Doxycycline after condomless sex prevents bacterial STIs among men on HIV PrEP or living with HIV who have sex with men and transgender women
Presenter: Annie Luetkemeyer, MD, Zuckerberg San Francisco General Hospital, University of California, San Francisco
Doxycycline taken within 72 hours of unprotected sex significantly reduces bacterial sexually transmitted infections (STI) among men who are either on HIV pre-exposure prophylaxis (PrEP) or are HIV-positive and have sex with men and transgender women, according to a randomized open-label trial.
The study was terminated early owing to pronounced efficacy of postexposure prophylaxis (PEP) doxycycline in preventing N. gonorroheae, C. trachomatis, or syphilis. US Centers for Disease Control quickly weighing in on the importance of the study, noting that the findings indicate that doxycycline PEP has the potential to prevent bacterial STIs among some individuals at substantial risk for repeat STI acquisition, with Annie Luetkemeyer, MD, professor of medicine, Zuckerberg San Francisco General Hospital, University of California, San Francisco emphasizing the same at the 24th International AIDS (IAS) Congress.
Eligible participants had at least one STI (syphilis, chlamydia, or gonorrhea) in the previous 12 months before the study and reported having condomless sex with at least one male partner in that time. Of 501 participants, 174 were living with HIV and 327 were taking HIV PrEP. They were randomized 2:1 to receive open-label doxycycline, a maximum of 200 mg every 24 hours within 72 hours after condomless sexual contact or standard of care. Individuals were followed for 12 months and had visits every 3 months while on study for STI testing or more frequently if an STI was diagnosed in the interim. Participants were enrolled from Seattle and San Francisco HIV and Sexual Health Clinics.
At a scheduled interim analysis, the Data Safety Monitoring Board recommended stopping enrollment due to significant effectiveness in both cohorts. STI incidence per quarter, the primary endpoint, was reduced by 66% (hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.24-0.46; P < .0001) in the doxycycline arm among the PrEP cohort. The percent of quarterly visits with an STI were 10.7% in those randomized to doxycycline versus 31.9% among those randomized to standard care. A 62% reduction (HR, 0.38; 95% CI, 0.24-0.60; P < .0001) in the occurrence of the primary endpoint was achieved with doxycycline prophylaxis versus standard care in the HIV-positive cohort.
“There was a statistically significant decrease in gonorrhea incidence in both the PrEP and people living with HIV cohorts, 55% [P < .0001] in PrEP and 57% [P = .001] in people living with HIV,” said Dr. Luetkemeyer. “The decline was even more pronounced in those who were diagnosed with chlamydia, with an 88% reduction [P < .0001] in those on PrEP and a 74% reduction [P = .0007] in those living with HIV.” Few cases of syphilis were documented during the study, with a significant 87% reduction (P = .0084) with doxycycline prophylaxis in the PrEP cohort and a 77% reduction in the HIV-positive cohort, although the latter missed significance (P = .095).
“Participants reported a median 7.5 sexual acts per month, and 87% of these were covered by doxycycline by self report,” she said.
The study builds on prior evidence, Luetkemeyer noted, citing a study showing that doxycycline as PEP reduced transmission of chlamydia and syphilis by about two thirds each, but without an effect on transmission of gonorrhea, in men who have sex with men taking intermittent HIV PrEP.
The impact of doxycycline PrEP on tetracycline resistance development in gonorrhea requires larger surveillance studies, she added.
Disclosures
Doxycycline was provided by Mayne Pharmaceuticals. Laboratory support was provided by Cepheid & Holigic.
References
Molina J-M, Charreau I, Chidiac C, et al. Post-exposure prophylaxis with doxycycline to prevent sexually transmitted infections in men who have sex with men: an open-label randomized substudy of the ANRS IPERGAY trial. Lancet Infect Dis 2018; 18(3):308-317. doi:10.1016/S1473-3099(17)30725-9
Centers for Disease Control and Prevention. NCHHSTP Newsroom. CDC response to doxy-PEP data presented at 2022 International AIDS Conference. https://www.cdc.gov/nchhstp/newsroom/2022/Doxy-PEP-clinical-data-presented-at-2022-AIDS-Conference.html. July 27, 2022.