Vertex CRISPR/Cas9 Gene-Edited Cell Therapy Process Explained

Vertex Pharmaceuticals’ Casgevy is a one-time therapy used to treat people with sickle cell disease (SCD) or transfusion-dependent beta thalassemia (TDT). The administration of Casgevy requires experience in stem cell transplantation thus Vertex is engaging with experienced hospitals to establish a network of authorized treatment centers throughout the U.S. to offer Casgevy to patients.

Casgevy is made specifically for each patient, using the patient’s own edited blood stem cells, and increases the production of hemoglobin F (fetal hemoglobin or HbF). Having more HbF increases overall hemoglobin levels and has been shown to improve the production and function of red blood cells.

Patient information found on the Vertex website includes the following detailed description of the treatment process, which has been condensed from the original:

How will I receive CASGEVY?

STEP 1: Before Casgevy treatment, a doctor will give you mobilization medicine(s). This medicine moves blood stem cells from your bone marrow into the blood stream. The blood stem cells are then collected in a machine that separates the different blood cells (this is called apheresis). This entire process may happen more than once. Each time, it can take up to one week.

STEP 2: After they are collected, your blood stem cells will be sent to the manufacturing site where they are used to make Casgevy. It may take up to 6 months from the time your cells are collected to manufacture and test Casgevy before it is sent back to your healthcare provider.

STEP 3: Shortly before your stem cell transplant, your healthcare provider will give you a conditioning medicine for a few days in hospital. This will prepare you for treatment by clearing cells from the bone marrow, so they can be replaced with the modified cells in Casgevy. After you are given this medicine, your blood cell levels will fall to very low levels. You will stay in the hospital for this step and remain in the hospital until after the infusion with Casgevy.

STEP 4: After the Casgevy infusion, you will stay in hospital so that your healthcare provider can closely monitor your recovery. This can take 4-6 weeks, but times can vary. Your healthcare provider will decide when you can go home. (Source: Vertex Website, 16 January, 2024)