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Completed

NCT Number: NCT06170242

A Controlled Phase 2a Study to Evaluate the Efficacy of EDP-323 Against Respiratory Syncytial Virus Infection in a Virus Challenge Model

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.

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Key information

Conditions

RSV Infection Infections Mononegavirales Infections Paramyxoviridae Infections Pneumovirus Infections RNA Virus Infections Respiratory Syncytial Virus Infections Virus Diseases

Age range

18 year–55 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

hVIVO Services Limited

London, United Kingdom

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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.

Exclusion criteria

  • 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

Treatment and study plan

EDP-323 Dose Regimen 1

Drug

EDP-323 capsule

EDP-323 Dose Regimen 2

Drug

EDP-323 capsule

Placebo

Drug

Placebo capsule

Primary outcomes

  1. 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.

Secondary outcomes

  1. qRT-PCR: RSV Peak Viral Load (VLPEAK)

    Time frame: Day 1 to Day 12

    Measured by qRT-PCR in nasal samples.

  2. 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

    Measured by qRT-PCR in nasal samples.

  3. 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

    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.

  4. 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

    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.

  5. qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 High Dose

    Time frame: Up to Day 16

    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.

  6. qRT-PCR: RSV Viral Load Clearance Rate - EDP-323 Low Dose

    Time frame: Up to Day 16

    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.

  7. Viral Culture: RSV VL-AUC

    Time frame: Day 1 to Day 12

    Measured by viral culture (plaque assay) in nasal samples.

  8. Viral Culture: RSV VLPEAK

    Time frame: Day 1 to Day 12

    Measured by viral culture (plaque assay) in nasal samples.

  9. 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

    Measured by viral culture (plaque assay) in nasal samples.

  10. 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

    Measured by viral culture (plaque assay) in nasal samples.

  11. 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

    Measured by viral culture (plaque assay) in nasal samples.

  12. Viral Culture: RSV Viral Load Clearance Rate

    Time frame: Up to Day 16

    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.

  13. Area Under the Total Symptom Score (TSS)-Time Curve (TSS-AUC)

    Time frame: Day 1 to Day 12

    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.

  14. Peak TSS

    Time frame: Day 1 to Day 12

    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.

  15. Time to Peak TSS

    Time frame: Day 1 to Day 12

    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.

  16. Time to Resolution From Peak TSS

    Time frame: Day 1 to Day 12

    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.

  17. Total Weight of Nasal Discharge (Mucus) Produced

    Time frame: Day 1 to Day 12

    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).

  18. Total Number of Tissues Used

    Time frame: Day 1 to Day 12

    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).

  19. 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)

    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.

  20. 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)

    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.

  21. 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)

    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.

  22. 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)

    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.

  23. 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)

    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.

  24. 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 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.

  25. 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

    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.

  26. 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)

    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.

  27. 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)

    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.

  28. Number of Participants With Adverse Events (AEs) up to Discharge

    Time frame: Day -2 to Day 12

    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

  29. Number of Participants With Treatment-emergent Adverse Events

    Time frame: Day 1 to Day 28

    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

Sponsors and collaborators

Lead sponsor

Enanta Pharmaceuticals, Inc

Industry

Collaborators

  • hVIVO Services Limited

Registry information

Official study 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

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Dec 14, 2023
Registry last updated
Oct 7, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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