Clinical and biological characteristics of neuroblastoma in adolescents and young adults. Case study and literature review

Introduction.  Neuroblastoma (NB) is the most common extracranial solid tumor in infants, but it is more rarely found in older children. Only 1–2 % of cases are registered in adolescents and young adults. The long-term prognosis in these patients is highly unfavorable due to indolent clinical course formed by peculiar biological characteristics of tumors. We publish a case study of 11 patients with NB older than 10 years at the time of diagnosis. Case series description.  In 2008 to 2020 a total of 11 adolescent and young adults patients with median age of 14 (10–28) years were treated in Raisa Gorbacheva Memorial Research Institute of Children Oncology, Hematology and Transplantation, First Pavlov State Medical University of St. Petersburg. Seven of 11 patients had mediastinal neuroblastoma, in other cases the primary lesion was abdominal (n = 2), pelvic (n = 1), and in one case no primary lesion was defined. Ten of 11 patients had primary disseminated disease with lymph nodes (n = 5), bone (n = 5), bone marrow (n = 3), or hepatic (n = 1) metastases. Tumor morphology and cytogenetics were assessed in all patients, in 4 cases additional targeted sequencing of potentially pathogenic genes was performed. All patients received chemotherapy and local control measures according to high-risk NB guidelines, in 7 of 11 cases additional chemotherapy regimens were used. Seven of 11 patients also received dose-intensive consolidation with autologous hemopoietic stem cell transplantation (auto-HSCT). In case of primary resistance MIBG-therapy, targeted or immunotherapy were used. In 6 cases tumor morphology corresponded to undifferentiated neuroblastoma, in 5 cases to ganglioneuroblastoma. Although all cases were high-risk, they mostly lacked high-risk biological features seen in younger patients. None had MYCN amplification, the cytogenetic assay yielded the following aberrations: +2 (n = 2), del1p (n = 1), g17q (n = 1). All patients, in whom the targeted sequencing was performed had pathogenic mutations: ATRX (in two patients 19 and 28 years at diagnosis), TP53 and PIK3CA, FBXW7. Nine of 11 patients had primary resistant disease, in 7 cases response was obtained on second or subsequent therapy lines. Two patients responded two chemoand targeted therapy combination, in 3 cases monoor combined immunotherapy yielded prolonged (16–32 months) response. Six of 7 auto-HSCT recipients developed a relapse. 6 out of 11 patients are currently alive. In 2 cases, a complete response is maintained according to scintigraphy with  123 I-MIBG, lasting 86 and 14 months after completion of therapy. Conclusions.  NB is biologically different in adolescents and young adults. It is characterized by indolent clinical course with very high risk of late relapse. As most patients in this group are chemoresistant, the standard dose-intensive tactics may be less effective and perhaps more attention should be given to targeted and immunotherapy-based approaches.