The prophylactic and therapeutic efficacy of the broadly active antiviral ribonucleoside N4-Hydroxycytidine (EIDD-1931) in a mouse model of lethal Ebola virus infection

The unprecedented magnitude of the 2013-2016 Ebola virus (EBOV) epidemic in West Africa resulted in over 11 000 deaths and spurred an international public health emergency. A second outbreak in 2018-2020 in DRC resulted in an additional >3400 cases and nearly 2300 deaths (WHO, 2020). These large outbreaks across geographically diverse regions highlight the need for the development of effective oral therapeutic agents that can be easily distributed for self-administration to populations with active disease or at risk of infection. Herein, we report the in vivo efficacy of N⁴-hydroxycytidine (EIDD-1931), a broadly active ribonucleoside analog and the active metabolite of the prodrug EIDD-2801 (molnupiravir), in murine models of lethal EBOV infection. Twice daily oral dosing with EIDD-1931 at 200 mg/kg for 7 days, initiated either with a prophylactic dose 2 h before infection, or as therapeutic treatment starting 6 h post-infection, resulted in 92-100% survival of mice challenged with lethal doses of EBOV, reduced clinical signs of Ebola virus disease (EVD), reduced serum virus titers, and facilitated weight loss recovery. These results support further investigation of molnupiravir as a potential therapeutic or prophylactic treatment for EVD.

Accelerated first-in-human clinical trial of EIDD-2801/MK-4482 (molnupiravir), a ribonucleoside analog with potent antiviral activity against SARS-CoV-2

A recently published article described the safety, tolerability, and pharmacokinetic profile of molnupiravir (Painter et al. 2021), a novel antiviral agent with potent activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19). Here, we report an unprecedented collaboration between sponsor, contract research organization (CRO), and regulatory authorities that enabled accelerated generation of these phase I data, including administration of the first-in-human (FIH) dose of molnupiravir within 5 days of receiving regulatory approval in the United Kingdom (UK). Single and multiple ascending dose (SAD and MAD, respectively) cohorts were dosed in randomized, double-blind, and placebo-controlled fashion, with a 6:2 active-to-placebo ratio in each cohort. A food-effect (FE) cohort included 10 subjects who were randomized to receive drug in the fasted or fed state followed by the fed or fasted state to complete a fed and fasted sequence for each subject. Dose escalation decisions were accelerated and MAD cohorts were initiated prior to completion of all SAD cohorts with the provision that the total daily dose in a MAD cohort would not exceed a dose proven to be safe and well-tolerated in a SAD cohort. Dosing in healthy volunteers was completed for eight single ascending dose (SAD) cohorts, seven multiple ascending dose (MAD) cohorts, and one food-effect (FE) cohort within approximately 16 weeks of initial protocol submission to the Research Ethics Committee (REC) and Medicines and Healthcare products Regulatory Agency (MHRA). Working to standard industry timelines, the FIH study would have taken approximately 46 weeks to complete and 33 weeks to enable phase 2 dosing. Data from this study supported submission of a phase 2/3 clinical trial protocol to the US Food and Drug Administration (FDA) within 8 weeks of initial protocol submission, with FDA comments permitting phase 2 study initiation within two additional weeks. In the setting of a global pandemic, this model of collaboration allows for accelerated generation of clinical data compared to standard processes, without compromising safety.