Gene Therapy for Controlling HIV Shows Early Promise
Small study hints treatment could someday help patients fight AIDS virus without drugs
"Ideally, you'd like both copies knocked out," Levine said.
Of the four patients in this study whose viral levels declined after stopping their medication, one had undetectable HIV levels when the drug treatment was restarted. Levine's team later found that the patient naturally carried one copy of the CCR5 mutation.
So that patient, Levine said, essentially got a "head start," because there was no need for both CCR5 copies to be knocked out.
For her part, Johnston agreed that boosting the efficiency of the CCR5 knockout technique will be key. She said it also has to be tested in larger and more diverse groups of people with HIV, and researchers need to understand how the immune system responds over the long term.
And the "holy grail," Johnston said, would be to apply gene therapy to the bone marrow stem cells that give rise to the immune system, and not only T-cells.
Worldwide, more than 33 million people are living with HIV/AIDS, and 97 percent of them are in low- to middle-income countries, according to the U.S. Department of Health and Human Services.
If this or any other gene therapy were found to control HIV without the use of drugs, there would still be the questions of how to get it to people, and how to pay for it.
According to the World Health Organization, most people living with the disease globally do not have access to the current treatments.
But Johnston said she believes that if scientists can develop an effective gene therapy, others would find a way to get it to people living with HIV.
"I'm optimistic," she said. "For many years, people didn't think it would ever be possible to cure HIV. Now the question is no longer, 'Is it possible?' It's 'How are we going to do it?'"
The study was partly funded by Richmond, Calif.-based Sangamo BioSciences, which is developing the zinc-finger nuclease technology used in the research. Several co-researchers on the work are employees of the company.