G-CSF-mobilized peripheral blood progenitor cells for allogeneic transplantation of resistant or relapsing acute leukemias.

ABSTRACT

Peripheral blood progenitor cells (PBPC) were mobilized by G-CSF in normal HLA identical siblings and used for allogeneic transplantation in eight patients with refractory or relapsed acute leukemias. G-CSF administration was well tolerated and no significant side-effects were registered. The number of circulating WBC peaked at day 5 after G-CSF (range 22.6-74.6 x 10(9)/l) with a median of 65 CD34+ cells/microl (38-155). As a consequence of leukaphereses, platelets progressively decreased, reaching the nadir after the last procedure (84-205 x 10(9)/l). A mean of two aphereses (1-3) were performed between day +4 and +7 during which 10 liters of blood were processed each time by a cell separator. Conditioning regimens were fractionated total body irradiation (FTBI) plus either HDAra-C (2 g/m2 x 2/day for 6 days) (n=5) or melphalan (110 mg/m2) (n= 1) and busulfan (4 mg/kg/day for 4 days) and melphalan (110 mg/m2) in two patients relapsed after a previous FTBI-based allogeneic or autologous BMT. At transplantation, a median of 6.9 x 10(6) CD34+ cells/kg (4.2-16.5) and 279 x 10(6) CD3+ cells/kg (161-786) were infused. Engraftment of both neutrophils (> or v=1.5 x 10(9)/l) and platelets (> or v=20 x 10(9)/l) was observed in all patients after a median time of 18 days (range 11-20 and 10-26, respectively). The evaluation of engraftment after transplantation was accomplished by PCR analysis of four hypervariable genomic regions (VNTR) (ApoB, ApoC2, YNZ-22, and MCT 118) which allowed to demonstrate the condition of donor chimaera in all patients after transplantation. As far as the clinical outcome, two patients died of interstitial pneumonitis at day +243 and +69 and two patients died at day +62 and +152 of pulmonary aspergillosis. Four patients remain alive in remission between day +88 and +287 with grade 0-l GVHD. Allogeneic PBPC transplantation is associated with a complete hematologic recovery and despite the infusion of a large amount of mature CD3+ lymphocytes, apparently acute GVHD is not worse than expected after transplantation of bone marrow progenitors.