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RV521/78 µCi -RV521.

Phase 2

Respiratory Syncytial Virus Infections | Small molecule | Respiratory |Pfizer, Inc.|Last Updated: Jul 31, 2025

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDBiomarker
Total Trials3
Total Enrollment84
FDA Designations
No designations recorded
Clinical Trials (3)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT03258502A Study to Learn About the Effects of Multiple Doses of Sisunatovir on People With Respiratory Syncytial Virus (RSV) InfectionPHASE2 COMPLETED 66 — — Jul 19, 2017Oct 31, 2017Jul 31, 20251 United Kingdom
NCT05873764A Study to Learn About Effect of Sisunatovir in Healthy Adult Male ParticipantsPHASE1 COMPLETED 9 — — May 25, 2022Jul 12, 2022May 16, 20241 United States
NCT04065698Pharmacokinetics and Safety of RV521 FormulationsPHASE1 COMPLETED 9 — — Aug 13, 2019Sep 9, 2019Jun 7, 20241 United Kingdom
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Study Endpoints
Primary Endpoints
Change in viral load
Baseline to study day 12
Tmax (Time of maximum observed concentration)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

Cmax (Maximum observed concentration)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

AUC0-inf (Area under the concentration-time curve (AUC) extrapolated to infinity)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

AUC0-last (AUC from the time of dosing to the time of the last measurable concentration)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

lambdaz (Rate constant associated with the terminal elimination phase)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

t1/2 (half-life of the terminal elimination phase)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

CL/F (Apparent clearance of the drug from plasma after oral administration)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

Vz/F (Volume of distribution associated with the terminal phase)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

CLR (renal clearance)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

Fe (fraction of administered drug excreted into urine)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

Ae0-t (cumulative amount of 14C excreted into urine from time 0 to the last sampling interval)
Day 1 (time 0) to Day 29

PK parameters of total radioactivity and RV521 following a single oral administration of \[ 14C\]-RV521 to healthy male subjects

Ae0-t (Cumulative amount of 14C excreted into urine and feces from time 0 to the last sampling interval (in units of mass-equivalents/g))
Day 1 (time 0) to Day 29

Mass balance parameters in urinary and fecal excretion of radioactivity

Aet (Amount of 14C excreted into urine and feces per sampling interval (in units of mass-equivalents/g))
Day 1 (time 0) to Day 29

Mass balance parameters in urinary and fecal excretion of radioactivity

Fet (Fraction of 14C excreted into urine and feces per sampling interval (in units of %))
Day 1 (time 0) to Day 29

Mass balance parameters in urinary and fecal excretion of radioactivity

Fe0-t (Cumulative fraction of 14C excreted into urine or feces from time 0)
Day 1 (time 0) to Day 29

Mass balance parameters in urinary and fecal excretion of radioactivity

14C associated with % of AUC of the total in plasma
Day 1 (time 0) to Day 29

Metabolite Profiling and Identification

14C associated with % of administered dose of the total in urine and feces
Day 1 (time 0) to Day 29

Metabolite Profiling and Identification

Time to maximum plasma concentration (tmax) for RV521
Baseline to study day 11
Terminal half life (t1/2) for RV521
Baseline to study day 11
Maximum observed plasma concentration (Cmax) for RV521
Baseline to study day 11
Area under the plasma concentration-time curve from time zero to last detectable plasma concentration (AUC0-t) for RV521
Baseline to study day 11
Area under the plasma concentration-time curve from time zero to infinity (AUC0-inf) for RV521
Baseline to study day 11
Secondary Endpoints
Spontaneously reported adverse events (AEs) during the Treatment Period
Day -1 to Day 29
Spontaneously reported serious AEs (SAEs) during the Treatment Period
Day -1 to Day 29
Use of concomitant medications
Day -1 to Day 29
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Study Design & Arms
AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
RV521EXPERIMENTALRV521 drug substance in capsule for oral administration
PlaceboPLACEBO_COMPARATORMicro-crystalline cellulose in capsule for oral administration
200 mg RV521/78 µCi [ 14C]-RV521EXPERIMENTAL200 mg RV521/78 µCi \[ 14C\]-RV521
Interventions
NameTypeDescription
RV521DRUGRV521 drug in capsules
PlaceboDRUGPlacebo in capsules
200 mg RV521/78 µCi [ 14C]-RV521.DRUG200 mg RV521/78 µCi \[ 14C\]-RV521
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Eligibility Criteria
Age Range18 Years — 45 Years
SexALL
Healthy VolunteersYes
Study Sites1

Inclusion Criteria: * Age 18 to 45 years, inclusive * In good health with no history of major medical conditions * A total body weight ≥ 50 kg and a body mass index (BMI) of \>/=18kg/m2 and \</=30kg/m2 Exclusion Criteria: * Evidence of any clinically significant or currently active major medical ...

Countries:United KingdomUnited States
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