First Gene Therapy For The Treatment Of β-thalassemia Approved

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Bluebird Bio’s gene therapy medicine Zynteglo has been approved by European Commission based its clinical data from 32 adults and adolescents, for the treatment of blood disorder β-thalassemia in patients 12 years and older who require regular blood transfusions.

The β-hemoglobinopathies is a condition, which includes β-thalassemia and sickle cell disease, are caused by the mutations in the β-globin gene. People with this genetic mutation cannot make enough β-globin protein, a component of haemoglobin, the protein in red blood cells that carries oxygen around the body. As a result, these patients have low red blood cell (RBC) levels and need frequent blood transfusions to survive.

The gene therapy adds a corrective gene whose protein product combines with the α-globin protein to produce functional hemoglobin, thus reversing the ineffective red blood cell production in β-thalassemia.

This ex vivo gene therapy requires the patient’s bone marrow stem cells (at least 12 × 106 CD34+ cells per kg body weight). The CD34+ cells are then transduced ex vivo with the gene encoding βA-T87Q-globin via a BB305 lentiviral vector pseudotyped with vesicular stomatitis virus glycoprotein G. Thereafter, the transduced CD34+ cells containing the βA-T87Q-globin gene are given in a single injection (about 5.0 × 106 cells per kg), after which they engraft in the bone marrow and differentiate into RBCs which produce a therapeutic hemoglobin called HbAT87Q.

Source: European Medicines Agency

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