Gene-Therapy Used to Cure Boy of Sickle Cell Disease


A revolutionary gene therapy technique developed by French researchers appears to have cured a teenage boy of sickle cell anemia, a blood disease that affects tens of thousands of Americans.

Credit: EM Unit, UCL Medical School, Royal Free Campus/Wikimedia Commons, CC BY 4.0

Typically, people with sickle cell disease are given blood transfusions to improve the functioning of hemoglobin — an oxygen-carrying blood protein that’s vital to normal health and development. In people with sickle cell disease, hemoglobin becomes distorted, twisting into a sickle-like shape that leads to pain and anemia.

But the new therapy offers hope that altering a person’s genetic material can prevent distortions to hemoglobin and essentially eradicate sickle cell disease from the body.

Researchers at Necker Children’s Hospital in Paris extracted bone marrow stem cells from a patient with sickle cell disease when he was 13 years old and injected the cells with genes that code for beta-globin, a part of hemoglobin that’s associated with the disorder.

By coaxing the boy’s beta-globin to interfere with the production of faulty hemoglobin — and therefore avoid the clumping of sickle-cells that’s a hallmark of the disease — the researchers engineered the production of normal, healthy hemoglobin, according to the study appearing in the New England Journal of Medicine.

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“The patient is now 15 years old and free of all previous medication,” lead author Marina Cavazzana told New Scientist. “He has been free of pain from blood vessel blockages and given up taking opioid painkillers.”

The initial gene therapy has researchers optimistic that the teenager won’t see a return of the disease. “All the tests performed on his blood show that he’s been cured, but more certainty can only come from long-term follow up,” Cavazzana told New Scientist.

Since the initial treatment, the French researchers have begun gene therapy on seven other individuals with sickle cell disease, and they call the results so far “promising.”

Hope for a Cure

National health estimates project that about 100,000 Americans are afflicted with sickle cell disease, according to the Centers for Disease Control and Prevention. Most signs and symptoms begin in early childhood and can appear as low red blood cell levels, chronic infections and recurrent episodes of pain, notes the National Institutes of Health.

The blood cells in sickle cell disease (right) do not flow through the circulatory system smoothly. Credit: National Human Genome Research Institute (NHGRI)/Wikimedia Commons, CC BY 2.0

About 50 million people worldwide suffer from sickle cell disease or carry the genetic mutation associated with it, note the researchers from Necker Children’s Hospital.

Gene therapy has been considered a potential breakthrough approach for many disorders, and some researchers think that the new study will propel further gene therapy-based techniques to the forefront. The success of the sickle-cell study “provides support for this and other genetic strategies targeting this horrible disease,” John Tisdale of the National Heart, Lung and Blood Institute told New Scientist.

For her part, Cavazzana is ready to test the cutting-edge approach among a wider audience. “We want to develop new clinical trials with this gene therapy model and enroll a large cohort of patients with sickle-cell anemia from the greater Paris area and France as a whole,” said Cavazzana in a statement.

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