Design of the START-trial: STimulation of ARTeriogenesis using subcutaneous application of GM-CSF as a new treatment for peripheral vascular disease. A randomized, double-blind, placebo-controlled trial

Peripheral arterial disease (PAD) affects a large percentage of the elderly population. Standard invasive treatment, apart from risk factor modulation, consists of bypass surgery or percutaneous transluminal angioplasty. However, symptomatic recurrence rates are high for both procedures and a substantial part of the patient population with PAD is not a candidate for invasive revascularization due to complexity of the lesion and/or co-morbidity. Therapeutic arteriogenesis has been proposed as an alternative treatment option. The present paper describes the design of the START-trial. This trial aims to determine the potential of the pro-arteriogenic substance granulocyte/macrophage colony stimulating factor (GM-CSF) to increase maximal walking distance in patients with intermittent claudication. A double-blinded, randomized, placebo-controlled study will be performed in 40 patients with peripheral obstructive arterial disease Rutherford grade I, category 2 or 3, that are candidates for bypass surgery or percutaneous transluminal angioplasty. Based on pharmacokinetic and toxicologic studies, a dose of 10 microg/kg will be used. Patients will be treated for a period of 14 days on each consecutive day, with the last injection applied on day 12. The primary endpoint will be the change in walking distance from day 0 to day 14 as assessed by an exercise treadmill test. Secondary endpoints will be the ankle-brachial index at rest and after exercise, the pain-free walking distance and cutaneous microcirculatory alterations as assessed by laser Doppler fluxmetry. Iliac flow reserve and conductance will be measured by magnetic resonance imaging.     

Granulocyte-macrophage colony-stimulating factor inhalation therapy for patients with idiopathic pulmonary alveolar proteinosis: a pilot study; and long-term treatment with aerosolized granulocyte-macrophage colony-stimulating factor: a case report

Abstract:   Idiopathic pulmonary alveolar proteinosis (IPAP) is considered to be caused by an autoantibody to the granulocyte-macrophage colony-stimulating factor (GM-CSF), which neutralizes GM-CSF and therefore impairs the differentiation of alveolar macrophages. The authors have previously characterized the BAL fluid and alveolar macrophages obtained from three IPAP patients who were successfully treated with aerosolized GM-CSF and demonstrated restoration of the cell number, expression of surface marker, and phagocytic ability of the alveolar macrophages as well as a decrease in the autoantibody levels in the BAL fluid. The condition recurred in one of the patients after 20 months. This patient underwent a second and third course of GM-CSF inhalation therapy with the same dose and schedule as the first one. Since the second therapeutic intervention did not succeed in producing any improvement in the symptoms and disease markers, the authors used a new nebulizer and a liquid preparation of the drug instead of the lyophilized preparation for the third therapeutic session and this restored the respiratory function considerably. A 6-month maintenance therapeutic regimen with a lower GM-CSF inhalation frequency brought about a further improvement in the disease markers. The results suggest that the efficacy of GM-CSF inhalation therapy might be related to the drug preparation mode, choice of nebulizer, and duration of treatment.     

A pilot study of low-dose recombinant human granulocyte-macrophage colony-stimulating factor in chronic neutropenia

Summary. Recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) is under investigation for the treatment of a wide range of haematological disorders. At commonly used doses of > 120 μg/m²/d, extramedullary toxicity is common. We report the effects of low-dose (LD) rhGM-CSF in patients with chronic neutropenia related to HIV infection, myelodysplastic syndrome and idiopathic neutropenia. Nine patients with a mean pre-treatment neutrophil count of 0·6 × 10⁹/1 (range 0·2–1·4 × 10⁹/1) received daily rhGM-CSF at doses of between 5 and 15 μg/m², Eight patients responded with a mean post-treatment ANC of 3·2 × 10⁹/1 (range 1·9–4·6 × 10⁹/1). There was no significant therapy-related morbidity. We conclude that in chronic neutropenia, LD rhGM-CSF is an acceptable treatment which has important cost/benefit implications.     

