Interferon-alpha protects Philadelphia-negative progenitors from exhaustion in chronic myeloid leukemia patients with cytogenetic response

Normal immature hematopoietic progenitors are relatively well preserved in most patients newly diagnosed with chronic myeloid leukemia, but tend to decline rapidly with time. Such exhaustion could reflect a suppressive effect of the Philadelphia positive clone expansion and/or be induced by Interferon-alpha treatment. A total of 51 CML patients were classified into three groups. Newly diagnosed untreated patients were group A (n=30). Of the 21 treated individuals with Interferon-alpha, for at least 12 months, 15 showed no cytogenetic response (group B) while six showed persisting major/complete response (group C). Patients belonging to groups A and B were mobilized with chemotherapy plus G-CSF while patients of group C received a short course of G-CSF only. Patients responding to IFN-alpha (group C) showed comparable numbers of bone marrow Ph- long-term culture initiating cells to those of newly diagnosed individuals (group A): 8.5 (