Aplastic anaemia following successful treatment of malignant epithelial tumours with radiation and/or chemotherapy

Hematopoietic recovery following chemotherapy is improved by BADGE-induced inhibition of adipogenesis

This study was designed to investigate the role of increased adipocytes in the bone marrow (BM) niche induced by high-dose chemotherapy in hematopoietic recovery. Arabinosylcytosine (Ara-C) was administered to adult C57BL/6J mice to induce adipogenesis in the BM. We investigated the effects of adipogenesis on hematopoietic recovery following chemotherapy, using the peroxisome proliferator-activated receptor gamma inhibitor, bisphenol A diglycidyl ether (BADGE). Adipocyte hyperplasia could be induced by Ara-C treatment in BM and inhibited by BADGE. The accelerated recovery of leukocyte counts, increased colony forming units, and a higher proportion of Ki67(+)CD45(+) BM cells and Ki67(+)Lin(-)Sca1(+)c-kit(+) hematopoietic stem cells were observed in the long bone marrow of adipocyte-inhibited mice, as well as an increase in the number of CD45(+) BM cells in the tail fatty marrow compared to controls. Adipocytes participated in creating a distinctive niche for hematopoietic cells. In addition, lower expression of stromal cell-derived factor-1α and hypoxia-inducible factor-1 alpha were detected in the BADGE-treated group. These results indicate that hematopoietic recovery is improved following chemotherapy in adipogenesis-inhibited mice. In addition, adipocytes may create an individual niche that affects the proliferation and migration of hematopoietic cells in vitro and in vivo.

Treatment of adults with severe aplastic anemia: primary therapy with antithymocyte globulin (ATG) and rescue of ATG failures with bone marrow transplantation

PURPOSE

To evaluate a policy of immunosuppression with antithymocyte globulin (ATG) as primary therapy for adults with severe aplastic anemia (SAA) regardless of the availability of an HLA-identical bone marrow donor.

PATIENTS AND METHODS

Thirty-one consecutive adults with SAA who satisfied the age criteria for allogeneic bone marrow transplantation (BMT) (age less than 51 years) were treated with ATG 20 mg/kg/day for 10 days along with high-dose corticosteroids. Patients with an HLA-identical donor received a transplant if they did not respond to ATG or if they developed life-threatening complications during or soon after ATG administration. Eight patients with no response to ATG were also treated with oral cyclosporine 12.5 mg/kg/day.

RESULTS

Eleven patients had a complete and five a partial response to ATG; two patients improved with cyclosporine treatment, resulting in an overall response rate of 58% to immunosuppression. Nine of 14 patients with donors received a BMT: seven because they did not respond to ATG and two because of serious infections. Seven grafts were obtained from related and two from unrelated donors. There was no significant difference in survival between those with and without a related HLA-identical donor (log-rank p value = 0.969). At a median follow-up of 58 months, 26 of 31 are alive with an actuarial survival of 80% at 5 years. Two patients died of infection, two died from complications of BMT, and one remains transfusion-dependent. One patient died of refractory leukemia at 30 months; one patient relapsed with hypoplasia 95 months after initial therapy with ATG. He showed a complete response to treatment with cyclosporine. No other late hematologic events have occurred.

CONCLUSIONS

This treatment approach resulted in the restoration of hematopoiesis and independence from transfusion in 80% of patients with SAA entered into the study. The efficacy of allogeneic BMT in salvaging cases in which ATG failed does not appear to be compromised. Follow-up for the development of clonal hematologic disorders remains an important part of this treatment policy.