Granulocyte colony-stimulating factor versus granulocyte-macrophage colony-stimulating factor for collection of peripheral blood progenitor cells from healthy donors

The harvesting of peripheral blood progenitor cells (PBPCs) after granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor stimulation instead of bone marrow in healthy donors has become increasingly popular. Donors, given the choice between bone marrow and PBPC donation, often prefer cytapheresis because of the easier access, no necessity for general anesthesia, and no multiple bone marrow punctures. In addition, accelerated engraftment and immunomodulation by granulocyte colony-stimulating factor-mobilized PBPCs are advantageous for the recipient. However, because of donor inconvenience and poor mobilization, there is a need to develop improved procedures. Aspects such as durability of hematopoietic engraftment, characterization of the earliest stem cell, and composition of PBPCs are not yet well defined, and international donor registration and follow-up must be considered when evaluating long-term safety profiles in healthy donors. This review concentrates on the most significant developments on mobilization of PBPCs published during the past year.     

Pharmacokinetics of human granulocyte-macrophage colony-stimulating factor using a sensitive immunoassay

A sensitive and reliable sandwich enzyme-linked immunosorbent assay (ELISA) has been developed for recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The assay is quantitative between 100 pg/mL and 2.5 ng/mL for bacterially synthesized hGM-CSF in human serum and is more sensitive and specific than the semisolid agar bioassay. As part of a phase I study, the pharmacokinetics of intravenous (IV) bolus injection and subcutaneous (SC) administration of hGM-CSF were studied. Following a single IV dose, an initial high blood level of hGM-CSF occurred, followed by a rapid decrease occurring in two apparent phases with a half-life (t1/2)alpha of less than five minutes and a t1/2 beta of 150 minutes. After an SC injection, detectable serum levels occurred within 15 to 30 minutes, and serum levels were sustained for a variable time depending on the dose. At the highest SC dose (10 micrograms/kg), a serum level of greater than 1 ng/mL (65 pmol/L) was maintained for greater than 12 hours after a single injection. This corresponds to the concentration of hGM-CSF supporting near-maximum proliferation in vitro.     

Plasma lipids as a risk factor in peripheral vascular disease

Plasma lipids were tested in 59 patients with symptomatic peripheral vascular disease (PVD) (confirmed by angiographic and, in many cases, operative examinations) and compared with the lipid balance in 47 nonarteriopathic subjects constituting the control group. Of all the elements considered, only the hypertriglyceridemia and the fall in the HDL cholesterol/total cholesterol ratio showed a statistically significant difference between the two groups. In particular, there was a significant difference between the two groups. In particular, there was a significant difference in the triglyceridemia present in the arteriopathic patients, as evidenced by the double check afforded by the frequency test (PVD: 25/59; control: 8/47; p less than 0.01) and the averages test (PVD: 201 +/- 131; control: 138 +/- 98; p less than 0.01).     

Granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor: comparisons and potential for use in the treatment of infections in nonneutropenic patients

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) enhance the antimicrobial functions of mature neutrophils. G-CSF differs from GM-CSF in its specificity of action on developing and mature neutrophils, its effects on neutrophil kinetics, and its toxicity profile. The toxicity profile of recombinant (r) GM-CSF is consistent with priming of macrophages for increased formation and release of inflammatory cytokines, whereas rG-CSF induces production of antiinflammatory factors, such as interleukin-1 receptor antagonist and soluble tumor necrosis factor receptors, and is protective against endotoxin- and sepsis-induced organ injury. The low toxicity of rG-CSF, results of animal models of infection, and extensive experience with neutropenic subjects have promoted clinical studies in nonneutropenic subjects, which indicate that rG-CSF may be beneficial as adjunctive therapy for treatment of serious bacterial and opportunistic fungal infections in nonneutropenic patients, including those with alterations in neutrophil function.     

