The US Food and Drug Administration (FDA) recently greenlit 2 cell-based gene treatments for sickle cell anemia, including the first therapy involving the genome editing technology known as CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats–CRISPER-associated protein 9).
Both treatments are approved for people aged 12 years or older and work by modifying people’s own blood stem cells and then transplanting them into their bodies via a single-dose infusion. They change blood cells in different ways, though.
Casgevy—the CRISPR-Cas9 gene editing treatment—increases fetal hemoglobin levels. Higher levels of fetal hemoglobin help stop red blood cells from sickling, improving blood flow and preventing painful vaso-occlusive crises. Twenty-nine of 31 trial participants who were followed up long enough to be evaluated did not have severe vaso-occlusive crises for at least 1 year after the treatment, the FDA news release reported.
Lyfgenia, the second treatment, genetically modifies blood stem cells to produce a form of hemoglobin that is similar to hemoglobin A but, like fetal hemoglobin, is also less prone to sickling. Within 18 months of treatment, 28 of 32 trial participants did not experience any vaso-occlusive episodes, according to the news release.
Adverse effects for both treatments include low platelet and white blood cell counts. Lyfgenia also carries a black box warning on the risk of blood cancer.
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