Study of Obeldesivir to Treat Children With Respiratory Syncytial Virus (RSV) Infection

A Phase 2, Randomized, Multicenter, Double-blind, Placebo-controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Efficacy of Obeldesivir in Participants From Birth to < 5 Years of Age With Respiratory Syncytial Virus (RSV) Infection

The goal of this clinical study is to check if obeldesivir (ODV; GS-5245) is safe and well-tolerated by children with respiratory syncytial virus (RSV) infection. It will also look at how well ODV helps reduce the time it takes for children to feel better and for their RSV symptoms to improve.

The primary objectives of this study are: a) to evaluate the safety and tolerability of ODV in pediatric participants with RSV infection; b) To evaluate the efficacy of ODV on time to alleviation of targeted RSV symptoms in pediatric participants with RSV infection.

Study Overview

• Status: Terminated
• Conditions: RSV Infection
• Intervention / Treatment: Drug: Obeldesivir; Drug: Obeldesivir Placebo

Detailed Description

Pediatric participants will be enrolled as follows:

• Cohort 1: Infants and children from 4 weeks postnatal age, weighing ≥ 1.5 kg to < 40 kg
• Cohort 2: Neonates, either born at term or preterm, weighing ≥ 1.5 kg to < 6 kg

• Study Type: Interventional
• Enrollment (Actual): 4
• Phase: Phase 2

Contacts and Locations

Study Locations

• Japan
  • Akashi, Japan, 674-0068
    • Yoshimura Child Clinic
  • Fkitakyushu, Japan, 806-0034
    • Japan Community Healthcare Organization Kyushu Hospital
  • Fukuoka, Japan, 814-0104
    • Uchida child clinic
  • Fukuoka, Japan, 814-0121
    • Shindo Children's Clinic
  • Fukuoka, Japan, 814-0123
    • SEKI Children's CLINIC
  • Ibaraki, Japan, 305-0008
    • Ryuseidai Children's Clinic
  • Isesaki, Japan, 372-0817
    • Isesaki Municipal Hospital
  • Kanagawa, Japan, 223-0051
    • Abe Child Clinic
  • Kasukabe, Japan, 344-0011
    • Okada Kodomonomori Clinic
  • Kobe, Japan, 651-2273
    • Yutaka Children Clinic
  • Kochi, Japan, 781-8555
    • Kochi Health Sciences Center
  • Nagoya, Japan
    • Japan Community Healthcare Organization Chukyo Hospital
  • Nerima-ku, Japan, 177-0051
    • Shimamura Memorial Hospital
  • Shizuoka, Japan, 424-8636
    • Shizuoka City Shimizu Hospital
  • Shizuoka, Japan, 420-0005
    • Shizuoka Welfare Hospital
• United States
  • Alabama
    • Birmingham, Alabama, United States, 35233
      • Children's of Alabama
    • Oneonta, Alabama, United States, 35121
      • Midway Medical Clinic
  • Arizona
    • Phoenix, Arizona, United States, 11040
      • Cohen Children's Medical Center Pharmacy New Pavillion
    • Phoenix, Arizona, United States, 85015
      • Velocity Clinical Research, Phoenix
  • California
    • Los Angeles, California, United States, 90095
      • UCLA (outpatient clinic)
    • Lynwood, California, United States, 90262
      • Alliance Research Institute
    • Modesto, California, United States, 95355
      • Paradigm Clinical Research
    • San Diego, California, United States, 92108
      • Paradigm Clinical Research Centers, LLC
    • Santa Maria, California, United States, 93454
      • FOMAT - Jeffrey Kaplan MD Inc Pediatric Medicine
  • District of Columbia
    • Washington D.C., District of Columbia, United States, 20016
      • Velocity Clinical Research, Washington DC
  • Florida
    • Doral, Florida, United States, 33172
