G- and GM-CSF in oncology and oncological haematology

Paradoxical role of alveolar macrophage-derived granulocyte-macrophage colony-stimulating factor in pulmonary host defense post-bone marrow transplantation

Impaired host defense post-bone marrow transplant (BMT) is related to overproduction of prostaglandin E(2) (PGE(2)) by alveolar macrophages (AMs). We show AMs post-BMT overproduce granulocyte-macrophage colony-stimulating factor (GM-CSF), whereas GM-CSF in lung homogenates is impaired both at baseline and in response to infection post-BMT. Homeostatic regulation of GM-CSF may occur by hematopoietic/structural cell cross talk. To determine whether AM overproduction of GM-CSF influenced immunosuppression post-BMT, we compared mice that received BMT from wild-type donors (control BMT) or mice that received BMT from GM-CSF-/- donors (GM-CSF-/- BMT) with untransplanted mice. GM-CSF-/- BMT mice were less susceptible to pneumonia with Pseudomonas aeruginosa compared with control BMT mice and showed antibacterial responses equal to or better than untransplanted mice. GM-CSF-/- BMT AMs displayed normal phagocytosis and a trend toward enhanced bacterial killing. Surprisingly, AMs from GM-CSF-/- BMT mice overproduced PGE(2), but expression of the inhibitory EP(2) receptor was diminished. As a consequence of decreased EP(2) receptor expression, we found diminished accumulation of cAMP in response to PGE(2) stimulation in GM-CSF-/- BMT AMs compared with control BMT AMs. In addition, GM-CSF-/- BMT AMs retained cysteinyl leukotriene production and normal TNF-alpha response compared with AMs from control BMT mice. GM-CSF-/- BMT neutrophils also showed improved bacterial killing. Although genetic ablation of GM-CSF in hematopoietic cells post-BMT improved host defense, transplantation of wild-type bone marrow into GM-CSF-/- recipients demonstrated that parenchymal cell-derived GM-CSF is necessary for effective innate immune responses post-BMT. These results highlight the complex regulation of GM-CSF and innate immunity post-BMT.

Granulocyte function in elderly patients receiving chemotherapy for aggressive non-Hodgkin's lymphoma. Effect of granulocyte colony-stimulating factor

BACKGROUND: Treatment with granulocyte colony-stimulating factor (G-CSF) is given in order to mitigate chemotherapy-induced granulocytopenia and the risk of infectious complications, which constitute a major threat to elderly patients, in particular, with malignant disorders. The aim of this study was to evaluate whether G-CSF therapy would improve granulocyte defence mechanisms against infectious agents in this elderly, high-risk patient population. METHODS: Fourteen elderly (>60 years) patients with aggressive non-Hodgkin's lymphoma were enrolled in the study. Using flow cytometry we studied the expression of CD11b, before and after stimulation with fMLP, and CD16, as well as granulocyte metabolic activation measured as intracellular accumulation of dichlorofluorescein during induction chemotherapy. Eight patients were randomised to receive G-CSF treatment (5 &mgr;g/kg) on days 2-15. Granulocyte studies were done regularly during one 3-week cycle of chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP) or CNOP (doxorubicin substituted by mitoxantrone). RESULTS: Patients receiving G-CSF showed a faster restitution of granulocyte counts. Granulocyte CD11b expression following fMLP stimulation in vitro decreased during G-CSF therapy (P<0.005). A less pronounced (but not significant) reduction in CD16 expression was noted in the G-CSF-treated group. In contrast, fMLP-stimulated metabolic activation did not show consistent changes during the treatment cycle. Two episodes of infections during granulocytopenia that required hospitalisation were observed in each group. CONCLUSIONS: G-CSF treatment efficiently accelerated granulocyte recovery following chemotherapy. This probably compensates for the transient functional aberrations in circulating granulocytes observed in this patient group.

