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Tumour-necrosis-factor-related apoptosis-inducing ligand (TRAIL) is being investigated as a targeted cancer therapeutic and the expression of its pro-apoptotic receptors, DR4 and DR5, increases during colorectal carcinogenesis. This study investigated the role of β-catenin in the regulation of these receptors. In human colorectal adenoma and carcinoma cell lines, downregulation of β-catenin resulted in lower total DR4 and DR5 protein levels. Similarly, cell membrane expression of DR4 and DR5 was reduced after downregulation of β-catenin in colon carcinoma cells, whereas induction of β-catenin in HeLa cells led to increased cell membrane expression of DR4 and DR5. Downregulation of β-catenin decreased the recombinant human TRAIL sensitivity of human colon carcinoma cells. Activation of the transcription factor T-cell factor-4 (TCF-4) is an important function of β-catenin. Dominant-negative TCF-4 overexpression, however, did not significantly affect TRAIL receptor expression or recombinant human TRAIL sensitivity. Human colorectal adenomas (N = 158) with aberrant (cytoplasmic and nuclear) β-catenin expression had a higher percentage of immunohistochemical DR4 and DR5 staining per tumour (mean: 73 and 88%, respectively) than those with membranous β-catenin staining only (mean: 50 and 70%, respectively, P < 0.01 for both). Furthermore, aberrant β-catenin staining co-localized with DR4 and DR5 expression in 92% of adenomas. In 53 human colorectal carcinomas, aberrant β-catenin expression was present in most cases and DR4/5 expression was largely homogenous. Similarly, in adenomas from APCmin mice, cytoplasmic β-catenin staining co-localized with staining for the murine TRAIL death receptor. In conclusion, the gradual increase in TRAIL receptor expression during colorectal carcinogenesis is at least partially mediated through increased β-catenin expression, independently of TCF-4-signalling. [ABSTRACT FROM AUTHOR]

To assess tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and clinical activity of the dual epidermal growth factor receptor (EGFR) 1 and 2 (HER2) tyrosine kinase inhibitor BIBW 2992. An escalating schedule of once-daily (OD) BIBW 2992 for 14 days followed by 14 days off medication was explored. Thirty-eight patients were enrolled. Dose levels were 10, 20, 30, 45, 70, 85, and 100 mg. At 100 mg dose-limiting toxicity (DLT) (common toxicity criteria grade 3 skin rash and grade 3 diarrhoea despite treatment with loperamide) occurred in two patients. In the next-lower dose of 70 mg, DLT (grade 3 fatigue and ALAT elevation) occurred in one of six patients. An intermediate dose level of 85 mg was studied. Here DLT occurred in two patients (grade 3 diarrhoea despite treatment and grade 2 diarrhoea lasting more than 7 days despite treatment). An additional 12 patients were treated at 70 mg. BIBW 2992 PK after single and multiple doses revealed moderately fast absorption, and no deviation from dose proportionality. Pharmacodynamics analysis in skin biopsies did not show significant changes in EGFR-associated biomarkers. However, a significant inhibitory effect on the proliferation index of epidermal keratinocytes was observed. No partial or complete responses were observed, stable disease lasting more than four cycles was seen in seven patients. The recommended dose for studies with BIBW 2992 for 14 days followed by 14 days off medication is 70 mg OD.British Journal of Cancer (2008) 98, 80–85. doi:10.1038/sj.bjc.6604108 www.bjcancer.com Published online 20 November 2007 [ABSTRACT FROM AUTHOR]

