Gene therapy can prevent cells from becoming infected with HIV, pointing the way to a possible cure.
Investigators from Quest Clinical Research in San Francisco used gene therapy to produce cells that lacked the CCR5 co-receptor that HIV uses to infect cells.
Their research was inspired by study of ‘elite controllers’ – HIV-positive individuals who maintain a healthy immune system and an undetectable viral load without HIV therapy. These individuals do not have CCR5 on their cells.
The small phase 1 study involved six HIV-positive patients. All were taking HIV treatment and had an undetectable viral load. However, they had had a poor immune response to treatment and their CD4 cell counts were in the 200 to 500 cells/mm3 range.
Blood was drawn from the patients, the T-cells were filtered out, and the blood was then returned. These cells were treated in the laboratory with a type of gene therapy called zinc finger technology that disables the CCR5 co-receptor.
Modification of cells was successful in about a quarter of cases. These cells were then re-introduced into the patients.
Five of the six patients experienced good increases in their CD4 cell count, and their immune profiles improved.
Three months later, 7% of CD4 cells lacked the CCR5 co-receptor.
The researchers emphasise that it’s too early to talk about a cure. But they believe their results are a proof of concept, and further research is planned.
Separate research showed that gene therapy also successfully altered some cells that used the CXCR4 co-receptor. This is normally found in patients who have extensive experience of antiretroviral therapy, or who are ill because of HIV. A protective effect was evident by 14 days after re-infusion, although the effect waned over time.