Mobilization of peripheral blood progenitor cells by chemotherapy and granulocyte-macrophage colony-stimulating factor for hematologic support after high-dose intensification for breast cancer.

High-dose therapy with autologous marrow support results in durable complete remissions in selected patients with relapsed lymphoma and leukemia who cannot be cured with conventional dose therapy. However, substantial morbidity and mortality result from the 3- to 6-week period of marrow aplasia until the reinfused marrow recovers adequate hematopoietic function. Hematopoietic growth factors, particularly used after chemotherapy, can increase the number of peripheral blood progenitor cells (PBPCs) present in systemic circulation. The reinfusion of PBPCs with marrow has recently been reported to reduce the time to recovery of adequate marrow function. This study was designed to determine whether granulocyte-macrophage colony-stimulating factor (GM-CSF)-mobilized PBPCs alone (without marrow) would result in rapid and reliable hematopoietic reconstitution. Sixteen patients with metastatic breast cancer were treated with four cycles of doxorubicin, 5-fluorouracil, and methotrexate (AFM induction). Patients responding after the first two cycles were administered GM-CSF after the third and fourth cycles to recruit PBPCs for collection by two leukapheresis per cycle. These PBPCs were reinfused as the sole source of hematopoietic support after high doses of cyclophosphamide, thiotepa, and carboplatin. No marrow or hematopoietic cytokines were used after progenitor cell reinfusion. Granulocytes greater than or equal to 500/microL was observed on a median of day 14 (range, 8 to 57). Transfusion independence of platelets greater than or equal to 20,000/microL occurred on a median day of 12 (range, 8 to 134). However, three patients required the use of a reserve marrow for slow platelet engraftment. In retrospect, these patients were characterized by poor baseline bone marrow cellularity and poor platelet recovery after AFM induction therapy. When compared with 29 historical control patients who had received the same high-dose intensification chemotherapy using autologous marrow support, time to engraftment, antibiotic days, transfusion requirements, and lengths of hospital stay were all significantly improved for the patients receiving PBPCs. Thus, autologous PBPCs can be efficiently collected during mobilization by chemotherapy and GM-CSF and are an attractive alternative to marrow for hematopoietic support after high-dose therapy. The enhanced speed of recovery may reduce the morbidity, mortality, and cost of high-dose treatment. Furthermore, PBPC support may enhance the effectiveness of high-dose therapy by facilitating multiple courses of therapy.     

Hematological recovery and peripheral blood progenitor cell mobilization after induction chemotherapy and GM-CSF plus G-CSF in breast cancer

In order to determine the effect of GM-CSF plus G-CSF in combination in breast cancer patients receiving an effective induction regimen, we compared hematological recovery and peripheral blood progenitor cell (PBPC) mobilization according to colony-stimulating factor (CSF) support. Forty-three breast cancer patients were treated by TNCF (THP-doxorubicin, vinorelbine, cyclophosphamide, fluorouracil, D1 to D4) with CSF support: 11 patients received GM-CSF (D5 to D14); 16 patients G-CSF (D5 to D14) and 16 patients GM-CSF (D5-D14) plus G-CSF (D10-D14). Between two subsequent cycles, progenitor cells were assessed daily, from D13 to D17. The WBC count was similar for patients receiving G-CSF alone or GM-CSF plus G-CSF, but significantly greater than that of patients receiving GM-CSF alone (P<0.001). The GM-CSF plus G-CSF combination led to better PBPC mobilization, with significantly different kinetics (P<0.001) and optimal mean values of CFU-GM, CD34+ cells and cells in cycle, at D15 compared to those obtained with G-CSF or GM-CSF alone. The significantly greater PBPC mobilization obtained with a CSF combination by D15 could be of value for PBPC collection and therapeutic reinjection after high-dose chemotherapies.     

Incidence of tumor-cell contamination in leukapheresis products of breast cancer patients mobilized with stem cell factor and granulocyte colony-stimulating factor (G-CSF) or with G-CSF alone.