Diurnal variations of serum GM-CSF levels

We aimed to investigate the daily variations of serum granulocyte-macrophage colony-stimulating factor (GM-CSF) levels and to correlate them with peripheral blood cells counts. Venous blood samples from eleven healthy volunteers were taken four times a day, being at 08:00, 14:00, 20:00 and 02:00h and serum GM-CSF levels measured by ELISA. We could not find a significant overall difference among GM-CSF levels at four different times of the day using the Friedman test. On the other hand, serum GM-CSF levels at night (20:00h) were found to be significantly increased when compared to the morning levels (08:00h) using the Wilcoxon test (P=0. 022). The levels of lymphocytes and white blood cells (WBCs) at 20:00h were also higher than the morning levels (08:00h) as expected. While there was a strong relationship between the morning levels of GM-CSF (08:00h) and all measurements of peripheral blood cells during the day, the levels of GM-CSF measured at 02:00, 14:00 and 20:00h were found to be significantly correlated with only the WBC levels. It was concluded that there may be a significant difference between morning and night levels of GM-CSF and morning levels of GM-CSF may be more important in the regulation of WBC counts during the day. These variations warrant further studies about diurnal rhythms of haematopoiesis chronotherapy with CSFs.

The role of granulocyte-macrophage-colony stimulating factor, cortisol, and melatonin in the regulation of the circadian rhythms of peripheral blood cells in healthy volunteers and patients with breast cancer

The circulating blood cells show highly reproducible circadian rhythms. However, the factors that regulate these rhythms are not well understood. In the current study, we examined the diurnal variations of peripheral blood cells (white blood cells, neutrophils, lymphocytes), granulocyte-macrophage-colony stimulating factor (GM-CSF), and melatonin levels, and considered the role of melatonin on these rhythms in healthy volunteers and in patients with early breast cancer. Fourteen premenopausal patients with early stage breast cancer (T2, N1 tumors) and 10 premenopausal healthy volunteers were included in the study. Blood samples were taken every 4 hr for a period of 24 hr. Peripheral blood cells were counted by automated analyser and also from peripheral blood films. GM-CSF levels were measured by ELISA and melatonin levels by radioimmunoassay (RIA). Serum melatonin, cortisol, and GM-CSF levels, and peripheral blood cell counts showed significant circadian rhythms in healthy volunteers. Except for GM-CSF, these circadian rhythms were found not to be suppressed in early breast cancer patients. While there were significant correlations of serum GM-CSF and cortisol levels with peripheral blood cell counts in healthy volunteers, only lymphocyte counts were found to be significantly correlated with serum GM-CSF and cortisol levels in patients with breast cancer. Serum melatonin levels were found to be significantly correlated with lymphocyte counts in both groups. Our results suggest that peripheral blood cells show significant circadian rhythms in both healthy volunteers and in patients with stage II (T2, N1) breast cancer, and GM-CSF, cortisol, and melatonin may have a role in the regulation of peripheral blood cell counts.

Granulocyte, granulocyte-macrophage, and macrophage colony-stimulating factors can stimulate the invasive capacity of human lung cancer cells

We and other researchers have previously found that colony-stimulating factors (CSFs), which generally include granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF), promote invasion by lung cancer cells. In the present study, we studied the effects of these CSFs on gelatinase production, urokinase plasminogen activator (uPA) production and their activity in human lung cancer cells. Gelatin zymographs of conditioned media derived from human lung adenocarcinoma cell lines revealed two major bands of gelatinase activity at 68 and 92 kDa, which were characterized as matrix metalloproteinase (MMP)-2 and MMP-9 respectively. Treatment with CSFs increased the 68- and 92-kDa activity and converted some of a 92-kDa proenzyme to an 82-kDa enzyme that was consistent with an active form of the MMP-9. Plasminogen activator zymographs of the conditioned media from the cancer cells showed that CSF treatment resulted in an increase in a 48-55 kDa plasminogen-dependent gelatinolytic activity that was characterized as human uPA. The conditioned medium from the cancer cells treated with CSFs stimulated the conversion of plasminogen to plasmin, providing a direct demonstration of the ability of enhanced uPA to increase plasmin-dependent proteolysis. The enhanced invasive behaviour of the cancer cells stimulated by CSFs was well correlated with the increase in MMPs and uPA activities. These data suggest that the enhanced production of extracellular matrix-degrading proteinases by the cancer cells in response to CSF treatment may represent a biochemical mechanism which promotes the invasive behaviour of the cancer cells.

