Effects of JNJ-53718678 in Adult and Adolescent Participants Who Had a Hematopoietic Stem Cell Transplantation and Who Are Infected With Respiratory Syncytial Virus (RSV)

A Randomized, Double-blind, Placebo-controlled Study to Evaluate the Clinical Outcomes, Antiviral Activity, Safety, Tolerability, Pharmacokinetics, and Pharmacokinetics/Pharmacodynamics of JNJ-53718678 in Adult and Adolescent Hematopoietic Stem Cell Transplant Recipients With Respiratory Syncytial Virus Infection of the Upper Respiratory Tract

The purpose of this study is to evaluate the effect of JNJ-53718678 on the development of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTIs) in adult hematopoietic stem cell transplant (HSCT) recipients with RSV upper RTI.

RSV is recognized as major respiratory pathogen in infants and young children and causes upper and lower respiratory illness among all age groups, often going undiagnosed. Immunocompromised (IC) participants have a reduced ability to combat infection due to an impaired or weakened immune system. Within the IC population, HSCT recipients are generally regarded as having a particularly high risk for more severe disease caused by RSV, representing a substantial unmet need for antiviral treatment of RSV infections in this participant population. JNJ-53718678 is an investigational, potent, small molecule, respiratory syncytial virus (RSV)-specific fusion inhibitor. The study will include a Screening Period (Day -2 to Day 1), a Treatment Period (Day 1 to Day 21), and a Follow-up Period (1 year). Assessments like chest X-ray, pulse/heart rate, respiratory rate, electrocardiogram (ECG), etc will be performed. Safety and efficacy will be assessed through the study. The total study duration for each participant will be approximately 49 days.

Inclusion Criteria:

• Received an autologous or allogeneic hematopoietic stem cell transplant (HSCT) using any conditioning regimen
• Absolute lymphocyte count (ALC) less than (<) 1,000 cells/microliter (mL)
• Participant has laboratory confirmed RSV diagnosis within 48 hours of randomization
• New onset of at least 1 of the following respiratory symptoms within 4 days prior to the anticipated start of dosing nasal congestion, rhinorrhea, cough or pharyngitis (sore throat), and/or worsening of one of these chronic (associated with previously existing diagnosis, example, chronic rhinorrhea, seasonal allergies, chronic lung disease) respiratory symptoms within 4 days prior to the anticipated start of dosing
• Peripheral capillary oxygen saturation (SpO2) greater than or equal to (>=) 92 percent (%) on room air

Exclusion Criteria:

• Admitted to the hospital primarily for a lower respiratory tract disease of any cause as determined by the investigator
• Requires supplemental oxygen at Screening or any time between Screening and randomization
• Documented to be positive for other respiratory viruses (limited to influenza, parainfluenza, human rhinovirus, adenovirus, human metapneumovirus, or coronavirus) within 7 days prior to or at the Screening visit, if determined by local SOC testing (additional testing is not required)
• Clinically significant bacteremia or fungemia within 7 days prior to or at Screening that has not been adequately treated, as determined by the investigator