Danish researchers have used an anti-cancer medicine to activate HIV hidden in the cells of patients taking anti-HIV drugs, exposing the virus to the immune system and making it susceptible to attack.
The results revealed on Tuesday constitute one of the major scientific discoveries hailed at the AIDS 2014 conference in Melbourne, as much of the language shifts away from finding a cure to focusing on big steps in HIV treatment and prevention.
HIV hides in a state of hibernation in CD4 cells, an essential part of the immune system. Yet CD4 cells are unable to fight HIV themselves — that role lies with the immune system’s killer T-cells.
But because killer T-cells can’t detect the HIV hidden within CD4 cells, they are unable to attack and eliminate it from the body. While HIV patients on antiretroviral drug treatment often go on to have undetectable levels of HIV in their system, it is never eliminated.
There is always a reservoir left hiding in cells, undetectable to current screening tools and ready to take hold of the immune system again should patients stop their antiretroviral therapy.
But a research team led by Ole Sogaard at Aarhus University’s department of infectious diseases in Denmark has used the anti-cancer drug romidepsin to activate the virus and bring it out of hiding. “Once you activate them, these particles will go to the surface and signal to the immune system that this cell is infected and needs to be cleared from the body.”
In the pilot study, researchers gave six patients three doses of romidepsin over three weeks. Before each dose, no viral particles were detectable in the patients. “But after the dose was given we easily measured the virus being released into the plasma in five of these six patients,” Sogaard said.
“We also saw the virus go back to undetectable levels after seven days, so it came up, then hid away again, returning back to a non-active state until the next dose of cancer drug was given.”
However, the researchers found the immune system did not seem to attack the virus after detecting it. “This suggests when you do this reactivation, you also need to target and activate the immune system and teach it to recognise these cells and attack,” Sogaard said.
“That’s what we’re doing next in this study. We will teach and prime the immune system to recognise HIV before we give patients the cancer drug.” — © Guardian Newspapers Limited, 2014
