Gene therapy offers hope for AIDS cure
Approach inspired by case in Germany
In a bold new approach ultimately aimed at trying to cure AIDS, scientists used genetic engineering in six patients to develop blood cells that are resistant to HIV, the virus that causes the disease.
It’s far too early to know if this scientific first will prove to be a cure, or even a new treatment. The research was only meant to show that, so far, it seems feasible and safe.
The concept was based on the astonishing case of an AIDS patient who seems to be cured after getting blood cells from a donor with natural immunity to HIV nearly four years ago in Berlin. Researchers are seeking a more practical way to achieve similar immunity using patients’ own blood cells.
The results announced Monday at a conference in Boston left experts cautiously excited.
“For the first time, people are beginning to think about a cure” as a real possibility, said Dr. John Zaia, head of the government panel that oversees gene therapy experiments.
Even if the new approach doesn’t get rid of HIV completely, it may repair patients’ immune systems enough that they can control the virus and not need AIDS medicines – “what is called a functional cure,” Zaia said.
This is the first time researchers have permanently deleted a human gene and infused the altered cells back into patients. Other gene therapy attempts tried to add a gene or muffle the activity of one, and have not worked against HIV.
A California biotechnology company, Sangamo BioSciences Inc., makes a treatment that can cut DNA at precise locations and permanently “edit out” a gene.
In the study, six men with HIV had their blood filtered to remove a small percentage of their T-cells. The gene-snipping compound was added in the lab, and about one-fourth of the cells were successfully modified. The cells were mixed with growth factors to make them multiply and then infused back into the patients.
Three men received about 2.5 billion modified cells. Three others received about 5 billion.
Three months later, five men had three times the number of modified cells expected. As much as 6 percent of their total T-cells appear to be the new type – resistant to HIV, Lalezari said.
The sixth man also had modified cells, but fewer than expected. In all six patients, the anti-HIV cells were thriving nearly a year after infusion, even in tissues that can hide HIV when it can’t be detected in blood.
“It is a huge step” and a first for the field of genetics, said John Rossi, a researcher at City of Hope in Duarte, Calif., where he and Zaia plan another study to test Sangamo’s approach. “The idea is if you take away cells the virus can infect, you can cure the disease.”
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