      • Dolphin Medical Research
    • Orlando, Florida, United States, 32829
      • Nona Pediatric Center
    • Tampa, Florida, United States, 33613
      • PAS Research
  • Georgia
    • Union City, Georgia, United States, 30291
      • Rophe Adult and Pediatric Medicine/SKYCRNG
  • Idaho
    • Idaho Falls, Idaho, United States, 83404
      • Clinical Research Prime
  • Iowa
    • Sioux City, Iowa, United States, 51106
      • Velocity Clinical Research, Sioux City
  • Louisiana
    • Lafayette, Louisiana, United States, 70508
      • Velocity Clinical Research, Lafayette
  • Montana
    • Great Falls, Montana, United States, 59405
      • Boeson Research
    • Kalispell, Montana, United States, 59901
      • Boeson Research
    • Missoula, Montana, United States, 59804
      • Boeson Research
  • Nebraska
    • Norfolk, Nebraska, United States, 68701
      • Velocity Clinical Research - Norfolk
    • Omaha, Nebraska, United States, 68134
      • Velocity Clinical Research, Omaha
  • New York
    • Syracuse, New York, United States, 13210
      • Child Health Care Associates
  • Oklahoma
    • Chickasha, Oklahoma, United States, 73018
      • Epic Medical Research -Oklahoma
    • Yukon, Oklahoma, United States, 73099
      • Tekton Research, LLC
  • Pennsylvania
    • Pittsburgh, Pennsylvania, United States, 15227
      • PAS Research
  • Texas
    • Burleson, Texas, United States, 76028
      • Helios Clinical Research
    • DeSoto, Texas, United States, 75115
      • Epic Medical Research - DeSoto
    • Edinburg, Texas, United States, 78539
      • PAS Research
    • Houston, Texas, United States, 77043
      • Biopharma Informatic, LLC
    • Houston, Texas, United States, 77084
      • Biopharma Informatic, LLC
    • Houston, Texas, United States, 77099
      • Pioneer Research Solutions Inc.
    • Houston, Texas, United States, 77008
      • Helios Clinical Research
    • Houston, Texas, United States, 77077
      • Sunrise Pediatrics
    • Lampasas, Texas, United States, 76550
      • Radiance Clinical Research
    • Richmond, Texas, United States, 77469
      • Pediatric Center
    • San Antonio, Texas, United States, 78232
      • Central Texas Medical Research, LLC
    • Tomball, Texas, United States, 77375
      • North Houston Internal Medicine and Pediatric Clinic
  • Utah
    • Kaysville, Utah, United States, 84037
      • Tanner Clinic
    • Layton, Utah, United States, 84041
      • Tanner Clinic
    • Provo, Utah, United States, 84604
      • Boeson Research PVU

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria:

• Participants assigned male or female at birth, from birth to < 5 years of age who meet one of the following criteria, where permitted according to local law and approved nationally and by relevant institutional review board or independent ethics committee:

  • Cohort 1: Infants and children from 4 weeks postnatal age, weighing ≥ 3 kg to < 40 kg (Part A) and ≥ 1.5 kg to < 3 kg (Part B)
  • Cohort 2: Neonates, either born at term or preterm, weighing ≥ 1.5 kg to < 6 kg
• RSV infection diagnosis ≤ 3 days prior to randomization.
• Negative test for influenza A/B, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 infection) ≤ 7 days prior to randomization.
• Onset of RSV signs or symptoms ≤ 3 days prior to randomization.
• Presence of at least 1 sign or symptom of RSV infection at screening and at randomization.

