A Phase 2a, Open-label, Single and Multiple Dose Study to Evaluate the Pharmacokinetics, Safety, Tolerability, and Treatment Effect of GBT440 in Pediatric Participants With Sickle Cell Disease

About the study

This study consists of four parts, Parts A, B, C, and D.

Part A is a single dose pharmacokinetic (PK) study in pediatric participants with Sickle Cell Disease ages 6 to 17 years.
Part B is a multiple dose, safety, exploratory, efficacy, and PK study in adolescent participants with Sickle Cell Disease ages 12 to 17 years.
Part C is a multiple dose, safety, tolerability, and PK study, which includes the assessment of hematological effects and the effect on TCD flow velocity of voxelotor in pediatric participants with Sickle Cell Disease ages 4 to 17 years.
Part D is a multiple dose, safety, tolerability, and PK study, which examines the hematological effects of voxelotor in pediatric participants with Sickle Cell Disease ages 6 months to < 4 years.

Study point of contact

Aimee Enriquez
(650) 741-7777
Mark Davis, MS
(925) 336-1055


11 United States sites

4 United Kingdom sites

3 Lebanon sites


6 Months - 17 Years




Phase 2

Study type






participation requirements

Male or female participants with homozygous hemoglobin SS (HbSS) or hemoglobin S beta0 thalassemia (HbS β0thal)


Part A – 6 to 17 years of age
Part B – 12 to 17 years of age
Part C – 4 to 17 years of age
Part D – 6 months to <4 years of age Hydroxyurea (HU) therapy: Parts A, B, and C: A participant taking hydroxyurea (HU) may be enrolled if the dose has been stable for at least 3 months with no anticipated need for dose adjustment during the study and no sign of hematological toxicity. Part D: A participant taking HU may be enrolled if the dose has been stable for at least 1 month. Titration to the maximum tolerated dose (MTD) is allowed during the study. Hemoglobin (HB): Part A - No restriction Parts B, C, & D - Hb ≤ 10.5 g/dL For Part C only: Participants 12 to 17 years of age must have a TCD velocity of ≥ 140 cm/sec measured anytime during screening.

participation restrictions

Any one of the following requiring medical attention within 14 days of signing the Informed Consent Form (ICF):

Vaso-occlusive crisis (VOC)
Acute chest syndrome (ACS)
Splenic sequestration crisis
Requires chronic transfusion therapy
History of stroke or meeting criteria for primary stroke prophylaxis (history of two TCD measurements ≥ 200 cm/sec by non-imaging TCD or ≥185 cm/sec by TCDi).
Transfusion within 30 days prior to signing the ICF

Exclusion Criteria for Part D Only:

Body weight <5 kg for 1 month prior to the screening visit and at the screening visit.


  • Oakland, California, United States, UCSF Benioff Children's Hospital Oakland, 94609 [Completed]
  • Washington, District of Columbia, United States, Children's National Medical Center, 20010 [Recruiting]
  • Atlanta, Georgia, United States, Children's Healthcare of Atlanta, 30342 [Active, not recruiting]
  • Chicago, Illinois, United States, Ann & Robert Lurie Children's Hospital of Chicago, 60611 [Recruiting]
  • Baton Rouge, Louisiana, United States, Our Lady of the Lake Regional Medical Center, 70808 [Completed]
  • Kansas City, Missouri, United States, Children's Mercy Hospital Kansas City, 64108 [Completed]
  • New Brunswick, New Jersey, United States, Rutgers - Cancer Institute of New Jersey, 08901 [Completed]
  • Greenville, North Carolina, United States, East Carolina University Brody School of Medicine, 27834 [Recruiting]
  • Philadelphia, Pennsylvania, United States, The Children's Hospital of Philadelphia, 19104 [Recruiting]
  • Pittsburgh, Pennsylvania, United States, Children's Hospital of Pittsburgh of UPMC, 15224 [Recruiting]
  • Memphis, Tennessee, United States, St. Jude Children's Research Hospital, 38105 [Recruiting]
  • Beirut, Hamrah, Lebanon, American University of Beirut Medical Center AUBMC, 1107-2020 [Recruiting]
  • Beirut, Lebanon, Rafik Hariri University Hospital (RHUH), 28337401 [Completed]
  • Tripoli, Lebanon, Nini Hospital, 1300 [Recruiting]
  • London, United Kingdom, University College London Hospitals NHS Foundation Trust, NW1 2PG [Recruiting]
  • London, United Kingdom, Evelina London Children's Hospital - Guy's and St. Thomas' NHS Foundation Trust, SE1 9RT [Recruiting]
  • London, United Kingdom, Royal London Hospital, Barts Health NHS Trust, SE1 9RT [Recruiting]
  • Manchester, United Kingdom, Royal Manchester Children's Hospital, Manchester University NHS Foundation Trust, M13 9WL [Withdrawn]
Last updated 2022-08-25