New roles for GLP-1 drugs amid a surge in sexually transmitted infections | CROI 2026

Glucagon-like peptide-1 receptor agonists (GLP-1s) and sexually transmitted infections (STIs) shared the spotlight at Tuesday’s plenary session at the Conference on Retroviruses and Opportunistic Infections (CROI) 2026, held from Feb. 23 to 25 in Denver, Colorado.

The session was split between Todd T. Brown, M.D., Ph.D., a clinical investigator at Johns Hopkins Medicine, who presented GLP-1 Receptor Agonists: Are They a Cure for Everything? and Jeanne Marrazzo, M.D., M.P.H., CEO of the Infectious Diseases Society of America, who presented Syphilis and Superbugs: Sexually Transmitted Infections in the Era of HIV Control.

GLP-1s show anti-inflammatory promise in HIV patients

Brown kicked off the session with his presentation on the effects of incretins, like GLP-1s, in HIV patients.

“With the exception, perhaps, of antiretroviral therapy, I can't think of another class of medications where there has been so much buzz,” Brown said during his presentation.

He shared that these drugs seem to have an anti-inflammatory effect in people with and without HIV. In studies, this has been observed as large reductions of systemic inflammation markers, especially the C-reactive protein (CRP), which occur before weight loss.

Brown cited a recent study of HIV patients randomized to receive either tirzepatide or placebo. Results showed an approximately 48% reduction in CRP, independent of changes to body fat loss or improved glycemia.

He also highlighted potential immune and tissue mechanisms that could explain the reasons for this.

Rising STIs in the era of HIV control

Marrazzo’s presentation focused on the rising tide of STIs, even as cases of HIV have been going down.

Since 2015, cases of gonorrhea, syphilis and congenital syphilis have increased by 37%, 155% and 696%, respectively.

“Congenital syphilis occurs as a huge failure of the public health system and really affects the most marginalized, vulnerable people,” Marrazzo said.

Approximately 31% of all primary and secondary cases of syphilis occurred in men who have sex with men, who make up the largest population of HIV cases. However, the number of syphilis cases in women has started to catch up. In 2024, women accounted for 29% of new syphilis cases, a trend that is being seen in Europe as well.

STIs may be able to be prevented, specifically with doxycycline post-exposure prophylaxis (DoxyPEP), according to early data from San Francisco that shows this regimen decreased syphilis and chlamydia cases among men who have sex with men and transgender women by 51% and 49%, respectively. The Centers for Disease Control and Prevention currently recommend that healthcare providers discuss DoxyPEP with all gay, bisexual, and other men who have sex with men and transgender women with a history of at least one bacterial STI (gonorrhea, chlamydia and syphilis) in the last 12 months.

DoxyPEP should be prescribed as 200 mg of doxycycline within 72 hours after oral, vaginal or anal sex, according to the CDC.

It’s anticipated that WHO guidelines for DoxyPEP will be released later this year. European guidance came out in January 2026, Marrazzo explained.

“I think DoxyPEP is a medium-term solution to a long-term problem that will only be solved by durable immunity induced by vaccines, especially for syphilis,” Marrazzo said.

Marrazzo explained that potential reasons why DoxyPEP is not a long-term solution include the possibility of antibiotic-resistant infections.