Predictive parameters for mobilized peripheral blood CD34+ progenitor cell collection in patients with hematological malignancies

Comparing peripheral blood stem cell collection using the COBE Spectra, Haemonetics MCS+, and Baxter Amicus

Peripheral blood stem cells (PBSC) have become the most common source of hematopoietic cells for allogeneic or autologous blood and marrow transplantation (BMT). We performed an evaluation of PBSC collections using three different apheresis systems in two major transplantation centers in Singapore. Patients undergoing autologous BMT and donors collecting for allogeneic BMT were harvested using the COBE Spectra, Haemonetics MCS+, or Baxter Amicus. There were 99 Spectra collections (61 were autologous), 81 MCS+ collections (35 were autologous) and 38 Amicus collections (33 were autologous). Our data shows that the Amicus not only processed larger peripheral blood volumes but also yielded larger PBSC volume (P-value<0.05). In terms of PBSC products, the Spectra produced more WBC, WBC/liter blood processed, and WBC/kg (P-value<0.05). The Spectra and MCS+ produced comparable amount of CD34+ cells. Amicus collected 50% less platelets compared to Spectra and MCS+. The total CD34+ cells in the PBSC products was linearly correlated to the circulating CD34+ cells using Spectra, MCS+, and Amicus. Our results suggest that, compared to MCS+ and Amicus, collecting PBSC using the COBE Spectra can produce more WBC with a similar number of CD34+ cells. With a linear correlation of circulating CD34+ cells to the total CD34+ cells in the products, the availability of an automated procedure, no rotating seal, and a small extracorporeal volume, the Spectra appears to be the preferred machine for PBSC collection.

Poor harvest of peripheral blood stem cell in donors with microcytic red blood cells

BACKGROUND

The outcome of peripheral blood stem cell (PBSC) harvest depends on mobilization and leukapheresis. Some poor harvests might not be directly related to poor mobilizations.

STUDY DESIGN AND METHODS

We retrospectively analyzed the results of 793 consecutive healthy donors who underwent PBSC donation to evaluate the impact of low mean corpuscular volume (MCV) of red blood cells on the outcomes of hematopoietic stem cell mobilization and leukapheresis.

RESULTS

The circulating CD34+ cells in peripheral blood after five doses of granulocyte-colony-stimulating factor injection were similar in donors with low MCV and those with normal MCV (68.0×10(6) /L vs. 69.2×10(6) /L, p=0.38). The procedural settings were not different between the two groups. However, the apheresis outcome of donors with low MCV was significantly lower in total CD34+ cells, cell dose, apheresis yield, and collection efficiency than those with normal MCV (277.6×10(6) vs. 455.0×10(6) ; 4.9×10(6) /kg vs. 8.2×10(6) /kg; 16.9×10(6) /L vs. 27.3×10(6) /L; 0.285 vs. 0.388; all p<0.0001). Similar results were noticed in subgroup analysis using the severity of microcytosis and Mentzer index for the donors with MCV of less than 80fL. The collection efficiency was significantly correlated with the MCV (r=0.30, p<0.0001).

CONCLUSION

Low MCV was associated with poor apheresis outcomes in PBSC donors. This effect is not related to poor mobilization of CD34+ cells into the peripheral blood. Further studies to elucidate the detailed mechanism and develop strategy to avoid poor harvest are necessary.

Investigation of various methods for the cryopreservation of canine bone marrow-derived CD34(+) cells

Optimal condition for the cryopreservation of canine CD34(+) cells was explored. Canine bone marrow CD34(+) cells were isolated from 5 healthy dogs by a magnetic- activated cell-sorting system using a monoclonal antibody specific to canine CD34. These cells were cryopreserved by 4 different methods: 2 different cryoprotectant solutions-solutions A (fetal bovine serum containing 10% dimethylsulfoxide (DMSO) and B (physiological saline containing 5% DMSO, 6% hydroxyethyl starch, and 4% bovine serum albumin)-were used in combination with 2 different freezing procedures-in a rate-controlled programmed freezer (PF) and in an ordinary freezing container. The cell viability, cell recovery rates, and colony-forming unit (CFU) recovery rates were examined following cryopreservation for 1 week, 4 weeks, and 6 months. The values of these parameters were significantly higher for the CD34(+) cells that had been frozen in Solution B than for those that had been frozen in Solution A, regardless of the freezing procedure employed. The highest CFU recovery rate following cryopreservation for 6 months corresponded to the cells that had been cryopreserved with Solution B and frozen in a PF. In conclusion, cryopreservation with Solution B in a PF proved to be the most efficient of the 4 cryopreservation procedures investigated in terms of maintaining the quality of canine bone marrow-derived CD34(+) cells. This method will be useful for clinical applications involving the use of canine bone marrow-derived CD34(+) cells.

