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Sarcoma
Volume 2013 (2013), Article ID 450478, 12 pages
http://dx.doi.org/10.1155/2013/450478
Research Article

Insulin-Like Growth Factor 1 Receptor as a Therapeutic Target in Ewing Sarcoma: Lack of Consistent Upregulation or Recurrent Mutation and a Review of the Clinical Trial Literature

1Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
2Department of Gastroenterology and Nutrition, Boston Children's Hospital, 300 Longwood Avenue Boston, MA 02115, USA
3Department of Pathology and Human Oncology & Pathogenesis Program, Room S-801, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, NY 10065, USA
4Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
5Division of Pediatric Oncology, Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD 21287, USA

Received 27 July 2012; Revised 5 December 2012; Accepted 9 December 2012

Academic Editor: Maria Tsokos

Copyright © 2013 Alison O'Neill et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The insulin-like growth factor 1 receptor (IGF-1R) has been considered an important therapeutic target in Ewing sarcoma (ES), generating a need to identify the subset of patients most likely to respond to IGF-1R inhibitors. We assessed IGF-1R expression in ES cell lines and patient tumors to understand the variable clinical responses to anti-IGF-1R therapy. Using ligand-binding displacement, we measured between 13,000 and 40,000 receptors per cell in ES cell lines. We used ELISA to quantify IGF-1R in patient tumors, which expressed 4.8%  ± 3.7 to 20.0%  ± 0.2 of the levels in a positive control cell line overexpressing IGF-1R. Flow cytometry showed markedly reduced IGF-1R expression in ES cell lines compared to a standard positive control cell line. The IGF1R gene was sequenced in 47 ES tumor samples and 8 ES cell lines; only one tumor sample showed a nonsynonymous mutation, R1353H, in a region with low functional impact. Finally, we assessed IGF-1R pathway activity in the ES stem cell (ESSC) population, to characterize its potential for resistance to anti-IGF-1R therapy, using Luminex technology. We found no significant differences in IGF-1R pathway activity between ESSCs and the total cell population. Overall, our findings suggest that IGF-1R as a therapeutic target in this sarcoma may require reevaluation.