M. Del Tacca

Relationship between 5-fluorouracil disposition, toxicity and dihydropyrimidine dehydrogenase activity in cancer patients.

BACKGROUND Previous work demonstrated that 5-fluorouracil (5-FU) metabolism is a critical factor for treatment tolerability. In order to study the predictivity of pharmacokinetics with respect to the occurrence of 5-FU toxicity, this study investigates the relationship between the pharmacokinetics of 5-FU and its metabolite 5-fluoro-5,6-dihydrouracil (5-FDHU), dihydropyrimidine dehydrogenase (DPD) activity in peripheral blood mononuclear cells (PBMNC) and treatment tolerability. PATIENTS AND METHODS Pharmacokinetics and metabolism of 5-FU and activity of DPD in PBMNC were examined in 110 colorectal cancer patients given adjuvant 5-FU 370 mg/m2 plus L-folinic acid 100 mg/m2 for five days every four weeks. Drug levels were examined by HPLC. while toxicities were graded according to WHO criteria. RESULTS DPD activity in patients with mild toxicities (WHO grade < or = 1) was 197.22 < or = 11.34 pmol of 5-FDHU/min/ mg of protein, while in five patients with grade 3-4 gastrointestinal toxicity, DPD ranged from low to normal values (range 31.12-182.37 pmol/min/mg of protein). In these patients. 5-FU clearance (CL) was lower (range 14.12-25.17 l/h/m2), and the area under the curve (AUC) was higher (range 14.70-26.20 h x microg/ml) than those observed in 84 patients with mild toxicities (CL, 56.30 +/- 3.60 l/h/M2; AUC, 7.91 +/- 0.44 h x microg/ml). The severity of adverse events was associated with increased 5-FU/5-FDHU AUC ratio and reduced 5-FU CL, while 5-FU and 5-FDHU pharmacokinetics were not related to DPD activity. CONCLUSION This study shows that DPD activity in PBMNC is unrelated to 5-FU/5-FDHU disposition and patients with severe toxicity display marked pharmacokinetic alterations while a reduction of DPD activity may not occur.

Review article: molecular, pathological and therapeutic features of human enteric neuropathies

Background  Considerable information has been gathered on the functional organization of enteric neuronal circuitries regulating gastrointestinal motility. However, little is known about the neuropathophysiological mechanisms underlying gastrointestinal motor disorders.

Dose-finding study and pharmacokinetics of epirubicin and paclitaxel over 3 hours: a regimen with high activity and low cardiotoxicity in advanced breast cancer.

PURPOSE To determine the maximum-tolerated dose (MTD) of paclitaxel over 3 hours with a fixed dose of epirubicin, to investigate the plasma pharmacokinetics of this combination, and to evaluate the toxicity and the activity in previously untreated metastatic breast cancer patients. PATIENTS AND METHODS Fifty patients with metastatic breast cancer, measurable disease, and normal left ventricular ejection fraction (LVEF) were eligible. Epirubicin was administered as an intravenous (I.V.) bolus at the fixed dose of 90 mg/m2 before the infusion of paclitaxel over 3 hours. The initial dose of paclitaxel was 135 mg/m2 and was increased by 20 mg/m2 in subsequent cohorts of six patients until dose-limiting toxicity (DLT). Plasma pharmacokinetics of paclitaxel and epirubicin was performed at cycle 1 in at least two patients per dose level of paclitaxel (175 up to 225 mg/m2). RESULTS The DLT of this combination was febrile neutropenia in two of eight patients who received paclitaxel at 225 mg/m2. The mean peak plasma concentration of paclitaxel ranged between 5.1 and 6.2 micromol/L at doses of 175 to 225 mg/m2. The concentration of epirubicinol decreased from 47.3 +/- 9.4 to 37.9 +/- 7.5 ng/mL in patients treated with paclitaxel 175 and 225 mg/m2. The most relevant toxicity was grade 4 neutropenia (61% of all courses). The pharmacokinetic data of paclitaxel, in particular the time above the threshold level of 0.05 micromol/L, were not significantly related to myelosuppression. Cardiac toxicity was mild: three patients (6%) developed mild congestive heart failure that was responsive to therapy. Among 49 assessable patients, 41 responses (84%; 95% confidence interval [CI], 70% to 92%) were observed, and nine (18%) of these were complete. CONCLUSION Our study demonstrates that (1) the MTD is epirubicin 90 mg/m2 and paclitaxel 200 mg/m2; (2) no clear relationship exists between pharmacokinetic data of paclitaxel and myelosuppression, while the increase in the dose of paclitaxel is associated with a reduction in epirubicinol plasma levels; and (3) the association is feasible, with low cardiotoxicity, and has a high activity in metastatic breast cancer.

