PHILADELPHIA-CHROMOSOME-NEGATIVE PERIPHERAL-BLOOD STEM-CELLS CAN BE MOBILIZED IN THE EARLY PHASE OF RECOVERY AFTER A MYELOSUPPRESSIVE CHEMOTHERAPY IN PHILADELPHIA-CHROMOSOME-POSITIVE ACUTE LYMPHOBLASTIC-LEUKEMIA

Ten patients in first or second relapse with Philadelphia chromosome a cute lymphoblastic leukaemia, ineligible for allogeneic sibling marrow transplantation, were treated with an intensive chemotherapy regimen including idarubicin, intermediate-dose arabinosylcytosine, etoposide and G-CSF. Peripheral blood stem cells were collected by leukapheresis during initial early WBC recovery from chemotherapy-induced aplasia. In 5/10 patients all metaphases in leukapheresis products were found t o be Philadelphia-chromosome-negative and they have been used as autot ransplants after conditioning with TBI/etoposide/cyclophosphamide (or idarubicin) and G-CSF. All five patients showed sustained engraftment and one of them is alive and well Philadelphia-chromosome-negative 18 months after transplant. These preliminary results suggest that it is possible to recover Philadelphia-chromosome-negative blood stem cells after intensive chemotherapy, even in advanced patients, and to perfor m autografting with these cells.