Effects of high dose medroxyprogesterone acetate on endogenous granulocyte macrophage-colony stimulating factor secretion and bone marrow cellularity in patients under cytotoxic chemotherapy

Endogenous cytokine release and bone marrow cellularity of cancer patients receiving chemotherapy were investigated to elucidate the effect of high dose medroxyprogesterone acetate (MPA). MPA (1000 mg/day p.o.) was started after the first cycle of chemotherapy in patients with neutropenia. Administration of MPA was stopped a week after the second cycle of chemotherapy. Blood samples and bone marrow aspirations were obtained for granulocyte macrophage-colony stimulating factor (GM-CSF) assay one week after the first and second cycles of chemotherapy. GM-CSF levels and bone marrow cellularities were compared before and after MPA treatment. Twelve of fifteen patients included in the study had a significant decrease in endogenous cytokine (GM-CSF) secretion after high dose MPA treatment. This result supports the hypothesis that decreased cytokine release leads to a decrease in myeloid progenitor cell proliferation and protects cells from the cytotoxic effects of chemotherapy. As a result of this protection, the myeloid cell population increases in bone marrow. No changes in erythrocytes and platelet counts were obtained.

G-CSF increases secretion of urokinase-type plasminogen activator by human lung cancer cells

We reported previously that granulocyte colony-stimulating factor (G-CSF) can promote the invasion of human lung cancer cell lines in vitro. However, the exact mechanism of its stimulatory effect on invasion remains to be elucidated. In the present study we mainly focused our attention on the components of the plasminogen activation system in human lung cancer cell lines, because of the central role that plasminogen activators play in regulating extracellular proteolysis. We showed that G-CSF induced a dose-dependent increase in the urokinase-type plasminogen activator (uPA) activity in the conditioned medium of a PC-9 lung cancer cell line. When the amounts of uPA activity were quantitated by densitometry, we found that even at a concentration of 0.01 microg/ml, G-CSF had a stimulatory effect on the uPA release, while high concentrations caused a 3.6-fold increase at a maximum concentration of 1 microg/ml. A Western blot analysis of the conditioned medium confirmed the findings observed in a zymographic analysis. The observed increase in uPA protein was paralleled by a significant increase in the uPA mRNA levels after treatment with G-CSF. However, our experiments failed to identify any alteration in the plasminogen activator inhibitor (PAI) secretion caused by G-CSF. In addition, we also found the expression of G-CSF receptor by PC-9 cells, suggesting the possible pathway activated by G-CSF.

Ribosomal proteins sustain morphology, function and phenotype in acute myeloid leukemia blasts

