Aurora B kinase inhibitor AZD1152: determinants of action and ability to enhance chemotherapeutics effectiveness in pancreatic and colon cancer.

BACKGROUND: AZD1152, the prodrug for AZD1152-hydroxyquinazoline pyrazol anilide (HQPA), is a selective inhibitor of Aurora B kinase activity. Preclinical evaluation of AZD1152 has been reported in several human cancer models. The potentiality of this compound in combination therapy warrants further investigation in solid tumours. EXPERIMENTAL DESIGN: This study explored the effects of AZD1152-HQPA in colon and pancreatic tumour cells. The antitumour properties of AZD1152, either as single agent or in combination with chemotherapeutics, were evaluated in each study model. The efficacy and the toxicity of AZD1152 alone and in combination with gemcitabine were validated in pancreatic tumour xenograft model. RESULTS: AZD1152-HQPA treatment resulted in a dramatic increase of chromosome number, modification of cell cycle and induction of apoptosis. The most effective combination was that with chemotherapeutics given soon after AZD1152 in both tumour cell types. The effectiveness of the sequential schedule of AZD1152 with gemcitabine was confirmed in nude mice bearing MiaPaCa-2 tumours, showing inhibition of tumour volumes and delaying of tumour growth after the interruption of the treatments. Here we show that AZD1152-HQPA enhances oxaliplatin and gemcitabine effectiveness in colon and pancreatic cancer, respectively. First, we provide advances into administration schedules and dosing regimens for the combination treatment in in vivo pancreatic tumour.

Genetic polymorphisms of thiopurine S-methyltransferase in a cohort of patients with systemic autoimmune diseases.

OBJECTIVES: Azathioprine (AZA) is a purine antimetabolite, prodrug widely used as a disease modifying drug in several rheumatic conditions. The aim of the present study was to evaluate the prevalence of TPMT genetic polymorphisms in a cohort of Italian Caucasian patients affected by rheumatic diseases and treated with AZA, and to establish correlations with the tolerability of AZA treatment. RESULTS: Seventy-eight Caucasian patients, 16 males and 62 females, median age 41 years (min-max: 24-76) were enrolled. At the time of evaluation, the median duration of treatment with AZA was 8 months (min-max: 2-150 months); the median dose of AZA per kg of body weight was 1.42 mg (min-max: 0.5-2). Among the 78 patients evaluated, 76 presented a wild type genotype (TPMT *1), while polymorphic alleles were identified in 2 patients (2.6%). Twenty-five patients (32%) experienced different types of adverse events (AE) under AZA treatment. Eighteen patients (23.1%) discontinued AZA because of AE. No correlation was observed between polymorphic TPMT alleles and the development of AE. CONCLUSIONS: Our analysis supports the view that TPMT genotyping alone is not sufficient to adequately personalize the AZA dosage in rheumatic patients. Further studies based on phenotypic analysis of TPMT enzyme and assay of AZA metabolite appear to be required.

A pharmacokinetic and pharmacodynamic study on metronomic irinotecan in metastatic colorectal cancer patients.

The pharmacokinetics (PK) and pharmacodynamics (PD) of metronomic irinotecan have not been studied in cancer patients. The aim of the study is to investigate the PK/PD profile of irinotecan/SN-38 administered by metronomic schedule. Twenty chemotherapy-refractory or chemotherapy-resistant patients with metastatic colorectal carcinoma were enrolled. Irinotecan was infused continuously as follows: irinotecan 1.4 mg m(-2) day(-1) (n=7), 2.8 mg m(-2) day(-1) (n=5) and 4.2 mg m(-2) day(-1) (n=8). Drug levels were examined by HPLC, whereas ELISAs and real-time RT-PCR were used, respectively, for the measurement of plasma levels and gene expression in peripheral blood mononuclear cells of vascular endothelial growth factor/thrombospondin-1. Pharmacokinetic analysis demonstrated that the steady-state levels (C(ss)) of SN-38 were between 1 and 3.3 ng ml(-1). From a PD point of view, higher thrombospondin-1 (TSP-1) plasma levels (153.4+/-30.1 and 130.4+/-9.2% at day 49 vs pretreatment values at 1.4 and 2.8 mg m(-2) day(-1) dose levels, respectively) and increased gene expression in PBMC were found during the metronomic irinotecan infusion, especially at the lower doses. Four patients (20%) obtained a stable disease (median 3.9 months) despite progressing during previous standard irinotecan schedule. Toxicities >grade 1 were not observed. Metronomic irinotecan administration is very well tolerated and induces an increase of gene expression and plasma concentration of TSP-1 at low plasma SN-38 concentrations.

