Abstract 2043: Protein pathway activation mapping analysis of metastatic breast cancer reveals potential new targets for personalized therapy.
Authors: Pierobon Mariaelena , Reeder Kimberly A. , Jameson Gayle , Robert Nicholas , Anthony Stephen P. , Sachdev Jasgit , Vocila Linda , Wulfkuhle Julia , Baldelli Elisa , Liotta Lance , Petricoin Emanuel F. 
Published: August 2014

Introduction: It is well known that the development of distant metastasis is the strongest prognostic factor associated with cancer mortality. Recent genomic and proteomic studies have demonstrated that the molecular profile of the metastatic lesions significantly differs from the primary tumor. For this reason, to improve response to therapy the identification of new drug targets needs to be based on the molecular profile of the metastatic lesions rather than the primary tumor. Since most targeted therapies work by modulating hyperactivated protein kinase signaling, the aim of this study was to utilize reverse phase protein arrays (RPPA) to quantitatively measure the drug target signaling architecture to identify new therapeutic options for Stage IV breast cancer patients based on the molecular profile of the metastatic lesion. Methods: Snap frozen material collected from 25 metastatic breast cancer patients enrolled in a prospective phase II trial (“Side Out” 1) were used for this study. Sites of metastasis were: liver (n=12), skin (n=5), lymph nodes (n=5), breast (n=2), and pelvis (n=1). All samples were subjected to Laser Capture Microdissection (LCM) and RPPA whereby the activation/phosphorylation level of 55 drug targets and linked substrates for FDA cleared/experimental therapies were measured. Results: Unsupervised hieratical clustering analysis revealed distinct patient subgroups driven largely by pathway activation more than by site of metastasis. Based on the activation level of the drug targets and the downstream effectors, three major clusters were identified. Each cluster appeared to be driven by a specific subset of drug targets: a) pan-HER family members, b) EGFR/SRC/ERK/mTOR, and c) IGFR/RAF/MEK/PLK1. Conclusion: This is the first study evaluating the activation status of FDA approved/experimental drug targets and downstream effectors in a relatively large number of breast cancer metastatic lesions. This type of approach provides a unique opportunity for identifying new drug targets for this group of patients and provides initial insights on which pathways should be considered in the delivery of targeted therapy to this group of patients.

1. A Pilot Study Utilizing Molecular Profiling by IHC, FISH, DNA Microarray, and Reverse Phase Protein Microarray (RPMA) of Patients’ Tumors to Find Potential Targets and Select Treatments for Patients with Metastatic Breast Cancer, sponsored by the Side Out Foundation

Citation Format: Mariaelena Pierobon, Kimberly A. Reeder, Gayle Jameson, Nicholas Robert, Stephen P. Anthony, Jasgit Sachdev, Linda Vocila, Julia Wulfkuhle, Elisa Baldelli, Lance Liotta, Emanuel F. Petricoin. Protein pathway activation mapping analysis of metastatic breast cancer reveals potential new targets for personalized therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2043. doi:10.1158/1538-7445.AM2013-2043