The gene therapy works like this: A deactivated virus is inserted into the patient’s bone marrow, which delivers the correct gene copy into blood stem cells, replacing the defective one. These cells are then frozen and undergo testing.
“This virus is able to effectively deliver a healthy copy of the gene into a stem cell in a way that was not possible before,” Mamcarz said.
The patient then receives two days of low-dose busulfan, a chemotherapy drug that makes space in the marrow for the stem cells to grow, and the cells are then infused back into the patient.
It takes about 10 days from the time the cells are taken out to when they are infused into the patient, Mamcarz said.
The proper immune cells were found within three months of the treatment in all but one patient, who needed a second dose of gene therapy, St. Jude says.
“This novel approach has shown really outstanding results for the infants,” Downing said. “The treatment has fully restored the immune system in these patients, which wasn’t possible before, and has no immediate side effects.”
