Evaluation of Intra-Lesional Interleukin 2 for the Treatment of In-Transit Melanoma Disease

Background: Intra-lesional interleukin 2 (IL-2) therapy trials for the treatment of in-transit melanoma using different treatment protocols have been published reporting varied results. This study assesses the results of IL-2 therapy in our institution and to evaluate the reproducibility of our response rates when using the same treatment protocol as another Canadian centre. Methods: A retrospective review was undertaken of patients with in-transit melanoma who were treated with intralesional IL-2 in a single institution from 2010 to 2016. Responses were evaluated using RECIST criteria. Demographic data, tumour characteristics, follow-up data, in-transit-free interval, and survival data were collected and analysed. Results: Forty-nine patients were identified. Overall tumour response rate was 72%, including complete response in 23 patients (47%) and partial response in 12 patients (24%). Stable disease was observed in 4% of patients and progressive disease in 25%. The main side effects were minor discomfort with injections and auto-limited flu-like symptoms. The presence of tumour-infiltrating lymphocytes may be a predictor of better response. Conclusion: This study confirms prior experience with intra-lesional IL-2, demonstrating it to be an effective, safe, and well-tolerated therapy for in-transit melanoma. Tumour-infiltrating lymphocytes as a predictor of better response warrant further study.