The Sickle Cell Foundation of Georgia responded to today’s approval of two new gene therapies by the U.S. Food and Drug Administration to treat patients with sickle cell disease.
Sickle cell disease is a debilitating disorder that affects millions of people globally, causing excruciating pain, stroke, deadly organ damage, and other complications due to the malformed cells.
The FDA approved two milestone treatments, Casgevy and Lyfgenia, representing the first cell-based gene therapies for the treatment of sickle cell disease (SCD) in patients 12 years and older. Additionally, one of these therapies, Casgevy, is the first FDA-approved treatment to utilize a type of novel genome editing technology, signaling an innovative advancement in the field of gene therapy, according to Friday’s announcement.
Casgevy, a cell-based gene therapy, is approved for the treatment of sickle cell disease in patients 12 years of age and older with recurrent vaso-occlusive crises. Casgevy is the first FDA-approved therapy utilizing CRISPR/Cas9, a type of genome editing technology, according to the FDA.
“We were anticipating the approval of one cell-based therapy today but to have two approved is remarkable,” said Sickle Cell Foundation of Georgia, Inc. Executive Director Tabatha McGee. “We still are cautiously optimistic because of the costs and unknown long-term side effects. With the Casgevy therapy, we are looking at a $1.2 million procedure. Who will pay for it? Medicaid, private insurance, the struggling patient, or big pharma?
CRISPR/Cas9 can be directed to cut DNA in targeted areas, enabling the ability to accurately edit (remove, add, or replace) DNA where it was cut. The modified blood stem cells are transplanted back into the patient where they engraft (attach and multiply) within the bone marrow and increase the production of fetal hemoglobin (HbF), a type of hemoglobin that facilitates oxygen delivery. In patients with sickle cell disease, increased levels of HbF prevent the sickling of red blood cells, according to scientists.
Lyfgenia is a cell-based gene therapy. Lyfgenia uses a lentiviral vector (gene delivery vehicle) for genetic modification and is approved for the treatment of patients 12 years of age and older with sickle cell disease and a history of vaso-occlusive events. With Lyfgenia, the patient’s blood stem cells are genetically modified to produce HbAT87Q, a gene-therapy-derived hemoglobin that functions similarly to hemoglobin A, which is the normal adult hemoglobin produced in persons not affected by sickle cell disease. Red blood cells containing HbAT87Q have a lower risk of sickling and occluding blood flow. These modified stem cells are then delivered to the patient, scientists say.
Both products are made from the patient’s own blood stem cells, which are modified and given back as a one-time, single-dose infusion as part of a hematopoietic (blood) stem cell transplant, according to an FDA news release.
Although the cause of the disease has been known since 1949, treatments were slow to emerge. In 1998, the FDA approved the first drug to treat sickle cell anemia, the most common form of sickle cell disease. This drug, called hydroxyurea, is effective in some but not all patients.
