Yesterday, GBT released their EHA abstract, which included some top-line data from the 900mg cohort of Part B in Phase 2a adolescent. Here are the key highlights:
- Abstract data was available for 12 patients who received voxelotor 900mg for 24 weeks. Data for all 25 patients treated with 900mg for 24 weeks will be presented June 15 @ 5:30. This data will include statistical results also.
Hemoglobin response fell
5/12 patients (42%) achieved Hb response of >1 g/dL increase (Figure) at 24 weeks. At ASH this figure was slightly higher as 6/11 patients (55%) achieved hemoglobin response > 1 g/dl at 16 weeks.
What does this mean? Hemoglobin response >1g/dl is the primary benchmark for SCD, so showing a decline from 55% to 42% is not ideal. However, it is important to note that ASH data was at 16 weeks, versus EHA at 24 weeks. In adults, GBT has shown 46% reduction at 24 weeks (in line with EHA data above). Also, n=12 patients is a small number to make any real conclusions.
Other measures support voxelotor’s efficacy
Median reduction in reticulocytes (32%) and indirect bilirubin (38%) was consistent with previous results in adolescent & adults with SCD.
Why is this important? Reticulocytes are immature red blood cells that sickle cell patients express because their bodies are constantly needing to produce new red blood cells. A reduction in reticulocytes indicates that mature red blood cells are lasting longer and GBT’s voxelotor is working.
Bilirubin is a product of red blood cell destruction. So a reduction in bilirubin shows voxelotor is protecting red blood cells and they are lasting longer. A decrease in both these measures is bullish for GBT’s efficacy.
PRO data indicates total SCD symptom scores were lower from screening to week 24
Remember, PRO is a secondary endpoint GBT is considering for their Phase 3 trial in adults. A lower score indicates that patients are experiences less daily symptoms from screening to week 24, which should be an indicator of better patient quality of life.
Voxelotor is safe
Among the 25 patients treated for up to 24 weeks, the majority of treatment-related adverse events (AEs) were grade 1 or 2, and there were no treatment-related serious AEs or drug discontinuations due to AEs. The most common treatment-related AEs included nausea (12%), vomiting (8%), headache (8%), and rash (8%), all of which are consistent with prior data.
One or more of PropThink's contributors are long GBT
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