Chemoimmunotherapy Combined With Autologous NK Cell Therapy for Pediatric Patients With Refractory and Relapsed High-Risk Neuroblastoma and Ganglioneuroblastoma

Inclusion Criteria: * Signed voluntary informed consent to participate in the clinical trial * Histologically verified diagnosis of neuroblastoma or ganglioneuroblastoma * Patients stratified to the high-risk group according to the criteria of the German Society of Pediatric Oncology and Hematology (GPOH) - NB 2004, aged from 18 months to 18 years, and meeting the following conditions: 1. Arm A: Refractory disease - patients who have completed the induction phase of therapy (6 cycles of N5/N6) with a poor response to therapy (MR, SD), with the exception of PD 2. Arm В: Relapsed/progressive disease - patients who develop any new tumor lesions (after having previously achieved СR), or any new tumor lesion; an increase of \>25% in any previously existing measurable lesion; or newly detected bone marrow involvement by NB cells in cases where the bone marrow had previously been free of involvement * Performance status ≥ 70% (Lansky or Karnofsky scale) at the time of determining the indication for chemoimmunotherapy combined with NK cell therapy. * Expected life expectancy ≥ 12 weeks. * No signs of drug-induced neuropathy or neuropathic pain. * Adequate liver function: alanine aminotransferase (ALT) / aspartate aminotransferase (AST) activity \< 5 × upper limit of normal (ULN). * Adequate renal function: creatinine clearance or glomerular filtration rate (GFR) \> 60 mL/min/1.73 m². * Coagulation parameters: prothrombin index (PTI) 70-120%; activated partial thromboplastin time (APTT) \< 36 seconds. * No clinical signs of heart failure; left ventricular ejection fraction (LVEF) ≥ 55%. * Adequate respiratory function (oxygen saturation by pulse oximetry \> 94% on room air, no dyspnea at rest), and no pathological findings on chest X-ray. * Completion of comprehensive assessment to evaluate the extent of the tumor process. Exclusion Criteria: * Lack of a signed voluntary informed consent form for participation in the clinical study. * Absence of comprehensive pre-treatment assessment results at the time of initiation of specific therapy. * Patients with NBL or ganglioneuroblastoma stratified to low or intermediate-risk group * Good response (PR, VGPR, CR) or PD at the end of the induction phase of therapy (applicable only to patients receiving therapy within the framework of the intensified induction phase). * Progressive or relapsed disease with central nervous system involvement and/or leptomeningeal involvement. * History of acute intolerance reactions to the main chemotherapeutic and immunobiological agents and supportive care drugs used in this clinical trial protocol. * Presence of complications of the underlying disease and comorbidities that preclude treatment within this protocol, including severe type I hypersensitivity reactions in the medical history. * Requirement for concomitant medications with known cross pharmacodynamic interactions with the drugs used in this clinical trial protocol. * Presence of ultrasonographic signs of heart failure (LVEF ≤ 55%), clinical and laboratory signs of chronic kidney disease of stage ≥ III, or kidney injury of grade I, F or L according to the standardized RIFLE criteria for acute kidney injury (an acronym for "risk, injury, failure, loss, end-stage"). * Pregnancy, due to the high teratogenicity and toxicity of the drugs used in this clinical trial protocol. Female patients of childbearing potential are required to undergo pregnancy testing. * Mental illness of the patient or legal guardians that makes it impossible to understand the nature of the study and compromises adherence to medical prescriptions and sanitary-hygienic requirements.