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.

Pharmacokinetics of azithromycin in serum, bronchial washings, alveolar macrophages and lung tissue following a single oral dose of extended or immediate release formulations of azithromycin.

OBJECTIVES: Antibacterial efficacy of azithromycin could be improved by achieving higher concentrations at the sites of infection. Azithromycin extended release (azithromycin-ER) formulation was developed to enable a higher dosage of 2 g to be administered as a single oral dose without decreasing the safety profile. The aim of this study was to compare the pharmacokinetics of azithromycin in serum, epithelial lining fluid (ELF), alveolar macrophages (AMs) and lung tissue following a single oral dose of azithromycin-ER or azithromycin immediate release (azithromycin-IR) formulation. PATIENTS AND METHODS: A total of 64 patients, diagnosed with lung cancer, requiring open-chest surgery for lung resection, completed the study. Subjects were randomized to receive oral administration of either a single 2 g dose of azithromycin-ER (32 subjects) or a single 500 mg dose of azithromycin-IR (32 subjects). Simultaneously, subjects within each treatment group were randomized to one of eight specific nominal post-dose time points for bronchoalveolar lavage and lung tissue sampling. Results For azithromycin-IR formulation, the AUC(0-24) in serum, ELF, AMs and lung tissue was 3.1, 2.3, 1674 mg.h/L and 130 mg.h/kg, respectively. For azithromycin-ER formulation, the AUC(0-24) in serum, ELF, AMs and lung tissue were 10.0, 17.6, 7028 mg.h/L and 505 mg.h/kg, respectively. The AUC(0-24) ratio following administration of azithromycin-ER relative to azithromycin-IR was 3.2, 7.7, 4.2 and 3.9 in serum, ELF, AMs and lung tissue, respectively. CONCLUSIONS: Within the first 24 h, a single 2 g azithromycin-ER dose produced dose-related increase in systemic exposure compared with a single 500 mg azithromycin-IR dose, which resulted in higher levels of azithromycin in ELF, AMs and lung tissue. Both formulations had similar safety profiles. By achieving high azithromycin exposure early in the course of treatment, without compromising tolerability, azithromycin-ER shows the potential for improved antibacterial efficacy compared with azithromycin-IR.

Somatostatin inhibits colon cancer cell growth through cyclooxygenase-2 downregulation.

BACKGROUND AND PURPOSE: Cyclooxygenase-2 (COX-2) is expressed in colonic neoplasms, where it supports cell proliferation via prostaglandin E(2) (PGE(2)) production. This study investigated the effects of somatostatin-14 on COX-2 expression, PGE(2) production and proliferation in colon cancer cells. EXPERIMENTAL APPROACH: Human colon adenocarcinoma cell lines Caco-2, HT-29 and HCT116 were used. The following techniques were employed: colourimetric assay for cell growth; 5-bromo-2'-deoxyuridine assay for DNA synthesis; enzyme immunoassay for PGE(2); COX-2 mRNA silencing; RT-PCR or Western blot for somatostatin receptor subtypes, cyclooxygenase isoforms, phosphorylated-ERK-1/ERK-2 and phosphorylated-Akt. KEY RESULTS: HT-29 and Caco-2 cells expressed COX-2 and somatostatin receptors (sst(3/4/5) and sst(3/5), respectively). HCT116 cells did express somatostatin receptors (sst(2/3/5)), but not COX-2. Somatostatin-14 inhibited basal COX-2 expression, PGE(2) production, DNA synthesis and growth in Caco-2 cells and these effects were prevented by BN81658 (sst(3) receptor antagonist). Basal proliferation of HT-29, HCT116 and COX-2-silenced Caco-2 cells was not affected by somatostatin-14. Stimulation of HT-29 cells with gastrin-17 elicited increments of ERK-1/ERK-2 and Akt phosphorylation, COX-2 expression, PGE(2) production, DNA synthesis and cell growth, which were all counteracted by somatostatin-14. Somatostatin-14-induced inhibition of COX-2 expression, PGE(2) production and DNA synthesis were blocked by BIM23056 (sst(5) receptor antagonist). CONCLUSIONS AND IMPLICATIONS: Somatostatin decreases COX-2 expression and function in colon cancer cells via activation of sst(3) or sst(5) receptors, and these effects contribute to the inhibitory action of somatostatin on cell proliferation. These findings can be relevant to the development of therapeutic strategies based on the modulation of the COX-2 pathway.

