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‘On-demand’ PEP reduces incidence of chlamydia, syphilis in MSM
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SEATTLE — “On-demand” postexposure prophylaxis, or PEP, using doxycycline reduced the incidence of chlamydia and syphilis in men who have sex with men who were being followed as part of another study investigating a similar regimen for pre-exposure prophylaxis, or PrEP, for HIV prevention.
Jean-Michel Molina, MD, of the University of Paris Diderot and department of infectious diseases at Saint-Louis Hospital in Paris, presented results of the substudy at CROI 2017.
Molina and colleagues noted an overall reduction in sexually transmitted infection (STI) incidence of 47% during the study period.
“Over the last couple of years, there has been an increase in the rate of STIs in a number of countries, particularly among MSM,” Molina said during a news conference here. “Because in PrEP programs we monitor and follow high-risk individuals for long periods of time, this is a good opportunity to do more research to try to reduce the rate of STIs in these high-risk individuals.”
Molina and colleagues enrolled 232 high-risk MSM who were being followed in the open-label phase of the ANRS IPERGAY trial, which showed that taking Truvada (emtricitabine/tenofovir disoproxil fumarate, Gilead Sciences) before and after each sexual encounter was highly successful at preventing HIV among MSM in France and Canada.
In their substudy, Molina and colleagues randomized participants 1:1 to receive either two 100-mg pills of doxycycline within 72 hours of condomless sexual intercourse, or no PEP, and provided each patient with risk-reduction counseling and condoms.
Patients were tested every 8 weeks for HIV and syphilis using serologic assays, and for chlamydia and gonorrhea using PCR assays. The median follow-up was 8.7 months. Molina said 21% of the participants discontinued the use of doxycycline at some point during the study period.
Overall, 73 patients acquired an STI during the study period, including 28 in the PEP arm (24%, 37.7 events per 100 patient years) and 45 who were not taking doxycycline (38.8%, 69.7 events per 100 patient years) for a hazard ratio (HR) of 0.53 (95% CI, 0.33-0.85), according to Molina and colleagues.
HRs for chlamydia and syphilis were 0.30 (95% CI, 0.13-0.70) and 0.27 (95% CI, 0.07-0.98), respectively. The HR for gonorrhea was 0.83 (95% CI, 0.47-1.47), but the lack of reduction in the incidence of gonorrhea was not surprising, Molina said, because most strains of the infection in France are resistant to doxycycline.
Patients in the PEP arm of the study could not exceed six pills per week and used a median of seven pills per month. Overall, 108 patients reported gastrointestinal adverse events, including 61 who were taking doxycycline, but only eight of them discontinued PEP as a result, showing the regimen was safe, according to Molina and colleagues.
They said the long-term efficacy of the “on-demand” PEP strategy and its impact on antibiotic resistance still need to be assessed.
“These results are encouraging, but we do not think that this is ready for implementation yet because these results were obtained from a limited number of people. We don’t have all their resistance yet. We think these data suggest we need to do more research in this area to try to reduce the incidence of STI among MSM.” – by Gerard Gallagher
Reference:
Molina J-M, et al. Abstract 91LB. Presented at: Conference on Retroviruses and Opportunistic Infections; Feb. 13-16, 2017; Seattle.
Disclosure: Molina reports being a consultant for Gilead Sciences, Merck, and ViiV Healthcare; and being on the speaker’s bureau and receiving research grant support from Gilead.