A Phase 2a, Open-label, Single and Multiple Dose Study to Evaluate the Pharmacokinetics, Safety, Tolerability, and Exploratory 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. Part B is a
multiple dose, safety, exploratory, efficacy, and PK study in adolescent Sickle Cell Disease
participants who were 12-17 years of age. 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 who are 4 to 17
years of age. Part D is a multiple dose, safety, tolerability, and PK study, which will
examine the hematological effects of voxelotor in pediatric participants with Sickle Cell
Disease who are between 9 months to < 4 years of age.

Study point of contact

Aimee Enriquez
(650) 741-7777
Margaret Tonda, PharmD
(650) 741-7761


11 United States sites

4 United Kingdom sites

2 Lebanon sites


9 to 17 Years




Phase 2

Study type








participation requirements

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

2. Age:

1. Part A – 6 to 17 years of age

2. Part B – 12 to 17 years of age

3. Part C – 4 to 17 years of age

4. Part D – 9 months to <4 years of age 3. 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. 4. Hemoglobin (HB): 1. Part A - No restriction 2. Parts B, C, & D - Hb ≤ 10.5 g/dL 10. 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

1. 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

– Dactylitis

2. Requires chronic transfusion therapy

3. 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).

4. Transfusion within 30 days prior to signing the ICF

Exclusion Criteria for Part D Only:

16. 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 [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 [Recruiting]
  • Kansas City, Missouri, United States, Children's Mercy Hospital Kansas City, 64108 [Recruiting]
  • New Brunswick, New Jersey, United States, Rutgers - Cancer Institute of New Jersey, 08901 [Withdrawn]
  • 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 [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 2021-05-11