A Study of Ziresovir (AK0529) in High-risk Adult With Respiratory Syncytial Virus (RSV) Infection.

A Randomized, Double-blind, Two-stage, Placebo-controlled Phase 2b/3 Clinical Study to Evaluate the Efficacy and Safety of Ziresovir (AK0529) in Adult Patients at High Risk for Respiratory Syncytial Virus (RSV) Infection.

Respiratory syncytial virus (RSV) is recognized worldwide as a significant pathogen causing lower respiratory tract infection in infants, the elderly, and immunocompromised patients, which may cause bronchiolitis or pneumonia, and affect the cardiovascular system, central nervous system and the renal system, resulting in hospitalization and death risks in children and also high-risk adults, particularly the elderly. The purpose of this study is to evaluate the efficacy of Ziresovir (AK0529) compared to placebo with respect to the time to resolution of RSV lower respiratory tract disease (LRTD) symptoms.

Inclusion Criteria:

• Aged 18-85 years (inclusive), regardless of gender.
• Diagnosed with RSV infection by antigen or nucleic acid test within 36 hours before first dose.
• Have at least one of the following high-risk conditions for RSV infection: Chronic respiratory disease; heart disease; immunocompromised status; other chronic disease; age ≥65 years.
• Presence of at least one new LRTD symptom or worsening of a pre-existing LRTD symptom (specifically: cough, expectoration, wheezing, shortness of breath), with at least one individual symptom rated as moderate or severe (score 2 or 3 per RiiQ Symptom Scale).
• Time from symptom onset (or worsening of pre-existing symptoms) to first dose ≤5 days. (Onset defined as time of first RSV-related symptom/sign confirmed by investigator; pre-existing symptoms are those due to underlying conditions)

Exclusion Criteria:

• Diagnosed with influenza or COVID-19 infection within 7 days prior to providing informed consent.
• Suspected bacterial co-infection.
• Received any potentially anti-RSV agents (e.g., ribavirin, long-acting interferon) within 5 half-lives prior to the first study dose, or plans to use such agents during the study.
• Received prohibited medications, or plans to use prohibited medications during the study.
• Has a severe or unstable gastrointestinal, hepatic, renal, hematologic disorder, or malignancy.
• Has a known allergy, hypersensitivity, or intolerance to AK0529 or to any excipients in the AK0529 or placebo formulation.
• Female participants with a positive pregnancy test result, or who are breastfeeding.
• Refusal to use effective contraception during the trial period.