Allogeneic Bone Marrow Transplants for Pediatric Severe Aplastic Anemia: Real-world Data comparing Matched Related and Unrelated Donors in a Developing Country. Retrospective study on behalf of the Pediatric Hematopoietic Stem Cell Transplant Working Group of the Brazilian Bone Marrow Transplantation Society (SBTMO) and the Brazil-Seattle Consortium (Gedeco).

In this study, we report on major MRD or URD BMT outcomes in pediatric patients with SAA in Brazil. This was a retrospective study, which included 106 patients ≤18 years old who received a first BMT for SAA. All patients received bone marrow as graft source from an MRD (n = 69) or a URD (n = 37). Conditioning regimen was non-myeloablative in 73.6% of cases, and GVHD prophylaxis comprised a calcineurin inhibitor plus methotrexate in 89.6% of patients. After a median follow-up of 4.5 years after BMT, 81 patients are alive, with a 4-year OS of 77% and no statistically significant difference between the MRD and URD groups (82% vs. 69%, respectively; P = .08). Grade III-IV aGVHD at 6 months and cGVHD at 2 years were observed in 8% and 14% of cases, respectively, and were not statistically different between the groups. Twenty-five (23%) patients died at a median of 2.9 months after BMT. Our study showed that 4-year OS after BMT was not statistically different between MRD and URD recipients. This study shows that the outcomes of pediatric patients transplanted for SAA with a URD in Brazil are approaching those of MRD transplants. In contrast, OS after MRD BMT was lower than we would expect based on previous reports. The wide range of preparatory regimens used by the study centers highlights the need for standardized protocols for these children. Our findings provide a benchmark for future studies focused on improving BMT outcomes in this setting in Brazil.

Late chimerical status after bone marrow transplantation in severe aplastic anemia according to two different preparatory regimens.

BACKGROUND: This study investigated the influence of two conditioning regimens on the chimerical status of 104 patients with acquired severe aplastic anemia. METHODS: Patients were monitored for at least 18 months after related bone marrow transplantation and reaching partial or complete hematologic recovery. Group I patients (n = 55) received 200 mg/kg cyclophosphamide alone and Group II (n = 49) received 120 mg/kg cyclophosphamide associated with 12 mg/kg busulfan. Patients were classified in three chimerism levels according to the percentage of donor cells in the peripheral blood. RESULTS: Chimerism ≤50% occurred in 36.4% of Group I and none of Group II; chimerism 51-90% was found in 20.0% of Group I and 10.2% of Group II; and chimerism >90% was found in 43.6% of Group I versus 89.8% of Group II. A significant association (p-value < 0.001) was found between conditioning type and chimerism levels. A higher number of infused cells was associated with higher levels of chimerism only in Group I (p-value = 0.013). Multivariate analysis showed that chimerism >90% is associated with the cyclophosphamide plus busulfan conditioning (p-value < 0.001) and higher number of infused cells (p-value = 0.009), suggesting that these factors are predictive of graft outcome. Regarding hematological recovery, higher chimerism levels were associated with higher neutrophil (p-value = 0.003) and platelet counts (p-value < 0.001) in Group I only. These results show that myeloablative conditioning favors full donor chimerism and non-myeloablative conditioning predisposes to mixed chimerism or autologous recovery of hematopoiesis. CONCLUSION: These data show that autologous recovery depends on the intensity of immunosuppression and that the immunosuppressive function of cyclophosphamide alone can induce this type of hematopoietic recovery.

Late chimerical status after bone marrow transplantation in severe aplastic anemia according to two different preparatory regimens

ABSTRACT Background: This study investigated the influence of two conditioning regimens on the chimerical status of 104 patients with acquired severe aplastic anemia. Methods: Patients were monitored for at least 18 months after related bone marrow transplantation and reaching partial or complete hematologic recovery. Group I patients (n = 55) received 200 mg/kg cyclophosphamide alone and Group II (n = 49) received 120 mg/kg cyclophosphamide associated with 12 mg/kg busulfan. Patients were classified in three chimerism levels according to the percentage of donor cells in the peripheral blood. Results: Chimerism ≤50% occurred in 36.4% of Group I and none of Group II; chimerism 51-90% was found in 20.0% of Group I and 10.2% of Group II; and chimerism >90% was found in 43.6% of Group I versus 89.8% of Group II. A significant association (p-value < 0.001) was found between conditioning type and chimerism levels. A higher number of infused cells was associated with higher levels of chimerism only in Group I (p-value = 0.013). Multivariate analysis showed that chimerism >90% is associated with the cyclophosphamide plus busulfan conditioning (p-value < 0.001) and higher number of infused cells (p-value = 0.009), suggesting that these factors are predictive of graft outcome. Regarding hematological recovery, higher chimerism levels were associated with higher neutrophil (p-value = 0.003) and platelet counts (p-value < 0.001) in Group I only. These results show that myeloablative conditioning favors full donor chimerism and non-myeloablative conditioning predisposes to mixed chimerism or autologous recovery of hematopoiesis. Conclusion: These data show that autologous recovery depends on the intensity of immunosuppression and that the immunosuppressive function of cyclophosphamide alone can induce this type of hematopoietic recovery.

