Sickle Cell DiseasePROSPECTNCT04930445
Oxbryta® Product Registry An Observational Study Designed to Evaluate the Effect of Oxbryta in Individuals With SCD
An observational study of Sickle Cell Disease, run by Pfizer at 43 sites in United States.
Trial summary
This registry is an observational study designed to evaluate the effect of Oxbryta in individuals with SCD in a real-world setting. Read more about this study
- Who is it for?
- Ages 4 years and older
- Conditions the study is for
- Sickle Cell Disease
- What is being tested?
- Oxbryta® (voxelotor) 500mg Tablets
- Type of treatment
- Pill or oral medicine
- How many people
- 265 participants
- Where
- 43 sitesUnited States
- Study dates
- 4 Feb 2022to 10 Oct 2024
- How long will I take part?
- 5 Years
- Phase
- Observational
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 4 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: All patients at each participating study site who have been treated with Oxbryta will be considered for inclusion in this study.
Who may be able to join
- Participants who meet all the following criteria will be eligible for enrollment:
- Willing and able to provide written informed consent (aged ≥ 18 years), parental/ guardian consent and participant assent (aged ≥ 12 to <18 years) per local regulations, or pediatric participants (aged 4 to <12 years) with parental/guardian consent per Institutional Review Board (IRB) policy and requirements, consistent with ICH guidelines
- Male or female participants with documented diagnosis of sickle cell disease (all genotypes)
- Undergoing treatment with Oxbryta according to the Oxbryta USPI
Who cannot join
- Participants meeting any of the following criteria will not be eligible for study enrollment:
- Current participation in an investigation clinical trial or expanded access program, in which the participant may be receiving voxelotor treatment.
- Medical, psychological, or behavioral condition that, in the opinion of the study doctor, would confound or interfere with evaluation of safety and/or effectiveness of the study drug, prevent compliance with the study protocol; preclude informed consent; or render the participant unable/unlikely to comply with the study procedures
Trial locations and contacts
43 sites in 1 country.
43 sites in 1 country
United States43 sites
Augusta University - Clinical Trials Office (clinic)
Augusta, Georgia, 30912
Augusta University
Augusta, Georgia, 30912
Children's Blood and Cancer Center at Dell Children's Medical Center
Austin, Texas, 78723
Dell Children's Medical Center
Austin, Texas, 78723
Boston University Medical Center
Boston, Massachusetts, 02118
Medical University of South Carolina Shawn Jenkins Women's and Children's Hospital
Charleston, South Carolina, 29425
Medical University of South Carolina
Charleston, South Carolina, 29425
Levine Cancer Institute
Charlotte, North Carolina, 28204
University of Illinois at Chicago (UIC) Clinical Research Center
Chicago, Illinois, 60612
University of Illinois at Chicago (UIC) Sickle Cell Center
Chicago, Illinois, 60612
University of Illinois Hospital and Health Sciences System(UI Health)
Chicago, Illinois, 60612
University of Illinois Hospital and Health Sciences System
Chicago, Illinois, 60612
University of Maryland Medical Center
College Park, Maryland, 21201
Duke University Hospital
Durham, North Carolina, 27710
Duke University Medical Center
Durham, North Carolina, 27710
Inova Schar Cancer Institute
Fairfax, Virginia, 22031
INOVA Health
Falls Church, Virginia, 22042-2325
University of Connecticut Health
Farmington, Connecticut, 06030-1163
University of Connecticut Health
Farmington, Connecticut, 06030
East Carolina University
Greenville, North Carolina, 27834-4300
ECU Health Medical Center Laboratory
Greenville, North Carolina, 27834
ECU Health Medical Center
Greenville, North Carolina, 27834
Foundation for Sickle Cell Disease Research
Hollywood, Florida, 33023
University of Texas Health Science Center at Houston