Translation of mRNA is a prerequisite for cell proliferation, differentiation and viability. We have studied the effect of ribosome protein factors (GPRE) on acute myeloid leukemia (AML) blast cells. Ribosomes were isolated from MPC-11 cells using ultra-centrifugation. GPRE were extracted using a high KCl procedure. Blast cells from six AML patients were grown in suspension cultures for 24 and 96 h. GPRE or granulocyte macrophage-colony stimulating factor (GM-CSF) were added at the start of the incubation. GPRE, but not GM-CSF, prevented chromatin condensation and fragmentation of blast cell nuclei in AML-M2, -M4 and -M5 and the loss of nucleoli in AML-M2 and -M5. The fraction of phagocytosing blast cells in AML-M1, -M2, -M4 and -M5 was increased by GPRE. GPRE stimulated opsonin-dependent and -independent attachment and internalisation of N. meningitidis. GPRE increased the fraction of blasts expressing CD11b and CD32 in AML-M2 and -M5. GPRE diminished the fraction of AML-M5 cells bearing CD35 and CD32. GPRE also decreased the fraction of CD11c-bearing AML-M2 and -M5 cells. GM-CSF potentiated effects of GPRE in AML-M1, -M2, -M4 and -M5. GPRE and GM-CSF in combination affected phagocytosis and surface antigen expression in blast cells that were not influenced by either factor alone. Neither GPRE nor GM-CSF induced terminal differentiation or DNA-synthesis. We conclude that GPRE affects AML blast cell morphology, function and surface molecule expression, possibly by inhibiting apoptosis. The effects of GPRE may be mediated by ribosomal proteins that regulate translation and modulate the subcellular distribution of mRNA species.

Granulocyte colony-stimulating factor and drugs elevating extracellular adenosine synergize to enhance haematopoietic reconstitution in irradiated mice

The activation of adenosine receptors has recently been demonstrated to stimulate haematopoiesis. In the present study, we investigated the ability of drugs elevating extracellular adenosine to influence curative effects of granulocyte colony-stimulating factor (G-CSF) in mice exposed to a sublethal dose of 4 Gy of 60Co radiation. Elevation of extracellular adenosine in mice was induced by the combined administration of dipyridamole, a drug inhibiting the cellular uptake of adenosine, and adenosine monophosphate (AMP), an adenosine prodrug. The effects of dipyridamole plus AMP, and G-CSF, administered either alone or in combination, were evaluated. The drugs were injected to mice in a 4-d treatment regimen starting on d 3 after irradiation and the haematopoietic response was evaluated on d 7, 10, 14, 18 and 24 after irradiation. While the effects of G-CSF on the late maturation stages of blood cells, appearing shortly after the completion of the treatment, were not influenced by dipyridamole plus AMP, positive effects of the combination therapy occurred in the post-irradiation recovery phase which is dependent on the repopulation of haematopoietic stem cells. This was indicated by the significant elevation of counts of granulocyte-macrophage progenitor cells (GM-CFC) and granulocytic cells in the bone marrow (d 14), of GM-CFC (d 14), granulocytic and erythroid cells (d 14 and 18) in the spleen, and of neutrophils (d 18), monocytes (d 14 and 18) and platelets (d 18) in the peripheral blood. These effects suggest that the repopulation potential of the combination therapy lies in a common multilineage cell population. The results of this study implicate the promising possibility to enhance the curative effects of G-CSF under conditions of myelosuppressive states induced by radiation exposure.

Effect of granulocyte-macrophage colony-stimulating factor on the number of leucocytes and course of Listeria monocytogenes infection in naive and leucocytopenic mice

This study concerns the effect of recombinant murine granulocyte-macrophage colony-stimulating factor (GM-CSF) on the number of circulating leucocytes, activation of peritoneal macrophages and proliferation of Listeria monocytogenes in various organs of naive and leucocytopenic mice. Mice were rendered leucocytopenic by sublethal total body irradiation or cyclophosphamide treatment. GM-CSF treatment enhanced the number of granulocytes and monocytes in peripheral blood during L. monocytogenes infection in naive mice, but not in irradiated or cyclophosphamide-treated mice. In naive mice, irradiated and cyclophosphamide-treated mice, GM-CSF did not affect the course of L. monocytogenes infection in thigh muscle, spleen and liver. However, GM-CSF treatment significantly increased the number of macrophages in the peritoneal cavity of naive mice during infection; these macrophages were more enlarged and showed a higher frequency of binucleated and multinucleated cells relative to non-GM-CSF-treated mice. Together, these results demonstrated that GM-CSF increased the number of circulating granulocytes and monocytes, and the number of peritoneal macrophages during infection with L. monocytogenes in naive mice, but did not affect the course of the infection in thigh muscle, spleen or liver of these mice. In leucocytopenic mice, however, GM-CSF did not affect the number of circulating phagocytes, which explains that this factor had no effect on the proliferation of the bacteria in the various organs.