Mobilization, harvesting and selection of peripheral blood stem cells in patients with autoimmune diseases undergoing autologous hematopoietic stem cell transplantation

Peripheral blood stem cells (PBSC) were mobilized in 130 patients with autoimmune diseases undergoing autologous hematopoietic stem cell transplantation using cyclophosphamide 2 g/m(2) and either granulocyte colony-stimulating factor (G-CSF) 5 mcg/kg/day (for systemic lupus erythematosus (SLE) and secondary progressive multiple sclerosis, SPMS) or G-CSF 10 mcg/kg/day (for relapsing remitting multiple sclerosis (RRMS), Crohn's disease (CD), systemic sclerosis (SSc), and other immune-mediated disorders). Mobilization-related mortality was 0.8% (one of 130) secondary to infection. Circulating peripheral blood (PB) CD34(+) cells/microl differed significantly by disease. Collected CD34(+) cells/kg/apheresis and overall collection efficiency was significantly better using Spectra apheresis device compared to the Fenwall CS3000 instrument. Patients with SLE and RRMS achieved the lowest and the highest CD34(+) cell yields, respectively. Ex vivo CD34(+) cell selection employing Isolex 300iv2.5 apparatus was significantly more efficient compared to CEPRATE CS device. Circulating PB CD34(+) cells/microl correlated positively with initial CD34(+) cells/kg/apheresis and enriched product CD34(+) cells/kg. Mean WBC and platelet engraftment (ANC>0.5 x 10(9)/l and platelet count >20 x 10(9)/l) occurred on days 9 and 11, respectively. Infused CD34(+) cell/kg dose showed significant direct correlation with faster white blood cell (WBC) and platelet engraftment. When adjusted for CD34(+) cell/kg dose, patients treated with a myeloablative regimen had significantly slower WBC and platelet recovery compared to non-myeloablative regimens.

Pre-mobilization therapy blood CD34+ cell count predicts the likelihood of successful hematopoietic stem cell mobilization

We examined pre-mobilization blood CD34+ cell count to predict ability to mobilize adequate peripheral blood progenitor cells (PBPC) in 106 cancer patients and 36 allogeneic donors. Mean pre-mobilization therapy blood CD34+ cell count was 3.1 cells x 10(6)/l (s.d. = 3.9, r = 0.3-37) and mean CD34+ cells collected were 5.3 x 10(6) cells/kg/leukapheresis procedure (s.d. = 7.0, r = 0.03-53). Yields correlated with pre-mobilization CD34+ cells x 10(6)/l (r = 0.37, P-value < 0.0001); correlation was stronger in allogeneic donors (r = 0.56, P-value = 0.0004) and males (r = 0.46, P-value < 0.0001). Based on classification and regression tree multivariate analysis, the predictive value of pre-mobilization blood CD34+ cell count was confounded by other variables, including age, gender, mobilization regimen and malignancy type. We generated an algorithm to predict a minimum PBPC yield of 1 x 10(6) CD34+ cells/kg/leukapheresis procedure after mobilization. A threshold pre-mobilization blood CD34+ cell count of 2.65 cells x 10(6)/l was the most important decision point in predicting successful mobilization. Only 2% of subjects with pre-mobilization blood CD34+ cell counts > 2.65 cells x 10(6)/l did not achieve the minimum per apheresis, whereas 24% with pre-mobilization values below threshold had inadequate mobilization. Prospectively identifying individuals at risk for mobilization failure would allow for improved treatment planning, resource utilization and time saving.

