The United States Food and Drug Administration has approved the first cell-based gene therapies for the treatment of Sickle Cell Disease in patients age 12 years and above.
In a statement by the FDA on Saturday, the treatment comes in two stages namely Casgevy and Lyfgenia,
The U.S. agency revealed that of the therapies, Casgevy is the first FDA-approved treatment to utilize a type of novel genome editing technology, signalling an innovative advancement in the field of gene therapy.
According to the Director, Office of Therapeutic Products, FDA Center for Biologics Evaluation and Research, Nicole Verdun, “Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need, and we are excited to advance the field, especially for individuals whose lives have been severely disrupted by the disease by approving two cell-based gene therapies today,”
“Gene therapy holds the promise of delivering more targeted and effective treatments, especially for individuals with rare diseases where the current treatment options are limited.
“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. Patients’ hematopoietic (blood) stem cells are modified by genome editing using CRISPR/Cas9 technology.
“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.
Continuing, she said, “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 haemoglobin, a type of haemoglobin that facilitates oxygen delivery. In patients with sickle cell disease, increased levels of HbF prevent the sickling of red blood cells.
“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, gene-therapy-derived haemoglobin that functions similarly to haemoglobin A, which is the normal adult haemoglobin produced in persons not affected by sickle cell disease.
“Both products are made from the patient’s own blood stem cells, which are modified and are given back as a one-time, single-dose infusion as part of a hematopoietic (blood) stem cell transplant. Prior to treatment, a patient’s own stem cells are collected, and then the patient must undergo myeloablative conditioning (high-dose chemotherapy), a process that removes cells from the bone marrow so they can be replaced with the modified cells in Casgevy and Lyfgenia. Patients who received Casgevy or Lyfgenia will be followed in a long-term study to evaluate each product’s safety and effectiveness.”
According to the FDA, sickle cell disease is a group of inherited blood disorders affecting approximately 100,000 people in the U.S. and is common in African American descent and, while less prevalent, also affects Hispanic Americans.
It noted that the primary problem in sickle cell disease is a mutation in haemoglobin, a protein found in red blood cells that delivers oxygen to the body’s tissues.
“This mutation causes red blood cells to develop a crescent or “sickle” shape. These sickled red blood cells restrict the flow in blood vessels and limit oxygen delivery to the body’s tissues, leading to severe pain and organ damage called vaso-occlusive events or vaso-occlusive crises,” the FDA stated.
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