Oral RSV Antiviral Eases Symptoms Without Meeting Main Trial Goal
In a phase 2 study, oral zelicapavir reduced the time to complete and sustained RSV symptom resolution by as much as one week among high-risk adults. However, the investigational once-daily N-protein inhibitor did not improve the primary endpoint of time to lower respiratory tract symptoms becoming mild or absent. Enanta is now considering endpoints for a phase 3 trial.
Zelicapavir is an experimental oral drug taken once daily. It aims at the RSV N-protein, a viral component, to block the virus from reproducing. It is not approved; Enanta is still developing it.
In a phase 2 study among high-risk adults, the drug missed its main goal: shortening the time until lower respiratory symptoms were mild or gone. Yet it cut the time to full, lasting symptom relief by up to seven days. Enanta is weighing phase 3 endpoints.
If later trials confirm benefit, a once-daily oral option could appeal to high-risk adults and clinicians. Faster symptom relief may reduce illness burden for patients and caregivers. But because the primary endpoint was missed and approval is uncertain, any public health effect may remain limited until phase 3 clarifies meaningful benefits and safety.