Enanta Pharmaceuticals has commenced a Phase IIb clinical trial of EDP-938 in adult patients with acute respiratory syncytial virus (RSV) infection.

The double-blind, randomised, multicentre, international, placebo-controlled trial will assess the safety and efficacy of EDP-938 versus a placebo on RSV infection. 

It will also assess the impact of EDP-938 on disease progression by analysing clinical symptoms. 

The trial will enrol nearly 180 subjects to receive 800mg EDP-938 or a placebo for five days and will subsequently be monitored for 28 days. 

Adult RSV patients in the non-hospital setting with up to 72 hours of respiratory tract infection symptoms will be part of the trial.

Participants will be regarded as at an increased risk for complications following RSV infection if they have a minimum of one of the risk factors: aged 65 years or above, chronic obstructive pulmonary disease (COPD) or asthma, or congestive heart failure.

The time to RSV lower respiratory tract disease symptoms resolution as evaluated by the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) symptom scale through to day 33 is the trial’s primary endpoint.

Further clinical efficacy measures, as well as antiviral activity versus a placebo, pharmacokinetics, and safety of EDP-938 will be included as secondary endpoints.

A new inhibitor of N-protein, EDP-938 is in the developmental stage to treat RSV infection. 

It preserved antiviral potency across all clinical isolates analysed in preclinical studies and was found to function against viral variants that are resistant to other mechanisms. 

Enanta Pharmaceuticals president and CEO Jay Luly said: “In previous clinical studies, EDP-938 significantly improved the percentage of people with undetectable RSV RNA at the end of treatment, consistent with inhibiting viral replication. 

“Additionally, EDP-938 has a favourable and consistent safety profile in approximately 500 people exposed to date.”

In August this year, the company reported positive topline data from a Phase I trial of oral antiviral, EDP-235, in healthy adults to potentially treat Covid-19.