Ziresovir Shows Promise in Alleviating Bronchiolitis Symptoms in Hospitalized Infants with RSV: Study

The researchers found that treatment with Ziresovir, an antiviral medication, significantly alleviated the signs and symptoms of bronchiolitis in infants and young children hospitalized with RSV infection, with no safety concerns reported.

Respiratory syncytial virus (RSV) is a major cause of serious illness in infants, and currently, there is no effective treatment available. However, results from a phase 2 trial indicate that ziresovir may be an effective option for treating infants hospitalized with RSV infection.

Against the above background, Xin Ni, Beijing Children’s Hospital, Beijing, China, and colleagues conducted a phase 3, multicenter, double-blind, randomized, placebo-controlled trial in China. The researchers enrolled participants aged 1 to 24 months hospitalized with RSV infection. They were randomly assigned in a 2:1 ratio to receive either ziresovir (doses ranging from 10 to 40 mg based on body weight) or a placebo, administered twice daily for five days.

The primary endpoint was the change in the Wang bronchiolitis clinical score from baseline to day three (defined as 48 hours after the first dose), with total scores ranging from 0 to 12, where higher scores indicated greater severity of symptoms. The intention-to-treat population included all participants with confirmed RSV infection who received at least one dose of either ziresovir or placebo, while the safety population encompassed all participants who received at least one dose of the treatment or placebo.

The following were the key findings of the study:

• The intention-to-treat population included 244 participants, and the safety population included 302.
• The reduction from baseline in the Wang bronchiolitis clinical score on day 3 was significantly greater with ziresovir than with placebo (−3.4 points versus −2.7 points).
• The reduction in the RSV viral load at day 5 was greater in the ziresovir group than in the placebo group (−2.5 versus −1.9 log10 copies per milliliter).
• Improvements were observed in prespecified subgroups, including participants with a baseline bronchiolitis score of at least eight and those six months of age or younger.
• The incidence of adverse events related to the drug or placebo was 16% with ziresovir and 13% with placebo.
• The most common adverse events that were assessed by the investigator as being related to the drug or placebo were diarrhea (in 4% and 2% of the participants, respectively), an elevated liver-enzyme level (in 3% and 3%, respectively), and rash (in 2% and 1%).
• Resistance-associated mutations were identified in 15 participants (9%) in the ziresovir group.

"We found that ziresovir treatment reduced signs and symptoms of bronchiolitis in infants and young children hospitalized with RSV infection and there were no safety concerns," the researchers concluded.

Reference:

Zhao S, et al "Ziresovir in hospitalized infants with respiratory syncytial virus infection" N Engl J Med 2024; DOI: 10.1056/NEJMoa2313551.