In vitro synergistic cytotoxicity of gemcitabine and pemetrexed and pharmacogenetic evaluation of response to gemcitabine in bladder cancer patients

The present study was performed to investigate the capability of gemcitabine and pemetrexed to synergistically interact with respect to cytotoxicity and apoptosis in T24 and J82 bladder cancer cells, and to establish a correlation between drug activity and gene expression of selected genes in tumour samples. The interaction between gemcitabine and pemetrexed was synergistic; indeed, pemetrexed favoured gemcitabine cytotoxicity by increasing cellular population in S-phase, reducing Akt phosphorylation as well as by inducing the expression of a major gemcitabine uptake system, the human equilibrative nucleoside transporter-1 (hENT1), and the key activating enzyme deoxycytidine kinase (dCK) in both cell lines. Bladder tumour specimens showed an heterogeneous gene expression pattern and patients with higher levels of dCK and hENT1 had better response. Moreover, human nucleoside concentrative transporter-1 was detectable only in 3/12 patients, two of whom presented a complete response to gemcitabine. These data provide evidence that the chemotherapeutic activity of the combination of gemcitabine and pemetrexed is synergistic against bladder cancer cells in vitro and that the assessment of the expression of genes involved in gemcitabine uptake and activation might be a possible determinant of bladder cancer response and may represent a new tool for treatment optimization.

Analysis of single nucleotide polymorphisms (SNPs) of cytidine deaminase (CDA) and xeroderma pigmentosum group D (XPD) genes for the prediction of clinical response to gemcitabine and cisplatin in advanced non-small cell lung cancer (NSCLC) patients

7219

Background: Detection of genomic differences predictive of drug response may allow to customize chemotherapy to the characteristics of individual patients. Gemcitabine alone or in combination with cisplatin are two of the most common regimens used in the treatment of advanced NSCLC. We investigated the correlation between selected SNPs of genes encoding enzymes involved in the activity of gemcitabine and cisplatin, including CDA, XPD and ERCC1, and the response to chemotherapy. Methods: Forty advanced NSCLC chemo-naïve patients were enrolled into the study; 16 patients, aged > 70 years, were treated with gemcitabine; 24 patients, aged < 70 years, were treated with cisplatin plus gemcitabine. SNPs CDA A79C, XPD A751C, XPD G312A and ERCC1 C118T were analyzed with the ABI PRISM 7900HT Sequence Detection System using TaqMan probe-based assay in DNA obtained from peripheral blood samples. Statistical analysis was performed using Pearson χ2 test, Kaplan-Meier curve and log rank test. Results: Up to now 31 patients, 11 treated with gemcitabine and 20 with cisplatin plus gemcitabine, are evaluable for response with RECIST criteria; correlation between response and genotype are showed in the table. Actuarial progression free survival (PFS) was longer in patients treated with gemcitabine ± cisplatin with CDA A79A genotype than in others (respectively 11.0 vs 2.5 months, p = 0.0092), while no correlation was found between the SNPs of XPD and ERCC1 and PFS in patients receiving cisplatin and gemcitabine. Conclusions: CDA A79A genotype resulted predictive of response and longer PFS in NSCLC patients treated with gemcitabine ± cisplatin. There was also a trend toward significant correlation between XPD A751A and better response in cisplatin-treated patients, while the SNPs in XPD 312 and ERCC1 118 were not associated with response to chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

Phase I/II trial of continuous hepatic arterial infusion (HAI) of Irinotecan in patients with hepatocellular carcinoma (HCC). Preliminary results

