Imiquimod efficacious in melanoma in situ tumor reduction

Key takeaways:

• Imiquimod treatment for 16 weeks exhibited a 90% tumor clearance rate in persistent MMIS at margins of resection.
• Long-term treatment efficacy should be assessed in larger studies.

Patients with persistent melanoma in situ have shown tumor clearance with imiquimod after surgery, according to a study.

“In a select population who have maxed out surgical options and/or refuse further resection with persistent margin positive melanoma in situ, imiquimod appears to be useful,” Jonathan S. Zager, MD, FACS, chief academic officer, director of regional therapies, chair of the department of oncologic sciences and professor of surgery at University of South Florida Morsani School of Medicine, told Healio.

Zager and colleagues conducted a retrospective review of adult patients with persistent melanoma in situ (MMIS) at the margins of excision of an invasive melanoma or MMIS alone who were treated at Moffitt Cancer Center between 2019 and 2021.

The 10 patients included in the study were either deemed not ideal candidates for surgical resection or refused surgical resection. Each was given topical imiquimod to use for 16 weeks.

Seven of the 10 patients underwent at least one surgical resection for either MMIS or invasive melanoma, and the median number of surgical attempts was two. Three patients did not receive any surgical intervention.

Treatment with imiquimod resulted in an overall 90% tumor clearance rate, with seven patients deemed free of disease via treatment scouting biopsies and two found to be clinically free of disease following confocal microscopy.

Persistent residual disease was found in one patient after two rounds of imiquimod. This patient underwent additional surgical excision, after which they were determined to be free of disease.

“Careful monitoring with scout biopsies and/or confocal imaging is needed to make sure disease is cleared and there are no signs of recurrence post imiquimod treatment,” Zager said.

Larger studies and extended follow-up periods are recommended by the study authors to assess long-term efficacy.