Maintaining outstanding outcomes using response- and biology-based therapy for intermediate-risk neuroblastoma: A report from the Children’s Oncology Group study ANBL0531.

10006 Background: This Phase III prospective reduction of therapy study used tumor biologic features to determine the minimal treatment needed to achieve excellent outcomes in patients with intermediate risk (IR) neuroblastoma (NB). Methods: Between 10/8/2007 and 6/30/2011, 464 patients enrolled; 401 had evaluable IR NB. Eligibility included newly diagnosed single copy MYCN NB and: age <12 years with stage 2A/B <50% resected or stage 3 with favorable biology, age <365 days with stage 3 or 4, and all patients <365 days with stage 4S, including those too ill to undergo biopsy. Toddlers age 365-<547 days with favorable biology stage 4 NB and age 365-<547 days with stage 3 and unfavorable histology (UH) received isotretinoin in addition to chemotherapy. Risk-stratification and therapy assignment utilized age, INSS stage, INPC, MYCN, and tumor ploidy. Therapy reduction was prescribed for tumors without loss of heterozygosity (LOH) at 1p36 and/or 11q23. Therapy included 2-8 courses of chemotherapy +/- surgery. ...