14061

Background: No standard therapies are available for HCC patients (pts) who are not eligible for curative treatments (surgery, RF, TACE or PEI). Methods: This dose finding phase I/II study investigates the tolerability of increasing doses of continuous HAI of CPT-11 (during days 1–5 every 21) in pts with histologically confirmed Child A/B HCC, confined to the liver, not eligible for curative treatments. Secondary endpoints are pharmacokinetics and efficacy. To date, 5 dose levels (DL) of CPT-11 have been investigated (from 7,5 to 17,5 mg/m2/die) and the 6th (20 mg/m2/die) being evaluated. An arterial port-a-cath was placed in the hepatic artery by percutaneous catheterization of the femoral or axillary artery. Before each cycle an angiography was performed to define the optimal liver perfusion. DLT was defined as one G4 hematogical and/or two G3 nonhematological toxicities or liver function impairment (Child C). AEs were graded using NCI-CTC. Responses were evaluated after the 3rd cycle with ultrasonography or CT scan (WHO criteria). Results: To date 16 pts have been enrolled and evaluated for tolerability. Median age is 63, 8 years (range 41–80), M/F 11/5, median ECOG 1 (0–2), Child-Pugh A/B 10/6 . Total n° of courses was 41 (median 2, range 1–10). DLT was not reached. Two grade 3 toxicities were reported at DL 4: diarrhea in 1 pt and anemia in another pt. There were no G4 toxicities. Most common G1–2 toxicities at any DL were: neutropenia 5 pts (31%), nausea/vomiting 4 pts (25%), diarrhea 3 pts (18%), thrombocytopenia 2 pts (12.5%). In two pts (DL3 and DL4) treatment was discontinued because of chemotherapy induced arteritis after 1 and 3 courses respectively. 12 pts were assessable for response: 3 PR, 6 SD, 3 PD. α-fetoprotein levels decreased significantly in 6 pts (50%). Pharmacokinetics data will be presented later. Conclusions: To date MTD hasn’t been reached. At DL 1–5 this schedule shows little and manageable toxicity - without impairment of liver function - and promising activity (PR+SD=75%).

No significant financial relationships to disclose.

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.

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.

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.

Interaction between gemcitabine and topotecan in human non-small-cell lung cancer cells: effects on cell survival, cell cycle and pharmacogenetic profile

The pyrimidine analogue gemcitabine is an established effective agent in the treatment of non-small-cell lung cancer (NSCLC). The present study investigates whether gemcitabine would be synergistic with the topoisomerase I inhibitor topotecan against the NSCLC A549 and Calu-6 cells. Cells were treated with gemcitabine and topotecan for 1 h and the type of drug interaction was assessed using the combination index (CI). Cell cycle alterations were analysed by flow cytometry, while apoptosis was examined by the occurrence of DNA internucleosomal fragmentation, nuclear condensation and caspase-3 activation. Moreover, the possible involvement of the PI3K-Akt signalling pathway was investigated by the measurement of Akt phosphorylation. Finally, quantitative, real-time PCR (QRT-PCR) was used to study modulation of the gemcitabine-activating enzyme deoxycytidine kinase (dCK) and the cellular target enzyme ribonucleotide reductase (RR). In results, it was found that simultaneous and sequential topotecan → gemcitabine treatments were synergistic, while the reverse sequence was antagonistic in both cell lines. DNA fragmentation, nuclear condensation and enhanced caspase-3 activity demonstrated that the drug combination markedly increased apoptosis in comparison with either single agent, while cell cycle analysis showed that topotecan increased cells in S phase. Furthermore, topotecan treatment significantly decreased the amount of the activated form of Akt, and enhanced the expression of dCK (+155.0 and +115.3% in A549 and Calu-6 cells, respectively), potentially facilitating gemcitabine activity. In conclusion, these results indicate that the combination of gemcitabine and topotecan displays schedule-dependent activity in vitro against NSCLC cells. The gemcitabine → topotecan sequence is antagonistic while drug synergism is obtained with the simultaneous and the sequential topotecan → gemcitabine combinations, which are associated with induction of decreased Akt phosphorylation and increased dCK expression.

Hematologic toxicity of immunosuppressive treatment

The administration of immunosuppressive agents may be associated with the occurrence of hematologic toxicity, such as anemia, due to bone marrow suppression or hemolysis, leukopenia, and thrombocytopenia. The administration of azathioprine and mycophenolate mofetil is more frequently associated with bone marrow suppression, while hemolytic-uremic syndrome may occur after administration of cyclosporine, tacrolimus, or muromonab (OKT3) and may be associated with the loss of the allograft. Moreover, microangiopathic hemolytic anemia and thrombocytopenia are rare, but potentially severe, complications of immunosuppressive treatment with tacrolimus and cyclosporine; they are characterized by intravascular hemolysis due to mechanical destruction of red cells as a result of pathological changes in small blood vessels. Viral infections (cytomegalovirus), administration of antiviral agents (gancyclovir), inhibitors of angiotensin-converting enzyme and angiotensin II receptor antagonists, antibacterial agents (sulfamethoxazole and trimethoprim), and allopurinol may aggravate bone marrow suppression, particularly when administered with agents that interfere with purine biosynthesis, including azathioprine and mycophenolate mofetil.