Monosomy 7 in donor cell-derived leukemia after bone marrow transplantation for severe aplastic anemia: Report of a new case and review of the literature.

Monosomy 7 arises as a recurrent chromosome aberration in donor cell leukemia after hematopoietic stem cell transplantation. We report a new case of donor cell leukemia with monosomy 7 following HLA-identical allogenic bone marrow transplantation for severe aplastic anemia (SAA). The male patient received a bone marrow graft from his sister, and monosomy 7 was detected only in the XX donor cells, 34 months after transplantation. The patient's bone marrow microenvironment may have played a role in the leukemic transformation of the donor hematopoietic cells.

Allogeneic bone marrow transplantation for severe aplastic anemia patients with risk factors for poor prognosis: is fludarabine a requirement? / Transplante alogênico de medula óssea em portadores de anemia aplásica severa com fatores de mau prognóstico: é necessário fludarabina?

Hematopoietic progenitor cell transplantation from HLA-identical sibling donors cures 70-90 percent of Severe Aplastic Anemia (sAA) patients. Older age, heavy exposure to transfusions, immunosuppression treatment (IST) with a long interval from diagnosis to transplant and infection at procedure are associated with poor outcomes. We transplanted 18 patients with sAA and at least one risk factor (RF) for poor prognosis (age >35 years, >50 transfusions prior to transplant, unresponsiveness to previous IST and bacterial or fungal infection at transplant) from 2001 to 2005, using cyclophosphamide (CY - 5 patients) or busulfan plus CY (13 patients). Sixteen patients engrafted, two died with no engraftment, three patients had evidence of graft failure at days +67, +524 and +638 (two died and one was rescued with IST). Grade III/IV mucositis occurred in 39 percent but neither aGVHD nor cGVHD were observed. The Kaplan-Meier probability of survival was 75 percent at 2.14 years, with a trend favoring survival by number of RF (1 versus =2 RF) (P = 0.06). These results are comparable to recent data reported with fludarabine-based conditioning in patients with poor prognosis sAA. Due to the small sample size, prospective clinical trials with larger cohorts of patients are needed to confirm the real benefits of fludarabine-based conditioning, and also to define the best agent(s) to be associated with Fludarabine as preparative regimen for sAA patients with poor prognosis.

Transplante de medula óssea de doador irmão HLA-idêntico pode curar 70 por cento-90 por cento dos portadores de anemia aplásica severa (AAs). Pacientes mais idosos, muito transfundidos, longamente tratados com imunossupressão (IS) e com infecções ao tempo do transplante têm pior evolução. Nós transplantamos 18 pacientes com AAs e pelo menos um dos fatores associados a pior prognóstico (idade >35 anos, >50 transfusões antes do transplante, falta de resposta à imunossupressão prévia e infecção bacteriana ou fúngica ao transplante) de 2001 a 2005, com ciclofosfamida (Cy - 5 pacientes) ou bussulfan mais Cy (13 pacientes). Dezesseis pacientes apresentaram pega do enxerto, dois morreram sem pega, três tiveram rejeição aos dias +67, +524 e +638 (dois morreram e um foi resgatado com IS). Mucosite grau III/IV ocorreu em 39 por cento e não observamos DECH aguda ou crônica. A probabilidade de sobrevida pelo método de Kaplan-Meier foi de 75 por cento aos 2,14 anos, e uma tendência a melhor sobrevida foi encontrada entre os portadores de apenas um fator de risco ao transplante (P: .06). Estes resultados são comparáveis a recentes relatos de literatura envolvendo condicionamentos baseados em fludarabina para tratar pacientes com alto risco. Devido à pequena amostra analisada, estudos clínicos prospectivos com maior número de pacientes são necessários, visando comprovar o real benefício dos condicionamentos baseados em fludarabina, definir o melhor agente a ser a ela associado e assim obter o melhor condicionamento para portadores de AAs com fatores de mau prognóstico para o transplante.