Gene-editing treatment shows promise for sickle Cell disease
Scientists are seeing promising early results from the first studies testing gene editing for painful, inherited blood disorders that plague millions worldwide, especially Black people.
Doctors hope the one-time treatment, which involves permanently altering DNA in blood cells with a tool called CRISPR, may treat and possibly cure sickle cell disease and beta thalassemia.
Partial results were presented Saturday at an American Society of Hematology conference and some were published by the New England Journal of Medicine.
Doctors described 10 patients who are at least several months removed from their treatment. All no longer need regular blood transfusions and are free from pain crises that plagued their lives before.
Victoria Gray, the first patient in the sickle cell study, had long suffered severe pain bouts that often sent her to the hospital.
Since her treatment a year ago, Gray has weaned herself from pain medications she depended on to manage her symptoms.
Sickle cell affects millions, mostly Black people. Beta thalassemia strikes about one in 100,000 people. The only cure now is a bone marrow transplant from a closely matched donor without the disease like a sibling, which most people don’t have.
Both diseases involve mutations in a gene for hemoglobin, the substance in red blood cells that carries oxygen throughout the body.
In sickle cell, defective hemoglobin leads to deformed, crescent-shaped blood cells that don’t carry oxygen well. They can stick together and clog small vessels, causing pain, organ damage and strokes.
Those with beta thalassemia don’t have enough normal hemoglobin, and suffer anemia, fatigue, shortness of breath and other symptoms. Severe cases require transfusions every two to five weeks.
The treatment studied attacks the problem at its genetic roots.
In the womb, fetuses make a special type of hemoglobin. After birth, when babies breathe on their own, a gene is activated that instructs cells to switch and make an adult form of hemoglobin instead. The adult hemoglobin is what’s defective in people with one of these diseases. The CRISPR editing aims to cut out the switching gene.
The treatment involves removing stem cells from the patient’s blood, then using CRISPR in a lab to knock out the switching gene. Patients are given strong medicines to kill off their other, flawed blood-producing cells. Then they are given back their own lab-altered stem cells.
Tests so far suggest the gene editing is working as desired with no unintended effects, Frangoul said.