Image by Betty Pace
A sickled red blood cell beside a normal one
ATLANTA—Results of a case study suggest voxelotor (previously GBT440) can be effective in severely ill patients with sickle cell disease (SCD).
Voxelotor is currently under investigation in the phase 3 HOPE study, which includes SCD patients age 12 and older.
A 67-year-old male SCD patient could not participate in the study due to severe, transfusion-refractory anemia, so he received voxelotor via compassionate access.
This patient’s results were presented at the Sickle Cell Disease Association of America (SCDAA) 45th Annual National Convention.
The patient had the HbSS genotype with severe anemia that was refractory to transfusion. The patient had developed red cell antibodies after receiving multiple transfusions, and these antibodies prevented further transfusions to correct his anemia.
The patient also had moderate chronic obstructive pulmonary disease requiring supplemental oxygen therapy, recurrent and frequent pain exacerbations, extreme fatigue, and clinical depression.
The patient received voxelotor at 900 mg orally once daily. He responded to the treatment within 1 to 2 weeks, experiencing improvements in pain, fatigue, and overall mental health (as measured by the Patient Health Quality-9 score).
The patient’s hemoglobin levels rose quickly, to approximately 1.5 g/dL above baseline, with a sustained increase over 66 weeks in the range of 1 to 1.5 g/dL.
There were reductions in reticulocyte count and bilirubin as well, both consistent with diminished hemolysis.
The patient’s blood oxygen saturation improved on the standard walk test, from 86 mmHg at baseline to 96 mmHg at 65 weeks, and he discontinued continuous oxygen supplementation.
The patient has not been hospitalized due to sickle cell pain since he started taking voxelotor.
He has experienced a treatment-related side effect—grade 2 diarrhea. This occurred 9 weeks after he started voxelotor treatment, when the dose was increased to 1500 mg daily, but it resolved upon return to 900 mg. The patient has experienced no other treatment-related side effects.
Clinical and laboratory improvements have continued for more than 17 months, and the patient remains on treatment today under compassionate use access.
“This severely ill SCD patient’s clinical response, assessed by both objective and subjective measures, illustrates why we are encouraged by the voxelotor program,” said Ted W. Love, MD, president and chief executive officer of Global Blood Therapeutics, the company developing voxelotor.
“We plan to present additional data from other severely ill sickle cell patients who have received voxelotor via single-patient compassionate access treatment at FSCDR [the Foundation for Sickle Cell Disease Research] at an upcoming medical meeting. Of course, controlled clinical trials are needed to assess the efficacy and safety of voxelotor in SCD patients, including those with severe anemia.”
