Sickle cell drug voxelotor tested for Long-Term safety – but trial ends early

NCT ID NCT04188509

Terminated Disease control Sponsor: Pfizer Source: ClinicalTrials.gov ↗

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study looked at the long-term safety of the drug voxelotor in 162 people with sickle cell disease who had already taken it in earlier trials. Everyone received voxelotor once daily. The main goal was to track side effects. The trial was terminated early, so the full safety picture may not be clear.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: voxelotor (GBT440)
What this could lead to: If successful, this could confirm that long-term use of voxelotor is safe and helps manage sickle cell disease symptoms.
What could go wrong: The trial was terminated early, so results may be incomplete. It only included people who had already taken voxelotor, which limits what we can learn about broader safety.

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Conditions

The condition(s) this trial relates to.

sickle cell disease

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

SICKLE CELL DISEASE

Contacts and locations

Locations

Ain Shams University Hospital - Clinical Research Center (MASRI-CRC)

Cairo, Egypt
Alexandria University Hospital - Clinical Research Center

Alexandria, 21131, Egypt
American University of Beirut - Medical Center

Beirut, Lebanon
Aminu Kano Teaching Hospital

Kano, 700233, Nigeria
Ann & Robert H. Lurie Children's Hospital of Chicago

Chicago, Illinois, 60611, United States
Barau Dikko Teaching Hospital/Kaduna State University

Kaduna, 800212, Nigeria
Barts Health NHS Trust , The Royal London Hospital

London, E1 1BB, United Kingdom
Cairo University Hospital, Abu El Rish Hospital

Cairo, 11562, Egypt
Children's Healthcare of Atlanta Scottish Rite

Atlanta, Georgia, 30342, United States
Children's Mercy Hospital

Kansas City, Missouri, 64108, United States
Children's National Medical Center

Washington D.C., District of Columbia, 20010, United States
College of Medicine, University of Ibadan

Ibadan, Oyo State, 200212, Nigeria
ECU Physicians, Brody Outpatient Clinic

Greenville, North Carolina, 27834, United States
Guy'S and St Thomas' Nhs Foundation Trust

London, SE1 7EH, United Kingdom
Lagos University Teaching Hospital

Lagos, 100254, Nigeria
Nini Hospital

Tripoli, Lebanon
UPMC Children's Hospital of Pittsburgh

Pittsburgh, Pennsylvania, 15224, United States
University College Hospital NHS Foundation Trust

London, Greater London, NW1 2PG, United Kingdom
University of Calabar Teaching Hospital

Calabar, Cross River State, 540281, Nigeria
Zagazig University Hospital

Zagazig, Alsharkia, Egypt

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