World AIDS Day 2020, Ending the HIV/AIDS Epidemic: Resilience and Impact
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We wrapped up HIV.gov's series of conversations with Carl Dieffenbach, Ph.D., about scientific highlights from the 22nd International AIDS Conference (AIDS 2018) as the conference began to wind down. Dr. Dieffenbach is the Director of the Division of AIDS at NIH's National Institute of Allergy and Infectious Diseases (NIAID).
During our Facebook Live interview, we:
Dr. Dieffenbach provided insights into how scientific research findings are analyzed and shared—both at conferences like AIDS 2018 and in peer-reviewed journal publications. At conferences, research is summarized in a brief oral or poster presentation. This often includes early findings from studies still in progress.
As an example, he cited findings presented this week from the ongoing Prevenir study comparing on-demand and daily dosing of HIV pre-exposure prophylaxis (PrEP) among gay, bisexual, and other men who have sex with men at high risk of HIV infection in the Paris region. (On-demand, or event-based, dosing means taking PrEP pills prior to and following sex instead of every day.) The lead researcher reported that, to date, no new HIV infections have occurred among study participants, regardless of whether they were taking daily or on-demand PrEP. This type of "mid-course look" at the data allows other researchers to think about what has been learned so far, react to it, and pose questions before the final results are published. Dr. Dieffenbach noted that early findings, such as those presented at conferences, are not always borne out in the final analysis.
Dr. Dieffenbach mentioned that final study results typically are published in peer-reviewed journals. Journal articles include much greater detail than can be captured in a conference presentation. Fellow researchers scrutinize and critique drafts of those articles prior to publication and often help sharpen the conclusions.
Looking back at some of the HIV prevention research highlights of AIDS 2018, Dr. Dieffenbach pointed to ongoing studies of monoclonal antibodies and findings from an early-stage vaccine study, noting that more results are yet to come. He also highlighted the findings from the PARTNER2 study. This study added to the existing body of evidence that if people living with HIV take antiretroviral treatment as prescribed to achieve and maintain an undetectable viral load, there is effectively no risk of transmitting HIV to their HIV-negative partners. Findings from PARTNER2 and previous studies provide ample evidence that treatment as prevention (TasP) works, Dr. Dieffenbach said. (View his more in-depth discussion of the PARTNER2 study findings in our conversation from earlier in the week.)
Regarding highlights of cure research, Dr. Dieffenbach discussed the RIVER study, a randomized controlled trial assessing a therapeutic vaccine to induce anti-HIV immune responses combined with an activator to wake up latent HIV. This approach—referred to as "kick and kill"—was an attempt to eliminate HIV reservoirs from the body. The researchers reported that this specific approach had no impact on measures of the HIV reservoir compared to antiretroviral therapy alone. But, Dr. Dieffenbach remarked, even a negative finding like this provides information that will inform future research. (See this video from NIAID on approaches to an HIV cure for more information.)
Finally, Dr. Dieffenbach re-capped some of the HIV treatment research studies presented at AIDS 2018. He noted that initial findings on some new fixed-dose antiretroviral drug combinations look very promising, but more research is needed to assess their durability. He also discussed both encouraging and potentially concerning information about the potent antiretroviral drug dolutegravir.
Interim data presented at the conference indicate that a two-drug combination of dolutegravir and lamivudine, another antiretroviral drug, was as effective as a three-drug regimen. There also has been discussion at the conference of a possible association between dolutegravir and infant neural tube defects. Researchers from the NIH-funded Tsepamo study previously reported that about 4 in 400 infants born to women who were taking dolutegravir at the time of conception had a neural tube defect—a very high rate of this serious birth defect. At the conference, researchers reported on an additional 170 births to women who had been taking the drug at the time of conception. No additional neural tube defects were observed among those births. Investigators will complete that study by March 2019, and we will then be able to make more definitive conclusions about any potential birth defect risks. (Carl discussed this study in more detail in another interview earlier this week.)
In a session on the safety of dolutegravir in pregnancy, researchers shared findings from an NIH-supported mathematical modeling study weighing the risks and benefits of dolutegravir-based treatment for women of childbearing age living with HIV. Dr. Dieffenbach explained that modeling studies take a set of information and put it into an equation to make predictions. In this case, the researchers assumed that the link between dolutegravir and neural tube defects is real and modeled outcomes for both adults and infants. They concluded that, compared to another common treatment regimen, use of a dolutegravir-based regimen would result in more birth defects, but it also would lead to many fewer deaths among women living with HIV, fewer HIV transmissions to partners, and fewer HIV infections among infants. As more information on the possible association with birth defects is gathered, the model will be revised to help better assess the risks and benefits of dolutegravir use. This type of analysis is used to inform updating of national HIV treatment guidelines in countries around the world.
The 22nd International AIDS Conference took place this week in Amsterdam. It gathered over 15,000 HIV researchers, public health experts, policy makers, and members of the HIV affected community from 160 nations to share and discuss the latest HIV science and innovations in prevention and treatment. Catch up on all of HIV.gov's coverage from the conference.