Serum G-CSF levels in patients undergoing G-CSF/Chemotherapy mobilized peripheral stem cell harvest and predictors of neutrophil and platelet recovery

Granulocyte colony-stimulating factor (G-CSF)/Chemotherapy mobilized peripheral blood progenitors are an effective source of stem cells which affords rapid and complete hematopoietic engraftment after myeloablative chemotherapy regimens. The dose of G-CSF most commonly used for mobilization is 5 μg/kg. We measured G-CSF levels in patients with chemosensitive malignancies undergoing peripheral stem cell harvest to determine whether there was a relationship between serum G-CSF levels and the yield of CD34⁺ hematopoietic progenitors. Peripheral blood stem cells (PBSCs) were mobilized by chemotherapy followed by G-CSF (5 μg/kg) started 24 hours after completion of chemotherapy. PBSCs were collected by daily leukapheresis during G-CSF stimulation once the WBC had recovered to 1.0 x 10⁹/L, with 10 liters of blood processed using a Fenwall CS 3000. G-CSF levels were monitored daily before and after leukapheresis. CD34⁺ cells from daily leukapheresis collections were determined in 11 patients. Immunophenotyping analyses of CD34⁺ and non-CD34⁺ cells for surface antigens CD38⁺, HLA-DR, CD71⁺, CD61⁺ and CD42a⁺ were performed on these daily leukapheresis. The mean (SD) number of days to neutrophil recovery (NR: ≥ 0.5 x 10⁹/L) after stem cell reinfusion was 9.2 (1.92). The corresponding values for platelet recovery (PR: ≥ 20 x 10⁹ L) were 8.1 (2.39) days. Using multiple regression analyses, the best predictors for NR were: last G-CSF (R² = 0.21); last G-CSF and CD34⁺ (R² = 0.67); last G-CSF, CD34⁺ and number of chemotherapy cycles (R² = 0.72). For PR: log G-CSF (R² = 0.35); log G-CSF and Ave CD34⁺/CD38^-/DR⁺ (R² = 0.41); log G-CSF, CD34⁺/CD38^-/DR⁺ and CD34⁺/CD38⁺/DR^- (R² = 0.49). G-CSF levels are significantly related to the number of prior chemotherapy cycles. G-CSF, average CD34⁺ cells and its subsets, and the number of chemotherapy cycles separately and jointly are important predictors of NR and PR.