An open-label pilot study of granulocyte colony-stimulating factor for the treatment of severe endoscopic postoperative recurrence in Crohn's disease

BACKGROUND/AIM: Recombinant human granulocyte colony-stimulating factor (rhG-CSF) promoted healing of Crohn's disease (CD)-like intestinal lesions in chronic granulomatous disease and glycogen storage disease Ib, both characterized by defective neutrophil functions. We performed a prospective, open-label pilot study with rhG-CSF for the treatment of CD. PATIENTS AND METHODS: Five patients with clinically inactive CD, but with severe endoscopic ileitis within 1 year after intestinal resection and ileocolonic anastomosis, received 300 microg of rhG-CSF (Filgrastim; Neupogen) subcutaneously, three times weekly for a total of 12 weeks. Safety was evaluated by assessment of clinical and laboratory data and disease activity. The primary parameter of efficacy was complete mucosal healing, as defined by the Rutgeerts score. Anti-inflammatory mediators were repeatedly measured during treatment. RESULTS: All patients completed the protocol in clinical remission. In 1 subject transient headache resolved after halving the rhG-CSF dosage. Complete mucosal healing was observed in 2 patients: in 1 patient after 12 weeks of therapy and in 1 patient 9 months after treatment cessation. In a single patient, closure of an anovaginal and of a perianal fistula was noted. Neutrophil counts and interleukin-1 receptor antagonist and soluble tumor necrosis factor receptor p55 and p75 levels were found to be increased during drug administration. CONCLUSION: rhG-CSF seems to be safe, well tolerated, and might provide efficacy in CD.     

Long-term marrow reconstitutive ability of autologous grafts in lymphoma patients using peripheral blood mobilized with granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor compared to bone marrow

OBJECTIVES: The aim of this study was designed to compare the in vivo long-term hematopoietic potential of bone marrow and peripheral blood grafts. MATERIALS AND METHODS: Marrow progenitor cell recovery was assessed for up to 4 years in 227 patients. One hundred patients were treated for malignant lymphomas by autologous bone marrow transplantation (BMT) and 127 by peripheral blood progenitor cell transplantation (PBPCT). RESULTS: Marrow progenitor cell counts were decreased for several years with both bone marrow and peripheral blood grafts. They were not different according to the origin of the graft, despite the reduced duration of peripheral blood cell recovery observed after PBPCT. Granulocyte colony-stimulating factor (G-CSF) used for PB graft mobilization and after transplantation resulted in faster neutrophil recovery compared to granulocyte-macrophage colony-stimulating factor (GM-CSF) with no evidence of decreased marrow progenitor cell recoveries. On the other hand, postgraft administration of GM-CSF enhanced long-term colony-forming unit granulocyte-macrophage reconstitution only after BMT. Factors that influenced marrow progenitor cell reconstitution have been identified by univariate and multivariate analysis: age, gender, type of lymphoma, and postgraft administration of hematopoietic growth factors (HGF) for the whole patient group; gender, graft progenitor cell yields, and type of HGF (G-CSF vs GM-CSF) for the PBPCT group; and only type of HGF for the BMT group.Despite faster peripheral blood cell recovery, persistent deficiency of marrow progenitor cells was found several years after PBPCT, as observed after BMT. G-CSF-mobilized PBPCT resulted in faster neutrophil recovery compared to GM-CSF mobilization, with no difference in long-term hematopoietic reconstitution.     

Increased production of granulocyte-macrophage colony-stimulating factor in Crohn's disease--a possible target for infliximab treatment

BACKGROUND: The presence of neutrophils among epithelial cells is one of the major features of the inflammation in Crohn's disease, and has been used to indicate disease activity. The survival of neutrophils outside the blood vessels is limited and their longevity is influenced by granulocyte-macrophage colony-stimulating factor (GM-CSF), which probably reduces neutrophil apoptosis. OBJECTIVE: To study GM-CSF production in intestinal cell cultures from Crohn's disease patients before and after infliximab treatment. PATIENTS: Colonic mucosal biopsies were obtained from 29 Crohn's disease patients before and after three infliximab infusions (5 mg/ml) and from ten healthy subjects. METHODS: Biopsies were cultured in RPMI at high concentrations of interleukin-2 (IL-2) (2000 U/ml) and IL-4 (500 U/ml), but without antigen addition. GM-CSF content was analysed after 5 days culture and related to the Crohn's disease activity index (CDAI) and compared with the GM-CSF production from healthy subjects. Peripheral leucocyte count, C-reactive protein and the degree of mucosal inflammation, evaluated histologically, were determined. In-vitro T cell GM-CSF production was studied with/without addition of infliximab and after stimulation. RESULTS: GM-CSF production was increased in Crohn's disease patients compared with healthy controls (P = 0.02) and correlated with the CDAI (Spearman rho = 0.65, P = 0.001). GM-CSF levels and mucosal histology score decreased (P = 0.007 and P = 0.01 respectively) after three infliximab infusions, as did the peripheral blood leucocyte count (P < 0.001). Infliximab inhibited in-vitro T cell GM-CSF production. CONCLUSION: In-vitro cell culture production of GM-CSF was increased in Crohn's disease and related to inflammation, but decreased after infliximab treatment, probably because intestinal T cell GM-CSF production was reduced.     

