Diphenylcyclopropenone for the treatment of cutaneous in-transit melanoma metastases - results of a prospective, non-randomized, single-centre study.

BACKGROUND: Current treatments for in-transit melanoma (ITM) metastases are frequently invasive and do not improve overall survival. Recently, there has been increasing investigation into the use of topical agents. Diphenylcyclopropenone or diphencyprone (DPCP) is a novel, topical therapy that has been reported to have immune-sensitizing properties useful in the treatment of ITM. OBJECTIVE: To assess the clinical outcomes of patients treated within a prospective, non-randomized, non-comparative study using DPCP for cutaneous ITM metastases. METHODS: A review was conducted assessing the outcomes of 58 patients prospectively treated using DPCP. Patients had satellite or in-transit disease (stage IIIB+), with all lesion morphology types included. The patients were treated through a single, specialized clinic with regular outpatient follow-up. DPCP was topically applied as an aqueous cream in 0.005-1% concentrations once to twice per week for up to 24-48 h of duration. To assess variables associated with response, a per-protocol statistical analysis was performed. RESULTS: Fifty-four patients were treated who satisfied eligibility criteria for analysis. The overall response rates were as follows: complete response 22%, partial response 39%, stable disease 24% and progressive disease 15%. The mean time to complete response was 10.5 months, mean duration (disease-free interval) 12.3 months and recurrence rate in complete responders 41%. Lesion morphology was predictive of clinical benefit with a higher response in epidermotropic disease (P < 0.05). CONCLUSIONS: DPCP provided a well-tolerated, convenient and efficacious treatment for cutaneous ITM metastases. Identifying patterns of response may assist treatment selection and improve patient-rated outcomes.