The efficacy of immunotherapy for in-transit metastases of melanoma: an analysis of randomized controlled trials.

Nearly 10% of patients with high-risk early-stage melanoma will develop satellite or in-transit metastases (ITM), classified as stage III disease similar to lymph node metastases. The pivotal registration trials of the CTLA-4 antibody ipilimumab, and the PD-1 antibodies nivolumab and pembrolizumab, also included patients with unresectable stage III disease. However, there has been no analysis of patients with ITM, and anecdotal retrospective small series have indicated a potential lesser effect. This study aimed to identify patients with unresectable ITM within the randomized trials, and to determine response, progression-free survival and overall survival. The pivotal phase III randomized intervention trials that included melanoma patients with ITM, with or without nodal metastasis, and were treated with ipilimumab, nivolumab or pembrolizumab was identified. The datasets from each trial were then searched to identify the specific details of the investigated patient population for a pooled analysis. The primary endpoint was complete response rate. Seven trials that included stage III patients, and with accessible datasets, were identified. There was a total of 4711 patients, however, no patients with ITM could be identified, as this data was not captured by the case report forms. Evidence from prospective clinical trials on the use of immunotherapy in patients with ITM is lacking. We recommend pooling data from multiple institutions to examine efficacy of available drug therapies in this patient population, but more importantly, prospective clinical trials of locoregional treatments with or without systemic drug therapies are required.
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