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FDA approves first gene therapies for sickle cell disease



(NewsNation) — The Food and Drug Administration on Friday approved two gene therapy treatments, Casgevy and Lyfgenia, for patients with sickle cell disease.

Casgevy is the first FDA-approved treatment to use a “novel genome editing technology” called CRISPR/Cas9, according to a news release. Gene editing technology allows researchers to modify genes that cause diseases like sickle cell.

“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,” Dr. Nicole Verdun, director of the Office of Therapeutic Products within the FDA’s Center for Biologics Evaluation and Research, said in a statement. “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.” 

NewsNation partner The Hill writes more than 30 FDA-approved therapies are used to treat illnesses such as cancers and hemophilia.

Both Casgevy and Lyfgenia are greenlit for those 12 and older.


Sickle cell disease is a blood disorder that affects about 100,000 people in the United States, according to the FDA. It’s most common in African Americans, the FDA said, though it also affects Hispanic Americans.

Sickle cell is caused by a mutation in hemoglobin, which is a protein found in red blood cells that delivers oxygen to the body’s tissues. Because of the mutation, the red blood cells develop a crescent, or “sickle,” shape, and restrict the flow in blood vessels. This can cause people severe pain and organ damage, called vaso-occlusive events (VOEs) or vaso-occlusive crises (VOCs). The FDA says recurring VOCs can cause life-threatening disabilities or death. 

Current treatments include medications and blood transfusions. The only permanent solution is a bone marrow transplant, which must come from a closely matched donor without the disease, bringing with it a risk of rejection.

 Both Casgevy and Lyfgenia are made from a patient’s own blood stem cells, which are then modified and given as a single-dose infusion as part of a transplant. 

CRISPR/Cas9, which Casgevy uses, can be directed to cut DNA in targeted areas.  This allows the DNA to be removed, added or replaced in the area where it was cut. Modified blood stem cells are then transplanted back into the patient, where they are attached and multiply within the bone marrow, increasing the production of fetal hemoglobin. Fetal hemoglobin, the FDA says, facilitates oxygen delivery. 

Lygenia genetically modifies a patient’s blood stem cells to produce HbAT87Q, a gene-therapy-derived hemoglobin that functions similarly to the kind of hemoglobin produced in someone without sickle cell. 

Casgevy’s safety and effectiveness were tested in an ongoing trial in adult and adolescent sickle cell patients with a history of at least two severe vaso-occlusive crises in each of the two years before the screening. Of the 31 patients able to be evaluated after using Casgevy, 29, or 93.5%, were free from severe VOC episodes for at least 12 consecutive months. Side effects included low levels of platelets and white blood cells,; mouth sores; nausea, musculoskeletal pain; abdominal pain; vomiting; febrile neutropenia; headaches and itching, according to the FDA.


Researchers analyzed Lyfgenia with data from a multicenter study in sickle cell patients between 12 and 50 years old with a history of vaso-occlusive events. Twenty-eight of the 32 patients (88%) saw a complete resolution of VOEs in the 6 to 18 months after they were infused with Lyfgenia. For this therapy, the most common side effects were mouth sores on people’s lips, mouth and throat; low levels of platelets, white and red blood cells; and febrile neutropenia consistent with chemotherapy and underlying disease. 

Blood cancer has occurred in patients treated with Lyfgenia, the FDA cautioned, so there’s a black box warning included in the label.

The Associated Press contributed to this report.

Source: WFLA

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