Granulocyte colony-stimulating factor: a noninvasive regeneration therapy for treating atherosclerotic peripheral artery disease.

BACKGROUND: The purpose of this study was to determine whether treatment with granulocyte colony-stimulating factor (G-CSF), which mobilizes endothelial progenitor cells from bone marrow, can safely improve the clinical outcomes of patients with atherosclerotic peripheral artery disease (PAD). METHODS AND RESULTS: Thirty-nine patients with intractable PAD were randomly assigned to 3 groups: a negative control group (n=12) treated with conventional drug therapy; a positive control group (n=13) treated with conventional drug therapy plus bone marrow transplantation (BMT); and a G-CSF group (n=14) treated with conventional therapy plus subcutaneous injection of 2-5 microg/kg of recombinant human G-CSF once daily for 10 days. One month after treatment, subjective symptoms improved significantly in the G-CSF and BMT groups. Ankle-brachial pressure index and transcutaneous oxygen pressure increased significantly in the BMT and G-CSF groups, but no such improvements were seen in the group receiving conventional therapy alone. CONCLUSIONS: G-CSF improves the clinical signs and symptoms of patients with intractable PAD to the same degree as BMT does. This noninvasive treatment may thus represent a useful new approach to managing the disease.     

Successful treatment of chronic disseminated candidiasis with fluconazole and a granulocyte-macrophage colony-stimulating factor combination.

We report a case of chronic disseminated candidiasis in a patient with acute non-lymphoid leukaemia. After 12 months of combined therapy with fluconazole and granulocyte-macrophage colony-stimulating factor, lesions in the liver and spleen resolved completely. The patient has given birth to a healthy baby and has been in complete hematological remission for 3 years.     

Pulse pressure as a risk factor for peripheral vascular disease in type 2 diabetic patients

This study examined whether pulse pressure (PP) could be an independent predictor and associated with severity of peripheral vascular disease (PVD) in 396 type 2 diabetic patients (143 men and 253 women, aged 64.1 +/- 11.2 years). Peripheral vascular disease was diagnosed by an ankle-brachial index (ABI) < 0.90 and as severe PVD if ABI < 0.80. Association was evaluated before and after adjustment for age, sex, diabetes duration, hypertension, smoking, fasting plasma glucose (FPG), total cholesterol (TC), usage of insulin, and usage of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB); and for systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP), respectively. Results showed that PP increased from no (n = 348) to mild (n = 25) and severe (n = 23) PVD (one-way ANOVA, p < 0.001; multiple comparisons, p < 0.05 for any two groups). The PP increase from no to mild PVD was due to SBP increase; while further increase to severe PVD was due to both DBP drop and an even higher SBP. Adjusted odds ratio (AOR) for PVD for every 1-mmHg PP increment was 1.035 (1.012-1.058). When PP was categorized as tertiles (< 50, 50-59 and > or = 60 mmHg), respective AOR for PVD for second and third vs. first tertile was 2.605 (1.008-6.729) and 2.835 (1.123-7.156). Pulse pressure was also predictive for ABI independent of the effects of the confounders and the other parameters of blood pressure. In conclusion, PP was an independent predictor and correlated with severity of PVD in type 2 diabetic patients.     

