RSV InfectionPhase 2NCT06170242
A Controlled Phase 2a Study to Evaluate the Efficacy of EDP-323 Against Respiratory Syncytial Virus Infection in a Virus Challenge Model
A Phase 2 study testing EDP-323 Dose Regimen 1 and EDP-323 Dose Regimen 2 in people with RSV Infection, run by Enanta Pharmaceuticals, Inc at 1 site in United Kingdom.
Trial summary
A randomized, Phase 2a, double-blind, placebo-controlled study to evaluate the safety, pharmacokinetics and antiviral activity of multiple doses of orally administered EDP-323 in healthy subjects infected with RSV-A Memphis 37b. Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- RSV Infection
- What is being tested?
- EDP-323 Dose Regimen 1 and EDP-323 Dose Regimen 2
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 142 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 20 Nov 2023to 12 Jul 2024
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- An informed consent document signed and dated by the subject.
- Age 18 to 55 years, inclusive.
- In good health with no history of major medical conditions.
- A total body weight ≥ 50 kg and Body Mass Index (BMI) ≥ 18 kg/m2 and ≤ 35kg/m2.
Who cannot join
- Pregnant or nursing females
- Acute or chronic medical illness
- History of, or currently active, symptoms or signs suggestive of upper or lower respiratory tract (URT or LRT) infection within 4 weeks prior to the first study visit.
- Abnormal lung function
- Positive for HIV, active hepatitis B or C test
- Nose or nasopharynx abnormalities
- Receipt of any investigational drug within 3 months prior to the planned date of viral challenge/first dose of study drug
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Randomized, Phase 2a, Double-blind, Placebo-controlled Study to Evaluate the Safety, Pharmacokinetics and Antiviral Activity of Multiple Doses of Orally Administered EDP-323 Against Respiratory Syncytial Virus Infection in a Virus Challenge Model in Healthy Adults
A randomized, Phase 2a, double-blind, placebo-controlled study to evaluate the safety, pharmacokinetics and antiviral activity of multiple doses of orally administered EDP-323 in healthy subjects infected with RSV-A Memphis 37b. This study is designed to assess the antiviral effect of EDP-323 compared to a placebo control in the respiratory syncytial virus challenge model.
- Conditions
- RSV Infection
- Being tested
- EDP-323 Dose Regimen 1, EDP-323 Dose Regimen 2, Placebo
- Keywords
- challenge study, RSV, antiviral, RSV-A Memphis 37b
- 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.
EDP-323 Dose Regimen 1Drug
EDP-323 capsule
EDP-323 Dose Regimen 2Drug
EDP-323 capsule
PlaceboDrug
Placebo capsule
| Study group | Role | What they receive |
|---|---|---|
| EDP-323 Arm A | Experimental | Subjects will take EDP-323 Dose 1 orally for 5 days Receives: Drug: EDP-323 Dose Regimen 1 |
| EDP-323 Arm B | Experimental | Subjects will take EDP-323 Dose 2 orally for 5 days Receives: Drug: EDP-323 Dose Regimen 2 |
| Placebo Arm C | Placebo comparator | Subjects will take matching placebo orally for 5 days Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Quantitative Reverse Transcription-polymerase Chain Reaction (qRT-PCR): RSV Area Under the Viral Load-time Curve (VL-AUC)
Measured by qRT-PCR in nasal samples.
Measured: Day 1 to Day 12
Secondary outcomes (29)
qRT-PCR: RSV Peak Viral Load (VLPEAK)
Measured by qRT-PCR in nasal samples.
Measured: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to RSV VLPEAK
Measured by qRT-PCR in nasal samples.
Measured: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to RSV Viral Load Negativity
The time from the assessment at the time of the first dose of IMP to qRT-viral load negativity was analyzed using the Kaplan-Meier method. Viral load negativity was reached at the first time when the viral load was undetectable (< lower limit of detection [LLOD]) by qRT-PCR, after which no further detectable assessment appeared. Measured by qRT-PCR in nasal samples.
Measured: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to First Negative Slope of RSV Viral Load
Time to first negative slope = time of the timepoint after which there are two consecutive declines in viral load - time of the nearest viral load assessment to the first dose of IMP. Measured by qRT-PCR in nasal samples.
Measured: Day 1 to Day 12
qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 High Dose
Calculated as the slope of the RSV viral load over time from time of RSV VLPEAK to 1, 2, 3, and 4 days later. Estimates for fixed effects of a mixed linear model, modeling the viral load from peak up to the 4 following days, with time from VLPEAK, group and interaction between time and group as fixed effects and a random intercept within each participant. The model was a distinct analysis for the EDP-323 high dose and placebo groups where the estimates for both groups are model-dependent and impacted by the overall model. A negative slope indicated that the viral load decreased over time. Measured by qRT-PCR in nasal samples.
