[Bestatin treatment of patients with myelodysplastic syndromes].

Seven patients with myelodysplastic syndromes (M-DS) were treated with 30 mg Bestatin daily. Six of the patients (85.7%) responded. Clonogenic bone marrow cell culture studies in the patients have demonstrated intrinsic hemopoietic stem cell and progenitor cell abnormalities. After Bestatin treatment, these abnormalities involved in differentiation and maturation of hematopoietic progenitors were markedly improved and resulted in the improvement of hematological findings in responders. Addition to the culture system of Bestatin at a concentration of 0.01 microgram/ml and 1 microgram/ml enhanced CD4 positive T cell colony formation without enhancing CFU-GM and CFU-GEMM. These results suggest that the effects on hematopoiesis of Bestatin may be mediated by T cells, not by direct action of the drug.