Respiratory Syncytial Virus InfectionsPhase 2/3NCT07658534
A Study of Ziresovir (AK0529) in High-risk Adult With Respiratory Syncytial Virus (RSV) Infection.
A Phase 2/3 study testing Ziresovir (AK0529) in people with Respiratory Syncytial Virus Infections, run by Shanghai Ark Biopharmaceutical Co., Ltd. at 9 sites in China.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 18 to 85 years
- Conditions the study is for
- Respiratory Syncytial Virus Infections
- What is being tested?
- Ziresovir (AK0529)
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 290 participants
- Where
- 9 sitesChina
- Study dates
- 3 Mar 2026to Jan 2029
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 85 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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)
Who cannot join
- 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.
Trial locations and contacts
9 sites in 1 country. Contact the study team or a site near you to ask about taking part.
9 sites in 1 country
China9 sites, 9 recruiting
- Recruiting
China-Japan Friendship Hospital
Beijing, Beijing Municipality
Bin Cao, Professor, +86-010-84205566, caobin_ben@163.com
- Recruiting
Cangzhou Hospital of Integrated TCM-WM
Cangzhou, Hebei
Li Zhang，Professor, +86 0317-2179231, Zhangli19810210@hotmail.com
- Not yet recruiting
Guangzhou Medical University Panyu Central Hospital
Guangzhou, Guangdong
Yafei Qi, +86 020-34858888, a6598825@163.com
- Not yet recruiting
Zhejiang Hospital
Hangzhou, Zhejiang
Hong Wang, Professor, +86 0571-87987373, hong.wang11@163.com
- Recruiting
The First Affiliated Hospital of Nanyang Medical College
Nanyang, Henan
Yu Zhang，Professor, +86 0377-63328777, zhangyu9896@126.com
- Recruiting
People's Hospital of Rui'an City
Rui’an, Zhejiang
Liang Hong，Professor, +86 0577-5623293, rahoshongliang@163.com
- Recruiting
Taizhou Hospital of Zhejiang Province
Taizhou, Zhejiang
Youzu Xu, Professor, +86-0576-85120120, xuyouzu@sina.com
- Recruiting
Wuhan Sixth Hospital
Wuhan, Hubei
Fajiu Li，Professor, +86 027-82424252, 80670519@qq.com
- Not yet recruiting
Henan Infectious Disease Hospital (The Sixth People's Hospital of Zhengzhou)
Zhengzhou, Henan
Sanjing Li, Professor, +86 0371-60331627, zzlygrsk@163.com
About this study
Official title: 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.
- Conditions
- Respiratory Syncytial Virus Infections
- Being tested
- Ziresovir (AK0529), Placebo
- Keywords
- Ziresovir, RSV, Chronic Respiratory Disease, Heart Disease, The Elderly
- Medical subject headings
- Respiratory Syncytial Virus Infections, Heart Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ziresovir (AK0529)Drug
Active Substance: AK0529 Pharmaceutical Form: Enteric Capsules Route of Administration: Oral
PlaceboDrug
Active Substance: Placebo Pharmaceutical Form: Enteric Capsules Route of Administration: Oral
| Study group | Role | What they receive |
|---|---|---|
| Active drug(200mg) | Experimental | The participants will receive 200 mg AK0529 twice daily for 5 days from D1 to D5. Receives: Drug: Ziresovir (AK0529) |
| Active drug(300mg) | Experimental | The participants will receive 300 mg AK0529 twice daily for 5 days from D1 to D5. Receives: Drug: Ziresovir (AK0529) |
| Placebo | Placebo comparator | The participants will receive placebo of 200 mg, or 300 mg twice daily for 5 days from D1 to D5. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time from first dose to resolution of LRTD symptoms
LRTD symptoms (cough, shortness of breath, wheezing, expectoration) are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
Measured: Up to Day 27
Secondary outcomes (7)
Resolution rates of LRTD symptoms after treatment
LRTD symptoms (cough, shortness of breath, wheezing, expectoration) are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
Measured: Day 3, Day 6, Day 13, Day 27
Time from first dose to resolution of upper respiratory, systemic, and total symptoms
Upper respiratory, systemic, and total symptoms are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
Measured: Up to Day 27
Resolution rate of upper respiratory, systemic, and total symptoms
Upper respiratory, systemic, and total symptoms are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
Measured: Day 3, Day 6, Day 13, Day 27
Change from baseline in RSV viral load (VL)
RSV VL in nasopharyngeal samples from participants will be measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR)
Measured: Day 2 to Day6, Day 13, Day 27
Change from baseline in RiiQ total score and domain scores
RSV symptoms are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
Measured: Day 3, Day 6, Day 13, Day 27
Trough plasma concentration of AK0529
Plasma concentration of AK0529 is reported. This outcome measure is planned to be analyzed for specified arm only. In this outcome measure, only those time points for which individual participants had data are reported.
