A recent breakthrough brings hope to cure sickle cell disease (SCD). It is called Casgevy and was approved by the U.S. Food and Drug Administration (FDA) last December. It is the first gene therapy utilizing clustered regularly interspaced short palindromic repeats (CRISPR) to edit the patient’s blood stem cells and let them produce high levels of fetal hemoglobin, but not the mutated, sickle hemoglobin. FDA approves Casgevy to treat SCD patients at 12 years and older.
The gene that has been targeted is called BCL11A. It blocks fetal hemoglobin expression. So as its name indicates, fetal hemoglobin is only expressed in newborns. It can block the formation of sickled red cells. When BCL11A is no longer functioning with Casgevy, fetal hemoglobin will be expressed to make healthy red blood cells, not sickled cells.
Patient stem cells are first modified by Casgevy. Next, the modified cells are sent back to the patient. Since it uses the patient’s cells, they recover much faster.
The cost is ~$2.2 million and may be financially out of reach for most patients. Scientists are trying to find a pill that works similarly. It will bring down the cost dramatically.
