Tandem hematopoietic stem cell transplantation in children with solid tumors in the Russian Federation: results of a retrospective multicenter study

Relevance. Despite the overall decline in the use of auto-HSCT, there remains a need for treatment intensification in pediatric patients with highrisk solid tumors. Tandem auto-HSCT represents a promising approach to improve therapeutic efficacy, but its toxicity and impact on long-term outcomes require further investigation, particularly in the Russian patient population. The aim of study – to evaluate the feasibility, toxicity, and long-term outcomes of tandem autologous hematopoietic stem cell transplantation (auto-HSCT) in children with high-risk solid malignant neoplasms in the Russian Federation. Materials and methods . This retrospective multicenter study included 108 (100 %) pediatric patients (median age – 2 years) with solid malignant neoplasms who underwent tandem high-dose chemotherapy with auto-HSCT at 9 centers in the Russian Federation (2004–2024). Main diagnoses included brain tumors – n = 66 (61.1 %), germ cell tumors – n = 25 (23 %), and neuroblastoma – n = 12 (11.1 %). Toxicity was assessed using CTCAE v5.0 criteria, and survival analysis was performed using the Kaplan–Meyer method. Results . The most common complications were febrile neutropenia (88.9 %) and oropharyngeal mucositis (87.1 %), with severe toxicities (Grade 3–4) being rare. The 3-year overall survival was 72.2 %, and event-free survival was 62.7 %. Conclusion . The study demonstrated that tandem auto-HSCT is a feasible procedure with manageable toxicity. These findings suggest the potential of tandem auto-HSCT for children with high-risk solid tumors, though further prospective studies with long-term outcome assessments are needed to define optimal indications.