Enanta Pharmaceuticals has dosed the first participant in its Phase I clinical trial of EDP-323 to potentially treat respiratory syncytial virus (RSV) infection.

The first-in-human, double-blind, randomised, placebo-controlled trial will analyse the safety, tolerability and pharmacokinetics of EDP-323

It will have a single-ascending dose (SAD) portion with a two-part food-effect (FE) cohort and a multiple-ascending dose (MAD) portion.

Nearly 80 healthy subjects aged 18 to 65 years will be enrolled in the trial.

The SAD and MAD cohorts will enrol eight subjects who will be categorised into a 3:1 ratio to receive either EDP-323 or placebo.

A total of ten participants will be randomised in a 4:1 ratio in the SAD/FE cohort.

EDP-323 is a new oral inhibitor of L-protein.

According to in vitro findings, EDP-323 offered a substantial decline in replication of RSV with picomolar potency in primary human bronchial epithelial cells against RSV A and B.

A consistent potency across various RSV clinical isolates in several cell types was also reported.

EDP-323 was also linked to dose-dependent viral load decline in the lung, decreased lung immunopathology and a reduction in pro-inflammatory cytokines, including IFNγ, TNFα, and IL1β, in a mouse model of RSV infection.

Enanta Pharmaceuticals senior vice-president and chief medical officer Scott Rottinghaus said: “This first-in-human study of EDP-323, our selective, direct-acting antiviral specifically targeting the RSV L-protein, is an important milestone for Enanta as we mark the continued expansion of our clinical RSV portfolio.

“Compelling preclinical data show that EDP-323 potently blocks RSV replication and pathology across all RSV genotypes positioning EDP-323 as a potentially best-in-class potent oral antiviral treatment for RSV.

“EDP-323 could be used as a monotherapy or in combination with other RSV mechanisms, such as EDP-938, to broaden the addressable patient populations or treatment windows.”