Research ArticlePARASITIC DISEASES

Preclinical development of an oral anti-Wolbachia macrolide drug for the treatment of lymphatic filariasis and onchocerciasis

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Science Translational Medicine  13 Mar 2019:
Vol. 11, Issue 483, eaau2086
DOI: 10.1126/scitranslmed.aau2086

Nematodes go A·WOL

New drugs are urgently needed for treating the neglected tropical diseases, onchocerciasis and lymphatic filariasis. As part of the A·WOL consortium, Taylor et al. launched a drug discovery program that identified macrolide antibiotic molecules that were capable of eliminating the bacterial endosymbiont, Wolbachia, which is necessary for the viability and fertility of filarial worms. Two macrolide compounds cleared Wolbachia from filarial nematodes in animal models of lymphatic filariasis and onchocerciasis. The authors showed that the tylosin A analog, A-1574083 (ABBV-4083), had superior efficacy compared to tetracycline antibiotics for clearing Wolbachia in mouse and gerbil models of filarial infection. The safety and pharmacology profiles of A-1574083 have enabled this compound to be moved forward into clinical testing.

Abstract

There is an urgent global need for a safe macrofilaricide drug to accelerate elimination of the neglected tropical diseases onchocerciasis and lymphatic filariasis. From an anti-infective compound library, the macrolide veterinary antibiotic, tylosin A, was identified as a hit against Wolbachia. This bacterial endosymbiont is required for filarial worm viability and fertility and is a validated target for macrofilaricidal drugs. Medicinal chemistry was undertaken to develop tylosin A analogs with improved oral bioavailability. Two analogs, A-1535469 and A-1574083, were selected. Their efficacy was tested against the gold-standard second-generation tetracycline antibiotics, doxycycline and minocycline, in mouse and gerbil infection models of lymphatic filariasis (Brugia malayi and Litomosoides sigmodontis) and onchocerciasis (Onchocerca ochengi). A 1- or 2-week course of oral A-1535469 or A-1574083 provided >90% Wolbachia depletion from nematodes in infected animals, resulting in a block in embryogenesis and depletion of microfilarial worm loads. The two analogs delivered comparative or superior efficacy compared to a 3- to 4-week course of doxycycline or minocycline. A-1574083 (now called ABBV-4083) was selected for further preclinical testing. Cardiovascular studies in dogs and toxicology studies in rats and dogs revealed no adverse effects at doses (50 mg/kg) that achieved plasma concentrations >10-fold above the efficacious concentration. A-1574083 (ABBV-4083) shows potential as an anti-Wolbachia macrolide with an efficacy, pharmacology, and safety profile that is compatible with a short-term oral drug course for treating lymphatic filariasis and onchocerciasis.

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