Britain approves gene editing treatment for sickle cell disease

On Thursday, the United Kingdom’s drug regulation agency approved the world’s first gene therapy treatment to cure sickle cell disease and beta-thalassemia. Both diseases are genetic and caused by malformations in red blood cells. The treatment, Casgevy, uses the gene-editing tool CRISPR to correct a patient’s incorrectly formed genes. Britain’s Medicines and Healthcare Regulatory Agency said doctors take stem cells from a patient’s bone marrow, edit out the genetic errors in a lab, and then reinfuse them into the patient.

What kind of stem cells are they using? The treatment uses adult stem cells from a patient's own bone marrow, not embryonic stem cells taken from an underdeveloped infant. Adult stem cells, also known as somatic cells, can be found in bone marrow, skin, and brain tissue. Casgevy is approved for patients ages 12 and up, requires at least two hospitalizations, and is expected to cost several million dollars. Trial patients confirmed the treatments work, with 28 out of 29 sickle cell patients reporting they were free of severe pain that is common with the blood disorder. Additionally, 39 out of 42 beta-thalassemia patients also confirmed they didn’t need a blood transfusion for at least 12 months, as opposed to every few weeks. The U.S. Food and Drug Administration is reviewing Casgevy for approval in the United States.

Dig deeper: From the WORLD archives, read Sophia Lee’s report on the ethics of gene editing.