Extended cycles of anti‑GD2 antibody dinutuximab beta treatment combined with chemotherapy in patients with relapsed or refractory neuroblastoma: A retrospective study

Relapsed or refractory high‑risk neuroblastoma (R/R HR‑NB) is associated with a poor prognosis. Although 5 cycles of anti‑GD2 immunotherapy with dinutuximab beta show efficacy, the regimen needs optimization. The present study evaluated the use of extended dinutuximab beta immunotherapy combined with chemotherapy in pediatric patients with R/R NB. In this single‑center retrospective study, children with a median age 5.1 years (range, 2.0‑11.1 years) with R/R HR‑NB who were treated with >5 cycles of dinutuximab beta (10 mg/m²/day for 10‑days per 35‑day cycle), granulocyte‑macrophage colony‑stimulating factor (GM‑CSF) and isotretinoin, plus chemotherapy, were included. The primary outcome of the study was objective response rate (ORR). Secondary outcomes included disease control rate, progression‑free survival (PFS), overall survival (OS) and safety. A total of 30 patients (24 refractory and 6 relapsed) received dinutuximab beta immunotherapy for a median of 7 cycles (range, 6‑12 cycles). Patients with residual disease showed the best ORR of 65%. ORR and complete response (CR) rates improved from 40 and 20%, respectively, at cycle 5/6, to 55 and 30%, respectively, with extended therapy. Notably, 38.5% of patients achieved the best response during cycles beyond the standard 5 cycles. The CR maintenance rate was 90% of patients without residual disease. The 2‑year PFS and OS rate were 83.2 and 94.7%, respectively, with higher outcomes in CR patients (2‑year PFS rate, 90.0%; 2‑year OS rate, 100.0%). Commonly observed grade ≥3 adverse events during the extended phase included infections (90%), neutropenia (86.7%), leukopenia (63.3%) and pain (53.3%), and were generally manageable. No immune‑related deaths occurred. Overall, cycles beyond the standard 5 cycles of dinutuximab beta with chemoimmunotherapy were effective and tolerable in pediatric patients with R/R HR‑NB, demonstrating improved response and survival outcomes.