T.Biotech company Bluebird Bio plans to continue clinical trials of a gene therapy for sickle cell disease, which was discontinued in February after a participant was diagnosed with acute myeloid leukemia five years after treatment. The company released a statement yesterday (March 10) claiming an investigation found “it is very unlikely” that AML is therapy-related, and the company is seeking approval from US Food and Drug Administration Drug Administration (FDA) to resume studies.
The therapy works by taking a patient’s hematopoietic stem cells (HCS) and using a lentiviral vector to insert a healthy copy of a β-globin Gen. After the patient receiving the gene therapy was diagnosed with AML, Bluebird examined the cancer cells and found the vector DNA built into their genome. Upon additional testing from independent sources, the researchers found that the vector ended up within the country VAMP4 Gene and did not appear to have affected the expression or regulation of neighboring genes.
“VAMP4 It is not known to be associated with the development of AML or with processes such as cell proliferation or genome stability, ”said Philip Gregory, Bluebird’s Chief Scientific Officer, in the press release. In addition, the patient’s cells had mutations in other genes associated with leukemia.
In early February, a patient from another part of the study was diagnosed with myelodysplastic syndrome (MDS), a condition of malformed blood cells that often precedes AML, although more recently the company found the diagnosis to be uncertain. science Reports. The same vector is used in an experimental treatment for β-thalassemia, and although there were no cancers associated with this treatment, these studies have also been suspended.
“These [preliminary] Data actually dismiss the vector as causal, ”reports John Tisdale of the National Heart, Lung and Blood Institute, who was not involved in the study The New York Times.