Tislelizumab combined with Anti-GD2 antibody-based chemoimmunotherapy for pediatric relapsed/refractory high-risk neuroblastoma: a two-Case Report.

Neuroblastoma (NB) is one of the most common extracranial solid tumors in children. Patients with high-risk metastatic disease remain at substantial risk of relapse and have poor long-term outcomes. No standard salvage regimen has been established for relapsed/refractory (R/R) NB, and the role of immune checkpoint inhibitors in pediatric NB remains investigational. Here, we report two pediatric patients with R/R high-risk NB who received a tislelizumab-containing multi-agent regimen consisting of tislelizumab, an anti-GD2 monoclonal antibody, GM-CSF support, and sequential mICE/VIT chemotherapy. The anti-GD2 antibody, dinutuximab beta or naxitamab, was selected according to each patient's insurance coverage. Both patients tolerated treatment well, and no severe immune-related adverse events were observed during the reported follow-up period. After four cycles of combination therapy, Patient 1 showed marked regression of soft-tissue lesions and clearance of bone marrow involvement. Patient 2 achieved a complete response and remained disease-free during the 5-month follow-up period after treatment completion. However, the durability of this response remains uncertain because of the limited follow-up duration. These preliminary short-term observations suggest that this multi-agent regimen may be a feasible salvage approach for selected pediatric patients with R/R high-risk NB. However, the durability of these antitumor responses cannot be confirmed given the limited surveillance period. Notably, this retrospective two-case observation cannot distinguish the independent antitumor contribution of tislelizumab alone, as multiple therapeutic components were administered simultaneously without control groups to isolate single-agent efficacy. Larger prospective studies are warranted to further evaluate the efficacy and safety of this approach.