Topical 5% Imiquimod as Monotherapy for Primary Cutaneous and Cutaneous Metastatic Melanoma: Systematic Review of the Literature

Background: Surgery is the gold standard treatment for primary cutaneous melanoma but may not be suitable given some comorbiditiies, lesion size or location, or anticipated functional impairment. Imiquimod (IMQ) is a topical immunotherapy infrequently used for melanoma, often in combination with other treatments. Objective: The present work aims to review the available literature on the safety and efficacy of imiquimod in the treatment of cutaneous primary and metastatic melanoma. Methods: We systematically reviewed the literature on topical imiquimod as monotherapy for melanoma, excluding in situ disease. MEDLINE, EMBASE, and CINAHL searches were conducted using terms related to imiquimod and melanoma, results summarized according to the PRISMA Guidelines and quality of evidence assessed using the GRADE tool. Results: Of 559 citations identified, 14 case reports and series with 38 patients with 95 lesions met inclusion criteria. There was heterogeneity in treatment regimens, including the number of applications and treatment length. Complete clearance was observed in 39% of cases, while the stable or progressive disease was seen in 42% of cases; treatment efficacy was limited in cases with prior metastatic disease. Conclusion: The current literature for the use of imiquimod in cutaneous primary and metastatic melanoma remains scarce, with most evidence derived from case reports and series likely to be influenced by selection bias for positive treatment results. Nevertheless, imiquimod remains a relatively well-tolerated treatment for cutaneous primary and metastatic melanoma that may be used in selected cases.