In the search for an HIV cure--complete eradication of virus in the absence of ongoing antiretroviral therapy (ART)--one interim strategy involves identification of treatments that can induce sustained suppression of the virus, even if it remains present at very low levels.
The feasibility of such an approach is greatly strengthened by the existence of a small number of individuals known as post-treatment controllers, who maintain control of HIV growth after discontinuing ART. Writing in The Journal of Infectious Diseases, amfAR-funded scientist Dr. Steven Deeks from the University of California, San Francisco, with colleagues from eight AIDS Clinical Trials Groups (ACTG), identified such individuals and provided insights into their viral control.
In the CHAMP (Control of HIV after Antiretroviral Medication Pause) study, Deeks and colleagues sought to define the frequency of these post-treatment controllers. Reviewing participants in 14 ACTG studies enrolling over 700 individuals, they identified 67 people, of whom 38 were treated during early HIV infection and 25 during its chronic phase. These individuals maintained viral loads less than or equal to 400 copies at least two-thirds of the time after stopping ART, for a minimum of six months of follow-up.
Post-treatment controllers were over three times more prevalent among those who had started ART early in the course of their infection. But most impressive was the durability of HIV control. After one year, 75% still controlled their virus off ART. After five years, 22% still did. Deeks and colleagues also found that the level of virus at which participants in ART interruption trials restarted ART had a dramatic effect on the frequency of post-treatment controllers. Restarting ART at a threshold of 1000 viral copies would have failed to identify about half of those individuals.
The investigators also noted an unusual pattern: one of the 14 ACTG studies reported a surprisingly high number of post-treatment controllers. That study included cycles of ART treatment interruption, suggesting that the concept of “autovaccination,” by which bursts of virus following ART interruption stimulate effective immune responses, should be explored further in HIV cure research.
The authors concluded that “The presence of individuals who can maintain HIV suppression after discontinuing ART provides hope that the goal of sustained HIV remission is possible.”
Dr. Laurence is amfAR’s senior scientific consultant.