The increasing efficacy of breast cancer treatment

Breast cancer is the commonest malignancy in women and although identification of this multi-system disease has increased, the survival rates have not dramatically altered over the past four decades. Optimium treatment of patients with breast cancer is a subject of great debate and traditionally may be divided into surgery, radiotherapy, chemotherapy and hormone manipulation. Halsted's radical mastectomy, although initially superseded by more mutilating surgery involving removal of tumour, breast, pectoral muscles and axillary contents, has given way to more conservative surgery and breast conservation, so now removal of the tumour with a marginal of healthy tissue is possible. Additional loco-regional radiotherapy has added to the increasing number of treatment options available to both doctor and patient. Systemic adjuvant therapy, primarily hormonal therapy, is used with the aim of decreasing the incidence of recurrence and distant tumour development. Through the process of randomized controlled trials these new therapeutic treatments have shown to be effective in the treatment of locoregional disease. Surgery in patients with advanced systemic disease is limited, however radiotherapy is of considerable importance and can be used to treat or palliate sites of metastases. In recent years trials have assessed chemotherapeutic regimens. However, limited number of patients and adequate randomization have hindered the confident acceptance of these results. Cyclophosphamide, methotrexate and 5 fluorouracil still remain the standard chemotherapeutic regimen, however many new drugs are currently undergoing trials and these or combinations of these may prove to be of future clinical use. Dramatic advances in cell and molecular biology have allowed the development of novel breast cancer therapies. Specific oncogenes and loss of tumour suppressor genes have been associated with decrease patient survival, with the presence of lymph node metastases and with decreased relapse free survival. Growth factor receptor blockers and tyrosine kinase inhibitors may be developed to specifically eradicate breast cancer cells. Immunotherapy and gene therapy may produce effective therapies. Trials utilizing cytokines and trials increasing the immunogenicity of tumours have already reported promising results. Surgery, chemotherapy, radiotherapy and hormone manipulation are the major treatment arms of breast cancer therapy. However, breast cancer still accounts for 20 percent of all female cancer deaths and the overall survival of patients has remained relatively static over the past forty years. From our increasing understanding of the pathological processes involved in the development and spread of breast cancer, new pharmaceutical, immunological and gene therapies may dramatically increase the cure rate of this serious disease.

In vitro effects of recombinant human granulocyte-macrophage colony-stimulating factor (RhGM-CSF) on polymorphonuclear cell (PMN) and monocyte (MO) functional capacities in ovarian cancer patients versus human volunteers

Human polymorphonuclear cells (PMN) and monocytes (MO) from four ovarian cancer patients and seventeen normal donors were in vitro pretreated with different concentrations (25, 50 and 100 IU, respectively) of rhGM-CSF. Phagocytosis and killing of PMN and MO as well as PMN polarization were evaluated in cancer patients before treatment (T0) and at the end of each chemotherapeutic cycle (T1, T2, T3 and T4, respectively) in comparison with normal donors. RhGM-CSF did not affect phagocytosis and killing of PMN and MO. On the other hand, this cytokine was per se endowed with the capacity to enhance PMN polarization in both cancer patients (at T2 interval) and normal donors.

Successful treatment of herpes simplex virus (HSV) recurrent genital infection with recombinant human (rh) granulocyte-macrophage colony stimulating factor (GM-CSF): a case report

In the present work, we describe the treatment with rhGM-CSF of a woman affected by HSV recurrent genital infection and not responsive to specific antiviral therapy. The therapeutic regimen consisted of a subcutaneous administration of 300 mg/day of rhGM-CSF for six days. Before treatment with rhGM-CSF, polymorphonuclear cell and monocyte functional capacities and the antibacterial activity exerted by T cells were profoundly depressed. After treatment, a normalization of immune functions and a progressive disappearance of clinical manifestations were observed.

