In sickle cell disease, abnormal hemoglobin makes blood cells hard and crescent-shaped. These distorted cells clump together and block blood flow to the organs, causing bouts of extreme pain. The cells then die prematurely, giving way to a lack of healthy red blood cells, or anemia.
Beta thalassemia also causes anemia because the body produces less hemoglobin than normal.
People with life-threatening beta thalassemia need blood transfusions every three to five weeks and other medications throughout their lives.
“Sickle cell disease and beta thalassemia are painful, lifelong conditions that, in some cases, can be fatal,” Julian Beach, interim executive director of health care quality and access, said Thursday. health at the UK MHRA.
Casgevy is intended to restore functional hemoglobin in the body. The therapy is not traditional medicine. It is rather a complicated procedure. A patient’s stem cells are taken from their bone marrow and then sent to a laboratory to be manufactured. There, scientists use Crispr to modify a gene intended to activate a functional version of hemoglobin.
Patients must then undergo conditioning treatment to prepare their bone marrow to receive the modified cells. Afterward, they may have to spend a month or more in the hospital while the modified cells settle into the bone marrow and begin producing healthy red blood cells.
In a trial conducted by Vertex and Crispr Therapeutics, 45 patients were treated with Casgevy but only 29 were followed for at least 18 months. Among them, 28 were free of severe pain crises for at least a year after treatment.
In a study of patients with beta thalassemia, 54 patients have received Casgevy so far. Of 42 patients followed long enough, 39 did not need a blood transfusion for at least a year after treatment. The other three saw their transfusion needs decrease by more than 70 percent. Side effects of treatment include nausea, fatigue, fever and increased risk of infection. Both trials are ongoing.
Because Crispr is designed to permanently alter the genome, scientists believe the effects could last for years or even decades.
Currently, sickle cell disease can be cured with a bone marrow transplant from a closely matched tissue donor, but only about 20 percent of patients have one. Transplants are also risky and may not work. They can cause a life-threatening complication in which the donor’s stem cells attack the recipient’s body.
Vertex and Crispr Therapeutics have not announced pricing for the therapy, but it might be expensive. Vertex says it is working closely with national health authorities in the United States to ensure access to eligible patients as quickly as possible.