Houston, Texas, 77030
Nemours Children's Specialty Care
Jacksonville, Florida, 32207
University of California, San Diego
La Jolla, California, 92093-0987
Mississippi Center for Advanced Medicine
Madison, Mississippi, 39110
St. Jude Children's Research Hospital
Memphis, Tennessee, 38105
University of Miami Hospital
Miami, Florida, 33136
University of South Alabama
Mobile, Alabama, 36617
Newark Beth Israel Medical Center
Newark, New Jersey, 07112
Center for Inherited Blood Disorders
Orange, California, 92868
Bass Center for Childhood Cancer and Blood Disorders (Stanford Lucile Packard Children's Hospital)
Palo Alto, California, 94304
Department of Pediatrics, Hematology section
Palo Alto, California, 94304
Stanford Children's Hospital
Palo Alto, California, 94304
Phoenix Children's Hospital
Phoenix, Arizona, 85016
UPMC Montefiore Hospital
Pittsburgh, Pennsylvania, 14213
UPMC Sickle Cell Center
Pittsburgh, Pennsylvania, 15123
UPMC Presbyterian
Pittsburgh, Pennsylvania, 15213
University of Pittsburgh Medical Center (UPMC)
Pittsburgh, Pennsylvania, 15261
Montefiore Medical Center
The Bronx, New York, 10467
Nemours Alfred I duPont Hospital for Children
Wilmington, Delaware, 19803
Nemours Children's Health, Wilmington
Wilmington, Delaware, 19803
About this study
Official title: An Open Label, Observational, Prospective Registry of Participants With Sickle Cell Disease (SCD) Treated With Oxbryta® (Voxelotor)
This registry is an observational study designed to evaluate the effect of Oxbryta in individuals with SCD in a real-world setting.
Read the detailed description
The study will be conducted at approximately 45 sites in the United States.
This registry is an observational study to evaluate the effects of Oxbryta in individuals with SCD. Any participant who is currently taking Oxbryta, or has been prescribed and will initiate treatment with Oxbryta, is eligible to participate. Eligible participants will receive treatment with Oxbryta as prescribed by their physician, as part of their usual care. Participants will be treated and evaluated per standard of care (SOC) and at the physician's discretion. This study will collect data that are recorded in the participants' medical records and other secondary data sources. Study data will be collected at regular intervals and entered in case report forms (CRFs) via an electronic data capture (EDC) system by the study staff. Participants will be considered to be on study for up to 5 years after their first dose of Oxbryta treatment, or until they withdraw their consent to participate, or are discontinued from the study. Treatment, including interruptions and restarting treatment, will continue at the discretion of the treating physician, and there are no pre-defined treatment requirements. Participants may receive any additional medications prescribed by their treating physician, or have any medical interventions that are deemed appropriate by the treating physician or study doctor. The participant or treating physician may discontinue Oxbryta at any time. Participants who discontinue treatment with Oxbryta earlier than 5 years will continue to be followed on study to collect clinical and quality of life (QoL) outcomes for up to 5 years after their first dose of Oxbryta treatment. Participant safety and tolerability will be assessed throughout the study data collection period by the study doctor and reported to the Sponsor.
- Conditions
- Sickle Cell Disease
- Being tested
- Oxbryta® (voxelotor) 500mg Tablets
- Keywords
- Registry Sickle Cell Disease
- Medical subject headings
- Anemia, Sickle Cell
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Oxbryta® (voxelotor) 500mg TabletsDrug
Also called Voxelotor, Oxbryta®
Participants will receive treatment with Oxbryta as prescribed by their physician, as part of their usual care. Participants will be treated and evaluated per standard of care (SOC) and at the physician's discretion. There are no pre-defined treatment requirements.