We have assessed tumor contamination of peripheral blood progenitor cells (PBPC) in 203 high-risk breast cancer patients who were prospectively randomized to mobilization with stem cell factor (SCF) plus granulocyte colony-stimulating factor (G-CSF) versus G-CSF alone. The patients then received high-dose cyclophosphamide, cisplatin, and carmustine (BCNU) with PBPC support. One bone marrow aspirate obtained before treatment, one whole blood specimen obtained before cytokine infusion, and one to five leukapheresis products were tested for the presence of tumor cells by an alkaline phosphatase immunocytochemical technique with a targeted sensitivity of 1.7 tumor cells per 10(6) hematopoietic cells. Tumor cells were detected in the bone marrow, peripheral blood, and/or PBPC of 21 patients (10%). In 14 patients, bone marrow specimens were tumor-positive; in seven patients, premobilization whole blood specimens were tumor-positive, and in eight patients, leukapheresis products were tumor-positive. In five patients, repetitive or multiple specimens were tumor-positive, and in three cases, marrow, peripheral blood, and PBPC products were all tumor-positive. Nine of the patients in whom tumor cells were found in marrow or peripheral blood were clinical stage II to III and 12 were clinical stage IV. Nine of the tumor-positive patients were in the SCF + G-CSF arm and 12 were in the G-CSF arm. Tumor cells were detected in leukapheresis products of eight patients: three in the G-CSF + SCF arm and five in the G-CSF arm. We conclude that detectable tumor-cell contamination of bone marrow, peripheral blood, and/or PBPC occurred in approximately 10% of patients in this trial and was observed in stage II to III patients, as well as in stage IV patients. No significant difference could be found in the rate of PBPC tumor-cell contamination between patients who received SCF + G-CSF compared with those who received G-CSF alone. Neither mobilization regimen was found to increase the rate of tumor-cell contamination when control premobilization blood samples were compared with leukapheresis products.     

Noncycling state of peripheral blood progenitor cells mobilized by granulocyte colony-stimulating factor and other cytokines

Incubation with high doses of tritiated thymidine in vitro was used to determine the percent of progenitor cells in the S phase of the cell cycle. Peripheral blood (PB), bone marrow (BM), and spleen populations from mice injected with granulocyte colony-stimulating factor (G-CSF) at 5 micrograms/day for 5 days and BM cells from uninjected littermates were assayed. Although the percentage of progenitor cells in S phase in the marrow (47% +/- 5%) and spleen (52% +/- 9%) was increased significantly in G-CSF-treated mice, only a small proportion of PB progenitor cells (PBPC) were in S phase (7% +/- 4%). In normal human subjects injected with G-CSF at 5 or 10 micrograms/kg/d, the proportions of PB myeloid (-1 +/- 4%) and erythroid (0% +/- 8%) progenitor cells in S phase were very low compared with the proportion of myeloid progenitor cells in S phase in normal BM (34% +/- 10%). Similarly, the large majority of steady-state PBPC and PBPC mobilized by interleukin-3 in combination with either granulocyte-macrophage colony-stimulating factor or G-CSF were also found not to be in S phase. Experiments indicated that the low percentages of PBPC in S phase were not ascribable either to inhibitory elements in the blood or to reduced responsiveness to growth factors.     

Severe congenital neutropenia: abnormal growth and differentiation of myeloid progenitors to granulocyte colony-stimulating factor (G-CSF) but normal response to G-CSF plus stem cell factor

Several mechanisms have been proposed to explain the pathogenesis of severe congenital neutropenia (SCN); however, the mechanism(s) still remains unknown. In particular, clinical observations suggest that abnormal responsiveness of myeloid progenitors to hematopoietic growth factors (HGFs) is a possible mechanism. Therefore, to better define the status of hematopoietic progenitors in the bone marrow (BM) of patients with SCN, the responsiveness of myeloid progenitors to HGFs from two SCN patients was compared with the responsiveness of progenitors from healthy individuals. BM cells (BMCs) from the first SCN patient required higher (10- to 100-fold) concentrations of granulocyte colony- stimulating factor (G-CSF) to achieve maximal and half-maximal colony growth in vitro compared with BMCs from controls. In contrast, the dose- response of interleukin-3 (IL-3) and granulocyte-macrophage-CSF (GM- CSF) in colony formation was normal. Interestingly, IL-3, GM-CSF, and G- CSF at optimal doses showed reduced ability to induce neutrophil differentiation of BMCs from a SCN patient compared with BMCs from controls. Despite an abnormal responsiveness of mature myeloid progenitors to G-CSF in this SCN patient, myeloid progenitors responsive to the combination of stem cell factor (SCF) and G-CSF showed normal dose-response. In contrast to G-CSF alone, the combination of G-CSF and SCF induced the formation of neutrophils almost to the same extent compared with cultures of normal BMCs. Furthermore, also on BM progenitor cells obtained from the second patient with SCN, SCF highly synergized with G-CSF to promote neutrophil progenitor cell growth and differentiation in vitro. Thus, these results indicate that one mechanism of the pathogenesis in SCN patients is reduced responsiveness of neutrophil progenitor cells to G- CSF and that SCF can enhance the responsiveness of these cells to G-CSF.     

