Open Orphan plc noted the announcement dated February 17 2022 from Enanta Pharmaceuticals Inc. on positive results from a human challenge study assessing its respiratory syncytial virus ("RSV") antiviral candidate, EDP-938. The results from this human challenge study have been published in TheNew England Journal of Medicine. hVIVO, a subsidiary of Open Orphan, conducted the Phase 2a, double-blind, placebo-controlled trial using its RSV Human Challenge Study Model.

The trial enrolled 178 healthy adult volunteers across two parts, 18-55 years of age, who were intranasally challenged with RSV-A Memphis 37b ("M37b"). Volunteers received either a dose of EDP-938 or placebo for five days after infection, with different dose levels of EDP-938 being assessed. The study demonstrated that both viral load and clinical symptoms were significantly lower in volunteers that received EDP-938 than those that received placebo, with similar safety profiles between placebo and the antiviral regimens.

Importantly, no serious adverse events occurred. RSV is a contagious, common respiratory virus that usually causes mild, cold-like symptoms and affects the respiratory tract of children and at-risk older adults; in severe cases, it can cause pneumonia and other life-threatening breathing difficulties. RSV is a significant public health threat and is one of the leading causes of hospitalisation to at-risk older adults.

hVIVO has two decades of experience and expertise in safely conducting challenge studies across a range of respiratory and infectious disease viruses, including various strains of influenza, RSV, HRV, asthma and malaria, etc.