Gene expression signatures as a guide to treatment strategies for in-transit metastatic melanoma

9077 Background: In an era of targeted therapeutics biopsies are increasingly used to personalize cancer treatment. The utility of a single biopsy from a melanoma patient with multifocal disease to define the characteristics of that patient’s tumor is unclear. The aim of this study was to evaluate the genetic and molecular relationship of multifocal lesions and determine if one lesion is representative of residual tumor burden. Methods: Expression across 38k genes was measured using GeneChip microarrays. Binary regression, unsupervised hierarchical clustering, principal component analysis (PCA) and analysis of variance (ANOVA) were used to evaluate the patterns of expression across lesions. Predictions of sensitivity to chemotherapy and oncogenic signaling pathway activation were evaluated using signatures derived from the NCI-60 panel of cancer cell lines. Results: 43 in-transit lesions were obtained from 17 different patients with multifocal extremity melanoma. PCA and unsupervised hierarchical clusteri...