Fexinidazole was co-developed by Sandoz and the non-profit Drugs for Neglected Diseases initiative.

Sleeping sickness, or human African trypanosomiasis (HAT), is a fatal neglected tropical parasitic disease endemic to Africa. It is transmitted by certain species of tsetse flies and occurs in 36 sub-Saharan African countries. About 65 million people in sub-Saharan Africa are at risk. Most infected people live in rural areas and depend on agriculture, fishing, animal husbandry or hunting. Trypanosoma brucei gambiense accounts for more than 98% of reported cases.

The disease begins with fever, headaches, joint pains and itching as the parasite multiplies in subcutaneous tissues, blood and lymph. The parasite then crosses the blood-brain barrier and infects the central nervous system, resulting in more serious symptoms including changes of behavior, confusion, sensory disturbances, poor coordination and changes in the sleep cycle. 

In 2017, 78% of Trypanosoma brucei gambiense sleeping sickness cases were reported in the Democratic Republic of Congo. On a positive note, the number of new cases is declining: 1,447 new cases were reported in 2017 compared to 9,870 cases in 2009 and 2,164 cases in 2016. Treatment is more effective the earlier it is caught. In the past, the treatment has involved an arsenic compound that killed 5% of all patients. Current treatments are now safe and effective, but require hospitalization and injection into the lumbar area, which is a challenge for patients and governments, 

A new drug developed under an unusual R&D model may soon be available for people suffering both phases of sleeping sickness. The European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) has recommended the approval of fexinidazole, the first all-oral treatment for sleeping sickness. The new drug is the result of a 10-year collaboration between the non-profit organization Drugs for Neglected Diseases initiative (DNDi), Sanofi and other African partners.

Fexinidazole is a 5-nitroimidazole derivative that was originally developed by Hoechst (now Sanofi) in the 1980s but abandoned for strategic reasons. DNDi' rediscovered the compound when conducting a search for molecules with anti-parasitic activity as part of a collaboration with the Swiss Tropical and Public Health Institute. DNDi and Sanofi signed a collaboration agreement in 2009 to develop, manufacture and distribute fexinidazole. DNDi would manage the pre-clinical, clinical and pharmaceutical development, while Sanofi would handle the industrial development, registration, production and distribution.

Sanofi submitted the application in December 2017 under a special provision for drugs intended for distribution outside of the EU that allowed the participation of endemic countries (DRC and Uganda) and of the WHO in the evaluation of the fexinidazole regulatory dossier, potentially accelerating approval in these countries.

The pill is taken once per day for 10 days. Importantly, it works both for early-stage infection and the later stage of infection when the parasites have crossed the blood-brain barrier. In the clinical study, fexinidazole showed high efficacy and safety in adults and children 6 years or older and has the potential to eliminate the need for hospitalization.