| Study group | Role | What they receive |
|---|---|---|
| Oxbryta Product Registry | Not described Receives: Drug: Oxbryta® (voxelotor) 500mg Tablets |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Hemoglobin From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Percent Reticulocyte Count From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Absolute Reticulocyte Count From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Bilirubin (Total, Direct and Indirect) Level From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used. Abbreviations used: overall number of participants analyzed=N and Number analyzed= n
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Iron Overload (Ferritin Levels) From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Iron Overload as Measured by T2-weighted Magnetic Resonance Imaging (MRI) From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) up to 60 months post-Oxbryta
Change in Serum Creatinine Level From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Albumin Creatinine Ratio (ACR) From Pre-Oxbryta Treatment (Baseline) Through Month 54 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54 months post-Oxbryta
Number of Participants According to Hemoglobinuria Results Post-Oxbryta
Hemoglobinuria was defined as urine dipstick results positive for blood +1 or greater and <=2 red blood cells (RBC) by high power field. Number of participants according to hemoglobinuria results (none/negative, trace, 1+, 2+, 3+, other: large, moderate, small, small=0-3, hereditary persistence of fetal hemoglobin [HPF], missing) was reported in this outcome measure. Small corresponded to trace or 1+ on dipstick, medium indicated 2+, large indicated 3+ or higher on dipstick. The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Change in Serum Cystatin C Results From Pre-Oxbryta Treatment (Baseline) Through Month 30 Post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 12, 18, 24, 30 months post-Oxbryta
Number of Participants According to Estimated Glomerular Filtration Rate (GFR) Results Post-Oxbryta
Estimated GFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Number of participants according to estimated GFR results (stage 1 [G1] - GFR >=90 milliliter/minute [mL/min] per 1.73 square meters [m^2], stage 2 [G2] - GFR 60 to 89 mL/min per 1.73 m^2, stage 3a [G3a] - GFR 45 to 59 mL/min per 1.73 m^2, stage 3b [G3b] - GFR 30 to 44 mL/min per 1.73 m^2, stage 4 [G4] - GFR 15 to 29 mL/min per 1.73 m^2, stage 5 [G5] - GFR < 15 mL/min per 1.73 m^2 or treatment by dialysis, missing) was reported descriptively in this outcome measure. Stages 1 and 2 indicate mild damage, while stages 3 to 5 reflected progressive severity, leading to potential renal failure. The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Measured: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Number of Participants With SCD Complications
SCD complications included acute pain crisis, acute chest syndrome (ACS), priapism, stroke, chronic or end stage kidney disease iron overload, leg ulcers, cardiac malfunction and pulmonary hypertension (PH) and RBC transfusions.
Measured: From date of first Oxbryta treatment through the end of study (up to Month 60)
Number of Participants With Treatment Initiation or Modification of SCD-related Medications
Number of participants with treatment initiation or modification of SCD related medications is reported in this outcome measure.
Measured: From date of first Oxbryta treatment through the end of study (up to Month 60)
Number of Participants With Red Blood Cell (RBC) Transfusions
Number of participants with RBC transfusions is reported in this outcome measure.
Measured: From date of first Oxbryta treatment through the end of study (up to Month 60)
Number of Participants According to Responses to Patient Global Impression of Change (PGIC) at Month 3 Through Month 60
PGIC was a single question that reflected a participant's or caregiver's belief about the effectiveness of treatment with Oxbryta on a 7-point scale depicting a participant's rating of overall improvement. Participants/caregivers rated their change as "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," or "very much worse".
Measured: Month 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60
Number of Participants According to Responses to Clinical Global Impression of Change (CGIC) at Month 3 Through Month 60
CGIC was a brief, stand-alone assessment of the clinician's view of the participant's global functioning prior to and after initiating Oxbryta. The CGI provided an overall clinician-determined summary measure that took into account all available information, including a knowledge of the participant's history, psychosocial circumstances, symptoms, behavior, and the impact of the symptoms on the participant's ability to function. Participants rated their change as "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," "very much worse," or "not assessed".
Measured: Month 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60
Number of Participants With Serious Adverse Events (SAEs) According to Severity
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect and other important medical events. Severity was classified using common terminology criteria for adverse events (CTCAE), version 5.0, where Grade 1 = mild, Grade 2 = moderate, Grade 3 = severe. Mild - SAEs does not interfere with participant's usual function b) moderate - SAEs interferes to some extent with participant's usual function c) severe - SAEs interferes significantly with participant's usual function.
Measured: From date of first Oxbryta treatment up to end of study (up to Month 60)
Number of Participants With Adverse Events (AEs) According to Severity
An AE was any untoward medical occurrence in a participant or clinical investigational participant administered a medicinal product and which did not necessarily have a causal relationship with this treatment. Severity was classified using CTCAE, version 5.0, where Grade 1 = mild, Grade 2 = moderate, Grade 3 = severe. AEs are classified according to the severity in 3 categories a) mild - AEs does not interfere with participant's usual function b) moderate - AEs interferes to some extent with participant's usual function c) severe - AEs interferes significantly with participant's usual function. AEs included both SAEs and non-SAEs.
