Topical Imiquimod or Diphenylcyclopropenone for the Management of Cutaneous In-transit Melanoma Metastases – A Phase II Single Centre Prospective Randomised Pilot Study

INTERVENTION: The investigational agents are diphenylcyclopropenone (DPCP) and imiquimod, two dermatological immunotherapies for topical administration to cutaneous in‐transit lesions. Each agent will be administered topically with a 5mm peripheral margin to uniformly treat between 5‐20 target lesions over a minimum of 12 months or until complete clinical resolution of loco‐regional disease. Treatment Arm A – 5% Topical Imiquimod Cream: Self‐application 5 times weekly, regular clinical review, time to best response and formal 12 month assessment, regular clinical surveillance for duration of remaining trial. Treatment Arm B – Topical DPCP Cream: Sensitisation with 2% solution then treatment using 0.005% solution ‐ titrated to effect to a maximum of 5% , Responders commence treatment regimen ‐ self‐application once weekly, regular clinical review, titration to effect, time to best response and formal 12 month assessment, regular clinical surveillance for duration of remaining trial. During the scheduled clinical review participants' records of dates (treatment log) of medication self‐administration will be used to monitor adherence. CONDITION: Cutaneous in‐transit melanoma metastases PRIMARY OUTCOME: Complete clinical response in treated lesions assessed using standardised measurement tools (e.g. callipers) in accordance with Response Evaluation Criteria In Solid Tumors (RECIST). SECONDARY OUTCOME: Estimated difference in the health‐related costs between imiquimod or DPCP versus ILI or PV‐10 through a comparison of health‐related costs. Length of time patients experience local disease/progression free survival assessed using standardised measurement tools (e.g. callipers) in accordance with RECIST.. Melanoma‐specific patient reported outcomes measured using the validated FACT‐M quality of life sub‐scale. Overall survival length and rate. Patients experiencing overall disease progression including death following the completion of the treatment / complete clinical response. This will be achieved through regular clinical assessment of treated lesions (applying RECIST), monitoring regional lymph nodes and radiologically evaluating for distant disease using standardised investigations such as CT/PET scanning. Proportions of patients experiencing complete response and partial response (overall response), stable disease and local disease progression as a composite secondary outcome. This will be achieved through regular clinical assessment of treated lesions (applying RECIST) and monitoring regional lymph nodes. Time to best response in treated lesions assessed using standardised measurement tools (e.g. callipers) in accordance with RECIST. INCLUSION CRITERIA: 1. Men or women aged 18 years or older. 2. Willing and able to comply with study requirements. 3. Capable of providing valid (written and informed) consent. 4. Histologically or cytologically proven in‐transit melanoma metastases. 5. Measurable disease between 2‐15mm in diameter that can be accurately assessed by ruler/calliper. 6. Between 5 to 20 in‐transit melanoma lesions. 7. Lesions present in anatomical locations amenable to imiquimod or DPCP treatment. 8. Cutaneous (superficial) macular, papular or small nodular in‐transit melanoma deposits. 9. Considered un‐suitable for surgery by the treating surgeon due to anatomical location or prohibitive disease factors or co‐morbidities, previous treatment failure or patient refusal. 10. 12 weeks minimum duration between completing comparative treatments (ILI or PV‐10) to prevent potentially confounding effects (treatment responses). 11. Patients must have, in the opinion of