RSV InfectionPhase 2NCT07482657
A Phase 2 Study to Investigate the Efficacy and Safety of Zelicapavir in Participants Aged ≥28 Days to ≤36 Months of Age Infected With Respiratory Syncytial Virus
A Phase 2 study testing zelicapavir in people with RSV Infection and RSV, run by Enanta Pharmaceuticals, Inc at 8 sites in Thailand.
Trial summary
Zelicapavir is a novel, orally administered, nonfusion replication inhibitor of RSV. It is being investigated in this Phase 2 study (EDP 938-203) as a potential treatment for RSV infection in both hospitalized and non-hospitalized children aged ≥28 days to ≤36 months who present with symptomatic RSV infection. Read more about this study
- Who is it for?
- Ages 28 days to 36 months
- Conditions the study is for
- RSV Infection, RSV, Respiratory Syncytial Virus (RSV)
- What is being tested?
- zelicapavir
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 150 participants
- Where
- 8 sitesThailand
- Study dates
- 9 Jul 2026to Dec 2026
- Phase
- Phase 2
- 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 28 days to 36 months
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Participants diagnosed with RSV infection using an approved diagnostic assay, without known and/or documented coinfection with SARS-CoV-2 or influenza
- Participant has signs of RSV infection with onset ≤3 days (72 hours) at the time of randomization
- In the Investigator's opinion, the participant's caregiver understands and is able to comply with protocol requirements, instructions, and restrictions, and the participant is likely to complete the study as planned. The caregiver(s) should be of legal age.
Who cannot join
- Participant has any condition that in the opinion of the Investigator would interfere with the evaluation of the study drug or participant safety.
- Participant has underlying immune deficiency. Participants with immunoglobulin A deficiency are not excluded.
- Participant has had major surgery within 6 weeks prior to randomization or has major surgery planned during the course of the study.
- Participant is currently taking either chronically or has taken within 7 days prior to randomization, or is anticipated to receive during the course of the study, systemic medications that are known to cause immunosuppression other than corticosteroids for >5 days.
- Participant has received an investigational agent within the last 30 days or 5 half-lives of the investigational agent, whichever is longer.
Trial locations and contacts
8 sites in 1 country. Contact the study team or a site near you to ask about taking part.
8 sites in 1 country
Thailand8 sites, 8 recruiting
- Recruiting
Center of Excellence for Pediatric Infectious Diseases and Vaccines Faculty of Medicine, Chulalongkorn University (CE-PID)
Bangkok, 10330
Napaporn Chantasrisawad, +66 2256 4930, napaporn.cha@chula.ac.th
Napaporn Chantasrisawad, MD
- Recruiting
Nakornping Hospital
Chiang Mai, 50180
Rujirek Kamolrattana, +66 5399 9000, rujirek71@gmail.com
Rujirek Kamolrattana, MD
- Recruiting
Maharaj Nakorn Chiang Mai Hospital
Chiang Mai, 50200
Tavitiya Sudjaritruk, +66 05393 6150, tavitiya.s@cmu.ac.th
Tavitiya Sudjaritruk, MD
- Recruiting
Chiangrai Prachanukroh Hospital
Chiang Rai, 57000
Suchada Ruenglerdpong, +66 5391 0600, suchada.lan.rueng@gmail.com
Suchada Ruenglerdpong, MD
- Recruiting
Khon Kaen Hospital
Khon Kaen, 40000
Ussanee Srirompotong, +66 4300 9900, u.srirompotong@gmail.com
Ussanee Srirompotong, MD
- Recruiting
Lampang Hospital
Lampang, 52000
Pakawadi Vuttipittayamongkol, +66 5423 7400, Pakawadi@hotmail.com
Pakawadi Vuttipittayamongkol, MD
- Recruiting
Lamphun Hospital
Lamphun, 51000
Sangravee Juhong, +66 53 569 100, Sangraveejuhong@gmail.com
Sangravee Juhong, MD
- Recruiting
Maha Sarakham Hospital
Maha Sarakham, 44000
Supawan Papakhee, +66 4372 3355, supawan.pa@chula.ac.th
Supawan Papakhee, MD
About this study
Official title: Phase 2, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy and Safety of Zelicapavir in Participants ≥28 Days to ≤36 Months of Age Infected With Respiratory Syncytial Virus
Zelicapavir is a novel, orally administered, nonfusion replication inhibitor of RSV. It is being investigated in this Phase 2 study (EDP 938-203) as a potential treatment for RSV infection in both hospitalized and non-hospitalized children aged ≥28 days to ≤36 months who present with symptomatic RSV infection.
