Rational for targeted polytherapy in sarcoma: Get the genie out of the bottle.

e13519 Background: While a change of paradigm occurred in the last decade from chemotherapy to targeted therapy for cancer treatment, this work investigates the optimal combination of targeted agents with doxorubicin in sarcoma. Methods: Three sarcoma cell lines were studied RD18 (rhabdomyosarcoma), A204 (undifferentiated sarcoma) and TC 71 (Ewing's sarcoma) and exposed to increasing concentrations of vorinostat (HDAC inhibitor), 17-DMAG (Hsp90 inhibitor), abacavir (anti-telomerase) and sorafenib (tyrosine kinase inhibitor) alone, combined 2 by 2, then with doxorubicin. Viability was assessed by MTS assay. The Chou and Talalay combination index (CI) was used to determine additive (CI=1), synergistic (CI 1). Cell cycle analysis, measure of apoptosis by Annexin V and caspase 3/7 activity were studied using flow cytometry analysis and luminescent assay. Results: In monotherapy, the agents showed 30% to 90% decrease in viability but abacavir, which remained less active. Combinati...