High-dose therapy and peripheral blood progenitor cell transplantation: effects of recombinant human granulocyte-macrophage colony-stimulating factor on the autograft

Between June 1989 and June 1992, 144 patients participated in sequential clinical trials using peripheral blood progenitor cells (PBC) as their sole source of hematopoietic rescue following high-dose chemotherapy. All patients had received prior extensive combination chemotherapy and had marrow defects that precluded autologous bone marrow transplantation (ABMT). PBC were collected according to a single apheresis protocol. The initial 86 patients (group 1) had PBC collected without mobilization. Beginning in April 1991, PBC were mobilized solely with recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF). Thirty-four patients (group 2) received rHuGM-CSF at a dose of 125 micrograms/m2/d by continuous intravenous infusion, and 24 patients (group 3) received rHuGM-CSF at a dose of 250 micrograms/m2/d by continuous intravenous infusion. Patients underwent at least six aphereses and had a minimum of 6.5 x 10(8) mononuclear cells (MNC)/kg collected. Cytokines were not routinely administered immediately after transplantation. A median of nine aphereses were required to collect PBC in group 1 and seven aphereses for groups 2 and 3 (P = .03). The time required to recover 0.5 x 10(9)/L granulocytes after transplant was significantly shorter (P = .0004) for the mobilized groups; the median time to recovery was 26 days for group 1, 23 days for group 2, and 18 days for group 3. Transplantation of PBC mobilized with rHuGM-CSF resulted in a shorter time to platelet (P = .04) and red blood cell (P = .01) transfusion independence. Mobilization with rHuGM-CSF alone resulted in efficient collection of PBC, that provided rapid and sustained restoration of hematopoietic function following high-dose chemotherapy. Mobilization of PBC with rHuGM-CSF alone is an effective method for patients who have received prior chemotherapy and have bone marrow abnormalities.     

Granulocyte colony-stimulating factor (G-CSF) increases neutrophil migration across vascular endothelium independent of an effect on adhesion: comparison with granulocyte-macrophage colony-stimulating factor (GM-CSF)

Granulocyte colony-stimulating factor (G-CSF) increases neutrophil counts, and enhances and primes many neutrophil functions, implicating a role for this growth factor in host defence. This study investigated whether G-CSF is able to directly influence the transendothelial migration of neutrophils, and how such effects might be related to other effects on neutrophil adhesive properties. G-CSF, like GM-CSF, increased surface levels of the adhesive receptor, CD11b/CD18, but down-regulated L-selectin expression on neutrophils. Unlike GM-CSF, however, G-CSF had no effect on neutrophil adhesion to endothelium. Despite the lack of effect on neutrophil adhesion, G-CSF was able to produce significant enhancement of neutrophil transmigration across unstimulated endothelium in vitro . When used at an optimal concentration of 100 ng/ml, G-CSF increased neutrophil migration to 217 ± 19% of baseline levels ( P <0.001, n  = 10). This effect was similar to that previously demonstrated for GM-CSF (which increased migration to 271 ± 40%, P <0.001, n  = 12). G-CSF-induced transmigration, like GM-CSF induced migration, was independent of concentration gradients, suggesting that these are not simply chemotactic effects. G-CSF differs from GM-CSF, however, in that although GM-CSF inhibited neutrophil migration across IL-1-activated endothelium (33 ± 8% inhibition, n  = 6, P <0.01), G-CSF had no effect on neutrophil migration across IL-1 activated endothelium. Hence G-CSF, despite having no effect on neutrophil adhesion to endothelium, is a powerful stimulator of transmigration, and, unlike GM-CSF, does not inhibit cell movement across inflamed endothelium. These results suggest that G-CSF is able to influence neutrophil recruitment into local infective sites, and, further, that G-CSF mobilized cells would be competent to migrate into tissues in response to inflammatory stimuli.     

Therapeutic use of cytokines to modulate phagocyte function for the treatment of infectious diseases: current status of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor, and interferon-gamma

The innate immune system represents the initial arm of host defense against pathogenic bacteria, fungi, and parasites. Neutrophils, monocytes, and tissue-based macrophages are major cellular components of this system. The potential ability to augment activity of the innate immune system has increased dramatically during the past 2 decades, with the discovery and development of cytokines. Four cytokines, namely granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), and interferon (IFN)-gamma, have received increasing attention as potential adjunctive agents for the treatment of infectious diseases. In various animal models of infection, therapeutic administration of each of the 4 cytokines has been shown to enhance pathogen eradication and to decrease morbidity and/or mortality. However, variable therapeutic efficacy has been reported in clinical trials conducted to date. This review summarizes the current status of the use of G-CSF, GM-CSF, M-CSF, and IFN-gamma in the treatment of infectious diseases.     