No Polarization of Type 1 or Type 2 Precursor Dendritic Cells in Peripheral Blood Stem Cell Collections of Non-Hodgkin's Lymphoma Patients Mobilized with Cyclophosphamide Plus G-CSF, GM-CSF, or GM-CSF Followed by G-CSF

Dendritic cells (DCs) are the most efficient antigen-presenting cells and play a role in immune reconstitution after autologous transplantation. Recent reports suggest that mobilization with granulocyte colony-stimulating factor (G-CSF) containing regimens polarizes DCs into pDC2, which could potentially result with increased Th2 response and decreased graft-versus-host disease (GVHD) in allogeneic transplantation and with decreased cytotoxic Th1 response and graft versus tumor effect, which in autologous transplantation could translate into increased relapse rate. Previously, we have shown that non-Hodgkin's lymphoma (NHL) patients receiving cyclophosphamide (CTX) plus granulocyte- macrophage (GM)-CSF, G-CSF or GM-CSF followed by G-CSF for stem cell collection, mobilize up to five-fold more mature CD80(+) DCs compared to CTX plus G-CSF mobilized patients. Here, we analyzed samples from the same study for the number of pDC1 and pDC2 subsets in blood and apheresis products obtained from these patients. Samples from 29 patients were collected. Patients mobilized with CTX plus G-CSF collected a mean of 1.2 +/- 0.4 x 10(6) pDC1/kg per day and 2.2 +/- 1 x 10(6) pDC2/kg per day, whereas patients mobilized with CTX plus GM-CSF collected a mean of 1.1 +/- 0.5 x 10(6) pDC1 and 1.5 +/- 0.9 x 10(6) pDC2/kg per day. Patients mobilized with CTX plus GM-CSF followed by G-CSF collected 2.5 +/- 1.1 x 10(6) pDC1 and 2 +/- 0.5 x 106 pDC2/kg per day, with significantly higher levels of pDC1 +/- pDC2 cells. No significant difference was observed in pDC1/pDC2 ratio between the three mobilization arms. Patients mobilized with the GM-CSFcontaining regimen had a higher probability for survival compared to patients receiving G-CSF alone (median of 55 months vs. 15 months; p = 0.02). These results support the hypothesis that higher levels of DCs in the graft might be associated with prolonged survival of autotransplanted NHL patients. Further similar studies are merited in a larger population of NHL patients.

Optimization of CD34+ collection for autologous transplantation using the evolution of peripheral blood cell counts after mobilization with chemotherapy and G-CSF

BACKGROUND

Peripheral blood progenitor cells (PBPC) collection after high dose chemotherapy can be influenced by several factors. We searched for parameters that may predict the best day to start harvesting of PBPC in order to collect most CD34+ cells with the least number of aphereses.

METHODS

We studied patients who underwent mobilization chemotherapy for autologous transplantation. The influence of age, sex, diagnosis, number of previous chemotherapy cycles, peripheral blood (PB) counts at day of mobilization (D0), day of neutrophils <1.0 x 10(9) l(-1) and day of nadir and interval between both (delta) on harvesting was investigated. Multivariate linear correlation models were built to predict the best harvesting with principles of parsimony. In patients where sequential CD34+ cell count was performed, the theoretical day of peak was calculated by interpolation in polynomial regression.

RESULTS

One hundred and thirty four patients entered the analysis: 36 Hodgkin's lymphoma (HL), 65 B-large cell lymphoma (NHL) and 33 multiple myeloma (MM). Day of harvesting correlated with nr CHT, hemoglobin on D0, day of granulocytes <1.0 x 10(9) l(-1), delta and dosis of mobilization therapy. The day of CD34+ peak could be calculated by the formula = (-0.41) x Hemoglobin D0 + (day peripheral CD34+ cells = 10 x 10(6) microl(-1)) x 0.99 + 7.8. This model could explain 81% of the variance of the peak day and was stable by bootstrap resampling. Day of peripheral CD34+ cells = 10 x 10(6) microl(-1) preceded the calculated peak by 3-9 days.

CONCLUSIONS

Although the day of best collection can be predicted using only sequential PB counts after mobilization chemotherapy, a model of prediction using peripheral CD34+ cell count is important especially for optimizing collection in poor mobilizing patients.

The Hyper-CVAD chemotherapy regimen has an adverse long-term impact on the ability to mobilize peripheral blood stem cells, which can be readily circumvented by using the early cycles for mobilization

