (or 21 mg/kg) for i.p. administration. Symbols and error bars represent means and standard errors of triplicate determinations, respectively.