Red Blood Cells (RBC) and High Fluorescence Reticulocytes (HFR) production increased by induction chemotherapy and GM-CSF plus G-CSF in peripheral blood of breast cancer patients

The preservation of erythrocytes is important during cytostatic chemotherapy. To study the synergistic effect of GM-CSF plus G-CSF on the red blood recovery, we looked at the kinetics of red blood cells, total reticulocytes and High Fluorescence Reticulocytes (HFR) from peripheral blood of 26 breast cancer patients, between 2 cycles of chemotherapy. After four days of TNCF (Thp-doxorubicin, Vinorelbine, Cyclophosphamide, Fluorouracil) treatment, 12 patients received either GM-CSF or G-CSF (D5-D16) and 14 received both of them (GM-CSF, D5-D14 and G-CSF, D10-D14). Our results showed a significantly lesser RBC decrease for patients receiving both CSFs versus only one CSF (p < 0.05). This greater RBC preservation was explained by the increase of HFR and total reticulocytes from D12 to D17 in the peripheral blood of patients receiving the two CSFs, with significantly values greater than that of patients receiving one CSF (p < 0.01) it showed that the synergistic GM-CSFplus G-CSF effect observed previously on PBPC results in a positive effect on erythroid lineage. GM-CSF plus G-CSF association exhibit in vivo multilineage (myeloid and erythroid) activity showing the interest to use different cytokines in combination to obtain a better hematological recovery after induction chemotherapy as well as a better quality of PBPC mobilization for transplantation after high-dose chemotherapy.     

Absence of breast cancer cells in a single-day peripheral blood progenitor cell collection after priming with cyclophosphamide and granulocyte-macrophage colony-stimulating factor

The effect of priming on occult tumor cell involvement of peripheral blood (PB) and PB progenitor cell (PBPC) collections is poorly characterized. Using sensitive immunocytochemistry (ICC) and tumor clonogenic assays (TCA) specific for epithelial-derived tumor cells, hematopoietic specimens were analyzed for PBPC and occult tumor cell involvement in 28 patients with chemotherapy-sensitive stage IIIB or IV breast cancer. Before PBPC priming, tumor was detected by ICC in PB of 1 of 23 (4%) patients and in bone marrow (BM) harvests of 4 of 27 (15%) patients. Fifteen days after cyclophosphamide and granulocyte- macrophage colony-stimulating factor (GM-CSF) priming, 2 of 28 (7%) patients had ICC-positive PBPC collections. The median amplification of CD34+ PBPC during this time was over 19-fold (range, < 1 to 199). One patient had pretreatment tumor involvement of both PB and BM. One patient grew tumor colonies in TCA; the PB and BM were ICC- and TCA- positive, but the PBPC collection was ICC-positive and TCA-negative. After cytoreduction with conventional-dose chemotherapy, patients with advanced breast cancer and histologically negative BM biopsy specimens have rare tumor cell involvement of PB and BM. Despite effective PBPC priming with cyclophosphamide and GM-CSF, clonogenic breast cancer cells were not found in the PBPC collection performed on day 15.     

Progenitor content of autologous grafts: mobilized bone marrow vs mobilized blood

The progenitor content of autologous peripheral blood progenitor and stem cell collections is a major determinant of prompt hematopoietic recovery following autologous stem cell transplantation. We analyzed unstimulated bone marrow (BM) and peripheral blood (PB) apheresis products in comparison to those collected following G-CSF or GM-CSF stimulation. We quantitated their committed (CFU-GM) and primitive (long-term culture-initiating cells, LTC-IC) progenitors in relation to hematologic recovery in 63 patients undergoing autografting for lymphoid malignancies. G-CSF, but not GM-CSF, substantially enriched the committed progenitor content (2.5-3.6-fold) of both PB and BM grafts. G-CSF also enriched the LTC-IC content of BM and PB compared to control grafts. GM-CSF augmented (11.5-fold) the LTC-IC content of stimulated BM, but not GM-CSF-mobilized PB. Neutrophil recovery was substantially quicker in recipients of BM or PB mobilized with G-CSF or GM-CSF. In contrast, red cell and platelet recovery was accelerated in recipients of GM-CSF-stimulated BM (but not PB) and G-CSF-stimulated PB (but not BM). No direct correlation between progenitor dose and hematopoietic recovery for neutrophils, platelets or red cells was observed. Cytokine stimulation can augment the committed and more primitive multilineage progenitor content of BM and PB grafts, to a differing extent. The uncertain relationship with multilineage myeloid recovery emphasizes the limitations in using clonogenic progenitor analyses to assess the adequacy of an autologous graft prior to transplantation.     