The aim of these meta-analyses was to evaluate the effectiveness of interventions for the prevention of oral mucositis in cancer patients treated with head and neck radiotherapy and/or chemotherapy, with a focus on randomized clinical trials. A literature search was performed for reports of randomized controlled clinical studies, published between 1966 and 2004, the aim of which was the prevention of mucositis in cancer patients undergoing head and neck radiation, chemotherapy, or chemoradiation. The control group consisted of a placebo, no intervention, or another intervention group. Mucositis was scored by either the WHO, the National Cancer Institute-Common Toxicity Criteria (NCI-CTC) score, or the absence or presence of ulcerations, or the presence or absence of grades 3 and 4 mucositis. The meta-analyses included 45 studies fulfilling the inclusion criteria, in which 8 different interventions were evaluated: i.e., local application of chlorhexidine; iseganan; PTA (polymyxin E, tobramycine, and amphotericin B); granulocyte macrophage-colony-stimulating factor/granulocyte colony-stimulating factor (GM-CSF/G-CSF); oral cooling; sucralfate and glutamine; and systemic administration of amifostine and GM-CSF/G-CSF. Four interventions showed a significant preventive effect on the development or severity of oral mucositis: PTA with an odds ratio (OR) = 0.61 (95% confidence interval [CI], 0.39-0.96); GM-CSF, OR = 0.53 (CI: 0.33-0.87); oral cooling, OR = 0.3 (CI: 0.16-0.56); and amifostine, OR = 0.37 (CI: 0.15-0.89). To date, no single intervention completely prevents oral mucositis, so combined preventive therapy strategies seem to be required to ensure more successful outcomes. [ABSTRACT FROM AUTHOR]

The aim of these meta-analyses was to evaluate the effectiveness of interventions for the prevention of oral mucositis in cancer patients treated with head and neck radiotherapy and/or chemotherapy, with a focus on randomized clinical trials. A literature search was performed for reports of randomized controlled clinical studies, published between 1966 and 2004, the aim of which was the prevention of mucositis in cancer patients undergoing head and neck radiation, chemotherapy, or chemoradiation. The control group consisted of a placebo, no intervention, or another intervention group. Mucositis was scored by either the WHO, the National Cancer Institute-Common Toxicity Criteria (NCI-CTC) score, or the absence or presence of ulcerations, or the presence or absence of grades 3 and 4 mucositis. The meta-analyses included 45 studies fulfilling the inclusion criteria, in which 8 different interventions were evaluated: i.e., local application of chlorhexidine; iseganan; PTA (polymyxin E, tobramycine, and amphotericin B); granulocyte macrophage-colony-stimulating factor/granulocyte colony-stimulating factor (GM-CSF/G-CSF); oral cooling; sucralfate and glutamine; and systemic administration of amifostine and GM-CSF/G-CSF. Four interventions showed a significant preventive effect on the development or severity of oral mucositis: PTA with an odds ratio (OR) = 0.61 (95% confidence interval [CI], 0.39-0.96); GMCSF, OR = 0.53 (CI: 0.33-0.87); oral cooling, OR = 0.3 (CI: 0.16-0.56); and amifostine, OR = 0.37 (CI: 0.15-0.89). To date, no single intervention completely prevents oral mucositis, so combined preventive therapy strategies seem to be required to ensure more successful outcomes. [ABSTRACT FROM AUTHOR]

Crijns APG, Duiker EW, de Jong S, Willemse PHB, van der Zee AGJ, de Vries EGE. Molecular prognostic markers in ovarian cancer: toward patient-tailored therapy. Int J Gynecol Cancer 2006; 16(Suppl. 1):152–165. In ovarian cancer the ceiling seems to be reached with chemotherapeutic drugs. Therefore a paradigm shift is needed. Instead of treating all patients according to standard guidelines, individualized molecular targeted treatment should be aimed for. This means that molecular profiles of the distinct ovarian cancer subtypes should be established. Until recently, most studies trying to identify molecular targets were single-marker studies. The prognostic role of key components of apoptotic and prosurvival pathways such as p53, EGFR, and HER2 has been extensively studied because resistance to chemotherapy is often caused by failure of tumor cells to go into apoptosis. However, it is more than likely that different ovarian cancer subtypes with extensive molecular heterogeneity exist. Therefore, exploration of the potential of specific tumor-targeted therapy, based on expression of a prognostic tumor profile, may be of interest. Recently, new profiling techniques, such as DNA and protein microarrays, have enabled high-throughput screening of tumors. In this review an overview of the current status of prognostic marker and molecular targeting research in ovarian cancer, including microarray studies, is presented. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cryopreservation and autografting of ovarian tissue may preserve fertility after cancer treatment, but could be hampered by tumour cell contamination. Epithelial tumour cell lysis can be obtained with cytotoxic T cell retargeting through the bispecific antibody BIS‐1, with combined affinity for the T‐cell receptor and epithelial glycoprotein‐2 (EGP‐2). Our aim was to study the concept of tumour cell purging in the setting of a suspension of ovarian tissue. METHODS: Human ovarian tissue was brought into suspension by mechanical and enzymatic treatment. Cells of the MCF‐7 breast cancer cell line and activated human lymphocytes were co‐ incubated for 4 h with or without BIS‐1 and with or without ovarian suspension. After incubation, MCF‐7 cell death and cell growth were evaluated by fluorescent cell detection and MTT assay, respectively. Ovarian tissue morphology was evaluated immunohistochemically. RESULTS: MCF‐7 cell death and cell growth inhibition increased with increasing ratios of lymphocytes to MCF‐7 cells. BIS‐1 addition gave further augmentation, with a maximum depletion of growing MCF‐7 cells of 89% (SD 11%) versus without BIS‐1, 23% (SD 15%; P < 0.001). Follicles remained morphologically intact. CONCLUSIONS: Purging of added epithelial tumour cells from ovarian tissue with BIS‐1 is possible in vitro. Morphologically, follicles remain intact after this procedure. This method may contribute to safer replacement of ovarian tissue in female cancer survivors. [ABSTRACT FROM AUTHOR]