Measured: From date of first Oxbryta treatment up to end of study (up to Month 60)
Number of Participants With AEs Leading to Dose Modification or Discontinuation of Oxbryta
An AE was any untoward medical occurrence in a participant or clinical investigational participant administered a medicinal product and which does not necessarily have a causal relationship with this treatment. Number of participants with AEs leading to dose modification or discontinuation of Oxbryta were reported in this outcome measure.
Measured: From date of first Oxbryta treatment up to end of study (up to Month 60)
Number of Participants With Positive Pregnancy Test and Fertility Complications
Number of participants with positive pregnancy test and fertility complications were reported in this outcome measure.
Measured: From date of first Oxbryta treatment up to end of study (up to Month 60)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jun 2021
- Study start4 Feb 2022
- Primary completion10 Oct 2024
- Study completion10 Oct 2024
Why it stopped: Emerging clinical data evaluated by Pfizer and shared with regulatory authorities indicates that the risk profile of voxelotor in people with SCD exceeds the benefits observed in previously generated global research, and requires further assessment.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Sickle Cell DiseaseStudies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Other
- Time perspective
- Prospective
- Enrolment
- 265 participants (actual)
- Target duration
- 5 Years
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04930445
- Sponsor's protocol ID
- GBT440-4R2
- Other IDs
- C5341019
- Acronym
- PROSPECT
- Status last verified
- Dec 2025
- First submitted
- 4 Jun 2021
- Last updated
- 31 Dec 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Publications
Andemariam B, Shah N, Ershler WB, Ivy ED, Darbari DS, Anderson A, Rai P, Wun T, Yu CR, Purdie DM, Valenzuela CM, Xu M. Safety and effectiveness of voxelotor in individuals with sickle cell disease in the RETRO and PROSPECT US registries. Blood Adv. 2026 May 12;10(9):3032-3043. doi: 10.1182/bloodadvances.2025018992.
PubMed 41701977
Study at a glance
From the registry record, last updated by the sponsor on 31 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Open Label, Observational, Prospective Registry of Participants With Sickle Cell Disease (SCD) Treated With Oxbryta® (Voxelotor)
- ClinicalTrials.gov ID
- NCT04930445
- Acronym / sponsor ID
- PROSPECT / GBT440-4R2
- Conditions
- Sickle Cell Disease
- Keywords
- Registry Sickle Cell Disease
- Study type
- Observational
- Recruitment status
- TerminatedReason stopped: Emerging clinical data evaluated by Pfizer and shared with regulatory authorities indicates that the risk profile of voxelotor in people with SCD exceeds the benefits observed in previously generated global research, and requires further assessment.
- Enrolment
- 265 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 4 Feb 2022 (actual)
- Primary completion
- 10 Oct 2024 (actual)
- Study completion
- 10 Oct 2024 (actual)
- First posted
- 18 Jun 2021 (actual)
- Results
- Posted 31 Dec 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This registry is an observational study designed to evaluate the effect of Oxbryta in individuals with SCD in a real-world setting.
Detailed description
The study will be conducted at approximately 45 sites in the United States.
This registry is an observational study to evaluate the effects of Oxbryta in individuals with SCD. Any participant who is currently taking Oxbryta, or has been prescribed and will initiate treatment with Oxbryta, is eligible to participate. Eligible participants will receive treatment with Oxbryta as prescribed by their physician, as part of their usual care. Participants will be treated and evaluated per standard of care (SOC) and at the physician's discretion. This study will collect data that are recorded in the participants' medical records and other secondary data sources. Study data will be collected at regular intervals and entered in case report forms (CRFs) via an electronic data capture (EDC) system by the study staff. Participants will be considered to be on study for up to 5 years after their first dose of Oxbryta treatment, or until they withdraw their consent to participate, or are discontinued from the study. Treatment, including interruptions and restarting treatment, will continue at the discretion of the treating physician, and there are no pre-defined treatment requirements. Participants may receive any additional medications prescribed by their treating physician, or have any medical interventions that are deemed appropriate by the treating physician or study doctor. The participant or treating physician may discontinue Oxbryta at any time. Participants who discontinue treatment with Oxbryta earlier than 5 years will continue to be followed on study to collect clinical and quality of life (QoL) outcomes for up to 5 years after their first dose of Oxbryta treatment. Participant safety and tolerability will be assessed throughout the study data collection period by the study doctor and reported to the Sponsor.
