Grant: Operating Grant

Over the past few decades, the incidence of anal cancer has been steadily rising around the world. Men who have sex with men (MSM) are at increased risk, particularly those living with HIV. In most regions, the incidence of anal carcinoma among MSM living with HIV is nearly 80 times higher compared with the general male population. These rates are similar or higher to those of cervical cancer prior to the introduction of PAP cytology screening. Infection by high-risk human papillomavirus (HR-HPV) genotypes is recognized as the main risk factor in the development of anal cancer. The most common sexually transmitted infection, HPV has been found to infect 70% of HIV-negative MSM, and 95% of MSM living with HIV. HPV can also cause genital warts (condylomas), which are benign skin lesions but can lead to physical and psychological discomfort. Treatment of both condylomas and precancerous lesions is often repetitive and costly. Despite recent evidence suggesting that HPV vaccination is effective among young men, these vaccines are exclusively prophylactic and only target a subset of HR-HPV genotypes. Therefore, an alternative prevention approach is warranted in the MSM population. Carrageenan, a polymer derived from algae, was recently found to have remarkably high inhibitory properties against all HPV types. As a proof-of-concept study, we suggest a blinded randomized control trial to evaluate the effectiveness of carrageenan in the prevention of HPV transmission in a high-risk MSM population. Study participants will be instructed to use the gel (treatment or placebo) prior to each act of anal intercourse for one year. HPV infection status will be measured at baseline, and at each follow-up visit. Should carrageenan exhibit microbicidal properties when used as the active ingredient in a personal lubricant, it would present a cost-effective method of reducing the burden of HPV infection in this population.