Key Exclusion Criteria:

• Currently requiring or expected to require hospitalization for RSV infection within 48 hours after randomization.
• Not expected to survive the current RSV-related illness.
• Documented previous infection and/or hospitalization for RSV during the current respiratory virus season.
• Diagnosed with acute concurrent active systemic infections requiring treatment with systemic antiviral, antibacterial, antifungal, or antimycobacterial therapy, or with any documented respiratory viral infection (other than RSV), ≤ 7 days prior to randomization.
• History of asthma or recurrent wheezing.
• Neuromuscular disease that affects swallowing.
• Cystic fibrosis.
• Participants who are immunocompromised.
• Alanine aminotransferase ≥ 5 × upper limit of normal (ULN).
• Abnormal renal function.
• Concurrent or previous treatment with other agents with actual or possible direct antiviral activity against RSV, received within 28 days or within 5 half-lives, whichever is longer, prior to randomization.
• Received palivizumab within 100 days, or nirsevimab within 1 year, or other RSV specific monoclonal antibody within 5 half-lives of the antibody, prior to randomization.
• Participant whose mother received RSV vaccination during pregnancy and who is < 1 year old prior to randomization.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cohort 1: Part A (Group 2) - Obeldesivir (ODV); Participants weighing ≥ 12 kg to < 20 kg, will receive ODV 175 mg, orally, twice on Day 1, followed by ODV 116.6 mg, orally, twice daily on Days 2 to 5.	Drug: Obeldesivir; Administered orally; Other Names: GS-5245; ODV
Experimental: Cohort 1: Part A (Group 3) - ODV; Participants weighing ≥ 6 kg to < 12 kg, will receive ODV 116.6 mg, orally, twice on Day 1, followed by ODV 58.3 mg, orally, twice daily on Days 2 to 5.	Drug: Obeldesivir; Administered orally; Other Names: GS-5245; ODV
Placebo Comparator: Cohort 1: Part A (Group 3) - Placebo; Participants weighing ≥ 6 kg to < 12 kg, will receive placebo-to-match ODV, orally, twice daily on Days 1 to 5.	Drug: Obeldesivir Placebo; Administered orally

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants Who Experienced Treatment-Emergent Adverse Events (TEAEs) by Day 28	TEAEs were defined as any adverse events that began on or after the date of first dose of study drug up to the date of last dose of study drug up to Day 28. The percentage of participants who experienced at least one TEAE was assessed from Day 1 through Day 28.	Up to Day 28
Percentage of Participants Who Experienced Grade 3 or 4 Treatment-Emergent Laboratory Abnormalities by Day 28	A treatment-emergent laboratory abnormality was defined as an increase of at least 1 toxicity grade from baseline at any time postbaseline up to and including the date of last study drug dose up to Day 28. A treatment-emergent laboratory abnormality severity was graded according to the Division of AIDS (DAIDS) Version 2.1. Grade 0: Values that do not meet the criteria for an abnormality of at least Grade 1;Grade 1: Mild; Grade 2: Moderate; Grade 3: Severe; Grade 4: Potentially life-threatening. The percentage of participants who experienced Grade 3 or 4 laboratory abnormalities was assessed from Day 1 through Day 28.	Up to Day 28
Time to Alleviation of Targeted Respiratory Syncytial Virus (RSV) Symptoms by Day 28	Alleviation of targeted RSV symptoms was defined as achievement of 2 consecutive daily assessments with improvement in score by at least 1 point for any targeted RSV symptom with baseline score is > 1, or no increase in score for any targeted RSV symptom with baseline score of 1, assessed from Day 1 to Day 28. The time to alleviation of targeted RSV symptoms by Day 28 was calculated as the symptom alleviation date minus the first dose date. Targeted RSV symptoms referred to the RSV symptoms (cough, respiratory signs, RSV signs, behavior impact).	Up to Day 28