Effects of a bicarbonate-alkaline mineral water on digestive motility in experimental models of functional and inflammatory gastrointestinal disorders.

This study investigates the effects of Uliveto, a bicarbonate-alkaline mineral water, in experimental models of diarrhea, constipation and colitis. Rats were allowed to drink Uliveto or oligomineral water (control) for 30 days. Diarrhea and constipation were evoked by 16,16-dimethyl-prostaglandin E(2) (dmPGE(2)) or loperamide, respectively. Colitis was induced by 2,4-dinitrobenzenesulfonic acid (DNBS) or acetic acid. Gastric emptying, small-intestinal and colonic transit were evaluated. dmPGE(2)-induced diarrhea reduced gastric emptying and increased small-intestinal and colonic transit. In this setting, Uliveto water enhanced gastric emptying, and this effect was prevented by L-365,260 (gastrin receptor antagonist). Loperamide-induced constipation reduced gastric emptying, small-intestinal and colonic transit, and these effects were prevented by Uliveto water. L-365,260 counteracted the effects of Uliveto on gastric emptying, while alosetron (serotonin 5-HT(3) receptor antagonist) blunted the effect of Uliveto on colonic transit. Gastric emptying, small-intestinal and colonic transit were reduced in DNBS-induced colitis, and Uliveto water enhanced gastric emptying and normalized small-intestinal and colonic transit. Gastric emptying, small-intestinal and colonic transit were also reduced in acetic acid-induced colitis, and Uliveto increased both gastric emptying and small-intestinal transit. In conclusion, Uliveto water exerts beneficial effects on gastrointestinal motility in the presence of bowel motor dysfunctions. The effects of Uliveto water on gastric emptying depend on gastrin-mediated mechanisms, whereas the activation of serotonergic pathways accounts for the modulation of colonic functions.

Cholecystokinin CCK2 receptors mediate the peptide's inhibitory actions on the contractile activity of human distal colon via the nitric oxide pathway.

BACKGROUND AND PURPOSE: Cholecystokinin is known to exert stimulant actions on intestinal motility via activation of type 1 cholecystokinin receptors (CCK(1)). However, the role played by cholecystokinin 2 (CCK(2)) receptors in the regulation of gut motility remains undetermined. This study was designed to examine the influence of CCK(2) receptors on the contractile activity of human distal colon. EXPERIMENTAL APPROACH: The effects of compounds acting on CCK(2) receptors were assessed in vitro on motor activity of longitudinal smooth muscle, under basal conditions as well as in the presence of KCl-induced contractions or transmural electrical stimulation. KEY RESULTS: Cholecystokinin octapeptide sulphate induced concentration-dependent contractions which were enhanced by GV150013 (CCK(2) receptor antagonist; +57% at 0.01 microM). These effects were unaffected by tetrodotoxin. The enhancing actions of GV150013 on contractions evoked by cholecystokinin octapeptide sulphate were unaffected by N(omega)-propyl-L-arginine (NPA, neuronal nitric oxide synthase inhibitor), while they were prevented by N(omega)-nitro-L-arginine methylester (L-NAME, non-selective nitric oxide synthase inhibitor). In the presence of KCl-induced contractions, cholecystokinin octapeptide sulphate elicited concentration-dependent relaxations (-36%), which were unaffected by NPA, but were counteracted by GV150013 or L-NAME. The application of electrical stimuli evoked phasic contractions which were enhanced by GV150013 (+41 % at 0.01 microM). CONCLUSIONS AND IMPLICATIONS: CCK(2) receptors mediate inhibitory actions of cholecystokinin on motor activity of human distal colon. It is suggested that CCK(2) receptors exert their modulating actions through a nitric oxide pathway, independent of the activity of the neuronal nitric oxide synthase isoform.

