Risk stratification including FOXO1 fusion status (FOXO1) in patients with rhabdomyosarcoma (RMS) treated on six recent frontline trials: A report from the Children's Oncology Group (COG).

Abstract

10528 Background: Clinical risk factors associated with outcome in children with either localized or metastatic RMS were identified by Meza et al. (2006) and Oberlin et al. (2008). We re-examined risk stratification by adding FOXO1 to traditional clinical prognostic factors in children with localized or metastatic RMS in a large cohort from COG frontline clinical trials. Methods: Data from six COG clinical trials (D9602, D9802, D9803, ARST0331, ARTS0431, ARST0531) accruing previously untreated patients with RMS from 1997 to 2013 yielded 1,853 eligible patients (two studies each for low, intermediate and high risk patients). Survival tree regression for event-free survival (EFS) and overall survival (OS) was conducted to determine prognostic impact of risk factors. Recursively, the factor most strongly associated with outcome was selected for branching and split using a goodness of fit measure. Factors included were age, FOXO1, group, histology, nodal status, number of metastatic sites, primary site, sex, tumor size, and presence of metastases in bone/bone marrow, soft tissue, effusions, lung, distant lymph nodes, and other sites. Results: 5-year overall EFS and OS was 0.67 (SE, 0.01) and 0.77 (SE, 0.01), respectively. Survival trees for EFS and OS found localized versus metastatic at the first split and included FOXO1 as a significant risk factor. Conclusions: FOXO1 improves risk stratification of patients with localized RMS, although histology and pattern of metastases are more predictive for patients with metastatic RMS. Our findings support incorporation of FOXO1 in risk stratified clinical trials. [Table: see text]