Enanta Pharmaceuticals Announces Positive Data From a Phase 1 Clinical Study of EDP-323, an Oral, L-Protein Inhibitor in Development for the Treatment of Respiratory Syncytial Virus

Enanta Pharmaceuticals, Inc. (NASDAQ: ENTA), a clinical-stage biotechnology company dedicated to creating novel, small molecule drugs for viral infections, today announced positive topline data from a Phase 1 study assessing the safety, tolerability, and pharmacokinetics (PK) of orally administered single ascending doses (SAD) and multiple ascending doses (MAD) of EDP-323 in healthy adult subjects. EDP-323, which received Fast Track designation from the U.S. Food and Drug Administration (FDA), is a novel L-protein inhibitor in development as a once-daily oral treatment for respiratory syncytial virus (RSV). Data from the Phase 1 study demonstrated favorable safety, tolerability, and PK supportive of once-daily dosing, with good exposure multiples, thereby supporting further clinical advancement of EDP-323.

“With the significant unmet need for effective antivirals to treat patients with RSV, we are pleased to report positive Phase 1 results for EDP-323. These data demonstrate that EDP-323 was generally safe and well-tolerated up to 800 mg, with a PK profile supportive of once-daily dosing and strong exposure multiples across both RSV A and B strains” said Scott T. Rottinghaus, M.D., Senior Vice President and Chief Medical Officer of Enanta Pharmaceuticals. “EDP-323 is an inhibitor of the L-protein, a distinct mechanism of action from EDP-938, our potent N-protein inhibitor, which allows the potential for each compound to be used alone or in combination therapy. With these positive results, we are advancing EDP-323 into a human challenge study by early fourth quarter of 2023 and we look forward to continuing to build upon our leadership in the RSV field.”

This first-in-human, randomized, double-blind, placebo-controlled, Phase 1 study enrolled healthy volunteers to evaluate the safety, tolerability, and PK of oral EDP-323 for seven days. The study evaluated a range of single and multiple doses in fasted and fed states. The SAD phase enrolled a total of six dose cohorts (doses ranging from 50 to 800 mg), one of which was a two-part food effect (FE) cohort. The MAD phase enrolled four dose cohorts (doses ranging from 200 to 800 mg). All SAD and MAD cohorts enrolled eight participants who were randomized to receive EDP-323 or placebo in a 3:1 ratio. The 200 mg SAD/FE cohort enrolled ten subjects randomized in a 4:1 ratio.