Measured: Up to Day 16
qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 Low Dose
Calculated as the slope of the RSV viral load over time from time of RSV VLPEAK to 1, 2, 3, and 4 days later. Estimates for fixed effects of a mixed linear model, modeling the viral load from peak up to the 4 following days, with time from VLPEAK, group and interaction between time and group as fixed effects and a random intercept within each participant. The model was a distinct analysis for the EDP-323 low dose and placebo groups where the estimates for both groups are model-dependent and impacted by the overall model. A negative slope indicated that the viral load decreased over time. Measured by qRT-PCR in nasal samples.
Measured: Up to Day 16
Viral Culture: RSV VL-AUC
Measured by viral culture (plaque assay) in nasal samples.
Measured: Day 1 to Day 12
Viral Culture: RSV VLPEAK
Measured by viral culture (plaque assay) in nasal samples.
Measured: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to RSV VLPEAK
Measured by viral culture (plaque assay) in nasal samples.
Measured: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to RSV Viral Load Negativity
Measured by viral culture (plaque assay) in nasal samples.
Measured: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to First Negative Slope of RSV Viral Load
Measured by viral culture (plaque assay) in nasal samples.
Measured: Day 1 to Day 12
Viral Culture: RSV Viral Load Clearance Rate
Calculated as the slope of the RSV viral load over time from time of RSV VLPEAK to 1, 2, 3, and 4 days later. Estimates for fixed effects of a mixed linear model, modeling the viral load from peak up to the 4 following days, with time from VLPEAK, group and interaction between time and group as fixed effects and a random intercept within each participant. A negative slope indicated that the viral load decreased over time. Measured by viral culture in nasal samples.
Measured: Up to Day 16
Area Under the Total Symptom Score (TSS)-Time Curve (TSS-AUC)
An individual TSS (10-items) was derived at each assessment of the diary card as the sum of the scores given to the 10 following symptoms on that symptom score card, giving a score between 0 and 3:
- Runny nose
- Stuffy nose
- Sneezing
- Sore throat
- Earache
- Malaise/Tiredness
- Headache
- Muscle and/or Joint Ache
- Cough
- Shortness of breath
TSS ranged from 0 to 30 with higher TSS indicating a higher disease burden and thus a worse outcome.
The calculation of the TSS-AUC was performed on the TSS measured 3 times a day using the trapezoidal summation rule based on actual time intervals in hours.
Measured: Day 1 to Day 12
Peak TSS
Defined as the highest recorded value of TSS.
An individual TSS (10-items) was derived at each assessment of the diary card as the sum of the scores given to the 10 following symptoms on that symptom score card, giving a score between 0 and 3:
- Runny nose
- Stuffy nose
- Sneezing
- Sore throat
- Earache
- Malaise/Tiredness
- Headache
- Muscle and/or Joint Ache
- Cough
- Shortness of breath
TSS ranged from 0 to 30 with higher TSS indicating a higher disease burden and thus a worse outcome.
Measured: Day 1 to Day 12
Time to Peak TSS
Time to peak TSS = time of peak TSS - time of the nearest TSS assessment to the first dose of IMP.
An individual TSS (10-items) was derived at each assessment of the diary card as the sum of the scores given to the 10 following symptoms on that symptom score card, giving a score between 0 and 3:
- Runny nose
- Stuffy nose
- Sneezing
- Sore throat
- Earache
- Malaise/Tiredness
- Headache
- Muscle and/or Joint Ache
- Cough
- Shortness of breath
TSS ranged from 0 to 30 with higher TSS indicating a higher disease burden and thus a worse outcome.
Measured: Day 1 to Day 12
Time to Resolution From Peak TSS
Time to resolution from peak TSS = time of the first 24-hour symptom-free time point - time of peak TSS.
An individual TSS (10-items) was derived at each assessment of the diary card as the sum of the scores given to the 10 following symptoms on that symptom score card, giving a score between 0 and 3:
- Runny nose
- Stuffy nose
- Sneezing
- Sore throat
- Earache
- Malaise/Tiredness
- Headache
- Muscle and/or Joint Ache
- Cough
- Shortness of breath
TSS ranged from 0 to 30 with higher TSS indicating a higher disease burden and thus a worse outcome.
Measured: Day 1 to Day 12
Total Weight of Nasal Discharge (Mucus) Produced
Each participant was given pre-weighed packets of paper tissues. Participants were asked to place single tissues used for nose blowing or sneezing into a specified collection bag (for that participant only).
Measured: Day 1 to Day 12
Total Number of Tissues Used
Each participant was given pre-weighed packets of paper tissues. Participants were asked to place single tissues used for nose blowing or sneezing into a specified collection bag (for that participant only).
