STOCKHOLM—An ongoing phase 2 study suggests voxelotor (GBT440) can benefit adolescents with sickle cell disease (SCD).
In the HOPE-KIDS 1 study, voxelotor produced sustained improvements in hemoglobin levels and a reduction in clinical measures of hemolysis in a cohort of adolescents with SCD, most of whom were also receiving hydroxyurea (HU).
The most common adverse events (AEs) related to voxelotor were nausea, vomiting, headache, and rash.
These results were presented in a poster (abstract PF709) at the 23rd Congress of the European Hematology Association (EHA).
HOPE-KIDS 1 is sponsored by Global Blood Therapeutics, Inc.
In this study, researchers are evaluating voxelotor in SCD patients ages 6 to 17. In part A, researchers evaluated a 600 mg daily dose of voxelotor. In part B, they are testing voxelotor at daily doses of 900 mg and 1500 mg in patients ages 12 to 17.
At EHA, the researchers presented data on 25 patients who received voxelotor at 900 mg/day for 24 weeks in part B. Eighty-eight percent of the patients (n=22) were also taking HU.
The patients’ median age was 14 (range, 12-17), and 56% were male. Ninety-six percent (n=24) had the HbSS genotype.
Forty-eight percent of patients had 1 to 4 vaso-occlusive crises (VOCs) in the past year, 8% had more than 4 VOCs, and 44% had 0 VOCs.
At baseline, the median hemoglobin was 8.9 g/dL, the median fetal hemoglobin was 10.8 g/dL, and the median time-averaged mean of maximum velocity was 110 cm/s.
All 25 patients were dosed with voxelotor, and 22 completed 24 weeks of dosing. One patient withdrew consent, 1 was lost to follow-up, and 1 patient discontinued due to noncompliance.
Of the 22 patients who completed 24 weeks of voxelotor treatment, all but 3 were receiving concurrent HU.
Voxelotor-related AEs occurring in at least 2 patients included nausea (12%, n=3), vomiting (8%, n=2), headache (8%, n=2), and rash (8%, n=2).
There was 1 case of grade 3 urticaria, which resolved and did not recur with continued dosing. There were no discontinuations of voxelotor due to AEs.
Patients experienced increased hemoglobin levels and improved clinical measures of hemolysis at 24 weeks, as evaluated by changes from baseline in hemoglobin, percent of reticulocytes, and percent of unconjugated bilirubin.
In all, 43% of patients (9/21) achieved a hemoglobin response (>1 g/dL) at 24 weeks. The median hemoglobin change from baseline was 0.7 g/dL, the median reduction in reticulocytes was 22.9%, and the median reduction in unconjugated bilirubin was 38.6%.
Sixty-two percent of patients (13/21) had a reduction in daily symptoms at 24 weeks, as assessed by total symptom scores (TSS). There was a 39% median reduction in TSS from baseline.
Fifty-five percent of patients (11/20) had a numerical decrease in transcranial doppler (TCD) flow at 24 weeks. Among hemoglobin responders (>1 g/dL), 88% (7/8) had a numerical decrease in TCD at 24 weeks.
“We continue to be encouraged by the results of the ongoing HOPE-KIDS 1 study, which are consistent with inhibition of HbS polymerization by voxelotor and support its ongoing clinical evaluation as a potential disease-modifying therapy for both adults and adolescents with SCD,” said Ted W. Love, MD, president and chief executive officer of Global Blood Therapeutics.
“Results to date support our ongoing development of voxelotor in a broad range of patients, including in our phase 3 HOPE study, which is also evaluating voxelotor at doses of 900 mg and 1500 mg per day in adolescents and adults. We continue to expect to announce top-line clinical data from part A of the HOPE study by the end of this quarter.”