A German AIDS patient was able to stop drugs he had been taking for 10 years after getting a transplant of stem cells from a donor with a rare gene variant known to resist the deadly disease. The transplant also cured his leukemia.
The stem cell donor was among the 1 percent of Caucasians who have the variant gene that lacks a section known as CCR5 that helps the AIDS virus enter a cell. Doctors in Berlin hoped that putting the donor’s stem cells in the patient would rebuild his immune system and blood cells so they would lack the CCR5 piece.
The results of the experiment pointed researchers to a new way of controlling the AIDS virus HIV that doesn’t force patients to take drugs for the rest of their lives.
One such trial sponsored by Sangamo Biosciences of Richmond, California, recently began at the University of Pennsylvania. It will test a gene therapy that aims to modify the immune cells in 12 patients infected with HIV so they lack the CCR5 receptor.
“The fact that you could put back into the patient CCR5- deficient cells and have those cells work to clear the virus — that gave us a lot of confidence,”.
The 40-year-old patient had been treated in Germany with antiviral drugs for 10 years, since his HIV infection was diagnosed. In July 2006, he developed leukemia and was given chemotherapy in an effort to eradicate the cancer.
After a few more months went by, his leukemia returned and doctors decided to try a stem cell transplant, a risky procedure that kills nearly a third of patients. They figured that as long as they were doing a transplant, they might as well look for a donor who didn’t have the key section of CCR5.
“Our thinking was that if we do this and replace his immune system with cells that are resistant to HIV, we can do two things at once” by stopping his leukemia and his HIV infection.
Stem cells from bone marrow, which are also found in circulating blood, have the ability to form blood cells including the white blood cells that fight infection. These are the cells that are attacked by the virus, crippling patients’ immune systems.
The genomes of 60 potential donors were scanned and found one who lacked the CCR5 section. The day after they transfused the donor’s stem cells into the patient, they stopped the antiviral therapy that had suppressed his HIV levels.
“There’s been no rebound of HIV Now, two years after transplantation, we can’t find any HIV in this patient.”