Abstract
Ewing's sarcoma (EwS) is the second most common bone cancer in children and adolescents. Current chemotherapy regimens are mainly ineffective in patients with relapsed disease and cause long-term effects in survivors. Therefore, we have developed a combinatorial therapy based on a novel drug candidate named ML111 that exhibits selective activity against EwS cells and synergizes with vincristine. To increase the aqueous solubility of hydrophobic ML111, polymeric nanoparticles (ML111-NP) were developed. In vitro data revealed that ML111-NP compromise viability of EwS cells without affecting non-malignant cells. Furthermore, ML111-NP exhibit strong synergistic effects in a combination with vincristine on EwS cells, while this drug pair exhibits antagonistic effects towards normal cells. Finally, animal studies validated that ML111-NP efficiently accumulate in orthotopic EwS xenografts after intravenous injection and provide superior therapeutic outcomes in a combination with vincristine without evident toxicity. These results support the potential of the ML111-based combinatorial therapy for EwS.