High doses of favipiravir in two men survivors of Ebola virus disease carrying Ebola virus in semen in Guinea

BACKGROUND: Persistence of Ebola virus (EBOV) in semen remains of deep concern, as sexual transmission of EBOV seems plausible up to 6 months after acute phase of Ebola virus disease (EVD). Favipiravir, a broad spectrum antiviral product, has been evaluated in reducing EVD mortality in Guinea in 2014–2015 in the JIKI trial, the pharmacokinetic results of which suggest that an increase of dose might be necessary to achieve a therapeutically relevant exposure. In FORCE trial, we aimed at evaluating the tolerance and activity of high doses of favipiravir in male EVD survivors with EBOV RNA detection in semen in Guinea. CASE: In 2016, we launched a phase IIa open-labeled multicenter dose escalation study. Male survivors of EVD with EBOV RT-PCR positive on semen received a loading dose of 2400 mg BID of favipiravir on day 1 then a maintenance dose of 1800 mg BID from day 2–14. The primary outcome was the tolerance, assessed daily during period treatment and up to day 90. Unfortunately only two participants were included and the trial was stopped for lack of recruitment. No clinical adverse event of grade 3/4 was reported for both patients. One patient experienced a grade 3 hypocalcemia at day 10 and 14. CONCLUSIONS: High doses of favipiravir were well tolerated in these two participants. Better characterized tolerance and pharmacokinetics of high doses of favipiravir are of utmost importance considering that favipiravir is a candidate treatment for a variety of emerging severe viral diseases with poor prognosis.