Linezolid cerebrospinal fluid concentration in central nervous system infection.

We report two cases of central nervous system infection due to methicillin-resistant Staphylococcus epidermidis treated with linezolid. The first case was a 72-year old woman with ventriculitis in the presence of intraventricular catheter: therapeutic effectiveness was documented clinically and microbiologically; serum and cerebrospinal fluid levels were measured after the first and fourth doses: trough linezolid concentrations in cerebrospinal fluid were 1.44 and 2.9 mg/L respectively, higher than the minimum inhibitory concentration (MIC). The second case was a 27-year old man with post-traumatic cerebral abscess; during 5 days linezolid was not found in his cerebrospinal fluid despite very high serum level peak, and the drug was not detectable in cerebral tissue surgically removed after 14 days of therapy. Linezolid may not reach therapeutic concentrations in cerebrospinal fluid, and, when possible, we suggest that drug levels be monitored.

In vitro studies on gemcitabine combinations with other antiblastics.

The use of gemcitabine in combination with chemotherapeutic agents, including cisplatin, pemetrexed and taxanes, is characterized by the enhancement of their anticancer activity. The analysis of the underlying pharmacodynamics has revealed that modulation of nucleotide pools, drug metabolism, and cellular DNA repair capability are the most common factors to explain the additive to synergistic interaction between gemcitabine and anticancer agents in several human cancers in vitro and in vivo.

Constitutive expression of cyclooxygenase-2 in the neuromuscular compartment of normal human colon.

Prostaglandins regulate various functions throughout the gastrointestinal system. Their biosynthesis depends on cyclooxygenase isoforms, named COX-1 and COX-2. The initial hypothesis that COX-2 is an inducible enzyme has been challenged and its constitutive expression in the stomach has been established. In this study, an immunohistochemical analysis was performed to evaluate the distribution and cellular localization of COX-2 in normal human colon. Colonic surgical specimens were processed for COX-2, protein HuC/HuD, neurofilament, S-100 protein and CD117/c-kit immunodetection. COX-2 protein was found to be constitutively expressed in the colonic wall: detectable amounts were localized in mucosal, submucosal and muscular layers, mainly in the neuromuscular compartment. In particular, COX-2 was expressed in muscularis mucosae, submucosal ganglia, longitudinal muscle layer and myenteric ganglia, the neurons of which displayed different degrees of immunostaining. Intramuscular interstitial cells of Cajal, regarded as important sites for the regulation of enteric neuromuscular activity, were also partly COX-2 immunoreactive. This study provides a detailed mapping of COX-2 expression in human colon, and allows better understanding of the roles played by this isoenzyme in gut physiology.

MCF-10A cells infected with the int-2 oncogene induce angiogenesis in the chick chorioallantoic membrane and in the rat mesentery.

A growing body of evidence demonstrates the relevant role of the int-2 (FGF-3) oncogene in human carcinomas. To investigate its angiogenic activity, the human epithelial mammary cell line MCF-10A was infected with a retroviral expression vector carrying the int-2 oncogene. Infected cells were entrapped in an alginate pellet and placed on the chorioallantoic membrane of chick embryos. After 7 days, a dense capillary network was found to grow toward the pellet, whereas parental cells did not show any angiogenic activity. Conditioned medium from int-2-infected cells was injected i.p. twice daily into rats over a period of 10 days. The mesentery of treated rats showed numerous small blood vessels originating from larger vascular arcades and growing through the stromal layer of the mesentery. In control experiments, neither medium for cell culture nor conditioned medium from parental cells was found to induce angiogenesis. In conclusion, the stimulation of blood vessel growth by int-2-infected cells suggests that the production of the int-2 protein is associated with the acquisition of the angiogenic phenotype.

Intravenous azidothymidine with fluorouracil and leucovorin: a phase I-II study in previously untreated metastatic colorectal cancer patients.

