Analysis of NRAS gain in 657 patients with melanoma and evaluation of its sensitivity to a MEK inhibitor

Publication date: January 2018
Source:European Journal of Cancer, Volume 89
Author(s): Junya Yan, Xiaowen Wu, Jiayi Yu, Huan Yu, Tianxiao Xu, Kevin M. Brown, Xue Bai, Jie Dai, Meng Ma, Huan Tang, Lu Si, Zhihong Chi, Xinan Sheng, Chuanliang Cui, Yan Kong, Jun Guo
BackgroundNeuroblastoma rat-sarcoma (NRAS) mutations have been described in Chinese patients with melanoma. However, the status and the clinical significance of NRAS gain have not been investigated on a large scale.MethodsA total of 657 melanoma samples were included in the study. NRAS copy number was examined using the QuantiGene Plex DNA assay. The sensitivities of cell lines and patient-derived xenograft (PDX) models containing NRAS gain to a MAP/ERK kinase (MEK) inhibitor (binimetinib) were also evaluated.ResultsThe overall incidence of NRAS gain was 14.0% (92 of 657). Incidence of NRAS gain in acral, mucosal, chronic sun-induced damage (CSD) and non-CSD melanomas was 12.2%, 15.8%, 9.5% and 19.4%, respectively. NRAS gain was mutually exclusive to NRAS mutations (P = 0.036). The median survival time for melanoma patients with NRAS gain was significantly shorter than that for patients with normal NRAS copy number (P = 0.006). For patients containing NRAS gain, the median survival time for higher copy number (>4 copies) was significantly shorter than those with lower copy number (2–4 copies; P = 0.002). The MEK inhibitor (binimetinib) inhibited the proliferation of melanoma cells and the tumour growth of PDX models with NRAS gain.ConclusionsNRAS gain is frequent in patients with melanoma and may predict a poor prognosis of melanoma. The melanoma cells and PDX models containing NRAS gain are sensitive to MEK inhibitor (binimetinib), indicating that NRAS gain might be a new therapeutic target for melanoma.



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