Efficacy and Safety of ALX-0171 in Adult Hematopoietic Stem Cell Transplant (HSCT) Recipients Who Present With Respiratory Syncytial Virus (RSV) Infection

Study Overview
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Brief Summary
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The primary objective of the study is to evaluate the antiviral effect and safety of inhaled ALX-0171 in adults diagnosed with respiratory syncytial virus (RSV) respiratory tract infection after hematopoietic stem cell transplantation (HSCT). The secondary objective is to assess the clinical activity, pharmacokinetics (PK), virology, and immunogenicity of inhaled ALX 0171 in adults diagnosed with RSV respiratory tract infection after HSCT.

Official Title
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A Randomized, Double-blind, Multicenter Study to Evaluate the Efficacy and Safety of ALX 0171 Versus Placebo, in Addition to Standard of Care, in Adults Who Have Undergone Hematopoietic Stem Cell Transplantation and Present With a Respiratory Syncytial Virus Respiratory Tract Infection

Conditions
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Respiratory Syncytial Virus Lower Respiratory Tract Infection

Intervention / Treatment
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* Biological: ALX-0171 Dose 1
* Biological: ALX-0171 Dose 2
* Biological: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject has received an HSCT using any conditioning regimen and for any underlying etiology (i.e., subject has received an autologous or allogeneic HSCT) Subject is clinically diagnosed with RSV infection with new onset or acute worsening Symptoms likely related to RSV infection have appeared within 5 days of screening and their severity requires initial or maintained hospitalization. Documented RSV infection in the upper respiratory tract (URT) Subject has: Diagnosis of RSV lower respiratory tract (LRT) disease or Diagnosis of RSV URT disease with high risk of progression to lower respiratory tract infection (LRTI) Others as defined in the protocol Exclusion Criteria: Subject has clinically significant bacteremia or fungemia within 7 days of screening Subject has clinically significant bacterial, fungal or viral pneumonia Subject presents evidence of shock requiring intensive care unit (ICU) monitoring and/or vasopressor treatment Subject requires or is expected to require invasive mechanical ventilation or intensive non-invasive respiratory support. Standard oxygen supplementation up to 6 L/minute is permitted provided it can be interrupted for the duration of study drug administration. Others as defined in the protocol

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: ALX-0171 Dose 1<br> | Biological: ALX-0171 Dose 1<br>* Oral inhalation of ALX-0171 Dose 1 once daily for a maximum of 14 days<br>|
| Experimental: ALX-0171 Dose 2<br> | Biological: ALX-0171 Dose 2<br>* Oral inhalation of ALX-0171 Dose 2 once daily for a maximum of 14 days<br>|
| Placebo Comparator: Placebo<br> | Biological: Placebo<br>* Oral inhalation of Placebo once daily for a maximum of 14 days<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time-weighted average change from baseline in log10 RSV nasal viral load |  | From Day 1 to Day 7 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Safety as measured by the incidence of treatment-emergent (serious) adverse events |  | From Screening to Day 42 | 
| Nasal RSV load parameter: time to undetectable shedding |  | From Day 1 to Day 42 | 
| Clinical stabilization (defined as respiratory rate <25/minute and stable oxygen saturation >92% on room air for at least 12 hours) |  | From Day 1 to Day 42 | 
| Number of days without oxygen or with oxygen supplementation |  | From Day 1 to Day 42 | 
| Progression to lower respiratory tract (LRT) disease in subjects presenting with upper respiratory tract infection (URTI) at baseline |  | From Day 1 to Day 42 | 
| Concentration of ALX-0171 in serum | Measurement of ALX-0171 serum concentration at different time points from baseline until Day 14. | Day 1 to Day 14 | 
| Immunogenicity as measured by the concentration of anti-ALX 0171 antibodies in serum |  | From Day 1 to Day 42 |