PURPOSE: To determine the plasma pharmacokinetics and the maximum-tolerated dose (MTD) of intravenous (IV) azidothymidine (AZT) administered 90 to 120 minutes after fluorouracil (5-FU) and leucovorin and to preliminarily evaluate the antitumor activity of this combination in metastatic colorectal cancer. PATIENTS AND METHODS: 5-FU 500 mg/m2 IV bolus was administered once a week in the middle of a 2-hour infusion of leucovorin; AZT was given as a 90 to 120-minute IV infusion 60 minutes after 5-FU. Initial AZT dose was 0.5 g/m2, and it was escalated in successive cohorts of three patients by 0.5 to 2 g/m2. RESULTS: Thirty-five chemotherapy-naive metastatic colorectal cancer patients were entered onto the study, and AZT doses ranged from 0.5 to 10 g/m2. The peak AZT plasma concentration increased from 21.9 to 995.6 micromol/L. The area under the concentration/time curve (AUC) also showed a progressive, but not linear increase from 40.34 to 3,108 h x micromol/L. The most relevant toxicity was diarrhea, which was severe in six patients (17%). Toxicities were not AZT-dose-related, except fpr hypotension, which occurred in patients treated at AZT doses > or = 7 g/m2 and became dose-limiting for AZT 10 g/m2. Among 34 assessable patients, 15 objective responses were observed (44%; 95% confidence interval 27 to 62), lasting a median of 44 weeks; five (15%) were complete. CONCLUSION: AZT doses > or = 6 g/m2 administered IV over 90 to 120 minutes produce maximum plasma concentration and AUC similar to those previously reached in murine tumor models. Dose-limiting toxicity is hypotension, which occurs at AZT 10 g/m2. The recommended AZT dose for further studies is 8 g/m2. The combination of 5-FU plus leucovorin plus AZT is feasible with acceptable toxicities, and has promising activity in metastatic colorectal cancer.

Cardiotoxicity of epirubicin/paclitaxel-containing regimens: role of cardiac risk factors.

PURPOSE: To evaluate the incidence of clinically relevant cardiac toxicity after treatment with epirubicin/paclitaxel-containing regimens in patients with metastatic breast cancer and to identify high-risk patients in whom the benefit of chemotherapy may be negated by the occurrence of congestive heart failure (CHF). PATIENTS AND METHODS: A total of 105 patients who were referred for epirubicin/paclitaxel treatment were included in this study. Treatment regimens were as follows: (1) epirubicin 90 mg/m(2) plus paclitaxel 135 to 225 mg/m(2) over 3 hours (n = 76); and (2) gemcitabine 1,000 mg/m(2) on days 1 and 4 plus epirubicin/paclitaxel (n = 29). The occurrence of CHF was detected by physical examination, and left ventricular function was evaluated by bidimensional echocardiography to support the diagnosis. Cardiac risk factors examined in this study included age, prior radiotherapy to the chest, hypertension, and diabetes. RESULTS: No patient experienced CHF while on treatment. Nine patients (9%) developed CHF after cumulative epirubicin doses of 1,080 mg/m(2) (n = 4), 720 mg/m(2) (n = 2), 630 mg/m(2) (n = 1), and 540 mg/m(2) (n = 2). One of the two patients who developed CHF after a cumulative epirubicin dose of 540 mg/m(2) had received consolidation with high-dose chemotherapy. Median time to appearance of cardiologic symptoms was 3 months after the end of treatment (range, 3 to 6 months). Overall, the incidence of CHF was 13% and 4% in patients with or without cardiac risk factors, respectively. The cumulative risk of developing CHF was estimated as 7.7% at a cumulative doses of 720 mg/m(2) and 48.7% at a cumulative dose of 1,080 mg/m(2). CONCLUSION: This study shows that the incidence of CHF after an epirubicin/paclitaxel regimen is low up to cumulative epirubicin doses of 990 mg/m(2), thus allowing the safe administration of this regimen even in patients who received epirubicin in the adjuvant setting. However, the risk of developing CHF increases when a cumulative dose exceeding 990 mg/m(2) is reached, concomitantly with the presence of an additional cardiac risk factor.

Sequence effect of irinotecan and fluorouracil treatment on pharmacokinetics and toxicity in chemotherapy-naive metastatic colorectal cancer patients.

