Bone Marrow Transplantation in the Treatment of Children with Cancer: Current Status

Treatment of high-risk solid tumors of childhood with intensive therapy and autologous bone marrow transplantation

Autologous bone marrow transplantation (ABMT) allows delivery of intensive, marrow-ablative chemotherapy or chemoradiotherapy to children with high-risk solid tumors. Results from several studies of neuroblastoma suggest that outcome is improved by ABMT; however, relapses can occur months to years after complete clinical remission. Other high-risk tumors including peripheral neuroepithelioma, Ewing's sarcoma, rhabdomyosarcoma, Wilms' tumor, and brain tumors also appear to be responsive to intensive marrow-ablative therapy, although few studies have been reported. For tumors that can metastasize to marrow, a sensitive method is necessary for detecting tumor cell contamination. Immunocytologic analysis with monoclonal antibodies can identify one neuroblastoma cell per 10(5) normal marrow cells; this method also is applicable to other tumors with appropriate antibodies. Ex vivo removal (purging) of tumor cells decreases the probability of infusing tumorigenic cells with the ABMT. There is considerable experience in tumor detection and purging for neuroblastoma, but little has been done for other childhood solid tumors. Future investigations of ABMT will aim to further increase disease-free survival by intensifying induction and marrow-ablative regimens and by developing therapies to be given after ABMT that are directed at minimal residual disease. As pilot investigations mature, the efficacy of ABMT and conventional chemotherapy will be compared in multi-institution randomized studies.

Enhancement of murine bone marrow ablation by combining whole body hyperthermia with total body irradiation and cyclophosphamide

Bone marrow ablation using combined whole body hyperthermia (WBH), total body irradiation (TBI), and cyclophosphamide (Cy) was investigated in C3H f/Sed mice to demonstrate cytotoxic synergism between the three modalities. TBI was given on day 0. WBH treatment was for 1 hr at 41.8 degrees C, given in daily sessions for 1, 2 or 3 modalities. TBI was given on day 0. WBH treatment was for 1 hr at 41.8 degrees C, given in daily sessions for 1, 2 or 3 consecutive days following TBI. Total cyclophosphamide doses were 160 and 240 mg/kg given in 2 daily injections on days 1 and 2 following TBI. Polymorphonuclear leukocyte and lymphocyte numbers were determined by differential cell counts. The total peripheral blood cell counts were also determined. WBH alone, given in daily sessions for 3 days, did not reduce the total peripheral blood cell counts. However, when WBH was added to TBI (6.3 Gy) peripheral blood cellularity was reduced on day 2, but no significant heat/radiosensitization was evident after day 2. WBH (3 daily sessions) significantly reduced the peripheral blood cellularity and resulted in bone marrow ablation when it was combined with TBI and Cy. CY (160-240 mg/kg) combined with TBI (5.4 Gy) resulted in bone marrow ablation and subsequent death in 14-22% of mice treated; 60-100% of mice died from bone marrow ablation when WBH was added to TBI (5.4 Gy) and Cy (160-240 mg/kg). Femoral and vertebral tissue sections showed total loss of progenitor cells when WBH, TBI (5.4 Gy), and Cy (240 mg/kg) were combined whereas lessor treatment was associated with histologically verified reconstitution of progenitor cells inside the marrow cavities. These studies indicate that bone marrow ablation can be achieved when using WBH in combination with lower doses of TBI and Cy.