The Hyper-CVAD chemotherapy regimen is being increasingly applied to a number of haematological malignancies. We assessed the impact of Hyper-CVAD on peripheral blood stem cell (PBSC) yields and examined the optimal timing of PBSC collection when using this regimen. Seventy-four consecutive patients were identified in whom an attempt was made to collect PBSC, usually on recovery from cycle A or B. Where PBSC collection was attempted after cycle 3B, only 18% (3/17) of patients successfully mobilized. Fifty-seven patients were mobilized on recovery from cycle 1B (n = 13), 2A (n = 22), 2B (n = 14) or 3A (n = 8). Compared with cycle 2A, 1B was not superior in achieving the minimum of > or =2 x 10(6)/kg CD34+ cells (100% vs. 77%, p = 0.13), but was superior in terms of total CD34+ yield (21.4 vs. 3.2 x 10(6)/kg, p < 0.001), achieving the target CD34+ cell count of > or =5 x 10(6)/kg (92% vs 36%, p = 0.002), and obtaining both a minimum (92% vs. 18%, p < 0.001) and target (77% vs. 0%, p < 0.001) graft with a single apheresis. There were no significant differences in PBSC yields following cycles 2A, 2B and 3A. Hyper-CVAD has substantial stem cell toxicity which can be readily circumvented by using the early chemotherapy cycles for mobilization.

Predictive value of circulating immature cell counts in peripheral blood for timing of peripheral blood progenitor cell collection after G-CSF plus chemotherapy-induced mobilization

BACKGROUND

Enumeration of CD34+ cells in peripheral blood (PB) before apheresis predicts the number of CD34+ cells collected, although flow cytometric techniques used are complex and expensive. In an attempt to determine the optimal timing for peripheral blood progenitor cell (PBPC) collection, the usefulness of circulating immature cell (CIC) counts in PB was evaluated.

STUDY DESIGN AND METHODS

CIC counts in PB and CD34+ cell counts in the apheresis product from 249 collections were assessed, and the relationship between these two parameters was evaluated by with the Pearson rank correlation analysis, the Fisher exact test, and the U-test.

RESULTS

CIC counts were correlated significantly with the number of CD34+ cells per kg of patient's body weight in the apheresis product (Pearson rank correlation analysis: r = 0.635, p < 0.0001). When a level of 1 x 10(9) CICs per L was selected as a cutoff value, the sensitivity and specificity for collecting more than 1 x 10(6) CD34+ cells per kg of body weight were 75.7 and 85.5 percent, respectively.

CONCLUSION

The present study strongly suggests that the number of CICs in PB may estimate the number of CD34+ cells collected. The data indicate that CIC counts above 1 x 10(9) per L can be used as a good predictor for PBPC collections containing more than 1 x 10(6) CD34+ cells per kg of body weight in a single apheresis procedure.

Expression of adhesion molecules on CD34(+) cells in peripheral blood of non-hodgkin's lymphoma patients mobilized with different growth factors

Adhesion molecules on CD34(+) cells were implicated in the process of peripheral blood stem cell (PBSC) mobilization and homing. We studied the mobilization of CD34(+)Thy1(+) cells, CD34(+) very late-acting antigen (VLA)4(+) cells, and CD34(+)L-selectin(+) cells in non-Hodgkin's lymphoma patients mobilized with cyclophosphamide plus G-CSF, GM-CSF, or GM-CSF followed by G-CSF. The mean percentage of CD34(+) cells in the bone marrow (BM) expressing Thy1 was 23.6% +/- 11% and 17.8% +/- 8% in the PB before mobilization, and was markedly decreased to 4.5% +/- 3.3% in the apheresis collections. Similarly, the mean percentage of CD34(+) cells expressing L-selectin was 35.8% +/- 4.3% in the BM, 21.6% +/- 4.1% in the PB before mobilization and was markedly decreased to 9.1% +/- 2.5% in the apheresis collections. Patients in the three arms of the study had a similar pattern of CD34(+)Thy1(+) and CD34(+)L-selectin(+) cell mobilization. Also, a similar pattern of coexpression of CD34(+)Thy1(+) and CD34(+)L-selectin(+) cells was observed when the patients were regrouped as "good mobilizers" (> or =2 x 10(6) CD34(+)CD45(dim) cells/kg, in four collections) and "poor mobilizers" (<0.4 x 10(6) CD34(+)CD45(dim) cells/kg, in two collections). The mean percentage of CD34(+) cells expressing VLA-4 in the BM and PB was relatively high (73.4% +/- 12% and 65.4% +/- 6.6%, respectively) and dropped considerably in the PBSC collections to 43.5% +/- 7.1% with a similar pattern observed for patients in arms A, B, and C. However, when the patients were regrouped as "good mobilizers" and "poor mobilizers," a higher percentage of CD34(+) cells expressing VLA-4 was observed in the PBSC of the pooled "good mobilizers" (50.5% +/- 9% versus 36.3% +/- 6.4%; p = 0.01). We conclude that release of CD34(+) cells to the PB involves a general downregulation of Thy1, L-selectin and VLA-4 on CD34(+) cells, irrespective of the growth factor used for mobilization. However, good mobilizers had a relatively higher percentage of CD34(+) cells expressing the VLA-4 antigen.

