Recruiting
Phase 2
Phase 3

Osivelotor

Sponsor:

Pfizer

Code:

NCT05431088

Conditions

Sickle Cell Disease

Eligibility Criteria

Sex: All

Age: 12+

Healthy Volunteers: Not accepted

Interventions

Osivelotor

Study Details

Brief summary:

The purpose of this study is to evaluate the safety, tolerability, efficacy, pharmacokinetics and pharmacodynamics of osivelotor.

Conditions

Sickle Cell Disease

Study ID

NCT05431088

Start date

Sep 22, 2022

Status verified date

Aug, 2026

Completion date

Dec 31, 2032

Anticipated

Primary completion date

Dec 30, 2030

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 12+

Healthy Volunteers: Not accepted

Inclusion Criteria:

Part A and Part B:

  • Male or female with SCD, HbSS and HbSB-zero
  • Participants with Hemoglobin ≥ 5.5 and ≤ 10.5 g/dL during Screening and considered stable 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 need for dose adjustments during the study in the opinion of the Investigator.

Part B:

  • Participants with SCD ages 12 years and older, inclusive at screening.
  • Participants with more than or equal to 2 and ≤ 10 VOCs within 12 months of Screening.

OLE:

\- Participants who have completed the Part B successfully will be eligible.

Exclusion Criteria:

Part A and Part B:

  • Participants who had more than 10 VOC within 12 months of screening
  • Female participant who is breastfeeding or pregnant
  • Participants who receive RBC transfusion therapy regularly or received an RBC transfusion ---for any reason within 90 days of Day 1
  • Participants hospitalized for sickle cell crisis or other vaso-occlusive event within 14 days of signing the ICF or anytime during the screening period.
  • Participants in Sub-Saharan Africa or who have relocated from Sub-Saharan Africa within 6 months.

OLE:

  • Have any unresolved clinically significant adverse event, laboratory abnormality, or safety finding from Part B that, in the opinion of the Investigator, increases the risk of study drug administration.
  • Met permanent treatment discontinuation criteria during Part B.
  • Have withdrawn consent or are unable to comply with study procedure

Study Design

Enrollment

389 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

placebo comparator: Part B

Study 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.

experimental: OLE

Adult 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.

active comparator: Part A

Initially, 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.

Interventions

Osivelotor

Tablets which contain drug substance

Primary outcome measure

  • Part A [ Time Frame: Through week 12 ]
  • Part B [ Time Frame: Through week 48 ]
  • OLE [ Time Frame: Approximately 24 months after last patient enrolled ]

Central Contacts and Locations

Central contacts

Pfizer Pfizer CT.gov Call Center

1-800-718-1021ClinicalTrials.gov_Inquiries@pfizer.com

Locations

AMR Clinical

Recruiting

Mobile, Alabama, United States, 36608

Edward Jenner Research Group LLC.

Recruiting

Plantation, Florida, United States, 33317

Pediatric Hematology / Oncology a division of Kidz Medical services

Recruiting

West Palm Beach, Florida, United States, 33407

St. Mary's Medical Center

Recruiting

West Palm Beach, Florida, United States, 33407

Children's Center for Advanced Pediatrics

Recruiting

Atlanta, Georgia, United States, 30329

University of Illinois at Chicago Clinical Research Center

Recruiting

Chicago, Illinois, United States, 60612

University of Illinois Hospital and Health Sciences System - Investigational Drug Services (IDS)

Recruiting

Chicago, Illinois, United States, 60612

University of Illinois Hospital and Health Sciences System

Recruiting

Chicago, Illinois, United States, 60612

Southern Specialty Research

Recruiting

Flowood, Mississippi, United States, 39232

University Health

Recruiting

Kansas City, Missouri, United States, 64108

Jack & Sheryl Morris Cancer Center

Recruiting

New Brunswick, New Jersey, United States, 08901

Robert Wood Johnson University Hospital

Recruiting

New Brunswick, New Jersey, United States, 08901

Rutgers Cancer Institute of New Jersey

Recruiting

New Brunswick, New Jersey, United States, 08901

Icahn School of Medicine at Mount Sinai

Recruiting

New York, New York, United States, 10029

Jacobi Medical Center

Recruiting

The Bronx, New York, United States, 10461

Duke University IDS Pharmacy

Recruiting

Durham, North Carolina, United States, 27710

Duke University Medical Center

Recruiting

Durham, North Carolina, United States, 27710

ECU Physicians, Brody Outpatient Clinic

Recruiting

Greenville, North Carolina, United States, 27834

Prisma Health Laurens County Hospital

Recruiting

Clinton, South Carolina, United States, 29325

Prisma Health - Upstate

Recruiting

Greenville, South Carolina, United States, 29605

Prisma Health Greenville Memorial Hospital

Recruiting

Greenville, South Carolina, United States, 29605

Prisma Health Outpatient Radiology - Greenville

Recruiting

Greenville, South Carolina, United States, 29605

Prisma Health Patewood Hospital

Recruiting

Greenville, South Carolina, United States, 29615

Prisma Health Greer Memorial Hospital

Recruiting

Greer, South Carolina, United States, 29650

Prisma Health Hillcrest Hospital

Recruiting

Simpsonville, South Carolina, United States, 29681

Prisma Health North Greenville Hospital

Recruiting

Travelers Rest, South Carolina, United States, 29690

Inova Schar Cancer Institute

Recruiting

Fairfax, Virginia, United States, 22031

More Information

Sponsor

Pfizer

Last update posted

Aug 18, 2026

Last verified

Aug, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Pfizer on 2026-08-18.