New Gene Therapy Hope for HIV
When it comes to research on HIV and AIDS treatments, it can be hard to know when to celebrate a small advance-everyone wants to see progress, but so many experimental avenues that seemed promising have turned out to be dead ends. Still, a new study that tried a sophisticated form of gene therapy as an HIV treatment seems cause for cautious optimism. If it bears out under further testing, the technique could lead to a one-shot, long-lasting treatment that could replace the punishing regimen of daily medications.
Treating HIV currently comes down to controlling the viral load with a mixture antiretroviral drugs, but over time, this drug cocktail becomes less effective. Researcher John Rossi and his colleagues tried to craft a more permanent treatment by genetically modifying the HIV-infected patients' own blood stem cells and increasing the cells' ability to fight off the virus. The researchers weren't able to truly combat the virus in this experiment-the patients' viral loads remained the same-but their work moved beyond previous attempts in two ways: They successfully modified blood stem cells by giving them anti-HIV genes, and those cells survived for two years in patients.
According to ScienceNow: Earlier clinical studies the group conducted with the same strategy made little headway, but now the researchers have overcome two key obstacles, says Rossi, a molecular geneticist. One is that they managed to stitch the anti-HIV genes into a high percentage of the appropriate stem cells. The other is that the cells lived for a long time. "If we could increase the number of modified cells by 10- or 100-fold, we might be able to stop the virus itself," says Rossi.
The small study published in Science Translational Medicine tested the safety of the technique for HIV-infected patients, and served as a proof of concept. The four patients in this study were undergoing therapy for AIDS-related lymphoma at City of Hope cancer center in California. Part of the usual treatment for this condition is to remove blood stem cells (found in bone marrow) before cell-damaging chemotherapy, and to then return them after treatment. Researchers wanted to test their virus-fighting cells' survival skills, so with each patient's normal blood stem cells, the researchers also reintroduced a small number of modified cells.
"They modified the cells in three ways: They boarded up the cells' doors to keep the HIV virus out, and made two genetic changes to the cells' internal defenses so that the virus would have a harder time copying itself if it made it through," according to ScienceNow.
As a safety precaution, the researchers didn't implant enough of these novel cells to test how well they might fight the virus, but they did get a glimpse of how long the modified cells could stay in a person's system. Up to two years after the treatment, patients still had low levels of these special cells.
"That's a major finding," Rossi added. While the number of cells expressing those genes was too low to provide any therapeutic benefit, it's "proof of principle" that gene therapy may provide long-term HIV treatment, he said.
As a next step, researchers hope to implant a greater number of modified cells in patients, to see how well they can fight and how long their defenses hold.
By Joseph Calamia
Reprinted with permission from Discover