In vivo purging of bone marrow in children with poor-risk neuroblastoma for marrow collection and autologous bone marrow transplantation.

ABSTRACT

PURPOSE: To evaluate the following prospectively in poor-risk neuroblastoma (NBL) patients (1) the feasibility and efficacy of in vivo purging of bone marrow; and (2) the outcome after autologous bone marrow transplantation (ABMT) when immunologically tumor-free, unpurged autografts were used. PATIENTS AND METHODS: Twenty-three children with poor-risk NBL were evaluated during induction chemotherapy by repeat bone marrow examinations, including aspirate, biopsy, and an immunofluorescence method using the anti-GD2 monoclonal antibody 3A7. Nineteen patients completed the program with surgery with or without local irradiation followed by ABMT. RESULTS: Autologous bone marrow grafts, both immunologically and cytologically clean, were obtained and used in 19 of 23 children. The overall 4-year disease-free survival of the 19 grafted children was 53%, with a toxic death rate of 16% and a posttransplant relapse rate of 37%. According to the in vivo purging efficacy of the 18 children with initial marrow disease, the following three groups were formed patients with (1) perfect in vivo purging (n = 5); (2) eventually successful in vivo purging (n = 8); and (3) unsuccesful in vivo purging (n = 5). The 4-year DFS was 100%, 67%, and 0%, respectively (P < 0.001). The five patients with unsuccessful in vivo purging failed because of resistant/progressive bulky disease. CONCLUSION: In patients with poor-risk NBL, in vivo purging of bone marrow by conventional chemotherapy is feasible, can be monitored, and the purging efficacy during the first 3 months after diagnosis is a strong prognostic factor reflecting tumor responsiveness to therapy. Autografting with immunologically clean, unpurged marrows gives a DFS well comparable to previous studies using ex vivo purging.