ICD-10 Specific code D57.2: Double heterozygous sickling disorders

Exagamglogene autotemcel is a cell therapy consisting of autologous CD34+ HSPCs ex vivo edited by CRISPR/Cas9-technology. The highly specific guide RNA enables CRISPR/Cas9 to make a precise DNA double-strand break at the critical transcription factor binding site (GATA1) in the erythroid specific enhancer region of the BCL11A gene. As a result of the editing, GATA1 binding is irreversibly disrupted and BCL11A expression reduced. Reduced BCL11A expression results in an increase in γ-globin expression and foetal haemoglobin (HbF) protein production in erythroid cells, addressing the absent globin in transfusion-dependent β-thalassemia (TDT) and the aberrant globin in sickle cell disease (SCD), which are the underlying causes of disease.

Melphalan is a bifunctional alkylating agent. Formation of carbonium intermediates from each of the two bis-2-chloroethyl groups enables alkylation through covalent binding with the 7-nitrogen of guanine on DNA, cross-linking the two DNA strands and thereby preventing cell replication.

Voxelotor is a haemoglobin S (HbS) polymerisation inhibitor that binds to HbS with a 1:1 stoichiometry and exhibits preferential partitioning to red blood cells (RBCs). By increasing the affinity of Hb for oxygen, voxelotor demonstrates dose-dependent inhibition of HbS polymerisation. Voxelotor inhibits RBC sickling and improves RBC deformability.