Welcome to Virtual CROI week two!
Here’s a roundup of the exciting science heard last week across the spectrum of HIV prevention, and on cure research (more on this further down) with a groundbreaking new case of HIV remission. We also want to be sure you are all aware of the CROI Margarita Breakfast Club dialogues—both last week and this week. Superb discussions last week and three more this week are not to be missed—recordings from last week’s conversations and registrations for this week are here.
The overarching message coming from CROI last week was clear: no one biomedical strategy will do the job, the world needs multiple options and real choices. In this round up, the importance of choice leads our coverage. (And listen to Carlos del Rio from Emory University put it all in context in a terrific US National Public Radio interview here.)
Choice and the Ring
New data from the REACH study, which incorporated informed choice into its design, made this point unmistakable. Almost all (98 percent) of the 247 adolescent girls and young women in this study where both daily oral PrEP and the Dapivirine Vaginal Ring were offered, chose one of the products over none at all. All participants tried each product for 6 months, followed by 6 months where they could choose their preferred method. Kenneth Ngure, presenting on the REACH Study, said about ⅔ of the participants chose the ring. But most of the women who had very high adherence to the daily oral pill preferred the daily pills to the ring. Ngure said overall adherence in the REACH trial surpassed levels seen in previous studies. More findings on factors driving adherence is under analysis. “REACH is just a small example of what the potential impact could be in the real world of HIV prevention, simply by allowing young women and girls the ability to choose,” said Ngure.
Choice and Injectable PrEP
HPTN 083, evaluating injectable cabotegravir as PrEP among gay men, transgender women and other men who have sex with men (MSM), presented updated data that evaluated new infections that have occurred since the trial unblinded in May 2020. Raphy Landovitz, from UCLA and HPTN 083 protocol chair, reported that adherence went down during this phase of the trial, but break-through infections among those receiving on-time injections remained rare. (He reported a total of 7 such cases in the life of the study that covers 4,660-person years.) The data continue to confirm both the safety and efficacy of cabotegravir for PrEP. Reflecting on the significance of the drop in adherence to both daily oral PrEP and injectable cabotegravir during the unblinded phase, Landovitz said complex barriers to adherence make it clear that “no one biomedical prevention option will address all issues in HIV prevention”.
Additional data from Susan Eshleman of John Hopkins University School of Medicine and the HPTN 083 team deepened the discussion on effective and feasible testing. Detecting HIV is a crucial part of prevention strategies that rely on antiretrovirals (ARVs). Exposure to a single ARV, which is the protocol for PrEP (in contrast to combination ARV used in treatment), can lead to resistant HIV. Eshleman reported on data showing that using a highly sensitive RNA-based HIV test to confirm a person is HIV negative could reduce the risk of someone with undetected HIV developing resistance to first line treatment. But she said access to these tests should not limit access to this highly effective intervention, “In the context of proven high efficacy, CAB-LA should be considered for HIV PrEP in settings where HIV RNA screening is not readily available.”
Choice and Vaccines
IAVI’s Mark Feinberg summarized the state of vaccine science. One the one hand, two recent large-scale trials showed no efficacy (Uhambo and Imbokodo). On the other hand, Feinberg said cutting edge approaches offer “a strong and vibrant source of promise” for HIV vaccine development, particularly the development of broadly neutralizing antibodies (bNAbs). Looking ahead, Feinberg predicted the next major priority to make a large-scale trial a possibility will be validating a “correlate of protection”, a mark or sign in the immune system that can be linked to preventing HIV acquisition.
As this research evolves, the need for many options that deliver real choices remains clear. In a later session on immune responses, South Africa Medical Research Council and HVTN leader Glenda Gray said the high rate of HIV in hard-hit places (as high as 4 percent) will mean effective prevention may well require a combination of strategies. “We will likely need a combination of PrEP with vaccines to combat high rates—4 percent incidence rate is just too much for a vaccine alone to overcome.”
Another Step in the Journey Toward a Cure
A fourth person was reported to achieve HIV remission, the first case among women, according to data from Yvonne Bryson from the David Geffen School of Medicine at University of California. The New York woman has no detectable HIV since she stopped treatment 14 months ago. Her treatment interruption followed a stem cell transplant from a donor with an HIV resistant mutation. As in the other three cases, the stem cell transplant was an urgent intervention to treat advanced cancer. This stem cell transplant pioneered an innovation where a family donor provided stem cells in combination with stem cells from umbilical cord blood that had the needed mutation. One possible implication for cure research is confirmation of the role of a critical receptor on white blood cells known as CCR5. HIV relies on CCR5 to enter and infect the cells. Mutations to CCR5 have once again led to a case of remission, and two of these cases have endured long enough to be confirmed as a cure. Want to learn more? One of last week’s Margarita Breakfast Club discussion was River Deep, Mountain High: Pathways Toward a Cure for HIV, with a wonderful discussion about these findings.