- Conditions
- RSV Infection, RSV, Respiratory Syncytial Virus (RSV)
- Being tested
- zelicapavir, Placebo
- Keywords
- RSV, children, Respiratory Syncytial Virus, Pediatric study
- Medical subject headings
- Respiratory Syncytial Virus Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
zelicapavirDrug
Oral suspension
PlaceboDrug
Placebo oral suspension to match zelicapavir
| Study group | Role | What they receive |
|---|---|---|
| zelicapavir | Experimental | zelicapavir, oral suspension, once daily for 7 days Receives: Drug: zelicapavir |
| Placebo | Placebo comparator | Matching placebo, orally, once daily for 7 days Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time to complete resolution of clinical signs of RSV as measured by RESOLVE-P
Measured: Day 1 through Day 14
Secondary outcomes (10)
Time to sustained resolution of clinical signs of RSV as measured by RESOLVE-P
Measured: Day 1 through Day 14
Change in severity of clinical signs of RSV from Baseline to D7 as measured by RESOLVE-P
Measured: Day 1 through Day 7
Proportion of participants with Lower Respiratory Tract Infection (LRTI)
Measured: D1 through D14
Change in severity of RSV from Baseline to D7 and D14
Measured: Baseline to D7 and D14
Proportion of outpatient participants who were hospitalized due to RSV or other causes during the study period
Measured: Day 1 through Day 35
Change in RSV viral load as measured by RT-qPCR
Measured: Baseline to D7
Proportion of participants with viral load Target Not Detected (TND)
Measured: Day 4, Day 7 and Day 14
Time to viral load TND
Measured: Day 1 through Day 14
Plasma PK Concentrations of zelicapavir
Measured: Up to Day 7
Safety as measured by frequency of adverse events (AEs)
Measured: Up to Day 35
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Mar 2026
- Study start9 Jul 2026
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for RSV InfectionStudies 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
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 150 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Enanta Pharmaceuticals, Inc
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- PENTA Foundation, AMS-PHPT Research Collaboration, Chiang Mai University
- Responsible party
- Sponsor
- Investigators
- Enanta Pharmaceuticals, Inc, Study director, Enanta Pharmaceuticals, Inc
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07482657
- Sponsor's protocol ID
- EDP 938-203
- Status last verified
- Jul 2026
- First submitted
- 16 Mar 2026
- Last updated
- 20 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 20 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Phase 2, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy and Safety of Zelicapavir in Participants ≥28 Days to ≤36 Months of Age Infected With Respiratory Syncytial Virus
- ClinicalTrials.gov ID
- NCT07482657
- Acronym / sponsor ID
- EDP 938-203
- Conditions
- RSV Infection, RSV, Respiratory Syncytial Virus (RSV)
- Keywords
- RSV, children, Respiratory Syncytial Virus, Pediatric study
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 150 participants (estimated)
- Lead sponsor
- Enanta Pharmaceuticals, IncIndustry (pharma, biotech, devices)
- Collaborators
- PENTA Foundation, AMS-PHPT Research Collaboration, Chiang Mai University
- Study start
- 9 Jul 2026 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 19 Mar 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.
Zelicapavir is a novel, orally administered, nonfusion replication inhibitor of RSV. It is being investigated in this Phase 2 study (EDP 938-203) as a potential treatment for RSV infection in both hospitalized and non-hospitalized children aged ≥28 days to ≤36 months who present with symptomatic RSV infection.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| zelicapavir | Experimental | Drug: zelicapavirzelicapavir, oral suspension, once daily for 7 days |
| Placebo | Placebo comparator | Drug: PlaceboMatching placebo, orally, once daily for 7 days |
Who may qualify
- Ages
- 28 days to 36 months
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (3 listed)
- Participants diagnosed with RSV infection using an approved diagnostic assay, without known and/or documented coinfection with SARS-CoV-2 or influenza
- Participant has signs of RSV infection with onset ≤3 days (72 hours) at the time of randomization
- In the Investigator's opinion, the participant's caregiver understands and is able to comply with protocol requirements, instructions, and restrictions, and the participant is likely to complete the study as planned. The caregiver(s) should be of legal age.
