A Study to Learn About the Amount of the Study Medicine (Sisunatovir) in Blood and Its Safety in Infants and Children With Pneumonia Caused by RSV

NCT06102174 | Terminated Phase 1 Results DMC FDA Drug

• 2 other identifiers: C52410092023-504425-39-00
• Study Type: interventional
• Target: 10
• Locations: 3 countries
• Sites: 9

Brief Summary

The purpose of the study is to learn about the safety and amount of sisunatovir in the blood of infants and children up to age 60 months. These children have Lower Respiratory Tract Infection (LRTI) caused by Respiratory Syncytial Virus (RSV). LRTI is the infection to the lower airways such as lungs. This study will help inform the amount of sisunatovir to be used in future studies of sisunatovir in children. This study is seeking for participants who:

• Are 1 day to less than or equal to 60 months of age
• weigh more than or equal to 2.5 kilograms to less than or equal to 23 kilograms.
• Have been tested to have RSV by medical tests.
• show signs of LRTI. All participants in the study will receive many amounts of sisunatovir or placebo. Placebo is a pill that does not have any medicine in it. Up to 7 visits are required for the study. Some of these visits include checking participants health over the phone and/or a visit at home. The study will compare the experiences of infants and children receiving sisunatovir to identify the amount of sisunatovir to be used in future studies in infants and children.

Conditions

Respiratory Syncytial Virus Infections

Keywords

Lower Respiratory Tract Infection

Outcome Measures

Primary Outcomes (5)

• Number of Participants With Treatment Emergent Adverse Events (TEAEs)

  An adverse event (AE) was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. All AEs were included for evaluation.

  From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

• Number of Participants Who Discontinued From Study Due to TEAEs

  An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs.

  From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

• Number of Participants Who Discontinued From Study Due to Serious TEAEs

  An AE was any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE was considered a TEAE if the event started during the effective duration of treatment. All events that start on or after the first dose of study intervention, but before the end of the study were flagged as TEAEs. A serious AE (SAE) was any untoward medical occurrence at any dose that: resulted in death; was life-threatening experience (immediate risk of death); required inpatient hospitalization or prolongation if existing hospitalization; resulted in persistent or significant disability/ incapacity; resulted in congenital anomaly/birth defect; other important event or situation as pre-specified in protocol.

  From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

• Number of Participants With Clinically Significant Laboratory Abnormalities

  Following parameters were analyzed for laboratory examination: hematology (hemoglobin, hematocrit, red blood cell count, platelet count, white blood cell count, mean cell volume, mean cell hemoglobin \& concentration); chemistry: urea and creatinine, estimated glomerular filtration rate (eGFR), gamma-glutamyl transferase (GGT), calcium, sodium, potassium, chloride, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, alkaline phosphatase, albumin, total protein, cystatin C; urinalysis: pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, albumin, creatinine (urine), urine albumin to creatinine ratio. Clinically significant laboratory abnormalities findings were based on investigator discretion.

  From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

• Number of Participants With Clinically Significant Vital Signs

  Vital signs included systolic and diastolic blood pressure, pulse rate/heart rate, temperature, respiratory rate, and oxygen saturation. Clinically significance vital signs findings were based on investigator discretion.

  From start of study intervention on Day 1 up to 28 days after last dose of study intervention (maximum up to 33 days)

Secondary Outcomes (1)

• Plasma Concentrations Versus Time Summary of Sisunatovir

  Day 3: Pre-dose, T1 and T2 hours post-dose; Day 5: Pre-dose; where T1 is the first analysis time point post-dose while T2 is the second analysis time point post-dose

Study Arms (2)

Placebo

PLACEBO COMPARATOR

Oral or Nasogastric tube (NG)

Drug: Placebo

Sisunatovir

ACTIVE COMPARATOR

Oral or NG tube

Drug: Active

Interventions

Placebo DRUG

Placebo

Placebo

Active DRUG

Sisunatovir

Also known as: PF-07923568, RV521

Sisunatovir

Eligibility Criteria

• Age: 1 Day - 60 Months
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• day to ≤60 months of age and weight ≥2.5 kg to ≤23 kg
• Positive RSV diagnostic test, antigen or molecular test
• Evidence of Lower Respiratory Tract Infection (LRTI)

You may not qualify if:

• Premature infants (gestational age less than 35 weeks) AND \<1 year of post-natal age
• Neonates with intrauterine growth restriction
• Expected to receive an antiviral for another viral infection within 10 days of screening
• Suspected or confirmed clinically significant moderate or severe bacterial infection that may interfere with the evaluation of response to the study intervention
• Known to have significant comorbidities that would limit the ability to administer the study intervention or evaluate the safety or clinical response to the study intervention

Sponsors & Collaborators

• Pfizer: lead

Study Sites (9)

Kaiser Permanente Los Angeles Medical center

Los Angeles, California, 90027, United States

Location

Kaiser Permanente

Los Angeles, California, 90027, United States

Location

Washington University School of Medicine

St Louis, Missouri, 63110, United States

Location

Kojunkai Daido Hospital

Nagoya, Aichi-ken, 457-8511, Japan

Location

Nintenkai Kagoshima Children's Hospital

Hioki, Kagoshima-ken, 899-2503, Japan

Location

Yamanashi Prefectural Central Hospital

Kofu, Yamanashi, 400-8506, Japan

Location

Osaka City General Hospital

Osaka, 534-0021, Japan

Location

Monti Clinical Research Centre

Mdantsane, Eastern Cape, 5219, South Africa

Location

University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)

Johannesburg, Gauteng, 2013, South Africa

Location

Related Publications (1)

• Toussi SS, Calvo C, Haumann B, Thomas E, Franke RM, Kudela M, Zhang S, Banerjee A, Rees S, Shoji S, Welch H, Jordan I, Srisingh K, Daud M, Nemeth A, Rojo P, Toh TH, Ogunade I, Oku S, Amo K, Towner W, Newland J, Alami NN. Safety and Pharmacokinetics of the RSV Fusion Inhibitor Sisunatovir Across Two Early-phase Studies in Infants and Children With RSV Lower Respiratory Tract Infection. Pediatr Infect Dis J. 2026 Feb 12. doi: 10.1097/INF.0000000000005169. Online ahead of print.

  PMID: 41673909 DERIVED

Related Links

• To obtain contact information for a study center near you, click here.

MeSH Terms

Conditions

Respiratory Syncytial Virus Infections

Interventions

Exercise; sisunatovir

Condition Hierarchy (Ancestors)

Pneumovirus Infections; Paramyxoviridae Infections; Mononegavirales Infections; RNA Virus Infections; Virus Diseases; Infections

Intervention Hierarchy (Ancestors)

Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena

Limitations and Caveats

Sponsor decided to maintain company confidentiality, hence dose strengths, dose frequency, and PK sampling time points have not been disclosed in the record.

Results Point of Contact

• Title: Pfizer ClinicalTrials.gov Call Center
• Organization: Pfizer Inc.

ClinicalTrials.gov_Inquiries@pfizer.com

18007181021

Study Officials

• Pfizer CT.gov Call Center

  Pfizer

  STUDY DIRECTOR

Publication Agreements

• PI is Sponsor Employee: No
• Restriction Type: OTHER
• Restrictive Agreement: Yes

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 6, 2023
• First Posted: October 26, 2023
• Study Start: February 15, 2024
• Primary Completion: September 3, 2024
• Study Completion: September 3, 2024
• Last Updated: December 30, 2025
• Results First Posted: December 30, 2025

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

ZA (2); JP (4); US (3)