Single Arm Romiplostim to Prevent CIT

This is a single-arm, multi-center clinical trial to assess the efficacy of romiplostim as a supportive care measure in patients with a new diagnosis of Ewing sarcoma receiving interval-compressed chemotherapy. Patients will be enrolled and started on romiplostim as early as cycle 1 day 1 of their chemotherapy, but no later than 2 weeks from the start of the 5th cycle. If their platelet count is \< 200,000/mm3, patients will start romiplostim based on their weight. Dose escalation of romiplostim may occur weekly if platelet count is \< 200,000/mm3. Once maximum dose of romiplostim is reached, this dose level will be maintained every 7 days (+/- 2 days).