Impact of preleukapheresis cell counts on collection results and correlation of progenitor-cell dose with engraftment after high-dose chemotherapy in patients with germ cell cancer.

PURPOSE To identify predictive factors for a good leukapheresis yield and to determine peripheral-blood progenitor cell (PBPC) dose requirements for rapid hematopoietic engraftment. PATIENTS AND METHODS Seventy-one patients with germ cell cancer (GCC) underwent PBPC harvest for autologous transplantation following high-dose therapy. Aphereses were performed after chemotherapy during granulocyte colony-stimulating factor (G-CSF) administration. RESULTS A median of two aphereses (range, two to five) resulted in 4.6 x 10(8) mononuclear cells (MNC)/kg, 15.7 x 10(4) colony-stimulating units granulocyte-macrophage (CFU-GM)/kg, and 6.0 x 10(6) CD34+ cells/kg. Peripheral blood MNC count correlated significantly with number of harvested CD34+ cells per kilogram (r = .49; P < .0001) and with CFU-GM count per kilogram (r = .35; P < .002). Circulating CD34+ cells from peripheral blood gave the best correlations to collected CD34+ cells per kilogram (r = .92; P < .0001), as well as to harvested CFU-GM per kilogram (r = .48; P < .0001). A preleukapheresis number of CD34+ cells greater than 4 x 10(4)/mL was highly predictive for a PBPC collection yield that contained more than 2.5 x 10(6) CD34+ cells/kg harvested by a single leukapheresis. After autologous transplantation, 41 patients were assessable for hematopoietic engraftment. They engrafted in a median time of 9 days (range, 7 to 18) to a WBC count greater than 1.0 x 10(9)/L, 10 days (range, 7 to 18) to an absolute neutrophil count (ANC) greater than 0.5 x 10(9)/L, and 11 days (range, 7 to 62) to a platelet (PLT) count greater than 20 x 10(9)/L. Good correlations were seen between reinfused CD34+ cell count and recovery of WBC count, ANC, and PLT count, with r values of .65 (P < .001), .65 (P < .001), and .45 (P < .03), respectively. Patients reinfused with a PBPC dose greater than 2.5 x 10(6) CD34+ cells/kg recovered hematopoiesis in a significantly shorter time than patients who received less than 2.5 x 10(6) CD34+ cells/kg. CONCLUSION Rapid hematopoietic engraftment can be achieved by a PBPC dose of greater than 2.5 x 10(6) CD34+ cells/kg. When circulating preleukapheresis CD34+ cell counts are greater than 4 x 10(4)/mL, a PBPC autograft that contains more than 2.5 x 10(6) CD34+ cells/kg can be collected by a single leukapheresis.