High-dose cyclophosphamide therapy without bone marrow transplantation produces durable treatment-free remission in severe aplastic anemia. This approach deserves further study in patients with severe aplastic anemia who are not suitable candidates for allogeneic bone marrow transplantation.

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Cell surface phenotypes of 113 B lineage acute lymphocytic leukemia (ALL) cases, defined by the presence of HLA-DR and at least one B-cell- specific antigen (either CD19, CD20, or CD22), were compared with antigen-defined stages of normal B lymphocyte development. The cases were first evaluated for expression of HLA-DR, CD19, CD34, CD10, CD20, and CD22 by indirect one-color immunofluorescence. Pairwise comparisons of cell surface marker expression were performed for each leukemic sample: no correlations were observed for paired antigen expression on the leukemic samples using antigens expressed either early or late during normal B lymphoid development. Complete immunophenotypes of the cases were then compared with normal B-cell developmental stages. Sixteen different complete immunophenotypes were observed on the leukemias that were not found in normal marrow; at least 78% of the cases demonstrated such “asynchronous” combinations of B lymphoid- associated differentiation antigens. Several samples were subsequently studied by two-color immunofluorescence, and the presence of doubly labeled cells with “asynchronous” antigen combinations was confirmed. These results indicate that the majority of B lineage leukemias exhibit “developmental asynchrony,” as compared with normal marrow B cells. The data further suggest that ALL cases do not accurately represent cells arrested at the stage where the leukemogenic event occurred. Rather, ALL appears to be a disease in which there may be maturation of leukemic blasts; but this maturation is “asynchronous” when compared with the normal developmental process.

Since 1980, adults with acute myelocytic leukemia (AML) have been treated on two clinical studies using intensive timed sequential therapy. All patients ages 16 to 80, including those with secondary AML (SAML) and those with AML preceded by a hematologic disorder (AHD), were treated, regardless of medical complications at the time of diagnosis. The first study combined high doses of cytarabine (ara-C, AC) and daunorubicin (DRN, D) in sequence (Ac2-D-Ac) and resulted in a complete remission rate of 55%. A group of these patients selected by functional status was able to receive a second course of therapy in remission, which resulted in a disease-free survival (DFS) of greater than 40% at 7 years. Because of toxicity in that study, 114 patients were entered on a second trial initiated 4 years ago, using a less aggressive first course, with amsacrine, to achieve a stable remission (Ac2-D-Amsa). This first treatment was followed by a more intensive second course (Ac6-D-Ac). With this two-step approach, a higher complete remission (CR) rate (76% for de novo AML and 54% for SAML-AHD) was achieved, and more patients were able to receive the second course of therapy. At the current median follow-up of 26 months, the median duration of DFS and overall survival are 11 and 14 months for patients with de novo AML. Age less than or equal to 55 is the most significant prognostic factor for both prolonged DFS and overall survival, with median durations of 17 and 18 months, respectively, for these younger patients. Patients with SAML-AHD remain relatively refractory to treatment despite aggressive chemotherapy, with median durations of DFS and overall survival of 9 months and 5 months, respectively.

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