Targeted treatment and immunotherapy in leptomeningeal metastases from melanoma

Background: Historically leptomeningeal metastases (LM) from melanoma have a poor prognosis, with a median survival of only 2 months despite treatment. Targeted therapy and immune checkpoint inhibitors are promising new treatment options in advanced melanoma. We sought to determine the impact of targeted therapy and immunotherapy on the outcome of melanoma patients with LM and to evaluate the influence of prognostic factors. We analyzed a series of 39 consecutive patients diagnosed with LM from melanoma between May 2010 and March 2015 treated at the Netherlands Cancer Institute. Thirty-four of these patients also had brain metastases (BM). Statistical analyses assessed the influence of clinical and biological characteristics on survival. Median overall survival of the entire cohort was 6.9 weeks (95% confidence interval 0.9-12.8). Due to a poor performance status or rapidly progressive disease, 14 patients received no treatment. Median overall survival of untreated patients after the diagnosis of LM was 2.9 versus 16.9 weeks for treated patients (P < 0.001). The median survival of 21 patients treated with systemic targeted therapy and/or immunotherapy, with or without RT was 21.7 weeks (range 2-235 weeks). Five patients had LM without BM. Three of these patients died within 3 weeks before any treatment was given, whereas 2 patients are in ongoing remission for 26 weeks (following dabrafenib) and 235 weeks (following WBRT and ipilimumab). Elevated serum lactate dehydrogenase and S100B at diagnosis of LM were associated with shorter survival. LM from melanoma still has an extremely poor prognosis. As observed in extracranial metastatic disease, new treatment modalities such as systemic targeted therapy and immune checkpoint inhibitors seem to increase overall survival in LM, and may result in long-term remission. These new treatment options should be considered in patients with LM.