Granulocyte colony-stimulating factor (G-CSF) mediated mobilization of leukemic cells in Philadelphia chromosome positive acute lymphoblastic leukemia expressing myeloid antigens (my+Ph+ALL).

The therapeutic benefit of G-CSF in the treatment of acute lymphoblastic leukemia has been well established. G-CSF has been used to shorten neutropenia induced by conventional dose cytotoxic chemotherapy and allogeneic bone marrow transplantation. Recently autologous peripheral blood progenitor cell transplantation has been explored to treat high-risk ALL. Several in vitro studies suggest that subpopulations of lymphoblasts express G-CSF receptors. Furthermore, enhanced growth of Ph+ ALL cells expressing myeloid antigens stimulated by G-CSF has been demonstrated in vitro. However, the clinical relevance of these findings has been questioned. We report a patient with my+Ph+ALL in whom the administration of G-CSF after high-dose Cytarabin and Mitoxantrone led to a significant mobilization of leukemic cells and contamination of the stem cell harvest during cytologic marrow remission.