Fexinidazole

Human African trypanosomiasis (HAT, also colloquially referred to as sleeping sickness), caused by T. brucei gambiense and T. brucei rhodesiense, remains a moderate risk (>1/10,000 inhabitants per year in endemic areas) despite focussed control efforts. Transmitted by the bite of an infected tsetse fly, HAT is biphasic with a first (hemolymphatic) stage that progresses to a second (meningoencephalitic) stage in which patients experience progressively worsening neurological symptoms and eventually die if left untreated. Historical treatment options for meningoencephalitic HAT include melarsoprol, eflornithine, and nifurtimox/eflornithine combination therapy (NECT), though melarsoprol is highly toxic and each treatment requires lengthy infusions that are difficult to administer in resource-limited settings. Fexinidazole, which was originally developed in the 1970s/80s by Hoechst AG and subsequently rediscovered through the Drugs for Neglected Diseases Initiative (DNDi) in 2005, is the first all-oral treatment for first and second stage HAT caused by T. brucei gambiense.

Fexinidazole received a positive opinion from the European Medicines Agency (EMA) in November 2018 and was approved by the FDA on July 16, 2021. It is currently marketed by Sanofi-Aventis.

Fexinidazole is a nitroimidazole indicated for the treatment of both first-stage (hemolymphatic) and second-stage (meningoencephalitic) Trypanosoma brucei gambiense human African trypanosomiasis (HAT) in patients 6 years of age and older weighing at least 20 kg.

Due to the decreased efficacy observed in patients with severe second stage HAT (cerebrospinal fluid white blood cell count (CSF-WBC) >100 cells/μL), fexinidazole should only be used in these patients if there are no other available treatment options.