Background: Ursodeoxycholic acid (UDCA) has been shown to affect membrane-damaging effects of bile acids in vitro and fecal bile acid composition in rats. This study evaluates the effect of UDCA on fecal bile acid composition and on cytolytic activity of fecal water in man to clarify the potential chemopreventive role of UDCA for colorectal cancer. Methods: In this placebo-controlled crossover intervention trial, the effect of 900 mg/day UDCA orally in 15 healthy volunteers was studied. At the end of each 4-week period, 72 h feces were collected. Total and individual bile acids in feces were determined by gas chromatography and soluble bile acids were analyzed by high-performance liquid chromatography. Cytolytic activity of fecal water was measured using an erythrocyte lysis assay. Results: In feces, the percentages of primary bile acids—cholic acid (CA) and chenodeoxycholic acid (CDCA)—and of secondary bile acid—deoxycholic acid (DCA)—decreased after supplementation with UDCA, whereas those of UDCA and LCA increased from 2.7 ± 0.4% to 23.7 ± 2.6%, P < 0.0001 and from 26.2 ± 1.2% to 49.4 ± 1.8%, P < 0.0001 respectively. The concentrations of these two bile acids in fecal water also increased after UDCA administration from 7.8 ± 1.9 µmol/l to 47.0 ± 6.7 µmol/l (UDCA), P < 0.0001 and from 2.5 ± 0.6 µmol/l to 18.3 ± 4.1 µmol/l (LCA), P < 0.002, respectively. Cytolytic activity of fecal water was not affected by UDCA. Conclusion: These results do not support a protective effect of UDCA supplementation against colorectal cancer in man. [ABSTRACT FROM AUTHOR]

The doxorubicin analogue MEN-10755 has been identified as a compound with promising antitumour activity based on structure-activity studies of a new series of anthracycline disaccharides. The high antitumour activity of MEN-10755 in human tumour xenografts, including doxorubicin-resistant xenografts, and its unique pharmacological and biological properties made this novel disaccharide analogue an interesting candidate for clinical evaluation. Two pharmacokinetic phase I studies with different dosing schedules were performed in adults with solid refractory malignancies. The pharmacokinetics of MEN-10755 were studied after a 15-min i.v. infusion given once every 3 weeks or once every week for 3 weeks followed by 1 week rest. Plasma and urine levels of MEN-10755 were measured by HPLC with fluorescent detection. It was possible to combine the pharmacokinetic results of the two studies because there was no accumulation of MEN-10755 before the next infusion of MEN-10755 in the weekly study with 1 week rest. The administered dose levels on day 1 in this study were all in the lower range from the 3-weekly study. The postinfusion plasma kinetics of MEN-10755 were best described by a triexponential model. The plasma peak levels (Cmax) of MEN-10755 showed a linear relationship with the administered dose. Peak plasma MEN-10755 levels ranged between 474 and 21,587 µg/l. The mean elimination half-life (T1/2γ) was 20.7±9.0 h. The AUC0–∞ was proportional to the administered dose. The mean plasma clearance of MEN-10755 was 6.0±2.2 l/h per m2 with a mean volume of distribution (Vss) of 95.6±43.4 l/m2. The mean renal excretion of unchanged drug within 24 h was 4.3±1.8%. Compared to epirubicin and doxorubicin, the pharmacokinetics of MEN-10755 were characterized by an approximately twofold shorter terminal half-life, a much lower total plasma clearance and a much smaller volume of distribution. [ABSTRACT FROM AUTHOR]