Suramin inhibits bFGF-induced endothelial cell proliferation and angiogenesis in the chick chorioallantoic membrane

The effects of suramin, an inhibitor of growth factor mitogenic activity, were evaluated on basic fibroblast growth factor (bFGF)-induced proliferation of bovine aortic endothelial cells and on angiogenesis in the chorioallantoic membrane (CAM) of chick embryos. The role of bFGF gene expression in endothelial cell growth was also investigated by using an antisense oligodeoxynucleotide to bFGF. The 4-fold increase in [3H]-thymidine uptake in endothelial cells in vitro upon stimulation with 10 ng ml-1 of bFGF was inhibited by suramin 300 micrograms ml-1. bFGF antisense oligomer (10 microM) reduced [3H]-thymidine incorporation in exponentially growing cells by 76%; this effect was reversed by bFGF 10 ng ml-1. In the CAM of chick embryos suramin 50 micrograms was a more potent inhibitor of angiogenesis than the combination of heparin 60 micrograms/hydrocortisone 50 micrograms; the mean value of the area with reduced vascularity was significantly larger in suramin-treated CAMs (2.4 cm2) than in heparin/hydrocortisone (0.6 cm2), while the reduction of vascular density was similar (- 35 and - 29% compared to controls, respectively), In conclusion, the effects of treatments with bFGF and bFGF antisense oligomer demonstrate that bFGF plays a relevant role in endothelial cell proliferation and may be the target of suramin since the drug is able to suppress basal and bFGF-induced endothelial cell growth; in addition to this, suramin is a more potent angiogenesis inhibitor in the CAM than the combination of heparin/hydrocortisone.

Antiangiogenic and anticolorectal cancer effects of metronomic irinotecan chemotherapy alone and in combination with semaxinib

Metronomic chemotherapy refers to the administration of chemotherapy at low, nontoxic doses on a frequent schedule with no prolonged breaks. The aim of the study is to rationally develop a CPT-11 metronomic regimen in preclinical settings of colon cancer. In vitro cell proliferation, apoptosis and thrombospondin-1/vascular endothelial growth factor (TSP-1/VEGF) expression analyses were performed on endothelial (HUVEC, HMVEC-d) and colorectal cancer (HT-29, SW620) cells exposed for 144 h to metronomic concentrations of SN-38, the active metabolite of CPT-11. HT-29 human colorectal cancer xenograft model was used, and tumour growth, microvessel density and VEGF/TSP-1 quantification was performed in tumours. In vitro and in vivo combination studies with the tyrosine inhibitor semaxinib were also performed. SN-38 preferentially inhibited endothelial cell proliferation alone and interacted synergistically with semaxinib; it induced apoptosis and increased the expression and secretion of TSP-1. Metronomic CPT-11 alone and combined with semaxinib significantly inhibits tumour growth in the absence of toxicity, which was accompanied by decreases in microvessel density and increases in TSP-1 gene expression in tumour tissues. In vitro results show the antiangiogenic properties of low-concentration SN-38, suggesting a key role of TSP-1 in this effect. In vivo, the CPT-11 metronomic schedule is effective against tumour and microvessel growth without toxic effect on mice.