Measured: Day 1 to Day 12
Maximum Plasma Concentration (Cmax)
Plasma pharmacokinetic (PK) parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, below the limit of quantification (BQL) values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Time to Cmax (Tmax)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Terminal Half-life (t1/2)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Apparent Systemic Clearance at Steady-state (CLss/F)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Terminal Elimination Rate Constant (λz)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Apparent Volume of Distribution at Steady-state (Vss/F)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The plasma PK parameters were estimated from the concentration-time profiles. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Plasma Concentration at 12 Hours (C12h) and 24 Hours (C24h)
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: First Dose: Day 1, 12 and 24 hours post-dose; Last Dose: Day 5, 12 and 24 hours post-dose
Area Under the Concentration-time Curve From Time 0 to Time of Last Quantifiable Concentration (AUC0-last)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The AUCs were calculated using linear up/log down method. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Area Under the Concentration-time Curve Over the Dosing Interval (AUC0-tau)
Plasma PK parameters for EDP-323 and metabolites (EP-038725 and EP-039082) were estimated using non-compartmental methods. The AUCs were calculated using linear up/log down method. In estimating the PK parameters, BQL values were set to zero. Actual sampling times, rather than scheduled sampling times, were used in all computations involving sampling times. If the actual time or dose time was missing, the scheduled time could be substituted in order to calculate the PK parameter.
In case of an actual sampling time deviating by >20% from the scheduled (nominal) time, this plasma concentration was excluded from descriptive statistics in the plasma concentration-time table.
Measured: Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Number of Participants With Adverse Events (AEs) up to Discharge
An AE was defined as any untoward medical occurrence in clinical study participants administered a pharmaceutical (investigational or non-investigation) product. An AE does not necessarily have a causal relationship with the study intervention. A serious AE (SAE) was defined as any untoward medical occurrence that, at any dose:
- Resulted in death
- Was life threatening
- Required inpatient hospitalization or prolongation of existing hospitalization
- Resulted in persistent disability/incapacity
- Was a congenital anomaly/birth defect
- Was an important medical event
Measured: Day -2 to Day 12
Number of Participants With Treatment-emergent Adverse Events
An AE was defined as any untoward medical occurrence in clinical study participants administered a pharmaceutical (investigational or non-investigation) product. An AE does not necessarily have a causal relationship with the study intervention. An SAE was defined as any untoward medical occurrence that, at any dose:
- Resulted in death
- Was life threatening
- Required inpatient hospitalization or prolongation of existing hospitalization
- Resulted in persistent disability/incapacity
- Was a congenital anomaly/birth defect
- Was an important medical event
Measured: Day 1 to Day 28
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Dec 2023
- Study start20 Nov 2023
- Primary completion17 Jun 2024
- Study completion12 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- 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
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 142 participants (actual)
Sponsor and investigators
- Lead sponsor
- Enanta Pharmaceuticals, Inc
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- hVIVO Services Limited
- Responsible party
- Sponsor
- Investigators
- Enanta Pharmaceuticals, Inc, Study director, Enanta Pharmaceuticals, Inc
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06170242
- Sponsor's protocol ID
- EDP 323-101
- Status last verified
- Sep 2025
- First submitted
- 27 Nov 2023
- Last updated
- 7 Oct 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized, Phase 2a, Double-blind, Placebo-controlled Study to Evaluate the Safety, Pharmacokinetics and Antiviral Activity of Multiple Doses of Orally Administered EDP-323 Against Respiratory Syncytial Virus Infection in a Virus Challenge Model in Healthy Adults
- ClinicalTrials.gov ID
- NCT06170242
- Acronym / sponsor ID
- EDP 323-101
- Conditions
- RSV Infection
- Keywords
- challenge study, RSV, antiviral, RSV-A Memphis 37b
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 142 participants (actual)
- Lead sponsor
- Enanta Pharmaceuticals, IncIndustry (pharma, biotech, devices)
- Collaborators
- hVIVO Services Limited
- Study start
- 20 Nov 2023 (actual)
- Primary completion
- 17 Jun 2024 (actual)
- Study completion
- 12 Jul 2024 (actual)
- First posted
- 14 Dec 2023 (actual)
- Results
- Posted 7 Oct 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A randomized, Phase 2a, double-blind, placebo-controlled study to evaluate the safety, pharmacokinetics and antiviral activity of multiple doses of orally administered EDP-323 in healthy subjects infected with RSV-A Memphis 37b. This study is designed to assess the antiviral effect of EDP-323 compared to a placebo control in the respiratory syncytial virus challenge model.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| EDP-323 Arm A | Experimental | Drug: EDP-323 Dose Regimen 1Subjects will take EDP-323 Dose 1 orally for 5 days |
| EDP-323 Arm B | Experimental | Drug: EDP-323 Dose Regimen 2Subjects will take EDP-323 Dose 2 orally for 5 days |
| Placebo Arm C | Placebo comparator | Drug: PlaceboSubjects will take matching placebo orally for 5 days |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- An informed consent document signed and dated by the subject.