This paper describes the production of recombinant Semliki Forest virus encoding murine or human granulocyte-macrophage colony-stimulating factor (GM-CSF) and the capacity of these vectors to transduce murine and human tumor cells ex vivo. High-titer stocks (up to 3 × 10[sup 9] particles/ml) of conditionally infective, replication-defective, recombinant SFV particles were generated using the SFV Helper-2 system. It is shown that the recombinant SFV/GM-CSF virus, as well as recombinant SFV carrying the β-galactosidase reporter gene, efficiently transduce both murine tumor cell lines as well as primary human renal carcinoma cells. Using ELISA's specific for GM-CSF, levels of GM-CSF production by the cells were determined. Levels of murine GM-CSF (mGM-CSF) produced by SFV/mGM-CSF transduced renal cell cancer cultures were equal to or higher than corresponding levels reported in the literature after transduction of similar renal carcinoma cell cultures using a retroviral vector system. The biological activity of GM-CSF was demonstrated by using cells which are dependent on GM-CSF for growth and by using primary bone marrow cells. All the transduced cell cultures (including the human renal cell carcinoma samples) produced GM-CSF for up to at least 4 days after transduction. The results imply that the recombinant SFV system can be used for rapid and facile preparation of autoIogous cancer cell vaccines. [ABSTRACT FROM AUTHOR]

The multidrug resistance proteins (MRPs) MRP1, MRP2, MRP3, MRP5 and P-glycoprotein (P-gp) act in concert with each other to give a net resultant pump function in acute myeloid leukemia (AML). The aim of the present study was to analyze the activity of these proteins, which might be upregulated at relapse as compared with de novo AML due to clonal selection. The mRNA expression and activity of P-gp and the MRPs were determined with RT-PCR and flow cytometry, in conjunction with phenotype, as measured with the monoclonal antibodies CD34, CD38 and CD33, in 30 paired samples of de novo and relapsed AML. P-gp and MRP activity varied strongly between the cases (rhodamine 123 efflux-blocking by PSC833: 5.4+/-7.7, and carboxyfluorescein efflux-blocking by MK-571: 4.3+/-6.7, n = 60). P-gp and MRP activity were increased in 23% and 40% of the relapse samples, and decreased in 30% and 20% of the relapse samples, respectively (as defined by a difference of >2 x standard deviation of the assays). Up- or downregulation of mRNA expression was observed for MDR1 (40%), MRP1 (20%), MRP2 (15%), MRP3 (30%), and MRP5 (5%). Phenotyping demonstrated a more mature phenotype in 23% of the relapsed AML cases, and a more immature phenotype in 23% of the relapses, which was independent of the karyotypic changes that were observed in 50% of the studied cases. P-gp and MRP activity correlated with the phenotypic changes, with higher P-gp and MRP activities in less mature cells (r = -0.66, P < 0.001 and r = -0.31, P = 0.02, n = 58). In conclusion, this study shows that P-gp and MRP activity are not consistently upregulated in relapsed AML. However, P-gp and MRP activities were correlated with the maturation stage as defined by immune phenotype, which was observed to be different in 46% of the relapses. [ABSTRACT FROM AUTHOR]

Long-term peripheral blood counts and factors influencing long-term trilineage haematological recovery of consecutive patients in a single institution treated with high-dose chemotherapy (HDC) and ABMT or PSCT for solid tumours were examined. Patients with a relapse-free survival of <1 year were included in the analysis (n = 131). Peripheral blood counts were examined 6 months and yearly following transplantation. Median follow-up was 4.1 years (range 1–10+ years). Three years after transplantation 91% of patients had normal white blood counts (WBC), 94% normal haemoglobin (Hb) and 75% normal platelets. Trilineage recovery was complete in 70% (n = 83) at 3 years and 85% (n = 50) at 5 years. Recovery of Hb occurred before WBC and platelet recovery. Approximately 25% of patients displayed an elevated MCV throughout the follow-up period. These long-term results were independent of age, high-dose regimen, number of reinfused stem cells and stem cell source. Double (n = 12) vs single (n = 119) transplantations showed significantly slower trilineage recovery and higher MCV. No secondary graft failure, myelodysplasia or leukaemia was encountered. In conclusion, complete trilineage recovery after HDC followed by ABMT or PSCT occurs slowly. PSCT and ABMT are capable of maintaining long-term haematopoiesis. Slower recovery is seen after double transplantations. The results suggest lasting implications for bone marrow function after autologous transplantation. Bone Marrow Transplantation (2001) 27, 959–966. [ABSTRACT FROM AUTHOR]