Some observations on the intrinsic nervous mechanism in Hirschsprung's disease

Both at rest and during transmural stimulation acetylcholine output from isolated longitudinal and circular muscle strips is significantly higher in the spastic segment than in the proximal dilated bowel. No difference has been found in the tissue concentration of acetylcholine between ganglionic and aganglionic specimens. The pattern of response to transmural stimulation is also similar in the spastic and dilated bowel. However, after cholinergic and adrenergic blockade transmural stimulation fails to induce relaxation in aganglionic specimens, as it does in normal colon. The hypotheses are advanced that the increase in acetylcholine output may be partly dependent on a failure of the intrinsic modulating mechanisms and that an alteration of the non-adrenergic inhibitory neurons may be involved in the motor disturbances of the aganglionic tract.

Prolonged fixed dose rate infusion of gemcitabine with autologous haemopoietic support in advanced pancreatic adenocarcinoma.

This study aimed to define the maximum-tolerated dose (MTD) of fixed dose rate (FDR) of gemcitabine (2′-2′-difluorodeoxycitidine) infusion with circulating haemopoietic progenitor support and to evaluate the activity of the treatment. Secondary end points were pharmacokinetic of gemcitabine and difluorodeoxyuridina (dFdU) measured at first course and the activity andexpression profile of cytidine deaminase (CdA) on circulating mononuclear cells. Patients with advanced pancreatic carcinoma received escalating dose of gemcitabine 10 mg m−2 min−1 every 2 weeks with circulating haemopoietic progenitor support. First dose level was 3000 mg m−2 and the doses were increased by 500 mg m−2 until MTD. In all, 23 patients were enrolled. Toxicities were mild or moderate; the only patient treated at 7000 mg m−2 died because of toxicity; therefore; the MTD was established at 6500 mg m−2. The overall response rate was 22.2%. The AUC of gemcitabine showed a dose-dependent increase, while the AUC of dFdU reached a plateau at 4500 mg m−2. A significant relationship was found between the AUC of dFdU and CdA expression and activity (P<0.05). Moreover, progression rate and survival were significantly related to CdA expression and activity levels. The activity of high-dose gemcitabine is not superior to that reported with less intensive FDR schedules. The predictive role of CdA expression and activity on outcome deserves further investigation.

Fluvastatin synergistically enhances the antiproliferative effect of gemcitabine in human pancreatic cancer MIAPaCa-2 cells

The new combination between the nucleoside analogue gemcitabine and the cholesterol-lowering drug fluvastatin was investigated in vitro and in vivo on the human pancreatic tumour cell line MIAPaCa-2. The present study demonstrates that fluvastatin inhibits proliferation, induces apoptosis in pancreatic cancer cells harbouring a p21ras mutation at codon 12 and synergistically potentiates the cytotoxic effect of gemcitabine. The pharmacologic activities of fluvastatin are prevented by administration of mevalonic acid, suggesting that the shown inhibition of geranyl-geranylation and farnesylation of cellular proteins, including p21rhoA and p21ras, plays a major role in its anticancer effect. Fluvastatin treatment also indirectly inhibits the phosphorylation of p42ERK2/mitogen-activated protein kinase, the cellular effector of ras and other signal transduction peptides. Moreover, fluvastatin administration significantly increases the expression of the deoxycytidine kinase, the enzyme required for the activation of gemcitabine, and simultaneously reduces the 5′-nucleotidase, responsible for deactivation of gemcitabine, suggesting a possible additional role of these enzymes in the enhanced cytotoxic activity of gemcitabine. Finally, a significant in vivo antitumour effect on MIAPaCa-2 xenografts was observed with the simultaneous combination of fluvastatin and gemcitabine, resulting in an almost complete suppression and a marked delay in relapse of tumour growth. In conclusion, the combination of fluvastatin and gemcitabine is an effective cytotoxic, proapoptotic treatment in vitro and in vivo against MIAPaCa-2 cells by a mechanism of action mediated, at least in part, by the inhibition of p21ras and rhoA prenylation. The obtained experimental findings might constitute the basis for a novel translational research in humans.

