ENGRAFTMENT AFTER MYELOABLATIVE DOSES OF I-131 METAIODOBENZYLGUANIDINE FOLLOWED BY AUTOLOGOUS BONE-MARROW TRANSPLANTATION FOR TREATMENT OF REFRACTORY NEUROBLASTOMA

Background. Metaiodobenzylguanidine (MIBG) labeled with I-131 has been used for targeted radiotherapy of neural crest tumors, with bone marr ow suppression being the primary dose-limiting toxicity. The purpose o f this study was to examine the engraftment and toxicity of higher mye loablative doses of I-131-MIBG with autologous bone marrow support. Pr ocedure. Twelve patients with refractory neuroblastoma were given infu sions of their autologous, cryopreserved bone marrow following 1-4 dos es of I-131-MIBG. The median cumulative administered activity per kilo gram of I-131-MIBG was 18.0 mCi/kg (range 14.1-50.2 mCi/kg), the media n total activity was 594 mCi (range 195-1,353 mCi), and the median cum ulative whole body irradiation from I-131-MIBG was 426 cGy (range 256- 800 coy). A median of 2.5 x 10(8) viable cells/kg (range 0.9-4.7 x 10( 8) cells/kg) was given in the bone marrow infusion. Results, All 12 pa tients achieved an absolute neutrophil count >500/mu l with a median o f 19 days, but only 5/11 evaluable patients achieved red cell transfus ion independence, in a median of 44 days; and 4/11 evaluable patients achieved platelet count >20,000/mu l without transfusion, in a median of 27 days. Conclusions. Autologous bone marrow transplantation may al low complete hematopoietic reconstitution following ablative I-131-MIB G radiotherapy in patients with neuroblastoma. Risk factors for lack o f red cell or platelet recovery include extensive prior chemotherapy, progressive disease at the time of transplant, especially in the bone marrow, and a history of prior myeloablative therapy with stem cell su pport. (C) 1998 Wiley-Liss, Inc.