Study design
- Observational model
- Other
- Time perspective
- Prospective
- Target follow-up
- 5 Years
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Oxbryta Product Registry | – | Drug: Oxbryta® (voxelotor) 500mg Tablets |
Who may qualify
- Ages
- 4 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- All patients at each participating study site who have been treated with Oxbryta will be considered for inclusion in this study.
Key inclusion criteria (4 listed)
- Participants who meet all the following criteria will be eligible for enrollment:
Key exclusion criteria (3 listed)
- Participants meeting any of the following criteria will not be eligible for study enrollment:
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Oxbryta® (voxelotor) 500mg TabletsAlso: Voxelotor, Oxbryta®Participants will receive treatment with Oxbryta as prescribed by their physician, as part of their usual care. Participants will be treated and evaluated per standard of care (SOC) and at the physician's discretion. There are no pre-defined treatment requirements. | Drug | Oxbryta Product Registry |
Primary outcome
Change in Hemoglobin From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Percent Reticulocyte Count From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Absolute Reticulocyte Count From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Bilirubin (Total, Direct and Indirect) Level From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used. Abbreviations used: overall number of participants analyzed=N and Number analyzed= n
Change in Iron Overload (Ferritin Levels) From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Iron Overload as Measured by T2-weighted Magnetic Resonance Imaging (MRI) From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) up to 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Serum Creatinine Level From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Albumin Creatinine Ratio (ACR) From Pre-Oxbryta Treatment (Baseline) Through Month 54 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Number of Participants According to Hemoglobinuria Results Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Hemoglobinuria was defined as urine dipstick results positive for blood +1 or greater and <=2 red blood cells (RBC) by high power field. Number of participants according to hemoglobinuria results (none/negative, trace, 1+, 2+, 3+, other: large, moderate, small, small=0-3, hereditary persistence of fetal hemoglobin [HPF], missing) was reported in this outcome measure. Small corresponded to trace or 1+ on dipstick, medium indicated 2+, large indicated 3+ or higher on dipstick. The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Change in Serum Cystatin C Results From Pre-Oxbryta Treatment (Baseline) Through Month 30 Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 12, 18, 24, 30 months post-Oxbryta
The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Number of Participants According to Estimated Glomerular Filtration Rate (GFR) Results Post-Oxbryta
Time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta
Estimated GFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Number of participants according to estimated GFR results (stage 1 [G1] - GFR >=90 milliliter/minute [mL/min] per 1.73 square meters [m^2], stage 2 [G2] - GFR 60 to 89 mL/min per 1.73 m^2, stage 3a [G3a] - GFR 45 to 59 mL/min per 1.73 m^2, stage 3b [G3b] - GFR 30 to 44 mL/min per 1.73 m^2, stage 4 [G4] - GFR 15 to 29 mL/min per 1.73 m^2, stage 5 [G5] - GFR < 15 mL/min per 1.73 m^2 or treatment by dialysis, missing) was reported descriptively in this outcome measure. Stages 1 and 2 indicate mild damage, while stages 3 to 5 reflected progressive severity, leading to potential renal failure. The pre-Oxbryta (baseline) value was the latest measurement on or prior to the first dose of Oxbryta. Post-Oxbryta value was the measurement for multiple assessments at the same specific visit, the average was used.
Number of Participants With SCD Complications
Time frame: From date of first Oxbryta treatment through the end of study (up to Month 60)
SCD complications included acute pain crisis, acute chest syndrome (ACS), priapism, stroke, chronic or end stage kidney disease iron overload, leg ulcers, cardiac malfunction and pulmonary hypertension (PH) and RBC transfusions.