Mobilization of peripheral blood progenitor cells by sequential administration of interleukin-3 and granulocyte-macrophage colony-stimulating factor following polychemotherapy with etoposide, ifosfamide, and cisplatin.

We report on the requirements that have to be met to combine a standard-dose chemotherapy regimen with broad antitumor activity with the mobilization of peripheral blood hematopoietic progenitor cells. Thirty-two cancer patients were given a 1-day course of chemotherapy consisting of etoposide (VP16), ifosfamide, and cisplatin (VIP; n = 46 cycles), followed by the combined sequential administration of recombinant human interleukin-3 (rhIL-3) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). Control patients received GM-CSF alone or were treated without cytokines. Maximum numbers of peripheral blood progenitor cells (PBPC) were recruited on day 13 to 17 after chemotherapy, with a median of 418 CD34+ cells/microL blood (range, 106 to 1,841) in IL-3/GM-CSF-treated patients, 426 CD34+/microL (range, 191 to 1,380) in GM-CSF-treated patients, and 46 CD34+/microL (range, 15 to 148) in patients treated without cytokines. In parallel, there was an increase in myeloid (10,490 colony-forming unit-granulocyte-macrophage [CFU-GM]/mL blood; range, 1,000 to 23,400), as well as erythroid (10,660 burst-forming unit-erythroid [BFU-E]/mL blood; range, 3,870 to 24,300) and multipotential (840 CFU-granulocyte, erythrocyte, monocyte, megakaryocyte [GEMM]/mL blood; range, 160 to 2,070) progenitor cells in IL-3 plus GM-CSF-treated patients. In GM-CSF-treated patients, significantly less precursor cells of all lineages were mobilized, particularly multipotential progenitors (400 CFU-GEMM/mL blood; range, 200 to 2,150). Only small numbers of CD34+ cells and clonogenic progenitor cells could be recruited in intensively pretreated patients. Our data document that after standard-dose chemotherapy-induced bone marrow hypoplasia, IL-3 plus GM-CSF can be used to recruit PBPC, which might shorten the hematopoietic recovery after high-dose chemotherapy in chemosensitive lymphomas or solid tumors.     

Engraftment syndrome after autologous hematopoietic stem cell transplant supported by granulocyte-colony-stimulating factor (G-CSF) versus granulocyte-macrophage colony-stimulating factor (GM-CSF)

The engraftment syndrome (ES) is a phenomenon observed in some patients undergoing autologous hematopoietic stem cell transplant (AHSCT). ES is characterized by fever, rash, capillary leak, and pulmonary infiltrates occurring at the onset of engraftment. Prior studies have suggested that the administration of hematopoietic growth factors post-transplant results in the increased frequency of ES. However, the relative contribution of granulocyte colony-stimulating factor (G-CSF) vs granulocyte-macrophage colony-stimulating factor (GM-CSF) to the development of ES remains unknown. A total of 152 consecutive patients who were treated with high-dose chemotherapy and AHSCT supported by either G-CSF or GM-CSF were analyzed retrospectively. In all, 20 patients developed ES, an incidence of 13%. ES was seen more frequently in patients who received GM-CSF (GM-CSF 24% vs G-CSF 4%, p=0.0001). The highest incidence of ES was observed in breast cancer patients (42% of breast cancer patients; 70% of all ES cases). Comparison of the incidence of ES by the priming regimen used comprising either of the growth factors revealed no significant association (p=0.8224). This study demonstrates that the incidence of ES is higher using GM-CSF, particularly in patients with breast cancer. It suggests that it might be advantageous to administer only G-CSF in breast cancer patients undergoing AHSCT to reduce ES-related morbidity.     

