Imiquimod for Anal High Grade Intraepithelial Neoplasia: A Systematic Review

INTRODUCTION: This study aimed to investigate the efficacy of imiquimod in Anal High Grade Squamous Intraepithelial Lesion (HSIL). METHODS: Electronic databases (Pubmed, MEDLINE, EMBASE and Cochrane Library databases) were searched from inception until December 2024 for articles reporting imiquimod as a treatment for anal HSIL. RESULTS: Five studies were identified (2 randomized controlled trials and 3 prospective non-randomized studies), containing data on 126 men of have sex with men living with HIV with anal HSIL. Most studies contained significant bias which prevented direct comparison. Reported complete response (CR) rates ranged between 14.3-78.6%, and 21.4-67% partial response (PR) rates of 3-weekly application for 16 weeks imiquimod course. A second course of imiquimod led to incremental response (CR 15-23.8%, PR 19-30%). Perianal HSIL showed superior response rates compared to intra-anal lesions (perianal HSIL CR ranging from 71.4 to 100%, intra-anal HSIL CR from 10.8 to 33.3%). DISCUSSION: In our systematic review we summarized the literature regarding imiquimod use for anal HSIL treatment, both perianal/intra-anal. Imiquimod can be proposed as a safe treatment of anal HSIL, and perianal HSIL may benefit more from imiquimod treatment. However, anal HSIL recurrence rates were high, and there are no long-term data on its efficacy. No studies investigated the role of imiquimod in women or in HIV- patients. CONCLUSION: Imiquimod can be proposed as a safe option for treatment of anal HSIL.