Beam Therapeutics’ early clinical data on its base-editing therapy BEAM-101 shows for the first time that the technology restores functional hemoglobin in people with sickle cell disease. In four patients treated with BEAM-101, functional fetal hemoglobin levels increased to over 60% at 1–6 months follow-up, and patients’ red blood cells had less sickling, reduced cell adhesion and improved flow properties. Moreover, no patients had the painful vaso-occlusive crises typical of sickle cell disease. Beam will release further data at December’s American Society for Hematology meeting.

BEAM-101 uses adenine base editors to introduce single-base changes in the promoter regions of the γ-globin genes HBG1 and HBG2 in patients’ stem cells ex vivo. These changes disrupt the binding of the BCL11A repressor, increasing the expression of fetal hemoglobin. If approved, BEAM-101 would sit alongside Vertex’s CRISPR-based therapy Casgevy (exagamglogene autotemcel) and bluebird bio’s gene therapy Lyfgenia (lovotibeglogene autotemcel). In separate trials, those sickle cell therapies increased functional hemoglobin to around 40% at two years.