Outcome of children with relapsed or refractory neuroblastoma: A meta-analysis of ITCC/SIOPEN European phase II clinical trials

Background: Few randomized trials have been conducted in children with relapsed/refractory neuroblastoma and data about outcomes including progression-free survival (PFS) in these patients are scarce. Procedure: A meta-analysis of three phase II studies of children with relapsed/refractory neuroblastoma conducted in Europe (temozolomide, topotecan-vincristine-doxorubicin and topotecan-temozolomide) was performed. Individual patient data with extended follow-up were collected from the trial databases after publication to describe trial outcomes (response rate, clinical benefit ratio, duration of treatment, PFS, and overall survival [OS]). Characteristics of subjects with relapsed/refractory neuroblastoma were compared. Results: Data from 71 children and adolescents with relapsed/refractory neuroblastoma were collected. Response definitions were not homogeneous in the three trials. Patients were on study for a median of 3.5 months (interquartile range [IQR] 1.9-6.2). Of those, 35.2% achieved a complete or partial response, 26.3% experienced a response after more than two cycles, and 23.9% received more than six cycles. Median PFS from study entry for all, refractory, and relapsed patients was 6.4 ± 1.0, 12.5 ± 6.8, and 5.7 ± 1.0 months, respectively (P = 0.006). Median OS from study entry for all, refractory, and relapsed patients was 16.1 ± 4.3, 27.9 ± 20.2, and 11.0 ± 1.6 months, respectively (P = 0.03). Conclusions: Baseline data for response rate, clinical benefit ratio, duration of treatment, PFS, and OS were provided. Two subpopulations (relapsed/refractory) were clearly distinct and should be included in the interpretation of all trials. These results should help informing the design of forthcoming studies in relapsed/refractory neuroblastoma.