PURPOSE: To investigate the sequence effect of irinotecan and a 48-hour infusion of fluorouracil (5-FU) modulated by leucovorin (LV) on the plasma pharmacokinetics of irinotecan and its metabolites, the toxicity profile of this combination, and irinotecan's maximum-tolerated dose (MTD). PATIENTS AND METHODS: Thirty-three metastatic colorectal cancer patients were randomized to receive a 60-minute infusion of irinotecan before or after a 48-hour infusion of 5-FU modulated by LV. The reverse sequence was used after 21 days for the second cycle. 5-FU 3,500 mg/m2 was preceded by l-LV 250 mg/m2. Irinotecan 150 mg/m2 (starting dose) was administered to the first three patients. The dose was escalated by 50 mg/m2 in subsequent groups of three to six patients to determine the MTD for both sequences. Pharmacokinetic analysis of irinotecan and its metabolites was performed after each cycle. RESULTS: Toxicities were affected by the sequence of administration of irinotecan and 5-FU, with an improved tolerability for irinotecan followed by 5-FU. The irinotecan MTD was reached at 300 mg/m2 when irinotecan followed 5-FU and at 450 mg/m2 when it preceded 5-FU. In seven of 23 patients who received both sequences at identical irinotecan doses, the dose-limiting toxicity was observed only when irinotecan followed 5-FU. Pharmacokinetic analysis revealed that the administration sequence significantly affected the SN-38 area under the concentration-versus-time curve (AUC), which was 40.1% lower (P <.05) when irinotecan preceded 5-FU. CONCLUSION: The sequence of treatment with irinotecan and infusional 5-FU affects the tolerability of this combination. This can be explained in part by a reduced SN-38 AUC when irinotecan preceded infusional 5-FU. Well-defined 5-FU/irinotecan regimens are needed because the administration sequence or the interval between the agents might affect treatment tolerance and perhaps also activity.

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.

Pharmacogenetic determinants of anti-cancer drug activity and toxicity.

Cellular responses to anti-cancer agents result from the interaction between drugs, cellular targets and mechanisms of damage repair. Despite the pharmacological advances in the treatment of cancer, the clinical efficacy of chemotherapy is unpredictable in most patients. However, new information on the genetics of cancer delineates strategies by which the genetic background of tumour cells and patients might be profiled to select anti-cancer agents with improved efficacy and tolerability. This article focuses on the application of pharmacogenetics in the characterization of differences in the pharmacokinetics and pharmacodynamics of anti-cancer agents among individuals to define the likelihood of response and reduce the incidence of adverse effects.

Mechanisms of protection by pantoprazole against NSAID-induced gastric mucosal damage.

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. In clinical settings, proton pump inhibitors have proven to be effective in preventing and healing NSAID-induced gastroduodenal lesions. The present study investigates the mechanisms of protection afforded by pantoprazole against gastric injury induced by different NSAIDs in rats. Animals were orally treated with indomethacin (100 micromol/kg), diclofenac (60 micromol/kg), piroxicam (150 micromol/kg) or ketoprofen (150 micromol/kg). Thirty minutes before NSAIDs, animals received pantoprazole 6 or 60 micromol/kg orally. Four hours after NSAIDs, the following parameters were assessed: histomorphometric evaluation of gastric mucosal damage; gastric mucosal levels of myeloperoxidase (MPO), malondialdehyde (MDA), reduced glutathione as an index of non-proteic sulfhydryl compounds (GSH), and prostaglandin E2 (PGE2); mucosal cyclooxygenase-1 and -2 (COX-1, COX-2) mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). Separate experiments were carried out to assay the effects of pantoprazole on gastric acid secretion in pylorus-ligated rats. The in vitro influence of pantoprazole (1-10 microM) on the oxidation of low density lipoproteins (LDLs) induced by copper sulphate was also examined. All NSAIDs elicited mucosal necrotic lesions associated with neutrophil infiltration and reduction of PGE2 levels. Increments of MPO and MDA contents, as well as a decrease in GSH levels, were detected in the gastric mucosa of indomethacin-, piroxicam- or ketoprofen-treated animals. Indomethacin enhanced mucosal COX-2 expression, while not affecting COX-1. At the oral dose of 6 micromol/kg pantoprazole did not affect NSAID-induced mucosal damage, whereas at 60 micromol/kg it markedly reduced injuries provoked by all test NSAIDs. Pantoprazole 60 micromol/kg also reversed the effects of NSAIDs on MPO, MDA, and GSH mucosal contents, without interfering with the decrease in PGE2 levels or indomethacin-induced COX-2 expression. However, at both doses, pantoprazole inhibited acid secretion in pylorus-ligated rats. Furthermore, pantoprazole concentration dependently reduced the in vitro oxidation of LDLs. Our results suggest that besides inhibiting acid secretion, the protection afforded by pantoprazole against NSAID-induced gastric damage depends on a reduction in mucosal oxidative injury, which may also account for an increment of sulfhydryl radical mucosal bioavailability. It is also suggested that pantoprazole does not influence the down-regulation of gastric prostaglandin production associated with NSAID treatment.