Effect of high-dose medroxyprogesterone acetate on tumor necrosis factor-alpha release in patients with chemotherapy-induced neutropenia

The aim of the study was to investigate the effects of high-dose medroxyprogesterone acetate (MPA) on the tumor necrosis factor-alpha (TNF-alpha) release in patients with chemotherapy-induced neutropenia. We also evaluated the effects of high-dose MPA on hematological parameters (leukocyte, neutrophil, platelet, hemoglobin, hematocrit) and side effects of MPA. One week following the first cycle chemotherapy, 20 patients who developed neutropenia were enrolled in the study. One gram/day MPA was administered orally to the patients and was continued from one week following the first chemotherapy cycle to one week after the second chemotherapy cycle. The patients received the second chemotherapy cycle at the same dosages as the first cycle. Before MPA treatment TNF-alpha levels were lower than post-treatment levels, but the difference was not statistically significant (P > 0.05). The differences in the mean leukocyte and neutrophil counts before and after the high-dose MPA treatment were statistically significant (p < 0.05).

G-CSF (filgrastim) as an adjunct to MOPP/ABVD therapy in Hodgkin's disease

The main objective of this study was to assess to what extent filgrastim (G-CSF, Amgen-Roche) can facilitate administration of the full dose intensity of MOPP/ABVD chemotherapy to patients with Hodgkin's disease. Sixteen patients with Hodgkin's disease were treated with MOPP/ABVD and filgrastim support between January 1992 and March 1994. Twenty-five patients treated with MOPP/ABVD 1987-1991 served as historical controls. The two groups were well matched for age, gender, stage, performance status and histological subgroups, but in the study group more patients had B-symptoms (p < 0.05). Dose intensity (DI) was calculated in mg/m2/week and the intended average dose was designated as 1. The planned average DI was reached by 8/16 patients in the study group but by only 1/25 in the control group (p < 0.001). The reasons for decreased DI in the study group were neutropenia (n = 5), thrombocytopenia (2 pts) and neurotoxicity (n = 1). In the control group the reason for decreased DI was neutropenia (n = 24). In the study group 15/16 patients achieved Complete Response (CR), 2/15 relapsed and 15/16 were surviving after a median follow-up 31 (6-48) months. In the control group 25/25 patients attained CR, 5/25 relapsed and 20/25 were surviving after a median follow up 67 (12-100) months. No severe toxicity was observed during filgrastim therapy. To conclude, the dose intensity during MOPP/ABVD therapy was significantly higher if filgrastim was administered, but the additional benefit that this confers remains to be determined. A large scale, retrospective analyses of treatment response and actual dose-intensity should help answer this question and give guidance as to if and when hematopoietic growth factors should be administered to patients with Hodgkin's disease.

Effect of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) on chemotherapy-induced myelosuppression in patients with chronic lymphocytic leukemia: a crossover study

Patients with advanced, refractory chronic lymphocytic leukemia (CLL) have an high morbidity and mortality from infections following chemotherapy-induced myelosuppression. A crossover study on the prophylactic effect of GM-CSF therapy on neutropenia was carried out in 12 patients with advanced CLL. The patients received GM-CSF in association with every second cycle of COP (cyclophosphamide, vincristine, prednisone) chemotherapy. A total of 40 COP cycles were analyzed. Blood neutrophil levels were significantly higher two to three weeks after the first COP cycle followed by GM-CSF (medians 2.24 and 5.47 x 10(9)/l) when compared to the first cycle without GM-CSF support (0.59 and 0.75 x 10(9)/l; p < 0.0195 and <0.002, respectively). In the next two cycles the same tendency persisted, although the difference was not statistically significant. There were no significant differences in the number of febrile days, days on intravenous antibiotics, hospitalization days, or the number of red blood cell transfusions. Mortality during COP treatment was 8%. In conclusion, GM-CSF efficiently ameliorates chemotherapy-induced neutropenia in CLL patients with a poor bone marrow reserve due to advanced disease.

