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A therapy for sickle cell anemia could give new hope to people with the disease, although the treatment comes with its own risks.
A Canadian woman was declared cured this month after receiving a bone marrow transplant using stem cells from her sister. She’s the first adult to be cured of sickle cell anemia using this method in Canada. She expressed hope that her recovery could lead to more adults undergoing the procedure.
Up until a few years ago, bone marrow transplants were thought to be too toxic for adults with sickle cell anemia. In these procedures, chemotherapy kills a patient’s marrow before it’s replaced with that of a donor.
But a National Institutes of Health study, published in 2014, followed 30 people with sickle cell anemia between the ages of 16 and 65 who had undergone marrow transplants. The disease was reversed in 26 of them.
If the treatment can be more widely used by adults, it could help parents trying to make difficult decisions about treating children with sickle cell anemia.
“Bone marrow transplant works easiest the younger you are, but the problem is a couple-fold,” said Dr. Charles Abrams, spokesman for the American Society of Hematology.
Some of those with the disease, he said, do much better than others.
“For some, the disease is absolutely horrendous almost from the beginning, and others have a more mild disease,” he told Healthline. “And we don’t always do a good job of predicting who’s going to have a rougher time.”
Taking the risk
That matters, because treating the disease with as intense a procedure as a bone marrow transplant comes with plenty of risks.
A small percentage of people will die, Abrams said, and others will become infertile.
“So it’s not a free lunch,” he said. “Most people don’t want to take a child who’s relatively healthy, although they have a disease that is likely to cause a lot of problems later, and undergo a procedure like this.”
Most, he said, wait until later in life. By then, the patient may not be as healthy or able to tolerate the transplant.
For some particular cases, though, it may be worth the risk, as the Canadian case shows.
Revée Agyepong, 26, underwent the procedure in Calgary in November.
“When Revée approached us, we had coincidentally been thinking about adult stem cell transplant for sickle cell disease based on the remarkably good outcomes that Alberta Children’s Hospital has been seeing with transplants in the pediatric population,” Dr. Andrew Daly, who led the procedure as head of the bone marrow transplant program at the Tom Baker Cancer Centre, said in a statement.
“She met all the necessary criteria in terms of being able to tolerate a transplant, but, most important, she had a sibling who was a 100 percent match,” he added.
How sickle cell anemia attacks
According to the American Society of Hematology, about 70,000 to 100,000 Americans have sickle cell anemia, also called sickle cell disease. It mostly affects people of African descent.
A genetic mutation causes red blood cells to form abnormally in the crescent shape of a sickle.
That can cause blood to get stuck in blood vessels. As a result, some organs or parts of the body don’t get enough blood, leading to pain, the death of vital organs, kidney disease, or heart attacks.
Bone marrow is where blood cells form. A transplant swaps out bone marrow with the genetic mutation that causes it to produce sickle-shaped red blood cells with marrow from a person without that mutation.
“In theory, if you could give this to everyone, you could cure everyone of the disease. And if there were no toxicity, we probably would,” Abrams said.
He said the transplant procedure was discovered when a patient with sickle cell anemia received a transplant to treat their leukemia, then found it reversed both diseases.
Today, it’s still the only potential cure available to those with sickle cell anemia, he said, “although there are others in the pipeline.”
Looking at gene-related treatments
Gene therapies are being developed to try to correct the genetic abnormalities in patients’ own genes without swapping them out.
Researchers generally see these developments, using the gene-editing tool CRISPR, as the future of curing sickle cell anemia.
Over the past couple years, scientists have been able to alter genes in blood stem cells from patients with sickle cell anemia and transplant them into mice. Several institutions and companies are reportedly working on submitting applications for clinical trials to further test these methods.
As for new potential treatments in the pipeline, the U.S. Food and Drug Administration (FDA) said it couldn’t discuss “treatments that may be undergoing FDA review, as that is confidential information.”
For now, there are only two drugs approved by the FDA to treat sickle cell anemia.
One is hydroxyurea. It can now be used in patients 2 years old and older.
The other is Endari. In July, it became the first new treatment approved in nearly 20 years.
Both work to reduce the frequency of “crises,” or the severe attacks of pain and other complications that arise from the disease.
Blood transfusions are also used to treat anemia, the lack of healthy red blood cells brought on by the disease.
But, Abrams said, “There a lot of very exciting things are on the horizon. [Bone marrow transplants using stem cells] is one of them, but it’s not as new as the others. It does work in some patients, but it can be a rough road.”