Abstract 3465: Impact of intratumoral protein signaling network activation heterogeneity: Implication for precision medicine (2014)

Abstract Background: The evaluation of intratumor heterogeneity has become a major topic in the oncological field and it has major implications in the delivery of individualized therapy. While a number of genomic studies have reported significant intratumoral heterogeneity the analysis of the activation of protein kinase-driven signaling networks, which constitute the targets of most of the targeted compounds, has been sparse, or did not focus specifically on the tumor cells. This study evaluated the activation/phosphorylation of the protein signaling networks and a number of major precision medicine-oriented drug target to assess whether the intratumoral heterogeneity could impact patient stratification for targeted treatment in the context of metastatic disease. Methods: 3 independent study sets were used for this analysis: 1) metastatic colorectal cancer (mCRC) liver biopsies were collected from 6 patients; for each biopsy, 2 different regions were microdissected, 2) 18 needle biopsies were collected from 2 different regions of the same lesion of 9 mCRC liver metastases, 3) 7 serial liver biopsies were collected from 3 mCRC before and after treatment. Specimens were frozen upon collection, stored at -80°C and subjected to laser capture microdissection to isolate pure tumor epithelium. Protein pathway activation mapping was performed using reverse phase protein microarray. To assess changes in the activation level of the members of the MAPK and the AKT-mTOR pathway, unsupervised hierarchical clustering analysis and fold change between the different areas of the tumors were evaluated. Results: Hierarchical clustering analysis of the activation of 47 key signaling protein drug targets revealed that the signaling activation of any given protein or pathway was largely the same within a patient's tumor, no matter where the biopsy was obtained, but large interpatient variation was observed. When we evaluated activation of the MAPK and AKT-mTOR pathways, we found that the relative levels of pathway activation were found to be similar in different regions of the tumor, while each patient looked distinct. Conclusions: This first of its kind protein drug target activation analysis of microdissected tumor cells from human metastatic tumors revealed that the activated signaling architecture is largely maintained within the same tumor while each patient's tumor has a distinct patient-specific signaling portrait. The data suggest that interpatient protein drug target activation heterogeneity is much larger than intratumoral heterogeneity and point to the need to determine precision medicine based profiling on a patient-by-patient basis. Citation Format: Erika M. Parasido, Alessandra Silvestri, Claudio Belluco, Vincenzo Canzonieri, Maria Grazia Diodoro, Massimo Milione, Lance A. Liotta, Emanuel F. Petricoin, Mariaelena Pierobon. Impact of intratumoral protein signaling network activation heterogeneity: Implication for precision medicine. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3465. doi:10.1158/1538-7445.AM2014-3465