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Title
Association of HIV pre-exposure prophylaxis (PrEP) use and bacterial sexually transmitted infections (bSTI) among men who have sex with men (MSM) and transgender women (TGW) in HVTN 704/HPTN 085
Presenter
Jorge Antonio Gallardo-Cartagena
Authors
J.A. Gallardo-Cartagena1, P. Hunidzarira2, K. Gillespie3, M. Juraska3, M. Neradilek3, P. Gilbert3, R. Cabello4, J.R. Lama5, J. Valencia5, J.C. Hinojosa6, J.J. Montenegro-Idrogo1, V.G. Veloso7, B. Grinsztejn7, R. De La Grecca3, S. Karuna3,8, S. Edupuganti9, K. Konda10, A. Roxby3,11,12, M. Cohen13, L. Corey3, J. Sanchez1, HVTN 704/HPTN 085 Study Team
Institutions
1Universidad Nacional Mayor de San Marcos, Centro de Investigaciones Tecnológicas, Biomédicas y Medioambientales, Callao, Peru, 2University of Zimbabwe, Clinical Trials Research Centre (UZ-CTRC), Harare, Zimbabwe, 3Fred Hutchinson Cancer Center, Vaccine and Infectious Diseases Division, Seattle, United States, 4Asociación Civil Vía Libre, Lima, Peru, 5Asociación Civil Impacta Salud y Educación, Lima, Peru, 6Asociación Civil Selva Amazónica, Lima, Peru, 7Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz (INI/Fiocruz), Rio de Janeiro, Brazil, 8GreenLight Biosciences, Inc, Lexington, United States, 9Emory University, Department of Medicine, Division of Infectious Disease, Atlanta, United States, 10University of Southern California, Keck School of Medicine, Department of Population and Public Health Sciences, Los Angeles, United States, 11University of Washington, Department of Medicine, Seattle, United States, 12University of Washington, Department of Global Health, Seattle, United States, 13University of North Carolina, Department of Medicine, Chapel Hill, United States

BACKGROUND: HIV prevention trials enroll participants with high vulnerability to HIV and provide access to an enhanced HIV prevention package, including PrEP. HVTN 704/HPTN 085 was a randomized clinical trial evaluating VRC01 for HIV prevention in MSM and TGW in the Americas and Switzerland. We conducted a post-hoc analysis to characterize bSTI burden and evaluate the association of PrEP use with bSTI incidence among trial participants.
METHODS: We included trial participants who received at least one VRC01/placebo infusion and had bSTI results from at least one bSTI visit (baseline and every 6 months). Participants received education about oral PrEP and could opt to use it. Prevalence of bSTI was summarized at each visit and categorized by socio-demographics, geographic region, and PrEP use (a time-varying covariate indicating self-reported PrEP use). We estimated incidence rates (for 100 person-years at risk [PYR]) of first bSTI occurrence among those who were negative at baseline, categorized by PrEP use. Cox proportional hazards models were used to evaluate the effect of PrEP use on bSTI incidence, additionally adjusted for age, region, race, ethnicity, and VRC01/placebo.
RESULTS: The analysis included 2687 participants, of whom 31.8% initiated PrEP during follow-up. The table summarizes bSTI baseline prevalence by region and incidence rates by PrEP use. The baseline prevalence of any bSTI was highest among <20yo (35.7%), Hispanic/Latinx (32.4%), non-Black/non-Whites (32.1%), TGW (35.3%), and MSM (28.9%). Oropharyngeal (gonorrhea 6.5%) and rectal bSTI were more prevalent (chlamydia 9.0% and gonorrhea 5.8%) than genitourinary bSTI (chlamydia 3.0% and gonorrhea 0.9%) at baseline. PrEP use was significantly associated with increased hazard of any bSTI (HR 1.7, 95%CI 1.4-2.1), chlamydia (HR 1.7, 95%CI 1.3-2.2), gonorrhea (HR 1.8, 95%CI 1.4-2.5), and syphilis (HR 1.9, 95%CI 1.3-2.8).

bSTI
Baseline prevalence summarized by n/N (%)Incidence rates for 100 PYR (95%CI)
Overall
Brazil
Peru
US/Switzerland
Overall
While on PrEP
While not on PrEP
Any bSTI
749/2687 (27.9%)
55/150 (36.7%)
392/1124 (34.9%)
302/1413 (21.4%)
28.6 (26.4-31.0)
37.2 (33.0-41.8)
24.0 (21.5-26.7)
Chlamydia
297/2687 (11.1%)
11/150 (7.3%)
158/1124 (14.1%)
128/1413 (9.1%)
16.1 (14.5-17.8)
20.4 (17.5-23.7)
13.5 (11.7-15.5)
Gonorrhea
273/2687 (10.2%)
22/150 (14.7%)
151/1124 (13.4%)
100/1413 (7.1%)
12.2 (10.9-13.7)
16.2 (13.7-19.1)
9.9 (8.4-11.6)
Syphilis
353/2687 (13.1%)
34/150 (22.7%)
194/1124 (17.3%)
125/1413 (8.8%)
6.7 (5.7-7.8)
8.8 (7.0-11.0)
5.5 (4.4-6.8)

CONCLUSIONS: HVTN 704/HPTN 085 engaged communities with significant HIV/STI vulnerability. While on PrEP, users had higher rates of bSTI, suggesting risk compensation and underscoring the need for advancing bSTI testing and prevention measures in HIV prevention trials.