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Taking peoplePhase 2/3

Tests osivelotor, a pill, in people with sickle cell disease

Tests the oral drug osivelotor in teens and adults with sickle cell disease.

Key facts

Who runs it
Pfizer
Where
Barakaldo, Barcelona, and Madrid, SpainSee the 4 sitesAlso in 12 other countries, 92 sites
Trial code
Registry title
A Phase 2/3 Study of Osivelotor in Adult and Adolescent Participants With SCD
Status
Recruiting
Phase
Phase 2/3
People taking part
389 people, planned
Started
22 Sept 2022
Expected to end
31 Dec 2032
Type of study
Interventional, 3 groupsOne group gets an existing treatment, for comparison.
Treatments tested
  • Osivelotor
Record updated
18 August 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for people aged 12 to 64 with sickle cell disease (HbSS or HbSB-zero) who have had some pain crises (vaso-occlusive crises, VOCs) in the past year.

Age
12 Years to 64 Years
Sex
All; men and women can join.
Disease stage
Sickle cell disease type HbSS or HbSB-zero, stable, hemoglobin from 5.5 to 10.5 g/dL at screening. For Part B: 2 to 10 VOCs within 12 months of screening.
Earlier treatment
If taking hydroxyurea and/or L-glutamine, the dose must have been stable for at least 90 days. No regular red blood cell transfusions, and none within 90 days of Day 1.
Biomarker or test result
Hemoglobin of at least 5.5 and at most 10.5 g/dL during screening.

Main reasons for not taking part

  • More than 10 VOCs within 12 months of screening
  • Pregnant or breastfeeding
  • Hospitalized for sickle cell crisis within 14 days of signing consent or during screening
  • Living in Sub-Saharan Africa, or moved from there within 6 months
  • Regular red blood cell transfusions, or one within 90 days of Day 1

The registry criteria, word for word

Show all 16 criteriaShow less

Who can take part

  • 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

Who cannot take part

  • Participants who receive RBC transfusion therapy regularly or received an RBC transfusion ---for any reason within 90 days of Day 1
  • 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
  • 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 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:
  • Met permanent treatment discontinuation criteria during Part B
  • Have withdrawn consent or are unable to comply with study procedure

Check if you might fit

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • Are you between 12 and 64 years old?

Where in Spain

Also in 12 other countries, 92 sites

  • Hospital Universitario de CrucesBarakaldo, SpainNot yet recruiting
  • Hospital Universitari Vall d'HebronBarcelona, SpainNot yet recruiting
  • Hospital General Universitario Gregorio MarañónMadrid, SpainNot yet recruiting
  • Hospital Universitario La PazMadrid, SpainNot yet recruiting

About the trial

What the trial wants to find out

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

The 3 groups in the trial

  • Part BPlacebo, for comparison

    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.

    Treatment: Osivelotor

  • OLETreatment being tested

    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.

    Treatment: Osivelotor

  • Part AExisting treatment, for comparison

    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.

    Treatment: Osivelotor

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
Official title
A PHASE 2/3 RANDOMIZED, MULTICENTER STUDY OF OSIVELOTOR ADMINISTERED ORALLY TO ADULT AND ADOLESCENT PARTICIPANTS WITH SICKLE CELL DISEASE
Plain-language title
Tests osivelotor, a pill, in people with sickle cell diseaseGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 11 November 2026.
Fit questions
Built from NCT05431088, who can take part
Record updated
18 August 2026