One Utilizes CRISPR Technology, Offering Hope for Patients Battling the Debilitating Blood Disorder
In a historic move, the Food and Drug Administration (FDA) has granted approval for two gene therapies designed to treat sickle cell disease, a painful and hereditary blood disorder predominantly affecting Black individuals in the U.S. These breakthrough treatments, deemed potential cures, target severe forms of the ailment in patients aged 12 and older.
The first of the approved therapies, developed by Vertex Pharmaceuticals in collaboration with CRISPR Therapeutics, marks a significant milestone as it utilizes CRISPR, the revolutionary gene-editing tool honored with the Nobel Prize in 2020. The second therapy, created by Bluebird Bio, employs a distinct approach.
Dr. Nicole Verdun of the FDA expressed enthusiasm for advancing the field, particularly for those whose lives have been profoundly impacted by sickle cell disease. With an estimated 100,000 people in the U.S. affected by sickle cell, and approximately one-fifth experiencing severe forms of the condition, the approval marks a critical development in addressing the substantial unmet need for effective treatments.
Sickle cell disease is most prevalent among Black individuals, with 1 in 365 Black babies born with the ailment nationally. The disorder results from a genetic mutation affecting hemoglobin, the protein in red blood cells responsible for carrying oxygen. Altered cells take on a sickle or crescent shape, obstructing blood flow and causing excruciating pain, organ damage, strokes, and other complications.
Current treatments involve medications, blood transfusions, and, in extreme cases, bone marrow transplants, which carry the risk of rejection. The newly approved gene therapies, Casgevy by Vertex and Lyfgenia by Bluebird, offer a revolutionary approach by permanently modifying DNA in the patient’s blood cells.
Casgevy aims to stimulate the production of fetal hemoglobin, present at birth and unaffected by the genetic mutation causing sickle cell disease. CRISPR technology is employed to eliminate a specific gene in stem cells collected from the patient. In contrast, Lyfgenia seeks to introduce copies of a modified gene, promoting the production of “anti-sickling” hemoglobin to prevent or reverse misshapen cells.
While the therapies show promising results in clinical studies, the long-term outcomes and potential side effects, including those associated with necessary chemotherapy, remain unknown. Concerns include infertility, hair loss, susceptibility to infection, and, in the case of Bluebird’s therapy, a risk of blood cancer, prompting the inclusion of a “black box warning” on the label.
Despite these considerations, patients and medical professionals express hope and optimism for the transformative potential of gene therapy in treating sickle cell disease. The road ahead includes addressing accessibility challenges, potential high costs, and ensuring comprehensive insurance coverage for these groundbreaking treatments.