ICD-10 Specific code D56.2: Delta-beta thalassaemia

Betibeglogene autotemcel adds functional copies of a modified β-globin gene into the patients' HSCs through transduction of autologous CD34+ cells with BB305 LVV, thereby addressing the underlying genetic cause of the disease. After betibeglogene autotemcel infusion, transduced CD34+ HSCs engraft in the bone marrow and differentiate to produce RBCs containing biologically active β^A-T87Q-globin (a modified β-globin protein) that will combine with α-globin to produce functional Hb containing β^A-T87Q-globin (HbA^T87Q).

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.

Thiotepa is a polyfunctional cytotoxic agent related chemically and pharmacologically to the nitrogen mustard. The radiomimetic action of thiotepa is believed to occur through the release of ethylene imine radicals that, as in the case of irradiation therapy, disrupt the bonds of DNA, e.g. by alkylation of guanine at the N-7, breaking the linkage between the purine base and the sugar and liberating alkylated guanine.