Protein network mapping of platinum-resistant and poor-survival ovarian cancer

5560 Background: Epithelial ovarian carcinoma (EOC) is the fifth leading cause of tumor related death in the female population, with only 30% of patients alive at 5 years after diagnosis. Platinum resistance is a major cause of treatment failure. The aim of the study was to perform broad-scale drug target activation mapping of EOC to identify new druggable targets for personalized therapy. Methods: 72 ovarian primary lesions collected from chemo-naïve EOC patients were analyzed. Highly enriched tumor epithelial cells were isolated by laser capture microdissection, lysed and subjected to reverse phase protein microarray analysis for multiplexed protein pathway activation mapping. The activation/phosphorylation level of 156 key signaling proteins was analysed. Based on the disease-free interval to platinum therapy, 61 stage II-IV patients were segregated into platinum-resistant (12 months). One-way analysis of variance was used to detect significant differences among the three groups in the drug target activation profile. Results: Expression of the drug target PDGF Receptor β and activation of ErbB2/HER2 (Y1248) were significantly higher in patients with resistant disease compared to sensitive groups (respectively, p 0.0033 and p 0.0134), while the expression of Estrogen receptor α was greater in the supersensitive group (p 0.0295). Moreover, overall survival analysis including all stages revealed that the expression level of Cox2 is significantly higher in patients with shorter survival (HR: 2.48, p 0.0179). Conclusions: Functional drug target activation mapping revealed the unique signaling architecture of platinum-resistant EOC. If confirmed in independent study sets, these results suggest that the utilization of drugs targeting PDGF Receptor β and ErbB2/HER2 could be evaluated in platinum resistant EOC and/or in combination with platinum therapy in order to overcome acquired resistance. Finally, this study indicates that Cox2 may play an important role in aggressive EOC, and that the addition of Cox-inhibitors to standard of care could be rationally evaluated as a novel therapeutic regimen for ovarian cancer.