Regulation of immunomodulatory functions by granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor in vivo

 The present study was designed to investigate in vivo immunomodulatory properties of hematopoietic growth factors. The influence on the activation of cytokine synthesis and on the expression of surface antigens associated with cellular activation of G-CSF or GM-CSF was investigated in cancer patients receiving these factors. One single dose of growth factor was administered to patients with bladder cancer (G-CSF group) or small cell lung cancer (GM-CSF group) before chemotherapy. After cytoreductive chemotherapy patients received supportive therapy with G-CSF or GM-CSF. Peripheral blood mononuclear cells and plasma samples were obtained for flow cytometry, Northern blot analysis, and assessment of cytokine protein levels after single-dose as well as after continous cytokine administration. Our results demonstrate differences in the induction of biological activities by GM-CSF and G-CSF in vivo which correlate well with in vitro findings. Among mature hematopoietic cells the effect of G-CSF is restricted to the granulocyte lineage. With GM-CSF moderate but unequivocal modulation of monocyte function was observed. On peripheral blood monocytes expression of MHC class-II molecules and CD44 was markedly stimulated. After one single dose of GM-CSF, plasma levels of sCD25 and IL-1RA were significantly induced (p<0.0001, p=0.032, respectively) and a trend to increased IL-8 levels was observed. The changes in plasma proteins were not correlated with shifts of mRNA expression for IL-8 and IL-1RA. T-cell activation was not observed with either cytokine. These results suggest that immunomodulatory features are differentially regulated by G-CSF and GM-CSF. The clinical relevance of a selective use of both hematopoietic growth factors in various disease settings remains to be determined. Received: 20 March 1996 / Accepted: 19 July 1996     

Mobilization of peripheral blood progenitor cells (PBPC) in patients undergoing chemotherapy followed by autologous peripheral blood stem cell transplant (SCT) for high risk breast cancer (HRBC).

We have determined the effect of delayed addition of G-CSF after chemotherapy on PBPC mobilization in a group of 30 patients with high risk breast cancer (HRBC) undergoing standard chemotherapy followed by high-dose chemotherapy (HDCT) and autologous SCT. Patients received FAC chemotherapy every 21 days followed by G-CSF at doses of 5 microg/kg/day starting on day +15 (groups 1 and 2) or +8 (group 3) after chemotherapy. PBPC collections were performed daily starting after 4 doses of G-CSF and continued until more than 2.5 x 10(6) CD34+ cells had been collected. In group 1, steady-state BM progenitors were also harvested and used for SCT. Groups 2 and 3 received PBPC only. The median number of collections was three in each group. Significantly more PB CD34+ cells were collected in patients receiving G-CSF starting on day 8 vs day 15 (9.43 x 10(6)/kg and 6.2 x 10(6)/kg, respectively) (P < 0.05). After conditioning chemotherapy all harvested cells including BM and PBPC were reinfused. Neutrophil and platelet engraftment was significantly faster in patients transplanted with day 8 G-CSF-mobilized PBPC (P < 0.05) and was associated with lower transplant related morbidity as reflected by days of fever, antibiotics or hospitalization (P < 0.05). Both schedules of mobilization provided successful long-term engraftment with 1 year post-transplant counts above 80% of pretransplant values. In conclusion, we demonstrate that delayed addition of G-CSF results in successful mobilization and collection of PBPC with significant advantage of day 8 G-CSF vs day 15. PBPC collections can be scheduled on a fixed day instead of being guided by the PB counts which provides a practical advantage. Transplantation of such progenitors results in rapid short-term and long-term trilineage engraftment.     

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in serum in bone marrow transplanted patients.

Colony-stimulating factors (CSF) are being increasingly used to accelerate hematopoietic recovery after bone marrow transplantation. To study the endogenous serum levels of CSF in bone marrow transplanted patients we have used immunoassays measuring granulocyte-macrophage colony-stimulating factor (GM-CSF) with a sensitivity of 0.10 ng/ml and granulocyte colony-stimulating factor (G-CSF) with a sensitivity of 0.05 ng/ml. Serum samples, taken from the conditioning treatment until engraftment, were analysed in 13 patients receiving allogeneic transplants and in eight patients receiving autologous transplants. Ten patients had acute myeloid leukemia, seven acute lymphoblastic leukemia, one acute undifferentiated leukemia, two non-Hodgkin's lymphoma and one multiple myeloma. Samples were taken 1-2 times before transplantation and 1-2 times per week after transplantation (median of 46 days in allotransplant recipients and 32 days in autotransplant recipients); 17% of the allogeneic transplanted patients and 35% of the autologous transplanted patients had detectable levels of G-CSF. In both types of transplantation the G-CSF concentrations were low: median 0.06 (range 0.05-0.14) and 0.08 (range 0.05-0.40) ng/ml respectively. GM-CSF was detected only in one analysed sample in all patients. There was no evidence of increased CSF levels related to engraftment or documented infections.     