Comparative pharmacokinetic analysis of 5-fluorouracil and its major metabolite 5-fluoro-5,6-dihydrouracil after conventional and reduced test dose in cancer patients.

The aim of this study was to investigate the clinical pharmacokinetics of 5-fluorouracil (5-FU) and its major metabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) in 20 colorectal cancer patients given two dose levels of 5-FU, 250 and 370 mg/m2, administered by i.v. bolus. A reverse-phase high-performance liquid chromatographic method was used for the simultaneous assay of 5-FU and 5-FDHU in plasma samples obtained at baseline and at multiple time points from 5 min to 4 h after 5-FU bolus as well as to assess the activity of dihydropyrimidine dehydrogenase (DPD) in peripheral blood mononuclear cells (PBMCs) before 5-FU dosing. Plasma pharmacokinetic parameters of patients given 250 mg/m2 5-FU were significantly different from those receiving 370 mg/m2; main differences were observed in the trapezoidal areas under the plasma levels-versus-time curve from to to the last measurable concentration (area under the curve, 3.77+/-0.21 versus 13.61+/-2.3 h x microg/ml), peak plasma concentration (Cmax, 18.15+/-1.35 versus 48.41+/-7.69 microg/ml), and total body clearance (CL(TB), 54.64+/-3.54 versus 25.43+/-2.3 l/h/m2). Significant differences were also observed in the main pharmacokinetic parameters of 5-FDHU after 250 and 370 mg/m2 5-FU including the area under the curve from to to 4 h (5.39+/-0.32 versus 8.75+/-1.24 h x microg/ml), Cmax (3.60+/-0.16 versus 5.26+/-0.55 microg/ml) and time to Cmax (Tmax, 0.45+/-0.03 versus 0.69+/-0.06 h). The mean DPD activity in PBMCs in this group of patients was 205.7+/-36.4 pmol of 5-FDHU/min/mg of protein and was within the normal range; however, no significant correlations were found between 5-FU or 5-FDHU pharmacokinetic parameters at two dose levels and DPD activity of PBMCs. The results of the present study provide the first detailed comparison of the distribution of 5-FU and its major metabolite 5-FDHU at the therapeutic level as well as at reduced test dose levels to obtain pharmacokinetic data to be used as reference values for the identification of patients at risk of major 5-FU toxicity due to impaired metabolism to 5-FDHU.

Idarubicin and idarubicinol effects on breast cancer multicellular spheroids.

Despite extensive preclinical evaluation in several experimental models, no studies have determined the effect of idarubicin and its metabolite idarubicinol on multicellular spheroids, a model which mimics the microregions of solid tumors. The principal aim of the present study was to investigate the in vitro cytotoxicity of idarubicin and its metabolite idarubicinol on MCF-7 breast cancer cells growing as monolayers or multicellular spheroids and to evaluate the influence of the length of exposure on the cytotoxic effect of both drugs. Cytoxicity was evaluated on monolayer and spheroid cultures exposed to idarubicin and idarubicinol 0.01-1000 ng/ml for 24 h or treated for 6, 12, 24 and 48 h to 100 ng/ml of both drugs. The IC50 of idarubicin and idarubicinol were 3.3+/-0.4 and 3.6+/-0.7 ng/ml, respectively, on MCF-7 monolayers and 7.9+/-1.1 and 5.3+/-0.7 ng/ml in multicellular spheroids, respectively. The antiproliferative effects of 100 ng/ml idarubicin and idarubicinol on MCF-7 spheroids was characterized by a marked time-dependence, which was less evident on MCF-7 growing as monolayer. In conclusion, the present experimental data demonstrate, for the first time, that idarubicin and idarubicinol have significant cytotoxic activity against multicellular spheroids, comparable to the antiproliferative effects on monolayer cells. In contrast, spheroids displayed substantial resistance after short exposure times that was not present in the two dimensional cultures.