Augmentation of Therapy for Combined Loss of Heterozygosity 1p and 16q in Favorable Histology Wilms Tumor: A Children’s Oncology Group AREN0532 and AREN0533 Study Report

PURPOSE: In National Wilms Tumor Study 5 (NWTS-5), tumor-specific combined loss of heterozygosity of chromosomes 1p and 16q (LOH1p/16q) was associated with adverse outcomes in patients with favorable histology Wilms tumor. The AREN0533/AREN0532 studies assessed whether augmenting therapy improved event-free survival (EFS) for these patients. Patients with stage I/II disease received regimen DD4A (vincristine, dactinomycin and doxorubicin) but no radiation therapy. Patients with stage III/IV disease received regimen M (vincristine, dactinomycin, and doxorubicin alternating with cyclophosphamide and etoposide) and radiation therapy. METHODS: Patients were enrolled through the AREN03B2 Biology study between October 2006 and October 2013; all underwent central review of pathology, surgical reports, and imaging. Tumors were evaluated for LOH1p/16q by microsatellite testing. EFS and overall survival were compared using the log-rank test between NWTS-5 and current studies. RESULTS: = .001), with trends toward improved 4-year overall survival. The most common grade 3 or higher nonhematologic toxicities with regimen M were febrile neutropenia (39.2%) and infections (21.6%). CONCLUSION: Augmentation of therapy improved EFS for patients with favorable histology Wilms tumor and LOH1p/16q compared with the historical NWTS-5 comparison group, with an expected toxicity profile.