Number of Participants With Treatment Initiation or Modification of SCD-related Medications
Time frame: From date of first Oxbryta treatment through the end of study (up to Month 60)
Number of participants with treatment initiation or modification of SCD related medications is reported in this outcome measure.
Number of Participants With Red Blood Cell (RBC) Transfusions
Time frame: From date of first Oxbryta treatment through the end of study (up to Month 60)
Number of participants with RBC transfusions is reported in this outcome measure.
Number of Participants According to Responses to Patient Global Impression of Change (PGIC) at Month 3 Through Month 60
Time frame: Month 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60
PGIC was a single question that reflected a participant's or caregiver's belief about the effectiveness of treatment with Oxbryta on a 7-point scale depicting a participant's rating of overall improvement. Participants/caregivers rated their change as "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," or "very much worse".
Number of Participants According to Responses to Clinical Global Impression of Change (CGIC) at Month 3 Through Month 60
Time frame: Month 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60
CGIC was a brief, stand-alone assessment of the clinician's view of the participant's global functioning prior to and after initiating Oxbryta. The CGI provided an overall clinician-determined summary measure that took into account all available information, including a knowledge of the participant's history, psychosocial circumstances, symptoms, behavior, and the impact of the symptoms on the participant's ability to function. Participants rated their change as "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," "very much worse," or "not assessed".
Number of Participants With Serious Adverse Events (SAEs) According to Severity
Time frame: From date of first Oxbryta treatment up to end of study (up to Month 60)
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect and other important medical events. Severity was classified using common terminology criteria for adverse events (CTCAE), version 5.0, where Grade 1 = mild, Grade 2 = moderate, Grade 3 = severe. Mild - SAEs does not interfere with participant's usual function b) moderate - SAEs interferes to some extent with participant's usual function c) severe - SAEs interferes significantly with participant's usual function.
Number of Participants With Adverse Events (AEs) According to Severity
Time frame: From date of first Oxbryta treatment up to end of study (up to Month 60)
An AE was any untoward medical occurrence in a participant or clinical investigational participant administered a medicinal product and which did not necessarily have a causal relationship with this treatment. Severity was classified using CTCAE, version 5.0, where Grade 1 = mild, Grade 2 = moderate, Grade 3 = severe. AEs are classified according to the severity in 3 categories a) mild - AEs does not interfere with participant's usual function b) moderate - AEs interferes to some extent with participant's usual function c) severe - AEs interferes significantly with participant's usual function. AEs included both SAEs and non-SAEs.
Number of Participants With AEs Leading to Dose Modification or Discontinuation of Oxbryta
Time frame: From date of first Oxbryta treatment up to end of study (up to Month 60)
An AE was any untoward medical occurrence in a participant or clinical investigational participant administered a medicinal product and which does not necessarily have a causal relationship with this treatment. Number of participants with AEs leading to dose modification or discontinuation of Oxbryta were reported in this outcome measure.
Number of Participants With Positive Pregnancy Test and Fertility Complications
Time frame: From date of first Oxbryta treatment up to end of study (up to Month 60)
Number of participants with positive pregnancy test and fertility complications were reported in this outcome measure.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 31 Dec 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41701977Andemariam B, Shah N, Ershler WB, Ivy ED, Darbari DS, Anderson A, Rai P, Wun T, Yu CR, Purdie DM, Valenzuela CM, Xu M. Safety and effectiveness of voxelotor in individuals with sickle cell disease in the RETRO and PROSPECT US registries. Blood Adv. 2026 May 12;10(9):3032-3043. doi: 10.1182/bloodadvances.2025018992.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: No. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Pfizer CT.gov Call Center study director
Pfizer
43 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Sickle Cell Disease, run by Pfizer at 43 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 31 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 43 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 31 Dec 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Hemoglobin From Pre-Oxbryta Treatment (Baseline) Through Month 60 Post-Oxbryta (time frame: Pre-Oxbryta (baseline) 3, 6, 9, 12, 18, 24, 30, 36, 42, 48, 54, 60 months post-Oxbryta). The study lists 20 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04930445, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 31 Dec 2025.