In this study we determined the in vivo localization of recombinant proteins expressed by intraperitoneally (i.p.) injected recombinant Semliki Forest virus (SFV) particles. Subsequently, we investigated the influence of i.p. administered SFV particles encoding recombinant murine granulocytemacrophage colony-stimulating factor (rmGM-CSF) on intraperitoneal recruitment and activation of cells. Finally, the therapeutic effect of SFV-GM-CSF treatment on an i.p. growing ovarian tumor was determined. Intraperitoneal injections of recombinant SFV particles encoding the reporter protein luciferase resulted in a high level of luciferase activity in cells of the peritoneal lining and tumor cells in the peritoneal cavity. Low levels of luciferase activity were found in liver, spleen and lungs. Injection of SFV-GM-CSF particles resulted in a slight increase in the number of peritoneal macrophages and in a significant increase in the number of neutrophils. In contrast to multiple i.p. injections with commercially available recombinant GM-CSF, i.p. injected SFVGM-CSF particles activated the macrophages to tumor cytotoxicity. Although treatment of tumor-bearing mice with SFVGM-CSF particles did not result in prolonged survival, tumor growth was inhibited for 2 weeks. Our findings indicate that macrophage-activating cytokines expressed by the efficient and safe recombinant SFV system when administered i.p. may provide an immunotherapeutic treatment modality additional to current chemotherapeutic treatment of intraperitoneally growing cancers. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess renal function in patients treated with the oral platinum drug JM216 [bisacetato-ammine-dichloro-cyclohexylamine-platinum(IV)], since the effects of JM216 on renal function have only partly been investigated using serum parameters or 51Cr-EDTA clearance. We used a sensitive method that assessed glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and indicators of tubular and glomerular damage. Methods: A group of 24 patients with either non-small-cell lung cancer (NSCLC) stage IIIb/IV or small-cell lung cancer (SCLC), limited disease (LD) or extensive disease (ED), treated with JM216 were studied. All patients had no prior chemotherapy, a performance score <2, a life expectancy of more than 3 months and normal liver, renal and bone marrow functions before treatment. All patients received oral JM216 120 mg/m2 per day for 5 consecutive days, repeated every 21 days with a maximum of six cycles. In six SCLC patients the dose was escalated to 140 mg/m2 per day after the first cycle. Prior to treatment, after the first cycle and after the end of treatment renal function was assessed by 125I-sodium thalamate and 131I-hippurate clearances to determine acute and cumulative changes in GFR and ERPF, respectively. Furthermore, tubular and glomerular damage were assessed by urinary excretion of β2-microglobulin, lactic dehydrogenase (LDH), alkaline phosphatase (ALP), gamma-glutamyltransferase (GT) and albumin. Results: In 20 evaluable patients no significant acute impairment of renal function was observed. Median (range) GFR, ERPF and filtration fraction (FF) before treatment were 101 ml/min (53–164 ml/min), 417 ml/min (227–719 ml/min), and 0.25 (0.19–0.33), respectively. After the first cycle values were 117 ml/min (71–189 ml/min), 418 ml/min (228–709 ml/min) and 0.28 (0.21–0.33), respectively. Also, no indications of tubular or glomerular damage were found. In four patients renal function was evaluated at the end of treatment (one after three cycles, one after five cycles and two after six cycles). Median (range) GFR, ERPF and FF were 99 ml/min (74–139 ml/min), 401 ml/min (277–496 ml/min) and 0.26 (0.23–0.30), respectively, revealing no delayed nephrotoxicity. Conclusion: We conclude that oral JM216 shows no nephrotoxicity. [ABSTRACT FROM AUTHOR]

