Urgent use of voxelotor in sickle cell disease when immediate transfusion is not safe.

The use of blood transfusions to improve anemia resulting from sickle cell disease (SCD) is often limited by alloimmunization, which occurs due to exposure to incompatible antigen present on donor red blood cells (RBCs). This complication occasionally manifests as delayed hemolytic transfusion reactions (DHTRs) that cause hemolysis of the recipient's own RBCs and can lead to fatal anemia. In this case study, we report a patient with SCD who experienced a DHTR following chronic transfusion and was successfully treated with voxelotor, an orally administered sickle hemoglobin (HbS) polymerization inhibitor for the treatment of SCD. Laboratory tests following admission indicated pan-reactivity in antigens, and a rare donor registry was used to locate acceptable units. The patient experienced the DHTR 3 days after admission, which limited laboratory tests due to profound hemolysis. Alternative treatments were limited, and phenotypically matched units were incompatible, so voxelotor was selected as a last-resort treatment. Following initiation of voxelotor 1500 mg, the patient's hemoglobin levels returned to baseline (6 g/dl) within 10 days, with clinical improvements. This report provides evidence regarding the use of voxelotor in the treatment of profound anemia where other treatments could be unsafe or unavailable.