Efficacy and Safety of Fosmidomycin–Piperaquine as Nonartemisinin-Based Combination Therapy for Uncomplicated Falciparum Malaria: A Single-Arm, Age De-escalation Proof-of-Concept Study in Gabon

Background: Fosmidomycin-piperaquine is being developed as nonartemisinin-based combination therapy to meet the challenge of emerging artemisinin resistance. Methods: The study was a phase 2, single-arm, proof-of-concept study of the efficacy, tolerability, and safety of fosmidomycin-piperaquine for the treatment of uncomplicated Plasmodium falciparum monoinfection in Gabon. Adults and children of both sexes with initial parasite counts between 1000 and 150000/µL received oral treatment with fosmidomycin (twice daily doses of 30 mg/kg) and piperaquine (once daily dose of 16 mg/kg) for 3 days and followed-up for 63 days. The primary efficacy endpoint was the per-protocol polymerase chain reaction (PCR)-corrected day 28 adequate clinical and parasitological response (ACPR). Results: One hundred patients were enrolled. The PCR-corrected day 28 ACPR rate was 83/83, or 100% (95% confidence interval, 96-100). Fourteen patients had asexual parasitaemia between day 28 and day 63; all were typed by PCR as new infections. Fosmidomycin-piperaquine therapy led to rapid parasite clearance (median, 36 hours; interquartile range [IQR], 6-60) and fever clearance time (median, 12 hours; IQR, 6-48). The electrocardiogram assessments showed 2 patients with prolonged QT interval >500 msec following study drug administration. The majority of adverse events affected the gastrointestinal and respiratory tracts and were transient and mild to moderate in severity. Conclusions: This is the first report of the use of the combination fosmidomycin-piperaquine. The combination appeared to have high efficacy and be safe and well tolerated despite observed transient changes in electrocardiogram with prolongation of the QT interval. Clinical Trials Registration. NCT02198807.