Hematopoietic recovery following high-dose combined alkylating-agent chemotherapy and autologous bone marrow support in patients in phase-I clinical trials of colony-stimulating factors: G-CSF,GM-CSF,IL-1, IL-2, M-CSF

Summary Hematopoietic recovery in 115 patients with metastatic breast cancer or metastatic melanoma, enrolled in phase-I studies of recombinant growth factors while undergoing treatment with high-dose chemotherapy with autologous bone marrow support, was examined with assays of bone marrow progenitor cells and peripheral blood progenitor cells, and by evaluation of peripheral blood counts. Groups of patients receiving hematopoietic cytokine support [with interleukin-1 (IL-1), interleukin-2 (IL-2), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), or monocyte CSF (M-CSF)] post marrow infusion were compared with contemporaneous control patients not receiving growth factor support. Patients receiving GM-CSF demonstrated statistically significant increases in the growth of granulocyte/macrophage colony-forming units (CFU-GM) in the bone marrow and peripheral blood compared with control patients. The effect of GM-CSF was dose dependent in the early period post marrow infusion (day +6) with bone marrow CFU-GM colonies at doses 8–16 g/kg/ day 34 times those measured in controls. Significant increases in bone marrow multipotential progenitor cells (CFU-GEMM) were seen in patients receiving GMCSF day + 21 post marrow infusion. Patients receiving IL-1 demonstrated significant increases in bone marrow CFU-GM at day +21, maximal at dosages of 24–32 ng/kg/day. There were no significant increases in burst forming unit-erythroid (BFU-E) among any study group. Patients receiving G-CSF had significantly increased absolute neutrophil counts (ANC) and total white blood cell counts (WBC) by day +11 post transplant compared with control patients. Patients receiving GM-CSF demonstrated significantly increased WBC (greater than 2000/mm³) at day +11 and ANC greater than 500/mm³ at day +16. Optimal dose of GCSF and GM-CSF to stimulate neutrophil recovery post transplant was 4–8 g/kg/day and 8–16 g/kg/day, respectively. Platelet recovery did not differ among the six study groups. These data demonstrate accelerated myeloid recovery after high-dose chemotherapy and autologous bone marrow support in patients receiving either G-CSF or GM-CSF. Moreover, GM-CSF and IL-1 stimulate myelopoiesis at the level of bone marrow CFU-GM, while G-CSF causes earlier neutrophil recovery peripherally.This work has been supported in part by The National Heart, Lung, and Blood Institute, grant P01CA47741. Joanne Kurtzberg, MD is a scholar of the Leukemia Society of America     

Use of cytokines during prolonged neutropenia associated with autologous bone marrow transplantation.

Molecular cloning, expression, and formulation of recombinant myeloid colony-stimulating factors (CSFs) have afforded the potential to reduce therapy-associated toxicity in patients who receive intensive chemotherapy. The use of granulocyte CSF and granulocyte-macrophage CSF has resulted in acceleration of hematopoietic recovery in patients undergoing autologous bone marrow transplantation. This acceleration is associated with a reduction of treatment-related toxicity, although a period of absolute leukopenia prevails despite infusion of bone marrow and recombinant CSFs. Addition of CSF-primed peripheral blood progenitor cells to bone marrow in the supportive care of these patients has provided a further reduction in the duration of absolute leukopenia and an associated reduction in the incidence of infections and other complications associated with bone marrow transplantation. The ability of CSFs to mobilize hematopoietic progenitor cells offers the possibility of utilizing these cells for a variety of medical purposes, including modification of the therapeutic approach to malignant disease.     

Recombinant human thrombopoietin in combination with granulocyte colony-stimulating factor enhances mobilization of peripheral blood progenitor cells, increases peripheral blood platelet concentration, and accelerates hematopoietic recovery following high-dose chemotherapy

