Responses to Topical Diphenylcyclopropenone as an Adjunct Treatment for In-Transit Melanoma: A Tertiary Referral Center Experience

BACKGROUND: In-transit cutaneous metastases occur in 5% to 10% of patients with melanoma. Recently, topical diphenylcyclopropenone (DPCP) has been described as a treatment option. OBJECTIVE: To evaluate efficacy of DPCP in treatment of in-transit cutaneous melanoma. METHODS: The authors retrospectively reviewed the records of 13 consecutive patients with in-transit metastases treated with topical DPCP between March 1, 2013, and January 31, 2017. The authors recorded the response of in-transit cutaneous melanoma lesions treated with DPCP measured by clinical examination. RESULTS: Among the 13 patients, 9 patients completed at least a 1-month course of DPCP treatment. Of these 9 patients, 6 (66.7%) maintained either stable disease or had a partial or complete regression, and 3 (33.3%) had progressive disease. Patients with less burden of disease (e.g., <15 lesions) responded more favorably than those with a greater burden of disease (e.g., >25 lesions or plaques). Both patients who received DPCP alone had progression of their cutaneous lesions. One patient who did not become sensitized to DPCP died within 2 months, and his anergy likely reflecting immense burden of disease. CONCLUSION: Topical DPCP is a low-cost, patient-applied treatment option for in-transit melanoma, most effective for patients with relatively low tumor burden and localized disease.