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
PK Parameter: AUCtau of GS-441524, Metabolite of Obeldesivir	AUCtau is defined as area under the plasma concentration-time curve during a dosing interval (AUCtau) of GS-441524, the active metabolite of obeldesivir.	Day 5 (predose, 2.5, and 3.5 hours post-dose)
PK Parameter: Cmax of GS-441524, Metabolite of Obeldesivir	Cmax is defined as maximum plasma concentration of GS-441524, the active metabolite of obeldesivir.	Day 1 (0.25, 0.75, and 2 hours post-dose); Day 5 (predose, 2.5, and 3.5 hours post-dose)
PK Parameter: Ctrough of GS-441524, Metabolite of Obeldesivir	Ctrough is defined as the trough observed drug concentration [measured concentration at predose of Day 5 (taken directly before next administration)].	Day 5: Predose
Change From Baseline in RSV Nasal Swab Viral Load at Day 5	Nasal swab samples was used to assess RSV viral load by reversetranscriptase-quantitative polymerase chain reaction (RT-qPCR), respiratory coinfection by multiplex respiratory pathogen PCR, potential infectious viral titer assessment, and potential resistance testing (by sequencing and/or phenotyping). Baseline was defined as the last available value collected on or prior to first dose of study drug.	Baseline, Day 5
Time to Sustained Alleviation of Targeted RSV Symptoms by Day 28	Sustained alleviation of targeted RSV symptoms was defined as 3 daily consecutive assessments (48-hour period) with improvement in score by at least 1 point for any targeted RSV symptom with baseline score is > 1; or no increase in score for any targeted RSV symptom with baseline score of 1, assessed from Day 1 to Day 28. The time to sustained alleviation of targeted RSV symptoms by Day 28 was calculated as the symptom alleviation date minus the first dose date. Targeted RSV symptoms referred to the RSV symptoms (cough, respiratory signs, RSV signs, behavior impact).	Up to Day 28
Time to Resolution of Targeted RSV Symptoms by Day 28	Resolution of targeted RSV symptoms was defined as: for 2 daily consecutive assessments, improvement in score resulting in score of ≤2 for any targeted RSV symptom with baseline score >2; no increase or an improvement in score resulting in score of ≤2 for any targeted RSV symptom with baseline score of 2; no increase in score for any targeted RSV symptom with baseline score of 1. The time to resolution of targeted RSV symptoms by Day 28 was calculated as the resolution date/time minus the first dose date/time. Targeted RSV symptoms referred to RSV symptoms (cough, respiratory signs, RSV signs, behavior impact).	Up to Day 28
Number of Participants With Palatability Questionnaire Response as Assessed by the Caregiver at Days 1 and 5	Caregivers were asked to rate how the study drug tasted to their child. A questionnaire was administered to caregivers to assess palatability. Palatability was assessed by caregivers using a questionnaire on Day 1 and Day 5 with response options: Super Good, Good, Maybe Good or Maybe Bad, Bad, or Super Bad.	Days 1 and 5
Number of Participants With Acceptability Questionnaire Response as Assessed by the Caregiver at Days 1 and 5	Caregivers were asked to evaluate how easy it was for children to take the study drug. A questionnaire was administered to caregivers to assess acceptability. Acceptability was assessed by caregivers using a questionnaire with response options: Super Easy, Easy, Maybe Easy or Maybe Hard, Hard, or Super Hard. The questionnaire evaluated how easy it was for children to take the study drug.	Days 1 and 5

Collaborators and Investigators

• Sponsor: Gilead Sciences
• Investigators: Study Director: Gilead Study Director, Gilead Sciences

Publications and helpful links

Helpful Links

• Gilead Clinical Trials Website

Study record dates

Study Major Dates

• Study Start (Actual): March 5, 2025
• Primary Completion (Actual): April 16, 2025
• Study Completion (Actual): April 16, 2025

Study Registration Dates

• First Submitted: January 15, 2025
• First Submitted That Met QC Criteria: January 15, 2025
• First Posted (Actual): January 20, 2025

Study Record Updates

• Last Update Posted (Actual): June 8, 2026
• Last Update Submitted That Met QC Criteria: May 12, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Infections; RNA Virus Infections; Virus Diseases; Pneumovirus Infections; Paramyxoviridae Infections; Mononegavirales Infections; Respiratory Syncytial Virus Infections
• Other Study ID Numbers: GS-US-685-6883; jRCT2031240735 (Other Identifier: Japan Registry of Clinical Trials)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No