MicroRNAs induced in melanoma treated with combination targeted therapy of temsirolimus and bevacizumab

• Published in: Journal of clinical oncology Vol. 30; no. 15_suppl; p. 8597
• Main Authors: Wagenseller, Aubrey G, Shada, Amber L, D'Auria, Kevin, Murphy, Cheryl F., Sun, Dandan, Molhoek, Kerrington R., Papin, Jason A, Dutta, Anindya, Slingluff, Craig L.
• Format: Journal Article
• Language: English
• Published: 20.05.2012
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2012.30.15_suppl.8597

Abstract only 8597 Background: Targeted therapies directed at commonly overexpressed pathways in melanoma have clinical activity in numerous trials. Little is known about how these therapies influence microRNA expression, particularly with combination regimens. A better understanding of how microRNAs are altered with treatment may contribute to understanding mechanisms of therapeutic effects as well as mechanisms of tumor escape from therapy. Methods: Using microRNA arrays, we analyzed microRNA expression levels in melanoma samples from a Cancer Therapy Evaluation Program-sponsored phase II trial of combination temsirolimus and bevacizumab in stage III or IV melanoma, which elicited clinical benefit in a subset of patients. Seventeen patients were treated with temsirolimus for one week, then combination of both temsirolimus and bevacizumab. Metastatic melanoma biopsies were evaluated days 1, 2, and 23. Tumor samples were evaluated from 12 patients. Results: microRNA expression remained unchanged with temsirolimus alone; however, expression of 15 microRNAs was significantly upregulated (1.4 to 2.5-fold) with combination treatment, compared to pre-treatment levels. Interestingly, twelve of these fifteen microRNAs have been reported to possess tumor suppressor capabilities in various cancer types, including melanoma. We identified 15 putative oncogenes and B7-H3, IGF-1, and IGF-1R as potential targets of the 12 tumor suppressor microRNAs, based on published experimental evidence. For 18 of 25 pairings of microRNA and target-mRNA, changes in gene expression from pretreatment to post-combination treatment samples were inversely correlated with changes in microRNA expression, suggesting a functional effect of the microRNA changes induced by combination therapy. Clustering analysis based on selected microRNAs revealed signatures characteristic of clinical response to combination treatment and of tumor BRAF mutational status. Conclusions: We have identified microRNAs that may be involved in the mechanism of action of combination temsirolimus and bevacizumab in metastatic melanoma, possibly through inhibition of oncogenic pathways.