10015 Background: Data from a previous COG study (ARST0431) showed an early FFS improvement but no long-term survival benefit with intensive interval-compressed chemotherapy in metastatic RMS. ARST08P1 aimed to determine the feasibility of adding cixutumumab (insulin-like growth factor-1 receptor (IGF-1R) monoclonal antibody) or temozolomide to an intensive chemotherapy backbone. Methods: A series of non-randomized single-arm pilot studies were conducted. After determining feasibility, pilots were expanded to assess efficacy. Eligible patients were < 50yrs with metastatic RMS. Backbone therapy consisted of blocks of vincristine/irinotecan (weeks 1-6, 20-25, 47-51), interval-compressed vincristine/doxorubicin/cyclophosphamide alternating with ifosfamide/etoposide (weeks 7-9 and 26-34), and vincristine/actinomycin-D/cyclophosphamide (weeks 38-46). In Pilot 1, patients received cixutumumab (3, 6, or 9 mg/kg) IV once weekly throughout therapy. In Pilot 2, patients received oral temozolomide (100mg/m2) daily x...