Leukemia
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To evaluate diagnostic criteria, disease characteristics, and the clinical course of pediatric myelodysplastic syndrome (MDS), we reviewed 327 consecutive cases diagnosed with de novo acute myeloid leukemia (AML) or MDS at St Jude Children's Research Hospital between February 1980 and January 1993. Among 49 cases with <30% marrow blasts (consistent with FAB criteria and common diagnostic practice for MDS), eight had karyotypes associated with de novo AML (four with t(8;21)(q22;q22) and one each with inv(16)(p13q22), t(11;17)(q23;q21), t(9;11)(p22;q13), and i(1)(ql0)). We termed these cases AML with a low blast count (AML-LBC) and compared their clinical and morphologic features with those of the remaining 41 cases. ⋯ We conclude that the 30% blast threshold is ineffective for separation of AML and MDS in pediatric patients, and that genetic data should be included in this decision process. AML-LBC, defined by <30% blasts in bone marrow and cyto- (or molecular) genetic abnormalities associated with de novo AML, and characterized by absent or mild marrow dysplasia, is biologically and clinically distinct from MDS and should be treated as de novo AML. Outcome in pediatric MDS remains poor, and new treatment strategies are needed for these patients.
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Comparative Study
Co-expression of several molecular mechanisms of multidrug resistance and their significance for paclitaxel cytotoxicity in human AML HL-60 cells.
Overexpression of P-glycoprotein (PGP), MRP or LRP has been characterized as the 'proximal', while overexpression of the anti-apoptosis Bcl-2 or Bcl-xL relative to the pro-apoptosis Bax protein has been recognized as the 'distal' mechanism of multidrug resistance in human AML cells. In the present studies, we examined whether these mechanisms can co-exist in human AML HL-60 cells. We also determined how these mechanisms would affect the accumulation and cytotoxicity of a PGP substrate, such as Taxol (paclitaxel). ⋯ These results confirm the possibility of co-expression of multiple mechanisms of multidrug resistance in human leukemic cells which had been selected by exposure to a single drug. The results also indicate that MRP overexpression does not confer resistance against paclitaxel. In addition, these findings suggest that, for Bcl-2 and Bcl-xL, enforced overexpression to high levels is necessary to induce paclitaxel resistance in HL-60 cells.
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Review Case Reports
Sweet's syndrome involoving the musculoskeletal system during treatment of promyelocytic leukemia with all-trans retinoic acid.
Induction therapy of promyelocytic leukemia with all-trans retinoic acid is a standard therapy despite significant side-effects. The most important, the "retinoic acid syndrome", consists of a hyperinflammatory reaction with capillary leakage (edema, pleural, and pericardial effusion), infiltration of myeloid cells into internal organs and systemic signs of inflammation. We describe here two cases of another hyperinflammatory reaction during all-trans retinoic acid therapy, the Sweet's syndrome, consisting of infiltrates of the skin and internal organs by neutrophilic granulocytes. ⋯ Treatment with glucocorticoids led to resolution of the syndrome within 48 h. Three other cases of all-trans retinoic acid-associated Sweet's syndrome without involvement of internal organs, prominent on our cases, were published previously. Recognition of ATRA-associated Sweet's syndrome is of practical importance.
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Clinical Trial
Homoharringtonine in patients with myelodysplastic syndrome (MDS) and MDS evolving to acute myeloid leukemia.
Current anti-leukemic chemotherapy in patients with myelodysplastic syndromes (MDS) and MDS evolving to acute myeloid leukemia (AML) is associated with low response rates and high treatment-related toxicity. Homoharringtonine (HHT) is a novel cephalotaxime alkaloid with reported efficacy in relapsed and de novo AML and more recently, chronic myeloid leukemia. Although its mechanism(s) of action is not completely understood, in vitro studies have demonstrated both cytotoxic and differentiating activity in leukemic cells, as well as intra-cellular changes suggestive of apoptotic cell death. ⋯ Extramedullary toxicity was mild and consisted of hypo-tension, fluid retention, hypoglycemia, diarrhea, nausea and vomiting. HHT given in this dose and schedule demonstrated limited activity in MDS and MDS/AML and was associated with prolonged pancytopenia and marrow hypoplasia in many patients. Administration of HHT at a lower dose or in combination with hematopoietic growth factors may lead to better results, but treatment with HHT as single agent at this dose and schedule is not currently recommended for these patients.
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Comparative Study
Refractory cytopenia with multilineage dysplasia: further characterization of an 'unclassifiable' myelodysplastic syndrome.
Myelodysplastic syndromes (MDS) characterized by multilineage cytopenias and dysplasia but lacking an increase in blasts, with no Auer rods or monocytosis, do not exactly fit any of the categories of the French-American-British (FAB) classification of MDS and are often diagnosed as refractory anemia (RA), refractory anemia with ringed sideroblasts (RARS), or 'unclassifiable' MDS. It has been suggested that these 'unclassifiable' cases form a distinct subset with a clinical behavior more like that of refractory anemia with excess of blasts (RAEB) than that of RA or RARS, but few studies have been undertaken that characterize this group. We compared the clinical, hematologic, morphologic and cytogenetic features of 18 such patients - for whose disease we propose the designation 'refractory cytopenia with multilineage dysplasia' (RCMD) - to those of 42 patients meeting the FAB criteria for RA or RARS (14 patients) and RAEB (28 patients). ⋯ Abnormalities of chromosomes 5 and 7 (excluding del(5q) as an isolated finding) or complex aberrations were seen only in RCMD and RAEB. in RCMD, the median survival was 24 months, with a 4-year survival rate of48 +/- 13%, intermediate between the findings in RA/RARS (107 months and 77 +/- 12%, respectively) and RAEB (18 months and 27 +/- 9%, respectively). Our data indicate that RCMD is a distinct subset of MDS, with an unfavorable clinical outcome. The designation 'refractory cytopenia with multilineage dysplasia' emphasizes the differences between such cases and the primarily dyserythropoietic, indolent subgroups of MDS, such as RA or RARS.