Presence of a non-adrenergic inhibitory system in the human colon.

The presence in the intestinal wall of intramural non-adrenergic inhibitor neurones has been postulated by many workers. Burnstock, Campbell, Bennett, and Holman (1964) have reported that in the taenia coli of the guinea pig the inhibitory responses to transmural stimulation, which persist in the presence of bretylium and guanethidine, are mediated by intrinsic nerves which are distinct from the sympathetic and parasympathetic system. According to Burnstock, Campbell, and Rand (1966) the taenia coli of the guinea pig is also innervated by intramural inhibitory nerves with their cell bodies in Auerbachs plexus. These nerves could be excited by electrical stimulation of the taenia or by the application of ganglion-stimulating drugs. The intramural inhibitory nerves had different properties from sympathetic adrenergic nerves. Relaxation to stimulation was maximal at about 5 pulses/sec and was not blocked by bretylium, guanethidine, or DMPP. Bennett (1966) and Bennett, Burnstock, and Holman (1966) presented evidence for the existence in the guinea-pig taenia coli of inhibitory nerves distinct from sympathetic perivascular nerves. The evidence was based on the observation that the pattern of the inhibitory junction potential was not changed by antiadrenergic agents and the hyperpolarization produced by intramural stimulation was different from that produced by perivascular stimulation. Electrophysiological evidence of intestinal inhibitor nerves was reported also by Bulbring and Tomita (1967). The existence of non-adrenergic inhibitor nerves in the stomach wall has been shown by Martinson (1965a and b), by Campbell (1966), and by Bulbring and Gershon (1967). An inhibition resulting from activation of non-adrenergic inhibitory neurones by transmural stimulation has recently been described in rabbit ileum by Day and Warren (1968). All the results mentioned above were obtained from animal specimens. The present paper deals with similar studies in the human colon.

Role of cyclooxygenases 1 and 2 in the modulation of neuromuscular functions in the distal colon of humans and mice

Background: Cyclooxygenase isoforms (COX-1, COX-2) may exert differential regulatory actions on enteric motor functions under normal or pathological conditions. Aims: To examine the occurrence and functions of COX-1 and COX-2 in the neuromuscular compartment of normal distal colon using human and murine tissue. Methods: Gene expression (human, mouse), protein expression (human), gene deletion (mouse), and the effects of dual and isoform specific COX inhibitors on in vitro motility (human, mouse) were investigated. Results: Reverse transcription-polymerase chain reaction (RT-PCR) showed mRNA expression of COX-1 and COX-2 in human and wild-type mouse colonic muscle whereas only COX-2 or COX-1 was detected in COX-1 or COX-2 knockout animals. Immunohistochemistry localised both isoforms in neurones of myenteric ganglia, COX-1 in circular layer myocytes, and COX-2 in longitudinal muscle. Indomethacin (COX-1/COX-2 inhibitor), SC-560 (COX-1 inhibitor), or DFU (COX-2 inhibitor) enhanced atropine sensitive electrically induced contractions of human longitudinal muscle. The most prominent actions were recorded with indomethacin or SC-560 plus DFU. These results were confirmed under pharmacological blockade of non-cholinergic nerves. Atropine sensitive contractions evoked by carbachol in the presence of tetrodotoxin were enhanced by indomethacin or DFU but not by SC-560. In wild-type mice, contractile responses to electrical stimulation were enhanced by indomethacin, SC-560, or DFU. SC-560 potentiated electrically induced contractions in COX-2, but not COX-1, knockout mice. In contrast, DFU enhanced the contractions elicited by electrical stimuli in COX-1, but not in COX-2, knockout mice. Conclusions: These results indicate that COX-1 and COX-2 are expressed in the neuromuscular compartment of normal human colon where they modulate cholinergic excitatory control of colonic motility at prejunctional and postjunctional sites, respectively.