Plasma levels of SDF-1 and expression of SDF-1 receptor on CD34+ cells in mobilized peripheral blood of non-Hodgkin's lymphoma patients

CXCR4 is the receptor for the chemokine stromal derived factor-1 (SDF-1), is expressed on CD34+ cells, and has been implicated in the process of CD34+ cell migration and homing. We studied the mobilization of CD34/CXCR4 cells and the plasma levels of SDF-1 and flt3-ligand (flt3-L) in 36 non-Hodgkin's lymphoma patients receiving cyclophosphamide (Cy) plus G-CSF (arm A), Cy plus GM-CSF (arm B), or Cy plus GM-CSF followed by G-CSF (arm C) for peripheral blood stem cell (PBSC) mobilization and autotransplantation. We observed lower plasma levels of SDF-1 in PBSCs compared to premobilization bone marrow samples. The mean plasma SDF-1 levels were similar in PBSC collections in the three arms of the study. In contrast, SDF-1 levels in the apheresis collections of the "good mobilizers" (patients who collected a minimum of 2 x 10(6) CD34+ cells/kg in one to four PBSC collections) were significantly lower than the apheresis collections of the "poor mobilizers" (> or = 0.4 x 10(6) CD34+ cells/kg in the first two PBSC collections; 288 +/- 82 pg/ml versus 583 +/- 217 pg/ml; p = 0.0009). The mean percentage of CD34+ cells expressing CXCR4 in the apheresis collections was decreased in the PBSC collections compared with premobilization values from 28% to 19.4%. Furthermore, the percentage of CD34+ cells expressing CXCR4 in the good mobilizers was significantly lower compared with the poor mobilizers (14.7 +/- 2.1% versus 33.6 +/- 2.1%; p = 0.002). The good mobilizers had also significantly lower levels of flt3-L compared with the poor mobilizers (34 +/- 4 pg/ml versus 106 +/- 11 pg/ml; p = 0.006), Finally, the levels of flt3-L strongly correlated with SDF-1 levels (r = 0.8; p < 0.0001). We conclude: A) low plasma levels of SDF-1 and low expression of CXCR4 characterize patients with good mobilization outcome, and B) the levels of SDF-1 correlate with flt3-L, suggesting an association of these cytokines in mobilization of CD34+ cells.

Recent Developments in the Regulation of Peripheral Blood Stem Cell Mobilization and Engraftment by Cytokines, Chemokines, and Adhesion Molecules

Peripheral blood stem cells (PBSC) have become the preferred source of stem cells for autologous transplantation because of the technical advantage and the shorter time to engraftment. Administration of hematopoietic growth factors such as granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) results in mobilization of PBSCs into the peripheral blood. G-CSF and GM-CSF differ somewhat in the number and composition of CD34(+) cells and effector cells mobilized to the peripheral blood; however, the molecular mechanism underlying the release and engraftment of CD34(+) cells by these growth factors is poorly understood. This review provides a recent update on the involvement of hematopoietic growth factors, chemokines, adhesion molecules, and chemokine receptors in the regulation of stem cell release and engraftment. The involvement of very late antigen-4 (VLA-4), VLA-5, leukocyte function associated-1 molecule (LFA-1), and L-selectin and their receptors CXCR4 and its ligand SDF-1 will be discussed, and cross talk between these factors will also be reviewed in the context of stem cell release and engraftment. Finally, PBSC mobilization by chemokines will be reviewed in relation to hematopoietic growth factors.

Cytokines and vascular cell adhesion molecule-1 in the blood of patients undergoing HPC mobilization

BACKGROUND

The mechanism of HPC mobilization in humans is unclear. In this study, the relationship between PBPC mobilization and blood levels of G-CSF, endogenous cytokines (IL-8, SCF, thrombopoietin [TPO]), and the vascular cell adhesion molecule-1 (VCAM-1) was analyzed in patients with malignancy who were undergoing a PBPC mobilization regimen.

