Study of the expression of integrin pathway's proteins as predictive markers of response to neoadjuvant chemotherapy in pretreatment biopsies of patients with high-grade osteosarcoma.

10076 Background: Up to now, chemosensitivity to neoadjuvant chemotherapy performed for patients with osteosarcoma is evaluated on the surgical resection by the evaluation of the percentage of necrotic cells. No predictive profile of chemotherapy has been described yet. Because we have previously shown that integrin pathway controls genotoxic-induced cell death and hypoxia via ILK, FAK and RhoB, we hypothesized that the expression of the proteins involved in this pathway in pre-treatment biopsies could be associated with sensitivity to chemotherapy in osteosarcoma. Methods: We studied by immunohistochemistry β1, β3, β5, integrins, ILK, FAK, GSK-3β, RhoB and Ang-2 expression in 36 osteosarcomas biopsies of patients obtained before treatment. All the patients were treated by the SFOP OS94 chemotherapy protocol and underwent wide conservative surgery. Response to preoperative chemotherapy was assessed on the surgical resection by the Rosen’s protocol. An immunoreactive score (IRS) was assessed, combining the...