Allogeneic Hematopoietic Stem Cell Transplantation with Nonmyeloablative Conditioning in Patients with Myeloid Leukemias: Results of a Prospective Study of the Latin American Cooperative Onco Hematology Group (LACOHG).

Using a nonmyeloablative stem cell transplantation (NST) program previously shown to be effective in individuals receiving allografts in México, 29 patients with either acute myelogenous leukemia (AML, n = 12) or chronic myeloid leukemia (CML, n = 17) from the Latin American Cooperative Onco Hematology Group (LACOHG) were prospectively given allogeneic bone marrow allografts. Patients received a modified NST conditioning regimen consisting of oral busulphan 4 mg/kg on Days −6 and −5, IV cyclophosphamide 350 mg/m² on Days −4, −3, and −2, IV fludarabine 30 mg/m² on Days −4, −3, and −2, oral cyclosporine A 5 mg/kg twice daily starting on Day −1 (continuing until Day 180), and IV methotrexate 5 mg/m² on Days +1, +3, +5, and +11. Median patient age was 43 years (range, 10–63). All patients engrafted; median time to achieve an absolute neutrophil count >0.5 x 10⁹/L was 14 days (range, 0–21), whereas the median time to achieve a platelet count >20 x 10⁹/L was 12 days (range, 0–21). Follow-up periods ranged between 39 and 519 days (median, 249). In patients with CML, the median overall post-transplant survival has not been reached, whereas the 519-day overall survival was 88%, and the 100-day mortality was 0%. In patients with AML, the median overall post-transplant survival has not been reached, the 459-day overall survival was 66%, and the 100-day mortality was 8%. The results from this multicenter, multinational study complement and further support the efficacy of our NST preparative regimen. The initial experience obtained from individuals with CML and AML receiving allografts in 2 institutions in México has now been extended into other Latin American countries, and the results are acceptable.