The Past Need Not Be Prologue: Recommendations for Testing and Positioning the Most-Promising Medical Countermeasures for the Next Outbreak of Ebola Virus Infection

Abstract

Background: The 2013-2016 outbreak of Ebola virus disease (EVD) in West Africa led to unprecedented morbidity and mortality. Although different classes of putative antiviral agents with supportive preclinical data were available for testing, and although several attempts to perform meaningful evaluation of these agents were undertaken during the epidemic, different research methods, a lack of appropriate controls in most studies, and formidable logistical challenges to completion of studies under field conditions hampered the success of these efforts. Ultimately only 1 randomized, placebo-controlled clinical trial (PREVAIL II) was performed in this setting, and, owing to a decrease in the number of new cases available for study, it, too, ended prior to reaching definitive results. Retrospective review of the lessons learned from this outbreak argues strongly for the need for much better preparedness in terms of selecting the trial design and drug(s) for use during the next outbreak.

Methods: Using recent data provided by representatives from the pharmaceutical industry, clinical and laboratory subject matter experts from the National Institute of Allergy and Infectious Diseases, other US government agencies, and academic partners were consulted regarding the current state of knowledge about several lead compounds with putative activity against EVD. Consensus was sought on recommendations concerning the most promising treatment strategies against EVD that should be studied in the context of a randomized clinical trial during the next outbreak.

Results: Four compounds from 2 different classes (monoclonal antibody [mAb] cocktails and direct-acting antiviral agents [DAAs]) were highlighted as lead candidates, limitations in the current knowledge base about these drug classes were reviewed, and recommendations about the optimal clinical research design for studying combinations of these different agents were made.

Conclusions: Although achieving the desired sample size could be challenging, a randomized, controlled clinical trial based on a combination strategy of a mAb with a DAA was recommended as the most appropriate clinical trial design to be undertaken during the next outbreak of EVD.