Safety, Tolerability, and Preliminary Efficacy of [211At]MABG in Patients With Relapsed or Refractory Neuroblastoma

Inclusion Criteria: 1. Patients diagnosed with MIBG avid lesions, high-risk neuroblastoma per the Revised International Neuroblastoma Response Criteria (Revised INRC), with refractory, relapsed, or progressive disease. 2. All measurable soft tissue lesions must be MIBG-avid. 3. Age ≥ 1 year at enrollment. 4. Lansky performance status ≥ 50%. 5. Adequate organ function and hematologic parameters. Exclusion Criteria: 1. Antibody-based immunotherapy within fewer than 5 half-lives or 30 days (whichever is shorter), or who have not yet recovered from adverse effects of any biologic therapy. 2. Treatment with \[¹³¹I\]MIBG or Lu177 targeted radionuclide therapy less than 3 months of last administration. 3. Autologous stem cell transplant \<12 weeks, or Allogeneic stem cell transplant \<4 months (patients \>4 months post-transplant must be free of active GVHD). 4. Radiotherapy within 2 weeks prior to the first study dose (However, patients with a single-site irradiation that remains MIBG avid may be enrolled.) or extensive-field radiotherapy (e.g., craniospinal, whole abdomen, whole lung, or \>50% of bone marrow area) within 12 weeks prior to the first study dose. 5. Renal Insufficiency. 6. Active Infections.