Effects of physical training on peripheral vascular disease: a controlled study

The effects of physical exercise on 8 stage II peripheral vascular disease (PVD) patients were observed after a six-month training program. Doppler velocimetry (including the treadmill test), strain gauge plethysmography, and transcutaneous oxygen pressure were used to quantify the results, which were compared with those obtained in a control group of another 8 stage II PVD patients, under placebo therapy for six months. The results show physical exercise increased the walking capacity, both the pain-free walking time and the maximum walking time. No significant difference was observed in the other parameters studied, in either the exercise patients or the control group.     

Sequential administration of recombinant human granulocyte-macrophage colony-stimulating factor and human erythropoietin for treatment of myelodysplasia syndromes

Abstract: Treatment of myelodysplastic syndromes (MDS) with recombinant human erythropoietin (Epo) is successful in only 10% to 25% of patients. We performed a pilot study in 10 anaemic patients with MDS to examine whether sequentially applied recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and Epo improves haemoglobin levels and/or reduces red blood cell transfusion requirements. Morphological diagnoses of patients were refractory anaemia (RA) in 3 cases, RA with ring sideroblasts in 3 cases and RA with excess blasts in 4 cases. GM-CSF was given subcutaneously at a dose of 150 μg/m²/d during the initial 10 days. From day 11, Epo was administered by subcutaneous injections for 8 weeks at a dose of 100 U/kg/d and subsequently at an escalated dose of 200 U/kg/d in 3 patients. Changes in reticulocyte counts, haemoglobin levels, RBC support and ferrokinetic parameters were compared with pretreatment values. Two out of 8 évaluable patients showed a rise in haemoglobin levels at week 8 and 10, respectively, and lost their transfusion dependency for a period of 13 and 27 weeks. In 1 patient, haemoglobin level increased only after dose escalation of Epo (200 U/kg/d). Leukocyte counts remained uneffected by treatment with Epo, while 1 patient showed a 4-fold increase in platelet numbers. Toxicity was mild. Two patients died of pneumonia and global heart failure, respectively, unrelated to growth factor therapy. Based on this pilot study, we conclude that sequential treatment with GM-CSF and Epo does not increase erythroid responses in anaemic patients with MDS. Because of the delayed increase in haemoglobin in both responders, we surmise that the beneficial effects were induced by Epo alone.     

Interferon alfa-2b alone or combined with recombinant granulocyte-macrophage colony-stimulating factor as treatment of chronic hepatitis C

BACKGROUND: To compare the effect of combination therapy with interferon-alpha (INF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) to monotherapy with INF-alpha in patients with chronic hepatitis C infection. METHODS: Forty-five consecutive patients with chronic hepatitis C, all presenting with elevated serum alanine aminotransferases and viremia, were randomized to receive either 1) INF-alpha + GM-CSF for 3 months followed by INF-alpha alone for 9 months (n = 23) or 2) INF-alpha for 12 months (n = 22). Both drugs were administered 3 times weekly in doses of 3 mU (INF-alpha) and 50-100 microg depending on body weight (GM-CSF). RESULTS: At baseline, there was no difference between the treatment groups in terms of age, sex, ALT level, viral load, genotype or histological activity and fibrosis in a pretreatment liver biopsy. After 12 months' treatment, more patients treated with GM-CSF+ INF-alpha compared to patients receiving monotherapy had normalized ALT, 65% and 32%, respectively (P = 0.03), but there was no difference in percentages of patients with viral clearance between the 2 groups, 48% and 32%, respectively (P = 0.27). At 6 months' follow-up, the biochemical response had declined to 35% in the combination therapy group and to 23% in the monotherapy group (P = 0.37); viral clearance had declined to 22% and 27%, respectively (P = 0.67), and the overall sustained response rate was 22% and 23%, respectively (P = 1.00). CONCLUSIONS: Even though patients receiving INF-alpha + GM-CSF had a significant better biochemical response during treatment compared to patients receiving monotherapy, the sustained biochemical and virological response was not increased. Thus, GM-CSF hardly plays any role in the future treatment of chronic hepatitis C.