Key exclusion criteria (5 listed)
- Participant has any condition that in the opinion of the Investigator would interfere with the evaluation of the study drug or participant safety.
- Participant has underlying immune deficiency. Participants with immunoglobulin A deficiency are not excluded.
- Participant has had major surgery within 6 weeks prior to randomization or has major surgery planned during the course of the study.
- Participant is currently taking either chronically or has taken within 7 days prior to randomization, or is anticipated to receive during the course of the study, systemic medications that are known to cause immunosuppression other than corticosteroids for >5 days.
- Participant has received an investigational agent within the last 30 days or 5 half-lives of the investigational agent, whichever is longer.
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 |
|---|---|---|
| zelicapavirOral suspension | Drug | zelicapavir |
| PlaceboPlacebo oral suspension to match zelicapavir | Drug | Placebo |
Primary outcome
Time to complete resolution of clinical signs of RSV as measured by RESOLVE-P
Time frame: Day 1 through Day 14
10 secondary outcomes
Time to sustained resolution of clinical signs of RSV as measured by RESOLVE-P
Time frame: Day 1 through Day 14
Change in severity of clinical signs of RSV from Baseline to D7 as measured by RESOLVE-P
Time frame: Day 1 through Day 7
Proportion of participants with Lower Respiratory Tract Infection (LRTI)
Time frame: D1 through D14
Change in severity of RSV from Baseline to D7 and D14
Time frame: Baseline to D7 and D14
Proportion of outpatient participants who were hospitalized due to RSV or other causes during the study period
Time frame: Day 1 through Day 35
Change in RSV viral load as measured by RT-qPCR
Time frame: Baseline to D7
Proportion of participants with viral load Target Not Detected (TND)
Time frame: Day 4, Day 7 and Day 14
Time to viral load TND
Time frame: Day 1 through Day 14
Plasma PK Concentrations of zelicapavir
Time frame: Up to Day 7
Safety as measured by frequency of adverse events (AEs)
Time frame: Up to Day 35
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 20 Jul 2026.
- Individual participant dataSharing planned: No
Related trials for RSV Infection
Active, not recruitingPhase 3
A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus Given to Chinese Adults 18 to 59 Years of Age at Increased Risk of Respiratory Syncytial Virus Disease
Respiratory Syncytial Virus Infections
Active, not recruitingPhase 1
A Phase 1 Study to Evaluate JCXH-108, an mRNA-based Vaccine Against RSV
Respiratory Syncytial Virus (RSV), Infectious Disease
Not yet recruitingPhase 3
A Study to Evaluate Efficacy, Immunogenicity and Safety of a Recombinant Respiratory Syncytial Virus Vaccine in Older Adults Aged 60 Years and Older
Respiratory Syncytial Virus (RSV), Respiratory Syncytial Virus (RSV) Infection
RecruitingObservational study
Clinical Outcomes and Pharmacotherapy Effectiveness in the VA Health Care System (COPE-VA)
COVID-19, SARS-CoV-2 Infection, RSV
RecruitingPhase 2/3
A Study to Investigate the Efficacy and Safety of Zelicapavir Compared With Placebo in Adults With RSV Who Are at High Risk for Severe Disease
RSV
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.
Enanta Pharmaceuticals, Inc study director
Enanta Pharmaceuticals, Inc
8 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing zelicapavir in people with RSV Infection and RSV, run by Enanta Pharmaceuticals, Inc at 8 sites in Thailand.
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 3 inclusion and 5 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 20 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 8 sites in Thailand. 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 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.
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 Enanta Pharmaceuticals, Inc (617 607-0800, charris@enanta.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time to complete resolution of clinical signs of RSV as measured by RESOLVE-P (time frame: Day 1 through Day 14). 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 20 Jul 2026.