Can the stem cell mobilization technique influence CD34+ cell collection efficiency of leukapheresis procedures in patients with hematologic malignancies?

A total of 415 leukaphereses in 201 patients stimulated with growth factor (GF; n = 119) or chemotherapy-GF (n = 296) were studied to determine CD34 + cell collection efficiency (CE). The pre-apheresis leukocyte count was 1-93 × 10⁹/l (median 20), and peripheral blood CD34 count (PBCD34) was 1-1104/μl (median 19). The total number of CD34+ cells collected was 4-6531 × 10⁶ (median 151); corresponding to 0.1-111.4 × 10⁶ (median 2.3) per kg. There was strong correlation between PBCD34 and the number of CD34+ cells collected (r = 0.9; P < 0.0001). CE was 7-145% (median 46). On multiple regression analysis, a higher leukocyte count (P < 0.0001) was the most important predictor of lower CE. CE with leukocytes < 20 was 7-145% (median 53%) compared to 10-132% (median 40%) with leukocyte ≥ 20 (P < 0.0001). In all, 61% of the apheresis procedures performed after chemotherapy-GF occurred when leukocytes were < 20 compared to 21% of those performed after GF alone (P < 0.0001). We conclude that mobilizing patients with the combination of chemotherapy and GF rather than GF alone leads to leukapheresis being performed when the leukocyte count is low - in a range that results in optimum CD34+ cell CE. Autologous stem cells should be mobilized with chemotherapy-GF rather than GF alone whenever possible.