Lineage-specific growth factors mobilize peripheral blood progenitor cells (PBPC) and accelerate hematopoietic recovery after high-dose chemotherapy. Recombinant human thrombopoietin (rhTPO) may further increase the progenitor-cell content and regenerating potential of PBPC products. We evaluated the safety and activity of rhTPO as a PBPC mobilizer in combination with granulocyte colony-stimulating factor (G-CSF) in 29 breast cancer patients treated with high-dose chemotherapy followed by PBPC reinfusion. Initially, patients received escalating single doses of rhTPO intravenously (IV) at 0.6, 1.2, or 2.4 micrograms/kg, on day 1. Subsequent patients received rhTPO 0.6 or 0.3 micrograms/kg on days -3, -1, and 1, or 0.6 micrograms/kg on days -1 and 1. G-CSF, 5 micrograms/kg IV or subcutaneously (SC) twice daily, was started on day 3 and continued through aphereses. Twenty comparable, concurrently and identically treated patients (who were eligible and would have been treated on protocol but for the lack of study opening) mobilized with G-CSF alone served as comparisons. CD34(+) cell yields were substantially higher with the first apheresis following rhTPO and G-CSF versus G-CSF alone: 4.1 x 10(6)/kg (range, 1.3 to 17.6) versus 0.8 x 10(6)/ kg (range, 0.3 to 4.2), P =.0003. The targeted minimum yield of 3 x 10(6) CD34(+) cells/kg was procured following a single apheresis procedure in 61% of the rhTPO and G-CSF-mobilized group versus 10% of G-CSF-mobilized patients (P =.001). In rhTPO and G-CSF mobilized patients, granulocyte (day 8 v 9, P =.0001) and platelet recovery (day 9 v 10, P =.07) were accelerated, and fewer erythrocyte (3 v 4, P =.02) and platelet (4 v 5, P =.02) transfusions were needed compared with G-CSF-mobilized patients. Peripheral blood platelet counts, following rhTPO and G-CSF, were increased by greater than 100% and the platelet content of PBPC products by 60% to 110% on the first and second days of aphereses (P <.0001) with the greatest effect seen with repeated dosing of rhTPO at 0.6 microgram/kg. rhTPO is safe and well tolerated as a mobilizing agent before PBPC collection. Mobilization with rhTPO and G-CSF, in comparison to a comparable, nonrandomized G-CSF-mobilized group of patients, decreases the number of apheresis procedures required, may accelerate hematopoietic recovery, and may reduce the number of transfusions required following high-dose chemotherapy for breast cancer.     

Comparison of megakaryopoiesis in vitro of paired peripheral blood progenitor cells and bone marrow harvested during remission in patients with acute myeloid leukaemia

We have studied paired peripheral blood progenitor cells (PBPC) and bone marrow (BM) samples from 12 acute myeloid leukaemia (AML) patients following intensive chemotherapy, and assessed direct granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), megakaryocyte CFU (CFU-Mk) numbers and the production of CD61+ (platelet glycoprotein IIIa) cells in suspension culture in response to various haemopoietic growth factor combinations. We found that CFU-GM and BFU-E numbers per 105 mononuclear cells were similar in both AML PBPC and BM harvests; CFU-Mk numbers, however, were significantly higher in PBPC than BM. In addition, the higher total white cell count of the PBPC harvests meant that PBPC have much higher numbers of total progenitors per collection. CD61+ cell numbers in suspension cultures of AML PBPC and BM were lower than those of harvested normal marrow. However, response to pegylated recombinant human megakaryocyte growth and development factor (PEGrHuMGDF) both alone and in combination with other growth factors was qualitatively similar to that of normal BM. As with normal BM, response to PEGrHuMGDF alone did not increase further with addition of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), interleukin 6 (IL-6) or erythropoietin (EPO) in the AML PBPC and BM. Further responses over PEGrHuMGDF alone were seen when added with stem cell factor (SCF) or with a combination of SCF + IL-3 + EPO in both AML PBPC and BM cultures; however, the magnitude of the response was greater in the PBPC cultures. Response to PEGrHuMGDF + IL-3 was seen in the PBPC cultures but not in the AML BM. These data suggest that, in AML patients, there are proportionally more megakaryocyte progenitor cells in the mobilized PBPC than in the BM harvests, which would explain the more rapid platelet recovery following PBPC autografts.     

Enhanced antileukemic activity of allogeneic peripheral blood progenitor cell transplants following donor treatment with the combination of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) in a murine transplantation model

Allogeneic peripheral blood progenitor cells (PBPCs) have mostly been mobilized by granulocyte colony-stimulating factor (G-CSF). There is neither clinical nor experimental data available addressing the question if other hematopoietic growth factors or combinations thereof might influence engraftment, graft-versus-host disease (GvHD), and graft-versus-leukemia (GvL) effects after allogeneic peripheral blood progenitor cell transplantation (PBPCT). We used a murine model to investigate these parameters after transplantation of PBPCs mobilized with G-CSF and SCF either alone or in combination. Treatment of splenectomized DBA and Balb/c mice with 250 microg/kg/day G-CSF for 5 days resulted in an increase of CFU-gm from 0 to 53/microl. The highest progenitor cell numbers (147/microl) were observed after treatment with 100 microg/kg/day SCF administered in conjunction with G-SCF. No differences were detected with regard to the number of T cells (CD3+), T cell subsets (CD4+, CD8+), B cells (CD19+) and NK cells (NK1.1+) in PBPC grafts mobilized by G-CSF plus SCF compared to those mobilized with G-CSF alone. The antileukemic activity of syngeneic and MHC-identical allogeneic PBPC grafts was investigated in lethally irradiated Balb/c mice bearing the B-lymphatic leukemia cell line A20. In this model, PBPCs mobilized by G-CSF plus SCF exerted a significantly higher antileukemic activity compared to grafts mobilized by G-CSF alone (94 vs 71% freedom from leukemia at day 100, P<0.05). The antileukemic effect was lowest after BMT (38% freedom from leukemia). Since significant differences in the incidence of lethal GvHD were not observed, improved GVL-activity resulted in superior overall survival. Our data demonstrate that the utilization of specific hematopoietic growth factors not only improve the yield of hematopoietic progenitor cells but can also significantly enhance the immunotherapeutic potential of allografts.     

