The FDA approved Vertex/CRISPR Therapeutics’ Casgevy® and Bluebird Bio’s Lyfgenia®, the first cell-based gene therapies to treat sickle cell disease in patients 12 years and older. Casgevy® is the first FDA-approved treatment that uses CRISPR/Cas9 to genetically modify a patients’ hematopoietic stem cells. Lyfgenia® uses a lentiviral vector for genetic modification and is approved to treat patients with a history of vaso-occlusive events.
In each instance, the patient’s blood stem cells are harvested, and treated and the modified stem cells are transplanted into the patient where they engraft within the bone marrow and increase the production of foetal haemoglobin (for Casgevy®) and HbAT87Q, a gene-therapy derived haemoglobin that functions similarly to haemoglobin A (for Lyfgenia®), and in each instance the increased levels of reduce the risk of red blood cells sickling.