Trial Outcomes & Findings for Study of Obeldesivir to Treat Children With Respiratory Syncytial Virus (RSV) Infection (NCT NCT06784973)

Participants were enrolled at study sites in the United States.

7 participants were screened. The study was terminated early after 4 participants were enrolled. The decision was not based on any safety findings. The study was planned to include Cohort 1 Part A (inclusive of 4 groups based on participant's weight), Cohort 1 Part B, and Cohort 2. Due to the early termination, only Cohort 1 Part A (Groups 2 and 3) were enrolled.

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

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.

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.

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).

AUCtau is defined as area under the plasma concentration-time curve during a dosing interval (AUCtau) of GS-441524, the active metabolite of obeldesivir.

Cmax is defined as maximum plasma concentration of GS-441524, the active metabolite of obeldesivir.

Ctrough is defined as the trough observed drug concentration \[measured concentration at predose of Day 5 (taken directly before next administration)\].

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.

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).

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).

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.

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.