Children aged 2 to less than 4 years with sickle cell disease (SCD) demonstrated increased hemoglobin levels and a decrease in hemolysis markers after treatment with voxelotor in the HOPE-KIDS 1 trial.

Voxelotor is already approved by the United States Food and Drug Administration for the treatment of SCD among children aged 4 or older. A poster presented at the 2023 ASPHO Annual Meeting reported results from the part D portion of the phase 2a HOPE-KIDS 1 trial ( Identifier: NCT02850406). Results from the part C portion of children aged 4 to younger than 12 were reported previously and were consistent with findings from the pivotal trial among patients aged 12 or older.

Part D of the open-label trial treated 23 children aged 2 to less than 4 years with SCD with weight-based equivalent dose of voxelotor of 1500 mg/day for up to 48 weeks. Voxelotor is given as an oral suspension or in dispersible tablets. The primary endpoints were treatment-emergent adverse events (TEAEs) and serious AEs. Secondary endpoints included change from baseline at 24 weeks in hemoglobin levels and markers of hemolysis.

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At baseline, the median age at was 2.0 years, 60.9% of patients were male, and 39.1% of patients were Black or African American, 39.1% were White, and 21.7% were Middle Eastern or North African. HbSS was the most common SCD genotype, which was present among 82.6% of patients. The mean baseline hemoglobin was 8.4 g/dL, the mean fetal hemoglobin was 19.4%, and the mean white blood cell count was 10.9 x 109 /L. There were 69.6% of patients currently treated with hydroxyurea and concurrent hydroxyurea was allowed during the study.

TRAEs were reported among 91.3% of patients, including 42.9% that were grade 3, 28.6% that were grade 2, and 28.6% that were grade 1. There were no grade 4 or 5 events. The rate of serious AEs was 47.8%, with the most common being anemia and pyrexia. Treatment-related AEs that were unrelated to SCD occurred among 13.0% of patients, none of which were serious.

Of the 20 patients evaluable for efficacy at 24 weeks, the mean increase in hemoglobin from baseline was 0.6 g/dL. There were 45.0% of patients who demonstrated a hemoglobin response that was greater than 1 g/dL. Throughout the study, there were 75.0% of patients who achieved a hemoglobin response of greater than 1 g/dL at some point.

All markers of hemolysis decreased by 24 weeks. Indirect bilirubin decreased by 24.5%, reticulocytes by 3.65%, and lactate dehydrogenase by 0.4%.

The authors concluded that these findings were consistent with the results from part C of the same study and the pivotal HOPE trial in older age groups, “providing support for the use of voxelotor as a potential strategy for early mitigation of hemolysis and anemia in children with SCD aged 2 to less than 4 years.”

Disclosures: This research was supported by Pfizer. Please see the original reference for a full list of disclosures.


Fuh B, Inati A, Inusa BPD, et al. Interim safety and efficacy of voxelotor in children aged 2 to <4 years with sickle cell disease. ASPHO 2023; May 10-13, 2023. Abstract 378.