- Age 18 to 55 years, inclusive.
- In good health with no history of major medical conditions.
- A total body weight ≥ 50 kg and Body Mass Index (BMI) ≥ 18 kg/m2 and ≤ 35kg/m2.
Key exclusion criteria (7 listed)
- Pregnant or nursing females
- Acute or chronic medical illness
- History of, or currently active, symptoms or signs suggestive of upper or lower respiratory tract (URT or LRT) infection within 4 weeks prior to the first study visit.
- Abnormal lung function
- Positive for HIV, active hepatitis B or C test
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 |
|---|---|---|
| EDP-323 Dose Regimen 1EDP-323 capsule | Drug | EDP-323 Arm A |
| EDP-323 Dose Regimen 2EDP-323 capsule | Drug | EDP-323 Arm B |
| PlaceboPlacebo capsule | Drug | Placebo Arm C |
Primary outcome
Quantitative Reverse Transcription-polymerase Chain Reaction (qRT-PCR): RSV Area Under the Viral Load-time Curve (VL-AUC)
Time frame: Day 1 to Day 12
Measured by qRT-PCR in nasal samples.
29 secondary outcomes
qRT-PCR: RSV Peak Viral Load (VLPEAK)
Time frame: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to RSV VLPEAK
Time frame: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to RSV Viral Load Negativity
Time frame: Day 1 to Day 12
qRT-PCR: Time From the Assessment at the Time of the First Dose of IMP to First Negative Slope of RSV Viral Load
Time frame: Day 1 to Day 12
qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 High Dose
Time frame: Up to Day 16
qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 Low Dose
Time frame: Up to Day 16
Viral Culture: RSV VL-AUC
Time frame: Day 1 to Day 12
Viral Culture: RSV VLPEAK
Time frame: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to RSV VLPEAK
Time frame: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to RSV Viral Load Negativity
Time frame: Day 1 to Day 12
Viral Culture: Time From the Assessment at the Time of the First Dose of IMP to First Negative Slope of RSV Viral Load
Time frame: Day 1 to Day 12
Viral Culture: RSV Viral Load Clearance Rate
Time frame: Up to Day 16
Area Under the Total Symptom Score (TSS)-Time Curve (TSS-AUC)
Time frame: Day 1 to Day 12
Peak TSS
Time frame: Day 1 to Day 12
Time to Peak TSS
Time frame: Day 1 to Day 12
Time to Resolution From Peak TSS
Time frame: Day 1 to Day 12
Total Weight of Nasal Discharge (Mucus) Produced
Time frame: Day 1 to Day 12
Total Number of Tissues Used
Time frame: Day 1 to Day 12
Maximum Plasma Concentration (Cmax)
Time frame: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Time to Cmax (Tmax)
Time frame: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Terminal Half-life (t1/2)
Time frame: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Apparent Systemic Clearance at Steady-state (CLss/F)
Time frame: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Terminal Elimination Rate Constant (λz)
Time frame: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Apparent Volume of Distribution at Steady-state (Vss/F)
Time frame: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose), Day 2 pre-dose, Day 3 pre-dose, Day 4 pre-dose, Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Plasma Concentration at 12 Hours (C12h) and 24 Hours (C24h)
Time frame: First Dose: Day 1, 12 and 24 hours post-dose; Last Dose: Day 5, 12 and 24 hours post-dose
Area Under the Concentration-time Curve From Time 0 to Time of Last Quantifiable Concentration (AUC0-last)
Time frame: First Dose: Day 1 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 hours post-dose) and Day 2 pre-dose; Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Area Under the Concentration-time Curve Over the Dosing Interval (AUC0-tau)
Time frame: Last Dose: Day 5 (pre-dose, 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 24, 30, 36, 48, 60, and 72 hours post-dose)
Number of Participants With Adverse Events (AEs) up to Discharge
Time frame: Day -2 to Day 12
Number of Participants With Treatment-emergent Adverse Events
Time frame: Day 1 to Day 28
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Oct 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
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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. This study is not recruiting at the moment.
Enanta Pharmaceuticals, Inc study director
Enanta Pharmaceuticals, Inc
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing EDP-323 Dose Regimen 1 and EDP-323 Dose Regimen 2 in people with RSV Infection, run by Enanta Pharmaceuticals, Inc at 1 site in United Kingdom.
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 4 inclusion and 7 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: finished, as of the sponsor's last update on 7 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. 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?
Yes. Results are posted in the registry (first posted 7 Oct 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Quantitative Reverse Transcription-polymerase Chain Reaction (qRT-PCR): RSV Area Under the Viral Load-time Curve (VL-AUC) (time frame: Day 1 to Day 12). 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 7 Oct 2025; AzTrials last refreshed its copy on 26 Oct 2026.