USE OF RECOMBINANT HUMAN GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR IN PATIENTS WITH LYMPHOID MALIGNANCIES TRANSPLANTED WITH UNPURGED OR ADJUSTED-DOSE MAFOSFAMIDE-PURGED AUTOLOGOUS MARROW

The neutropenia-related morbidity and mortality occurring after autologous bone marrow transplantation (ABMT) is increased by marrow purging procedures. While phase I through III clinical trials showed the enhancing activity of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on neutrophil recovery after ABMT with unpurged marrow, controversial results have been reported when purged marrow was used. Therefore, it was the aim of the present study to evaluate the efficacy of rhGM-CSF administration in a group of patients (n = 15) with lymphoid malignancies transplanted in complete remission with mafosfamide-purged (n = 10) or unpurged (n = 5) marrow. Mafosfamide concentrations used for marrow purging were evaluated on an individual basis by means of a recently described technique that destroys the granulocyte-macrophage (granulocyte-macrophage colony-forming units [CFU- GM]) compartment, but spares 50% of the more primitive stroma adherent colony-forming cells (CFU-Blast). rhGM-CSF (10 μg/kg/d) was started within 24 hours of ABMT and administered in a 4-hour infusion daily until the absolute neutrophil count (ANC) reached 500 x 106/L and then for 7 more days. Patients receiving mafosfamide-purged or unpurged marrow failed to show any difference in terms of median number of days required to achieve an ANC ≥ 500 x 106 (13 v 14.0, P > .4) cells/L. As compared with retrospective controls, granulocytic recovery was reduced by a median time of 11 (P ≤ .0005) and 5 (P ≤ .0005) days for patients grafted with purged and unpurged marrow, respectively. The number of CFU-GM (mean ± SD) infused per kilogram of body weight was significantly lower in patients who received purged autografts as compared with those receiving unpurged autografts (0.85 ± 0.79 x 104 v 15.7 ± 9.2 x 104, P ≤ .0005). The dose of CFU-GM progenitors infused per kilogram of body weight did not correlate (r = .031, P > .05) with the time required to reach an ANC ≥500 x 106 cells/L. The number of CFU-Blast (mean ± SD) infused per kilogram of body weight was not significantly different between patients who received purged or unpurged autografts (5.05 ± 2.51 x 103/kg v 6.18 ± 2.66 x 103/kg, P ≤ .375). A statistically significant correlation (r = -.658, P ≤ .05) was observed between the number of CFU-Blast infused and the number of days required to reach an ANC ≥500 x 106 cells/L. No toxic effects specifically ascribed to rhGM-CSF were observed. In conclusion, our data provide evidence that rhGM- CSF is effective in accelerating neutrophil recovery in patients receiving transplants in complete remission with a very low dose of CFU-GM, provided that the primitive adherent CFU-Blast are spared by the purging procedure.