Modern Medical Laboratory Journal

Britain's medicines regulator has authorized the world's first gene therapy treatment for sickle cell disease, in a move that could offer relief to thousands of people with the disease. The new medicine, Casgevy, works by targeting the problematic gene in a patient's bone marrow stem cells so that the body can make properly functioning hemoglobin. Patients first receive a course of chemotherapy to make space for the new cells. Then, doctors take stem cells from the patient's bone marrow and use genetic editing techniques in a laboratory to fix the gene. The cells are then infused back into the patient for a permanent treatment.

In a clinical trial of Casgevy for sickle cell disease, 28 of the 29 patients experienced no episodes of major pain – which can lead to them being hospitalised – for at least a year afterward. When the treatment was used for those with beta thalassemia, 39 of the 42 trial participants did not need to have a red blood cell transfusion for at least 12 months after receiving Casgevy. 
Sickle cell disease is caused by mutations in the beta-globin gene, leading to the production of abnormal hemoglobin, the oxygen-carrying molecule in red blood cells. Normal red blood cells are shaped like donuts, but in sickle cell disease, the abnormal hemoglobin causes red blood cells to stiffen and adopt a spiky, sickle-like shape. The disease is estimated to affect 100,000 people in the United States and is more common among Black Americans. Sickle cell disease can be cured with a donor bone marrow transplant but use of this therapy has the best chance of success in patients who have a closely matched sibling donor, which is only a minority of patients.
Read more