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This study was designed to determine the prognostic significance of multidrug resistance, mediated by P-glycoprotein (Pgp) expression, in Ewing sarcoma. The clinical and laboratory features, treatment protocol, and outcome of 75 patients with Ewing sarcoma or peripheral neuroectodermal tumor treated between 1972 and 1997 were reviewed. Pgp expression was tested with the monoclonal antibody JSB-1. Thirty-four (64%) of the 53 tissue samples from untreated patients stained positive for Pgp. Progression-free and overall survival were 44 and 59%, respectively, in patients with negative findings, and 28 and 41% in those with positive findings; neither difference was significant. Of the 12 relapsed patients, 6 (50%) expressed more Pgp after chemotherapy than at diagnosis and 4 (33%) expressed less. Within these subgroups, 5 out of 6 and 3 out of 4 died from the disease. No correlation was found between Pgp and known prognostic factors of Ewing tumors. Pgp expression is probably an intrinsic factor of Ewing tumors but has no correlation to prognosis. [ABSTRACT FROM AUTHOR]

Congenital dyserythropoietic anemia (CDA) type I is a rare inherited bone marrow disorder characterized by moderate to severe macrocytic anemia with pathognomonic cytopathology of nucleated red blood cells. Previous studies have suggested that serum erythropoietin levels in affected patients are lower than expected for the degree of anemia. An earlier study demonstrated a substantial increase in the number of CFU-E in CDA type I pattern on addition of exogenous erythropoietin. The present study reports on the response to recombinant human erythropoietin in 8 patients with CDA type I. Eighteen weeks of treatment, starting at 300 IU/kg twice a week and gradually increasing to 500 IU/kg three times a week, did not have a substantial effect on the mean hemoglobin value. These results indicate that recombinant human erythropoietin (rHuEpo) is not beneficial to patients with CDA type I and that the relatively low levels of serum erythropoietin probably play no major role in the pathogenesis of the disease. [ABSTRACT FROM AUTHOR]