Complications of cyclophosphamide therapy

Cyclophosphamide is a powerful immunosuppressive agent that is commonly used clinically to treat neoplastic and inflammatory diseases affecting various sites, including the head and neck. The pharmacology of cyclophosphamide is reviewed with an emphasis on its toxicities and strategies for minimizing therapeutic adverse effects. Principles of therapy are discussed and illustrated by the use of cyclophosphamide in the treatment of Wegener's granulomatosis, a form of systemic vasculitis with prominent head and neck manifestations.

Hematopoietic growth factors in cancer patients with invasive fungal infections

Hematopoietic growth factors have been used in prophylaxis and treatment of neutropenic febrile episodes. Granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) are the most common growth factors in clinical use. Both successfully shorten the duration of neutropenia following myelo-suppressive or myeloablative chemotherapy. The influence of G-CSF and GM-CSF on documented infections and mortality from infections is less obvious. There is no clear evidence that treatment with growth factors reduces the incidence of fungal infections. Since mortality is not affected, considerations of morbidity and cost effectiveness currently dominate the indication for use of growth factors. At current costs, their use is indicated in prophylaxis when the likelihood of developing neutropenic febrile episodes following chemotherapy is 40% or more.

Continuous infusion or subcutaneous injection of granulocyte-macrophage colony-stimulating factor: increased efficacy and reduced toxicity when given subcutaneously

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a haematopoietic growth factor with a wide variety of applications in the clinic. In early phase I studies the continuous intravenous (c.i.) route of administration was often used. Later it was shown that subcutaneous (s.c.) administration was also effective. The optimal route of administration remains, however, poorly defined, and no studies have made a direct comparison between these two routes of administration. We treated patients with advanced breast cancer with moderately high-dose doxorubicin and cylophosphamide and GM-CSF. The first 14 patients received GM-CSF by c.i, while subsequently 47 patients received it s.c. Comparison between the two groups showed that c.i. GM-CSF was more toxic in several respects. There was a higher need for erythrocyte and platelet transfusions and a significant deterioration in the performance status. This study indicates that subcutaneous GM-CSF is the preferred route of administration. Randomised trials are, however, needed to confirm these conclusions.

Granulocyte-colony stimulating factor promotes invasion by human lung cancer cell lines in vitro

The effects of exogenous and endogenous granulocyte colony-stimulating factor (G-CSF) on invasion by cancer cells were studied, using lung cancer cell lines that produce G-CSF (NCI-H157) and lines that do not (PC-9 and NCI-H23). The invasive capacity of NCI-H157 cells was 26- to 27-fold higher than that of PC-9 and NCI-H23 cells. The invasiveness of PC-9 cells was stimulated by exogenous G-CSF, while that of NCI-H157 cells was not. Antibodies against G-CSF blocked the stimulation of PC-9 cell invasiveness by exogenous G-CSF. Anti G-CSF antibodies also inhibited invasion by NCI-H157 cells in the absence of exogenous G-CSF. These results suggest that endogenous and exogenous G-CSF both stimulate invasion by lung cancer cells.

Aging and haemopoiesis. Implications for treatment with haemopoietic growth factors

Senescence of the lympho-haemopoietic system is associated with an increased incidence of neoplasia, autoimmune diseases and infections. Myelosuppression, either in the context of cancer chemotherapy or in the face of severe infections, commonly manifests as pancytopenia, and has an adverse impact on the prognosis of the elderly cancer patient by increasing infection and bleeding-related morbidity. The physiological basis of this blunted haemopoietic response is unclear, and has been ascribed to age-related deficits in marrow progenitor cell numbers, changes in the marrow microenvironment, decreased production of regulatory growth factors, or a combination of these mechanisms. These age-related deficits tend to be subtle and are only of clinical importance either when present cumulatively or under conditions of extreme haemopoietic stress. Furthermore, some of these deficits can be circumvented with the use of haemopoietic growth factors (HGFs). Thus, the availability in the clinic of various HGFs has had a tremendous impact on the care of the elderly cancer patient. The HGFs currently approved for use are: granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor and epoetin-alpha (recombinant human erythropoietin). However, we still need to better elucidate age-related changes in the early stages of haemopoiesis. The question of haemopoietic exhaustion, particularly under prolonged growth factor stimulation, is real and still unanswered.