STUDY DESIGN AND METHODS

Fifty-four patients with multiple myeloma (MM) and 29 with breast cancer (BC) underwent a mobilization regimen combining conventional chemotherapy and G-CSF up to the last day of PBPC collection. The CD34+ cell count was determined on each day when leukapheresis was scheduled. Venous blood samples (n = 117) were drawn before apheresis for CD34+ cell count (flow cytometry) and cytokine (G-CSF, IL-8, SCF, TPO) and VCAM-1 measurements (ELISA).

RESULTS

In multiple regression analysis, SCF was a significant determinant of CD34+ cell levels in BC patients (R = 0.50, p = 0.03) and of VCAM-1 levels in MM patients (R = 0.32, p = 0.02). SCF was negatively correlated with CD34+ cell count in patients with BC. SCF and VCAM-1 blood levels were correlated in MM and BC patients.

CONCLUSION

SCF and VCAM-1 could play a role in PBPC mobilization in patients and could be useful measures by which to study patients undergoing a mobilization regimen.

Differential mobilization of CD34+ cells and lymphoma cells in non-Hodgkin's lymphoma patients mobilized with different growth factors

Co-mobilization of CD34(+) cells and tumor has been documented in patients with different types of cancer undergoing peripheral blood stem cell transplantation (PBSCT). Conflicting reports were published regarding the role of various growth factors in tumor cells mobilization, hence we studied the extent of CD34(+) cells and lymphoma cell mobilization in 35 non-Hodgkin's (NHL) patients primed by cyclophosphamide (Cy) in combination with granulocyte colony-stimulating factor (GCSF) (A, 13 patients), granulocyte-macrophage (GM)-CSF (B, 10 patients), or GM-CSF followed by G-CSF (C, 12 patients). CD34(+) cells were quantitated by flow cytometry and lymphoma cells by the TaqMan Real Time PCR for bcl-2 gene rearrangement. Successful collection in 4 days of > or = 2 x 10(6) CD34(+) cells/kg needed for prompt engraftment was obtained in 76%, 60%, and 58% of patients in arms A, B, and C, respectively. Lymphoma cell mobilization was detected in 35% patients tested, 78% of which had follicular lymphoma. Lymphoma cell mobilization was similar in the three arms of the study, however, presence of lymphoma cells was prevalent in patients who failed to mobilize the amount of 0.4 x 10(6) CD34(+) cells/kg in 2 days ("poor mobilizers") and reached 42%, compared to 17% in the "successful mobilizers" group of patients. Lymphoma cell contamination in PBSCs was detected proportionately in the peripheral blood and in the bone marrow. We conclude that bcl-2 gene rearrangement is prevalent in patients with follicular histology, and, in these patients, an inverse relationship was observed between mobilization of CD34(+) cells and lymphoma cells. Our results explain the high relative risk (1.98) for mobilization in patients with follicular histology.

Peripheral blood stem cell mobilization with cyclophosphamide in combination with G-CSF, GM-CSF, or sequential GM-CSF/G-CSF in non-Hodgkin's lymphoma patients: a randomized prospective study

We designed a randomized, prospective three-arm mobilization study to determine the kinetics of peripheral blood stem cell (PBSC) mobilization in 60 non-Hodgkin's lymphoma (NHL) patients primed with cyclophosphamide (CTX) in combination with granulocyte colony-stimulating factor (G-CSF) (arm A), granulocyte-macrophage (GM)-CSF (arm B) or GM-CSF/G-CSF (arm C). We also compared mobilization and transplant-related toxicities, pre- and post-transplant support and the probability of survival among the three arms. To date, 35 patients have been enrolled in the study; 13 patients have been enrolled in arm A, 10 patients in arm B, and 13 patients in arm C. Successful collection of the target of > or = 2 X 10(6) CD34+ cells/kg in one to four apheresis collections was 10/13, 6/10, and 7/12 in arms A, B, and C, respectively. The differences between arms were not statistically significant. The median time to achieve the target CD34+ cells in patients who successfully mobilized the target CD34+ cells was 3 days, 2 days, and 1 day, in patients in arms A, B, and C, respectively. The time for neutrophil engraftment was 11, 10, and 10 days in arms A, B, and C, respectively. The time for platelet engraftment was 11 days for patients in all arms of the study. Most importantly, no significant differences were observed among the three arms in the duration of neutropenic fever, the extent of mucositis, diarrhea, and nausea/vomiting, or in the number of units of platelets or red cells transfused after transplantation. Risk factors associated with poor mobilization were > or = 3 regimens of chemotherapy prior to mobilization, older age, and disease histology (follicular versus diffuse). Therefore, we conclude that the type of growth factor used for mobilization did not play a major role in the outcome of mobilization and recommend mobilizing NHL patients before they receive multiple regimens of chemotherapy.

