Imiquimod May Be Safe in Pre-Surgical Treatment for Lentigo Maligna

The surface of lentigo maligna (LM) lesions decreases with 1 month of imiquimod treatment, according to study results of published in the Journal of the American Academy of Dermatology & Venerology.

Researchers conducted a prospective, randomized, multicenter, phase III clinical trial (ClinicalTrials.gov Identifier: NCT01720407) to evaluate the effect of topical imiquimod 5%, an immunomodulator therapy approved for the treatment of superficial basal cell carcinoma. Patients (N=247) who were treatment-naive with histologically confirmed LM with a lesion size between 1.5 cm² and 20 cm² were recruited from 23 sites.

The participants were randomly assigned in a 1:1 ratio to receive either topical imiquimod (n=126) or placebo (n=121) for 4 weeks. They were instructed to apply the products 5 days per week. They underwent extralesional excision area with a 5-mm margin after a 4-week pause to allow for posttreatment inflammation resolution. Treatment success was defined as the absence of tumor cells in the excised margin.

The participants in the imiquimod and placebo cohorts were a mean age of 70.58 (SD, 9.86) and 72.53 (SD, 11.02) years, the man:woman ratios were 57:69 and 53:68, and they had initial LM areas of 4.16 (SD, 4.6) cm² and 4.11 (SD, 3.6) cm², respectively.

The treatment compliance rates were 95% for imiquimod and 98% for placebo.

Treatment success occurred among more of the imiquimod recipients (92%) than the placebo recipients (84%; P =.049). In addition, those in the imiquimod group underwent fewer revisions to obtain successful extralesional excision compared with controls (mean, 0.06 vs 0.18; P =.019), respectively.

Overall, the lesions decreased in size by 1.6 (SD, 3.9) cm² among the imiquimod recipients and increased in size by 0.2 (SD, 1.3) cm² among the placebo recipients (P <.002) from baseline to surgery.

Imiquimod was associated with a higher remission rate at 1 month compared with controls (26% vs 0.008%; P <.001), respectively. During a mean follow-up of 25.5 to 28.8 months, there were 3 recurrences in the imiquimod group and 2 in the placebo group occurred.

The imiquimod cohort reported more adverse events than controls, which were mainly of grades I and II severity. Many adverse events involved skin reactions at the application site.

This study may have been limited by its stratification approach. This may have affected the primary endpoint evaluation, which was only significant in the multivariate and not the univariate analysis.

The study authors conclude, “[N]eoadjuvant treatment with imiquimod significantly reduces the LM area after [1] month of treatment. Reducing the surface of LM with imiquimod is not associated with a higher risk [for] intralesional excision.”