Granulocyte-macrophage colony-stimulating factor accelerates growth of Lewis lung carcinoma in mice

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has not been found to exert any influence on the proliferation of Lewis lung carcinoma (LLC) cells in vitro. Nevertheless, when administered intraperitoneally, GM-CSF accelerated the growth of subcutaneously growing LLC in mice.

Inhibition of enriched stem cells in vivo and in vitro by the hemoregulatory peptide SK&F108636

Replacement of the labile sulfhydryl group (-SH) of the hemoregulatory peptide monomer pyroGluGluAspCysLys (HP5b) with an isosteric methylene group yields a chemically stable compound, SK&F108636. In this study, we describe the effects of SK&F108636 on highly enriched Lin-Sca1+ hematopoietic stem cells. SK&F108636 significantly reduced the fraction of cycling progenitor cells, granulocyte macrophage colony-forming cells (GM-CFC), in vitro and in vivo. There was no effect on GM-CFC or Mix-CFC colony formation. SK&F108636 significantly inhibited proliferation of high proliferative potential (HPP)-CFC in semisolid agar cultures stimulated by stem cell factor + interleukin 3 (IL-3) + IL-1, but had no effect in cultures stimulated with M-CSF + IL-3 + IL-1. SK&F108636 was shown to act directly on the stem cells since SK&F108636 inhibited proliferation of Lin-Sca1+ cells in single cell assays. Administration of SK&F108636 to lethally irradiated mice transplanted with 2000 Lin-Sca1+ cells significantly inhibited proliferation/differentiation of cells developing into colony forming units-spleen (CFU-S) (preCFU-S) and the reconstitution of HPP-CFC and GM-CFC. There was no effect of SK&F108636 on CFU-S colony formation or mature cell regeneration in bone marrow, spleen and blood. Hence, the hemoregulatory peptide monomer SK&F108636 is a potent primitive stem cell inhibitor in vivo and in vitro. Inhibition of stem cell proliferation by small specific inhibitors may protect hematopoiesis from myelotoxic side effects during chemotherapy treatment.

Cyclic AMP-elevating agents down-regulate the oxidative burst induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) in adherent neutrophils

Human neutrophils, plated on fibronectin-precoated wells, were found to release large quantities of superoxide anion (O2-) in response to GM-CSF. O2- production was reduced by prostaglandin E2 (PGE2) and the phosphodiesterase type IV (PDE IV) inhibitor RO 20-1724. Both agents are known to increase intracellular cyclic AMP (cAMP) levels by inducing its production (PGE2) or blocking its catabolism (RO 20-1724). When added in combination, PGE2 and RO 20-1724 had a marked synergistic inhibitory effect, which was reproduced by replacing PGE2 with a direct activator of adenylate cyclase, i.e. forskolin (FK). Moreover, the neutrophil response to GM-CSF was inhibited by a membrane-permeable analogue of cAMP in a dose-dependent manner. As GM-CSF and PGE2 are known to be generated at tissue sites of inflammation, the results suggest the existence of a PGE2-dependent regulatory pathway potentially capable of controlling the neutrophil response to GM-CSF, in turn limiting the risk of local oxidative tissue injury. Moreover, owing to its susceptibility to amplification by RO 20-1724, the PGE2-dependent pathway and in particular PDE-IV may represent a pharmacological target to reduce the generation of histotoxic oxidants by GM-CSF-responding neutrophils.