Regulators approved two gene therapies for sickle cell disease on Friday. Doctors hope they may be able to cure painful, inherited blood disease that mostly affects black people in the US
The Food and Drug Administration said the one-time treatments can be used for patients ages 12 and older with severe forms of the disease. One made by Vertex Pharmaceuticals and CRISPR Therapeutics is the first approved therapy based on CRISPR, the gene-editing tool that won its inventors the Nobel Prize in 2020. The other is made by Bluebird Bio and works differently.
In a statement announcing the approvals, FDA’s Dr. “Sickle cell disease is a rare, debilitating, and life-threatening blood disorder with significant unmet needs,” said Nicole Verdun. “We are excited to advance this field, especially for individuals whose lives are at risk.” severely impaired by disease.”
Two gene therapies are the first treatments approved in the United States for sickle cell. The FDA previously approved 15 gene therapies for other conditions. Some have list prices in the millions of dollars, and so do sickle cell treatments.
An estimated 100,000 people in the United States have sickle cell, and about one-fifth of them have the severe form. Sickle cell is most common among Black people, and 1 in 365 Black babies nationwide are born with the disease. Scientists believe that being a sickle cell carrier helps protect against severe malaria; Therefore, the disease is more common in mosquito-infested regions such as Africa or in people whose ancestors lived in these places.
The disease affects hemoglobin, the protein that carries oxygen in red blood cells. A genetic mutation causes cells to be sickle- or crescent-shaped, which can block blood flow, causing excruciating pain, organ damage, stroke and other problems.
Available treatments include medications and blood transfusions. The only permanent solution is a bone marrow transplant, which must come from a closely matched donor and carries the risk of rejection.
There is no need for a donor for gene therapies that permanently change the DNA in the patient’s blood cells. The goal of Vertex therapy, called Casgevy, is to help the body return to producing the form of fetal hemoglobin present at birth; this is the adult form that is defective in people with sickle cell disease. CRISPR is used to knock out a gene in stem cells collected from the patient.
Bluebird’s treatment, called Lyfgenia, aims to insert copies of a modified gene that helps red blood cells produce “anti-sickling” hemoglobin, which prevents or reverses misshapen cells.
When patients receive the treatment, stem cells are taken from their blood and sent to the laboratory. Before they can get the replaced cells back, they must undergo chemotherapy. The process requires at least two hospitalizations, one of which lasts four to six weeks.
Still, many patients say they would consider gene therapy given the severity of the disease.
Jalen Matthews, of Louisville, Kentucky, was diagnosed with sickle cell at birth and had his first episode of pain when he was 9 years old. Three years later, the disease led to spinal cord paralysis, which left him with some paralysis in his left arm and leg.
“I had to learn to walk again, feed myself, dress myself, do everything again,” said Matthews, now 26.
Today, he keeps sickle cell at bay with transfusions every two months, and his five units of blood are replaced with healthy cells. He said gene therapy might be a better option and plans to ask his doctor about it.
“This one-time treatment is much needed,” Matthews said.
The first approval for Bluebird’s treatment was FDA approval; Vertex was previously authorized in the UK and Bahrain.
Studies testing the therapies show that they work well. In the landmark Vertex study, 29 of 31 people treated with adequate follow-up were free of pain attacks for at least a year. In the Bluebird study, 28 of 32 patients experienced no serious pain or organ damage for six to 18 months after treatment.
However, doctors state that there are possible side effects and long-term results are unknown. The chemotherapy required for both carries risks such as infertility, hair loss, and vulnerability to serious infections.
Blood cancer has been reported with Bluebird treatment, so the FDA said the label would include a “black box warning” about that risk. With Vertex therapy, some scientists worry that CRISPR introduces the possibility of “off-target effects,” which are unexpected changes to a person’s genome.
D., director of the pediatric stem cell and cell therapy program at Children’s Hospital New Orleans. “It’s important to be cautious and optimistic about this therapy, but also know that there isn’t a lot of experience with it yet,” Benjamin Watkins said. .
Doctors said they don’t expect every medical center to offer gene therapies because those treatments require a lot of equipment and coordination among medical professionals. They also don’t expect many people to call them right away. Some may want to wait until more people receive the treatment, Watkins said.
Experts also warned that cost could be a barrier. Bluebird Bio’s list price is $3.1 million, while Vertex’s is $2.2 million. How much patients can pay will depend on insurance coverage and other factors. To help cover the cost, the U.S. Centers for Medicare and Medicaid Services announced a plan to form partnerships with state Medicaid agencies and pharmaceutical companies.
However, Dr. who treats sick children at NewYork-Presbyterian. Ultimately, gene therapy “could be transformative and could really change the landscape of sickle cell disease,” Monica Bhatia said.
Matthews, who volunteers with the Kentuckiana Sickle Cell Association, said he hopes the treatments will make a big impact.
“It’s a blessing,” he said. “This will really benefit all of us in the sickle cell community.”
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