Measured: Day 5
Incidence and severity of treatment-emergent AEs (TEAEs), SAEs, and other AEs
An adverse events (AEs) is any untoward medical occurrence in a clinical study participant administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. Any clinically significant physical examinations, vital signs, clinical laboratory tests (including biochemistry, hematology, cardiac enzymes and urine analysis), 12-lead electrocardiograms (ECGs) and spirometry results were recorded as adverse events. Any AE which occurred at or after the initial administration of study intervention through the end of the study (that is, Day 27) was considered treatment-emergent. A Serious Adverse Events (SAEs) is any adverse event that results in death, is life-threatening, requires hospitalization, causes persistent disability, or results in a congenital anomaly. The severity of AEs/ SAEs is categorized by CTCAE6.0.
Measured: Up to Day 27
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Jun 2026
- Study start3 Mar 2026
- Primary completionDec 2028 (estimated)
- Study completionJan 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Respiratory Syncytial Virus InfectionsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This clinical study is a randomized placebo-controlled parallel multi-center phase 2b/3 trial.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 290 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Shanghai Ark Biopharmaceutical Co., Ltd.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07658534
- Sponsor's protocol ID
- AK0529-2009
- Status last verified
- Mar 2026
- First submitted
- 30 Mar 2026
- Last updated
- 22 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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.
- ClinicalTrials.gov ID
- NCT07658534
- Acronym / sponsor ID
- AK0529-2009
- Conditions
- Respiratory Syncytial Virus Infections
- Keywords
- Ziresovir, RSV, Chronic Respiratory Disease, Heart Disease, The Elderly
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 290 participants (estimated)
- Lead sponsor
- Shanghai Ark Biopharmaceutical Co., Ltd.Industry (pharma, biotech, devices)
- Study start
- 3 Mar 2026 (actual)
- Primary completion
- Dec 2028 (estimated)
- Study completion
- Jan 2029 (estimated)
- First posted
- 22 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
- Model description
- This clinical study is a randomized placebo-controlled parallel multi-center phase 2b/3 trial.
| Arm | Type | Receives |
|---|---|---|
| Active drug(200mg) | Experimental | Drug: Ziresovir (AK0529)The participants will receive 200 mg AK0529 twice daily for 5 days from D1 to D5. |
| Active drug(300mg) | Experimental | Drug: Ziresovir (AK0529)The participants will receive 300 mg AK0529 twice daily for 5 days from D1 to D5. |
| Placebo | Placebo comparator | Drug: PlaceboThe participants will receive placebo of 200 mg, or 300 mg twice daily for 5 days from D1 to D5. |
Who may qualify
- Ages
- 18 to 85 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- 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)
Key exclusion criteria (8 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Ziresovir (AK0529)Active Substance: AK0529 Pharmaceutical Form: Enteric Capsules Route of Administration: Oral | Drug | Active drug(200mg), Active drug(300mg) |
| PlaceboActive Substance: Placebo Pharmaceutical Form: Enteric Capsules Route of Administration: Oral | Drug | Placebo |
Primary outcome
Time from first dose to resolution of LRTD symptoms
Time frame: Up to Day 27
LRTD symptoms (cough, shortness of breath, wheezing, expectoration) are assessed by the RiiQ symptom scale, which includes 13 symptoms: 2 upper respiratory (stuffy nose, sore throat), 4 lower respiratory (cough, expectoration, wheezing, shortness of breath), and 7 systemic (feeling feverish, headache, body aches/pains, neck pain, trouble sleeping, tiredness, poor appetite). Each symptom is scored as None (0), Mild (1), Moderate (2), or Severe (3), with a total score range of 0-39.
7 secondary outcomes
Resolution rates of LRTD symptoms after treatment
Time frame: Day 3, Day 6, Day 13, Day 27
Time from first dose to resolution of upper respiratory, systemic, and total symptoms
Time frame: Up to Day 27
Resolution rate of upper respiratory, systemic, and total symptoms
Time frame: Day 3, Day 6, Day 13, Day 27
Change from baseline in RSV viral load (VL)
Time frame: Day 2 to Day6, Day 13, Day 27
Change from baseline in RiiQ total score and domain scores
Time frame: Day 3, Day 6, Day 13, Day 27
Trough plasma concentration of AK0529
Time frame: Day 5
Incidence and severity of treatment-emergent AEs (TEAEs), SAEs, and other AEs
Time frame: Up to Day 27
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Jun 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
9 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing Ziresovir (AK0529) in people with Respiratory Syncytial Virus Infections, run by Shanghai Ark Biopharmaceutical Co., Ltd. at 9 sites in China.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 22 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 9 sites in China. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Chao Yu, Mater (+86 021-50681677, chao.yu@arkbiosciences.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time from first dose to resolution of LRTD symptoms (time frame: Up to Day 27). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Jun 2026.