Peripheral blood progenitor cells mobilized by recombinant human granulocyte colony-stimulating factor plus recombinant rat stem cell factor contain long-term engrafting cells capable of cellular proliferation for more than two years as shown by serial transplantation in mice

Mobilized peripheral blood progenitor cells (PBPC) have been shown to provide rapid engraftment in patients given high-dose chemotherapy. PBPC contain cells with long-term engraftment potential as shown in animal models. In this study we have further analyzed mobilized PBPC for their ability to support serial transplantation of irradiated mice. Transplantation of recombinant human granulocyte colony-stimulating factor (rhG-CSF) plus recombinant rat stem cell factor (rrSCF) mobilized PBPC resulted in 98% donor engraftment of primary recipients at 12 to 14 months post-transplantation. Bone marrow (BM) cells from these primary recipients were harvested and transplanted into secondary recipients. At 6 months posttransplantation, all surviving secondary recipients had donor engraftment. Polymerase chain reaction (PCR) analysis showed greater than 90% male cells in spleens, thymuses, and lymph nodes. Myeloid colonies from BM cells of secondary recipients demonstrated granulocyte/macrophage colony-forming cells (GM-CFC) of male origin in all animals. In comparison, transplantation of rhG-CSF mobilized PBPC resulted in decreased male engraftment in secondary recipients. BM cells from secondary recipients, who originally received PBPC mobilized by the combination of rrSCF and rhG-CSF, were further passaged to tertiary female recipients. At 6 months posttransplantation, 90% of animals had male-derived hematopoiesis by whole-blood PCR analysis. These data showed that PBPC mobilized with rhG-CSF plus rrSCF contained cells that are transplantable and able to maintain hematopoiesis for more than 26 months, suggesting that the mobilized long-term reconstituting stem cells (LTRC) have extensive proliferative potential and resemble those that reside in the BM. In addition, the data demonstrated increased mobilization of LTRC with rhG- CSF plus rrSCF compared to rhG-CSF alone.     

Retroviral transduction of human progenitor cells: use of granulocyte colony-stimulating factor plus stem cell factor to mobilize progenitor cells in vivo and stimulation by Flt3/Flk-2 ligand in vitro

The clinical application of gene transfer is hindered by the availability of the multipotential stem cells and the difficulty in obtaining efficient retroviral transduction. To assess potential means by which gene transfer into human hemopoietic stem cells might be enhanced, the retroviral transduction efficiency of human bone marrow cells (BM) or peripheral blood progenitor cells (PBPC) was compared at multiple time points after in vivo administration of granulocyte colony- stimulating factor (G-CSF). This was further compared with the transduction efficiency of cells mobilized with G-CSF plus stem cell factor (SCF) in a cohort of patients randomized to receive either one or two growth factors and with normal BM function. Using the LNL6 retrovirus, retroviral transduction efficiencies of up to 19% were observed for both PBPC and BM (n = 26 patients). There was at least a 100-fold increase in PBPC with G-CSF alone and a further 30-fold increase in the total number of progenitor cells available for retroviral transduction using the combination of SCF plus G-CSF. However, pretreatment of patients with G-CSF with or without SCF did not enhance the retroviral infectability of growth factor-mobilized progenitor cells. The effect of the growth factor, Flk-2/Flt3 ligand (FL), was also examined with respect to retroviral transduction efficiency of human progenitor cells. FL plus IL-3 in vitro increased the retroviral transduction efficiency up to eightfold compared with results observed using other combinations of cytokines tested (P < .001). These findings have clinical implications both for increasing the number of target cells for in vivo gene-marking/gene-therapy studies and improving the efficiency of gene transfer.