Gene editing therapy indicates possible sickle cell disease

Scientists see promising early results from the first studies testing gene editing for painful hereditary blood disorders that plague millions of people around the world.

Doctors hope that a one-time treatment that permanently alters the DNA of blood cells using a tool called CRISPR will treat sickle cell disease and beta-thalassemia, and in some cases cure it.

Partial results were presented at a conference of the American Society of Hematology on Saturday, and some were presented by the New England Journal of Medicine.

The doctor described 10 patients who were at least a few months away from treatment. Everyone no longer needs regular blood transfusions and is free from the pain crisis that previously plagued their lives.

Victoria Gray, the first patient in the sickle cell study, has long suffered from severe pain attacks and often sent her to the hospital.

“I had pain, sharp pain, and burning pain. 35-year-old Gray, who lives in Forrest, Mississippi, said:” I hurt everything where my blood bleeds. . “

Since treatment a year ago, Gray has withdrawn from the painkillers he relied on to manage his symptoms.

“That’s what I prayed for a lifetime,” she said. “I hope everyone will get the same results as I do.”

Sickle cells affect millions, primarily blacks. Beta thalassemia attacks 1 in 100,000 people. Currently, the only treatment is bone marrow transplantation from a closely matched donor, free of illnesses like siblings that most people do not have.

Both diseases involve mutations in the gene for hemoglobin, a substance in red blood cells that carries oxygen throughout the body.

In sickle cells, defective hemoglobin leads to deformed crescent-shaped blood cells that do not carry oxygen well. They can stick together and clog small blood vessels, causing pain, organ damage, and stroke.

Patients with beta-thalassemia do not have enough normal hemoglobin and suffer from symptoms such as anemia, malaise, and shortness of breath. In severe cases, blood transfusions are required every 2 to 5 weeks.

The treatments studied attack the problem with their genetic roots.

In the womb, the foetation makes a special type of hemoglobin. After birth, when the baby breathes on its own, the genes are activated and switch to cells, instructing them to make adult hemoglobin instead. Adult hemoglobin is a defect in people with one of these diseases. CRISPR editing aims to cut out switching genes.

“What we’re doing is turning the switch off and making the cells think they’re back in the womb,” said Dr. Heider Frangor, a research leader at the Sara Cannon Institute in Nashville. It was.

Treatment involves removing stem cells from the patient’s blood and using CRISPR in the lab to knock out switching genes. Patients are given powerful drugs to kill other defective blood-producing cells. They are then returned modified stem cells in their own laboratory.

Saturday results were for the first 10 patients, 7 for beta-thalassemia, and 3 for sickle cell disease. Two studies in Europe and the United States are underway and will enroll 45 patients each.

Previous tests have suggested that gene editing works as expected without unintended effects, Frangoul said.

“The preliminary results are very encouraging,” he said.

The study was sponsored by Zug-based CRISPR Therapeutics in Switzerland and Massachusetts-based Vertex Pharmaceuticals, a treatment manufacturer. Some research leaders consult with companies.

Separately, Dr. David Williams of the Boston Children’s Hospital at Harvard University has shown partial results from a study testing a new type of gene therapy that seeks to restore fetal hemoglobin production in people with sickle cell disease. Did.

Six patients, including a young 7-year-old, were treated and some of the blood stem cells were removed and modified in the laboratory to contain the hemoglobin switching gene. There was no risk of pain, five out of six did not require blood transfusions, and all had near-normal hemoglobin, he reported in conferences and medical journals.

A government grant was paid for the job. Williams is named after a treatment patent licensed by Boston Children to Bluebird Bioinks in Cambridge, Massachusetts. The company provided a treatment for the study that enrolled a total of 10 people to establish safety. Larger studies are planned to test efficacy.

Williams, who was not involved in Frangor’s work, said he would “validate this approach” to target the hemoglobin switching gene to address sickle cells.


Chief Medical Writer Marilyn Marchione contributed from Milwaukee.


The Associated Press’s Department of Health Sciences is supported by the Department of Science Education at the Howard Hughes Medical Institute. AP is solely responsible for all content.

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Gene editing therapy indicates possible sickle cell disease

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