Early total white blood cell recovery is a predictor of low number of apheresis and good CD34(+) cell yield

OBJECTIVE

We analysed peripheral blood progenitor cell (PBPC) mobilisation and collection in order to assess the main factors related to CD34(+) cell yields in patients affected by haematological malignancies.

PATIENTS AND METHODS

The features of CD34(+) cell mobilisation of patients with haematological malignancies that underwent autologous bone marrow transplantation were examined. Mobilisation chemotherapy consisted mainly of cyclophosphamide (CY) 4 or 7 g/m(2) followed by growth factors. Leukapheresis was started when the WBC counts reached 1.0x10(9)/l with the aim to collect at least 5x10(6) CD34(+) cells/kg body weight. The aphereses were performed on continuous-flow blood cell separators. The analysed variables were: age, diagnosis, CT mobilisation regimen, type of growth factor, number of previous CT lines, prior radiotherapy, days for WBC recovery and number of aphereses procedures to achieve the target of CD34(+) cells.

RESULTS

There were 41 consecutive patients (26 M/15 F): 21 non-Hodgkin's lymphoma (NHL), 15 Hodgkin's disease (HD), two chronic myeloid leukaemia (CML) and three multiple myeloma (MM). Eleven patients could not collect the proposed threshold of CD34(+) cells. CY 4 mobilised patients recovered WBC counts in less days (P=0.03). By ANOVA, the days to WBC recovery had a linear function of the predictors "number of aphereses" and "type of mobilisation CT" (coefficients: 0.86 and 0.95, respectively). For the number of aphereses and WBC recovery after CT mobilisation, we obtained a correlation coefficient of 0.36 (P=0.02).

CONCLUSION

This study shows that it is feasible to mobilise and collect PBPC in patients previously treated with CT with or without RT. There was a linear correlation between the days for WBC recovery and the number of aphereses needed to collect the target number of CD34(+) cells. The study suggests that early WBC recovery, using mainly CY 4 mobilisation chemotherapy, is an important predictor of a low number of aphereses to achieve a good CD34(+) yield.

High steady-state plasma levels of flt3-ligand in the peripheral blood is a good predictor for poor mobilization of CD34+ PBSC in patients undergoing high-dose chemotherapy and stem cell rescue

flt3-ligand (flt3-L) is a very effective mobilizer of hematopoietic stem cells (HSC) and is capable of inducing multilineage hematopoietic cell differentiation both in vivo and in vitro. We measured, by ELISA, the plasma peripheral blood flt3-L concentrations in 28 non-Hodgkin's lymphoma (NHL) patients before and after mobilization with three different mobilization regimens, including priming with cyclophosphamide (CY) plus G-CSF, CY plus GM-CSF, and CY plus GM-CSF (8 days) followed by G-CSF. We also determined the levels of flt3-L in the peripheral blood during four apheresis collections and 6 months after transplantation. The steady-state level of flt3-L in NHL patients (n = 18) who mobilized > or =2 x 10(6) CD34+ cells/kg in four apheresis collections was 34 +/- 4 pg/ml and was similar to the levels observed in 10 normal controls (27 +/- 7, p = 0.1) regardless of the mobilization protocol used. In contrast, patients who failed to mobilize a total of >0.4 x 10(6) CD34+ cells/kg in two consecutive apheresis collections (n = 10) had flt3-L levels of 106 +/- 11 pg/ml, significantly higher (p = 0.006) than that of the good mobilizers group, regardless of the mobilization protocol used. Similar results were observed in 29 multiple myeloma (MM) patients. A mean of 23.8 +/- 7.9 pg/ml and 450 +/- 85 pg/ml flt3-L was obtained in the good mobilizers (n = 24) and the nonmobilizers (n = 5) groups of patients, respectively. Statistical analysis revealed a significant difference (p = 0.0006) between the two groups of MM patients, but no correlation was observed between the levels of flt3-L and CD34+ cell/microl, in mobilized peripheral blood. Our results also suggest that measurement of plasma levels of flt3-L before mobilization can be clinically useful to predict for patients with poor mobilization outcome.