Nifurtimox and benznidazole are currently the only treatments available for Chagas disease, but concerns about their safety and tolerability mean that alternative treatments, or treatment regimens, are necessary, especially for adult patients. Pre-clinical results with fexinidazole showed that the safety profile and activity in acute and chronic animal models of disease support its clinical evaluation in patients.

In July 2014, the Phase II PoC trial started in Bolivia, to determine whether at least one of six dosing regimens of fexinidazole administered orally at either 1200mg/day or 1800mg/day over two, four, or eight weeks (longer period of administration than that of HAT Phase II/III study) are efficacious and safe compared to placebo in clearing T. cruzi parasitemia in adult patients with chronic Chagas disease.

After recruiting 47 participants by October 2014, some safety and tolerability issues were noticed. DNDi, the investigator teams and the data safety committee reviewed all data and agreed to conclude the trial without inclusion of additional participants. The safety review did not identify the same frequency or severity of adverse events for other fexinidazole indications.