In this exclusive ľֱ video, , infectious disease fellow in the Division of HIV, ID, and Global Medicine at the Zuckerberg San Francisco General Hospital, discusses the potential for urine adherence testing to predict future HIV seroconversion, studied in a large demonstration project for PrEP that he presented at the recent annual Conference on Retroviruses and Opportunistic Infections (CROI).
Following is a transcript of his remarks:
We've seen in the PrEP trials that adherence has been critical for efficacy. PrEP is a highly, highly effective drug, but the issue is how we implement it and how we support our patients in taking it. I've been working with Dr. Monica Gandhi, who's presenting some work validating this novel adherence test in a separate session.
What I did in is I took adherence information that we were able to get by using our novel adherence test. I looked at: do people with lower adherence by this test go on to develop HIV seroconversion? What we found is low versus high levels of tenofovir with this amino acid test were associated with 14-fold higher risk of developing HIV in the future. The idea is that if we have this adherence information at the bedside through the means of a point-of-care test we can intervene and help support our patients and prevent HIV infections.
The state of adherence measurement, it's been evolving very rapidly in PrEP, but most of the tools, essentially all the previously available tools we had relied on a type of machine called a liquid chromatography-mass spectrometry machine, which is a mouthful, and that machine is highly expensive. It requires trained personnel. Essentially, it's mainly done in one or two labs, this adherence testing.
What I did with Dr. Gandhi's lab at UCSF and also in collaboration with a biotechnology company, Abbott, we developed an antibody. Antibodies allow you to develop point-of-care tests like strip tests, so think of a urine pregnancy test or a urine toxicology test that are used in methadone clinics. The idea would be instead of limiting this tool to research, when I have a regular PrEP follow-up visit, I could actually have adherence information in the moment. Because PrEP is a prevention intervention, it's not like a lot of other diseases I treat in primary care, diabetes, hypertension, even HIV where I have sort of a surrogate marker of how people are doing, like A1C in diabetes or the viral load in HIV. We don't have that in PrEP. The goal of this test would be to have more information about how our patients' adherence is doing and be able to talk with them in the visit and support them and try to motivate them to have good adherence on PrEP and stay HIV negative.