A Phase 2/3 interventional study of zelicapavir and Placebo in RSV, sponsored by Enanta Pharmaceuticals, Inc. Recruiting at 4 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Enanta Pharmaceuticals, Inc · Phase 2/3, Interventional, and Treatment
Among 1,277 studies in Pulmonary Disease, Chronic Obstructive with a site in United States — 137 open to participants now, 171 under way, 20 of them phase 3. Pulmonary Disease, Chronic Obstructive · United States.
Among the 1,277 studies in Pulmonary Disease, Chronic Obstructive with a site in United States, this one is the 133rd largest by planned enrollment of the 1,036 interventional ones that give a count, is one of 37 that started in 2026, is one of 12 in phase 2/3, reaches primary completion later than 141 of the 170 other live ones, and was the 1,276th registered.
5,520 studies on the registry are indexed under Pulmonary Disease, Chronic Obstructive; 856 are open to participants now.
Browse Pulmonary Disease, Chronic Obstructive studies →137 of the 1,277 studies in Pulmonary Disease, Chronic Obstructive with a site in United States are open now. Recruiting first, the newest first:
Merck Sharp & Dohme LLC · Sites in United States
Regeneron Pharmaceuticals · Sites in United States
GlaxoSmithKline · Sites in United States
GlaxoSmithKline · Sites in United States, Japan
Connect Biopharm LLC · Sites in United States
A study can be open while its sites in United States have not opened yet or have stopped. Only those recruiting at a site in United States →
Of the 555 Pulmonary Disease, Chronic Obstructive studies recruiting now, 305 (55%) set no upper age limit and 82 (15%) stop at 75 or younger; 29 take children under 18; 87 take healthy volunteers.
This study: 18 Years and older · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
1,277 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 117 · Phase 2 230 · Phase 3 238 · Phase 4 98
First in 1994; this study’s year is marked. 37 started in 2026.
This study's planned enrollment of 860 is above the median of 62 across 3,839 interventional studies indexed under Pulmonary Disease, Chronic Obstructive.
Median enrollment 100 across the 1,036 interventional studies, 171 across the 237 observational. Of the 1,018 that completed or were terminated, 502 (49%) have results posted.
This tab as a report to print or save as PDF → With an account.
603 of 1,277 have an industry lead sponsor. The 10 most frequent:
Enanta Pharmaceuticals, Inc is the lead sponsor of 46 studies on the registry; 3 are open to participants now.
Of its 33 completed or terminated interventional studies of FDA-regulated products, 10 (30%) have results posted.
Enanta Pharmaceuticals, Inc has 1 study filed under Pulmonary Disease, Chronic Obstructive — fewer than ten, so there is no comparison to draw.
60 of the studies in Pulmonary Disease, Chronic Obstructive with a site in United States that are under way reach primary completion within a year, 3 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT05265299Phase 3Johns Hopkins UniversityTrial to Determine Effective Aspirin Dose in COPD | 2026-12 |
| NCT05878769Phase 3Hoffmann-La RocheA Study to Evaluate the Long-Term Safety of Astegolimab in Participants With Chronic Obstructive Pulmonary Disease (COPD) | 2027-06-30 |
| NCT07555483Phase 3Grifols Therapeutics LLCA Non-inferiority Pharmacokinetic and Safety/Tolerability Study of Two Different Doses of Weekly SC Alpha1-PI 15% Compared With Corresponding Standard IV Alpha1-PI in Participants With Alpha1-Antitrypsin Deficiency (AATD) | 2027-09-30 |
| NCT04968249University of MichiganMichigan Early Disease Progression Cohort | 2026-12 |
| NCT05879211Duke UniversityGoal Concordant Care Learning Laboratory | 2026-12 |
Among the 1,277 studies in Pulmonary Disease, Chronic Obstructive with a site in United States, from their registry updates:
This tab as a report to print or save as PDF → With an account.
Zelicapavir is a novel orally administered non-fusion replication inhibitor of RSV that is being developed for the treatment of patients with RSV infection. This phase 2b/3 study will evaluate the efficacy and safety of zelicapavir compared with placebo in adults with RSV who are at high risk for severe disease. High-risk participants include those who are either ≥75 years of age or ≥18 years of age with COPD and/or CHF. Participants will be non-hospitalized adults who have up to 72 hours of respiratory tract infection symptoms and test positive for RSV.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Age ≥75 years at the time of enrollment, or, age ≥18 at the time of enrollment and has at least one of the following conditions that predispose them to complications of RSV infection:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Zelicapavir 800 mg, orally
Drug: zelicapavir
Matching placebo, orally
Drug: Placebo
Zelicapavir 800mg, once daily for 7 days
Participants will take matching placebo, once daily for 7 days
Time to complete resolution of all 13 RSV symptoms as assessed by the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) symptom scale
Time frame: Day 1 through Day 21
Number of participants with hospitalization due to RSV
Time frame: Day 1 through Day 35
Number of participants with hospitalization or death due to any cause
Time frame: Day 1 through Day 35
Number of participants who died
Time frame: Day 1 through Day 35
Number of participants with non-protocol defined medical visits for any cause
Time frame: Day 1 through Day 35
Time to complete resolution of RSV LRTD symptoms by RiiQ
Time frame: Day 1 through Day 21
Time to complete resolution of all 29 RSV parameters as assessed by RiiQ symptom scale score
Time frame: Day 1 through Day 21
Time to alleviation of LRTD symptoms by RiiQ
Time frame: Day 1 through Day 21
Time to alleviation of all 13 RSV symptoms as assessed by RiiQ
Time frame: Day 1 through day 21
Time to alleviation of all 29 RSV parameters as assessed by RiiQ
Time frame: Day 1 through Day 21
Time to complete resolution of RSV infection symptoms as assessed by PGI-S scale
Time frame: Day 1 through Day 35
Time to resolution to pre-existing symptoms
Time frame: Day 1 through Day 21
Number of participants requiring mechanical ventilation
Time frame: Day 1 through Day 35
Number of participants requiring supplemental oxygen in hospital
Time frame: Day 1 through Day 35
Number of participants requiring ICU admission
Time frame: Day 1 through Day 35
Change from baseline in RSV viral load
Time frame: Up to Day 35
Percentage of participants with RSV RNA viral load TND
Time frame: Up to Day 35
Time to RSV RNA viral load TND
Time frame: Up to Day 35
Safety as measured by frequency of adverse events (AEs)
Time frame: Day 1 through Day 35
Plasma Concentrations of zelicapavir
Time frame: At Day 7
Started Oct 2026 (actual). Primary completion is estimated for Jul 2029, 33 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: EDP-938
Pulmonary Disease, Chronic Obstructive →