Enanta begins Phase 2b/3 RSV trial, targets 2027 data

• Enanta Pharmaceuticals announced that the first patient has been dosed in its global Phase 2b/3 RESOLVE trial evaluating zelicapavir for respiratory syncytial virus (RSV) infection in high-risk adults.
• The study will evaluate symptom resolution and hospitalization rates, with at least 200 patients in Phase 2b and approximately 660 expected in Phase 3, following encouraging results from an earlier study.
• Enanta expects topline Phase 2b results from RESOLVE in 2027, alongside data from its pediatric LOTUS trial, as it advances zelicapavir toward potential regulatory approval.

Enanta Pharmaceuticals (NASDAQ:ENTA) announced that the first patient has been dosed in RESOLVE, its global Phase 2b/3 clinical trial of investigational antiviral zelicapavir in adults at high risk of severe outcomes from respiratory syncytial virus infection.

The randomized, double-blind, placebo-controlled study will enroll RSV-positive adult outpatients aged 75 or older or those with chronic obstructive pulmonary disease or congestive heart failure, provided symptoms began no more than three days before enrollment.

Participants will receive 800 milligrams of zelicapavir or placebo orally once daily for seven days, with the primary endpoint measuring time to complete resolution of 13 RSV symptoms and a key secondary endpoint evaluating hospitalization rates.

Enanta expects topline Phase 2b results in 2027 from at least 200 participants, while the Phase 3 portion is planned to enroll approximately 660 patients to further evaluate treatment efficacy and safety.

The earlier Phase 2 RSVHR study showed a 6.7-day improvement in symptom resolution among high-risk adults and RSV-related hospitalization rates of 0% with zelicapavir versus 5% with placebo in the specified subgroup.

Zelicapavir is an investigational RSV N-protein inhibitor with FDA Fast Track designation, and Enanta is also evaluating the drug in its pediatric Phase 2b LOTUS trial, with results from both studies expected in 2027.

Zelicapavir has not been approved for RSV treatment, and the earlier Phase 2 subgroup findings require confirmation in the ongoing RESOLVE trial.