“Today might be considered a day when the research agenda moves from basic science and the lab into the clinic,” said Steven G. Deeks, an AIDS researcher at the University of California at San Francisco who is not directly involved in the studies. “It is an absolutely critical advancement.”
One strategy involves waking up sleeping cells infected with HIV so they can then be killed. Another requires treating people with HIV drugs immediately after infection, something that has been tried previously without the dramatic effects described on Thursday. The third strategy requires stem cell transplantation, a difficult and expensive procedure.
The outcomes described by the researchers do not constitute cures in the usual sense. In some patients, HIV remained detectable in some cells. In others, whether it remained after treatment was uncertain. But that may not make a difference. Most experts say a “functional cure” — in which the virus persists but the body controls it — would be a major breakthrough.
The researchers steered clear of using the word “cure.”
“We are very careful about what we say,” said David Margolis of the University of North Carolina. “But you cannot argue about the value of the goal.”
Curing HIV infection is difficult because in certain types of human cells the virus stitches itself into the infected person’s DNA, becoming in effect a part of the patient’s “self.” To make matters worse, those cells survive for decades. But like Sleeping Beauty, they can awaken with the right stimulation and live out their lives, which in their case means making HIV that attacks other cells and perpetuates the infection. A true cure would have to target those sleeping cells, probably by waking them up in order to kill them.
Only one person is believed to have been cured of HIV infection. He is Timothy Brown, an American who was treated in Germany and is known as “the Berlin patient.” He received a stem cell transplant for leukemia, and his forward-thinking physician, Gero Hutter, chose for a donor someone with a rare mutation whose cells couldn’t be infected with HIV. When Brown recovered, his body contained no detectable virus.
That surprising finding reignited cure research, which had been dormant after unsuccessful attempts in the 1990s.
In a session at the AIDS conference on Thursday, Timothy J. Henrich and Daniel R. Kuritzkes of Harvard Medical School described the experience of two people with HIV infection who, like Brown, had undergone stem cell transplants. In their cases, it was because of lymphoma, which like leukemia is also a blood cell cancer. The chemotherapy they received was less aggressive than Brown’s and more of their immune cells remained. The transplanted cells apparently hunted down those cells — some of which were infected with HIV — and killed them in a reaction known as “graft vs. host disease.”