Abstract. Various mechanisms are involved in multidrug resistance (MDR) for chemotherapeutic drugs, such as the drug efflux pumps, P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP). In this review the mechanisms involved in MDR are described and results are reviewed with particular attention to the in vivo imaging of Pgp and MRR Various detection assays provide information about the presence of drug effiux pumps at the mRNA and protein levels. However, these methods do not yield information about the dynamic function of Pgp and MRP in vivo. For the study of Pgp and MRP-mediated transport, single-photon emission tomography (SPET) and positron emission tomography (PET) are available. Technetium-99m sestamibi is a substrate for Pgp and MRP, and has been used in clinical studies for tumour imaging, and to visualize blockade of Pgp-mediated transport after modulation of the Pgp pump. Other [sup 99m]Tc radiopharmaceuticals, such as[sup 99m]Tetetrofosmin and several [sup 99]Tc-Q complexes, are also substrates for Pgp, but to date only results from in vitro and animal studies are available for these compounds. Several agents, including [[sup 11]C]colchicine, [[sup 11]C]verapamil and [[sup 11]C]daunorubicin, have been evaluated for the quantification of Pgp-mediated transport with PET in vivo. The results suggest that radio-labelled colchicine, verapamil and daunorubicin are feasible substrates with which to image Pgp function in tumours. Uptake of [[sup 11]C]colchicine and [[sup 11]C]verapamil is relatively high in the chest area, reducing the value of both tracers for monitoring... [ABSTRACT FROM AUTHOR]

Reinfusion of autologous hematopoietic peripheral blood stem cells (PBSC) or bone marrow is often accompanied by flushing, dyspnea, abdominal cramping, nausea and diarrhea. These symptoms and the observation that they can be prevented by ondansetron, a selective 5-HT3 receptor antagonist, led to the assumption that these side-effects are due to infusion of free serotonin during the reinfusion of PBSC or bone marrow. Twenty-five patients with solid tumors received, after myeloblative chemotherapy, a total of 30 reinfusions of PBSC and/or bone marrow. In 17 patients, serotonin levels in the bags containing the PBSC were measured. In all patients, platelet serotonin levels were determined before and 1 h post-reinfusion. In addition, before and 24 h after reinfusion urine was collected for determination of 5-hydroxyindole acetic acid (5-HIAA) and serotonin concentrations. Mean (± s.d.) total serotonin concentration in the bags was 2404 ± 1555 nmol/l. Mean total volume reinfused was 471 ± 185 ml. After reinfusion, the mean (± s.d.) levels of serotonin in platelets in patients increased from 3.2 ± 1.4 nm/109 at baseline to 3.8 ± 2.0 nm/109 (P = 0.02). Neither 24 h urinary 5-HIAA nor serotonin levels were affected. These results indicate that reinfusion of PBSC or bone marrow is accompanied by substantial infusion of free serotonin, which might explain the observed side-effects and justify the use of 5-HT3 receptor antagonists as pre- medication for this procedure. [ABSTRACT FROM AUTHOR]

We studied the effect of recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF) on the cytotoxic potential of murine peritoneal cells. Mice received rmGM-CSF intraperitoneally using different dosages and injection schemes. At different time points after the last injection, mice were sacrificed, peritoneal cells isolated and their tumour cytotoxicity was determined by a cytotoxicity assay using syngeneic [methyl-[SUP3]H]thymidine-labelled colon carcinoma cells. Also, the cytotoxic response to a subsequent in vitro stimulation with lipopolysaccharide was determined. Upon daily injection of 6000-54 000 U rmGM-CSF over a 6-day period, the number of peritoneal cells increased over ten fold with the highest rmGM-CSF dose. Increases in cell numbers was mainly due to increases in macrophage numbers. Upon injection of three doses of 3000 U rmGM-CSF per day for 3 consecutive days, the number of macrophages remained elevated for minimally 6 days. Although the peritoneal cells from rmGM-CSF-treated mice were not activated to a tumoricidal state, they could be activated to high levels of cytotoxicity with an additional in vitro stimulation of lipopolysaccharide. Resident cells isolated from control mice could be activated only to low levels of tumour cytotoxicity with lipopolysaccharide. Tumour cytotoxicity strongly correlated with nitric oxide secretion. When inhibiting nitric oxide synthase, tumour cell lysis decreased. Thus, the expanded peritoneal cell population induced by multiple injections of rmGM-CSF has a strong tumour cytotoxic potential and might provide a favourable condition for immunotherapeutic treatment of peritoneal neoplasms. [ABSTRACT FROM AUTHOR]