FDA Greenlights Ziresovir Trial for Infants

Shanghai Ark Biopharmaceutical (ArkBio) has secured FDA approval to initiate a Phase II clinical trial for its antiviral drug, ziresovir (AK0529). This trial focuses on treating infants suffering from severe respiratory syncytial virus (RSV) infections. The study will be randomized, multi-center, placebo-controlled, and double-blind, specifically targeting infants in the pediatric intensive care unit (PICU) who have urgent medical needs.

Ziresovir has previously demonstrated positive results in a Phase III clinical trial conducted in China involving children aged one to 24 months. The company reported that the drug successfully reduced viral load, shortened respiratory symptom duration, and lowered the risk of recurrent wheezing and asthma over a 24-month follow-up period. In 2025, the World Health Organization recognized ziresovir in its report on RSV therapeutics.

The upcoming Phase II trial in the US is designed to further examine ziresovir's clinical effectiveness in hospitalized infants. Key metrics will include the duration of oxygen therapy and sustained recovery time. ArkBio views this trial as a significant milestone in the global development of ziresovir, a therapy developed for respiratory, lung, and pediatric diseases. The company also has other ongoing developments, including AK3280 for idiopathic pulmonary fibrosis and the approved ADHD therapy AK0901 in China.