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Osivelotor

Phase 2

Sickle Cell Disease | Small molecule | Hematology |Pfizer, Inc.|Last Updated: Mar 20, 2026

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_CONTROLLEDDMC
Total Trials1
Total Enrollment389
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05431088A Phase 2/3 Study in Adult and Adolescent Participants With SCDPHASE2 RECRUITING 389Sep 22, 2022Dec 31, 2032Mar 20, 202649 United States, Brazil +4
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Study Endpoints
Primary Endpoints
Part A
Through week 12

Number of adult participants with change from baseline in hemoglobin (Hb) through week 12 as measured by change in osivelotor concentrations from baseline or percentage change from baseline of clinical measures of anemia Hb and hemolysis (including indirect bilirubin, reticulocytes and lactate dehydrogenase).

Part B
Through week 48

Co-primary endpoints: Hb response (increase from baseline of \>1 g/dL) at Week 48 (based on average of Hb levels at Week 40 and Week 48) and the Annualized rate of VOC through end of Week 48. A VOC is defined as an acute episode of pain that: * Has no medically determined cause other than a vaso-occlusive event, and * Results in a visit to a medical facility (hospitalization, emergency department, urgent care center, outpatient clinic, or infusion center), and * Requires parenteral narcotic agents, parenteral nonsteroidal anti-inflammatory drugs (NSAIDs), or an increase in treatment with oral narcotics. Complicated VOCs of acute chest syndrome (ACS), hepatic sequestration, splenic sequestration, priapism, and dactylitis that meet the requirements listed above will be included in this co-primary endpoint.

OLE
Approximately 24 months after last patient enrolled

Incidence of Treatment Emergent Adverse Events: * Incidence of SAEs * Incidence of AEs leading to discontinuation * Change from baseline in laboratory parameters.

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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
Part AACTIVE_COMPARATORInitially, participants will be randomized 1:1 to 100 mg and 150 mg daily. Upon review of the 150 mg safety data from at least 6 participants, there will be 1:1:1 randomization: 100 mg, 150 mg, and up to 200 mg. Participants will then receive maintenance once daily doses through Week 12.
Part BPLACEBO_COMPARATORStudy drug arm: Adult participants will receive osivelotor at 300 mg QD loading dose for 7 days followed by 150 mg QD through Week 48. Adolescent participant dose will be defined in a future protocol amendment. Placebo arm: Participants will receive placebo tablets for 48 weeks.
OLEEXPERIMENTALAdult Participants will receive 150 mg open-label osivelotor up to 2 years after the last participant's visit in Part B or when the drug is commercially available in that region. The appropriate doses for adolescents will be defined in a future protocol amendment.
Interventions
NameTypeDescription
OsivelotorDRUGTablets which contain drug substance
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Eligibility Criteria
Age Range12 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites49

Inclusion Criteria: Part A, Part B, and OLE: * Male or female with SCD * Participants with stable Hb value as judged by the Investigator * For participants taking hydroxyurea and/or L-glutamine, the dose must be stable for at least 90 days prior to signing the ICF or assent and with no anticipated...

Countries:United StatesBrazilIndiaKenyaNigeriaUnited Kingdom
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT05431088primaryCompletionDate: changed
LOWMay 24, 2026NCT05431088studyFirstPostDate: changed