An exploratory study on pharmacogenetics of inosine-monophosphate dehydrogenase II in peripheral mononuclear cells from liver-transplant recipients

Mycophenolate mofetil (MMF) is an immunosuppressant used for the prophylaxis of rejection in renal, pancreas, and liver transplantation. It inhibits the inducible isoform of the enzyme inosine-monophosphate dehydrogenase (IMPDH II) via its active metabolite mycophenolic acid (MPA). IMPDH II is necessary for de novo purine synthesis in activated lymphocytes. The aims of the present study were to evaluate the feasibility of a real-time polymerase chain reaction (PCR) quantitative assessment of IMPDH II gene expression in liver transplant recipients as well as to provide a preliminary evaluation of possible correlations with drug tolerability. RNA was extracted from peripheral blood mononuclear cells of liver recipients after at least 6 months of MMF administration. IMPDH II gene expression was assessed using quantitative, real-time PCR and normalized using glyceraldheyde-3-phosphate dehydrogenase (GAPDH). Finally, adverse events associated with MMF administration were recorded. Real-time PCR quantitation of IMPDH II gene expression was reliable, sensitive, and specific. The intrapatient variability for both IMPDH II and GAPDH assays was lower than 0.6% in all patients. The results demonstrated a wide interpatient variability, with the mean value +/- standard deviation of 0.949 +/- 0.525 (95% confidence interval, 0.669-1.229) and a median value of 0.797. Patients with treatment-related toxicities displayed a trend to a higher level of IMPDH II expression than those without toxicity (mean, 1.126 vs 0.771). In conclusion, pharmacogenetic analysis of IMPDH II may represent a novel approach to MMF therapeutic monitoring.

Teratogenesis and immunosuppressive treatment

Despite the potential risks to the mother and fetus caused by immunosuppressive drugs, uneventful pregnancies are now frequent among transplant recipients. Although there is no apparent increase in the type or incidence of malformations in the newborns or evidence of graft dysfunction, pregnancy-related complications, including premature termination and low birth weight, may be more frequent. To prevent graft rejection due to the increased immunologic reactivity of the transplant recipient during pregnancy, it is reasonable to wait 2 years after transplantation before conception, to have stable graft function and to be on low drug doses for maintenance immunosuppression. Among the immunosuppressive agents, corticosteroids may induce a number of treatment-related complications, including diabetes and osteoporosis; however, the incidence of fetal malformations during corticosteroid treatment is about 3.5%, a value close to that of the general population. Among immunosuppressive antibodies, no evidence of developmental toxicity has been demonstrated with basiliximab. On the contrary, some concerns have been raised about azathioprine, since its use has been associated with fetal abnormalities in animals; however, clinical data so far have indicated only a small teratogenic risk. Therefore, immunosuppressive therapy with selected drugs and antibodies does not apparently increase the risk of birth defects and may be continued in pregnancy. Finally, although breast-feeding is not recommended, because of drug transfer into maternal milk, the available clinical data do not support this limitation because of the low amount of drug absorbed by the infant and the absence of clinical toxicity in published case reports.

Imatinib administration in two patients with liver metastases from GIST and severe jaundice

Imatinib is the only effective and approved systemic therapy for the treatment of patients with advanced gastrointestinal stromal tumours (GISTs). Although metastases from GISTs most commonly involve the liver, yielding hyperbilirubinaemia, very few data on imatinib administration in subjects with jaundice are available. We provide evidence that imatinib tolerability was not adversely affected by jaundice in two patients with advanced GIST.

High-dose consolidation chemotherapy with Idarubicin and alkylating agents following induction with gemcitabine-epirubicin-paclitaxel in metastatic breast cancer: a dose finding study

Preliminary randomized studies have failed to show a survival benefit of high-dose chemotherapy with alkylators in advanced breast cancer. Idarubicin is an active agent in breast cancer and is suitable for dose escalation. We designed a dose finding study with escalating high-dose idarubicin (HD-Ida) followed by fixed high-dose thiotepa+melphalan (HD-TM) with peripheral blood progenitor cells (PBPC) in MBC patients with stable disease or in partial response after six courses of induction chemotherapy with gemcitabine 1000 mg/m(2) days 1 and 4, epirubicin 90 mg/m(2) day 1, taxol 175 mg/m(2) day 1 (GET). Aims of the study were to identify the maximum tolerated dose (MTD) of idarubicin, to evaluate the cardiac safety and activity of HD-Ida and HD-TM after GET and to study the pharmacokinetic profile of idarubicin and idarubicinol. A total of 14 patients were treated. Idarubicin was administered as a 48 h continuous i.v. infusion at the following dose levels: 40 mg/m(2) (three patients), 50 mg/m(2) (three patients), 60 mg/m(2) (five patients) and 70 mg/m(2) (three patients). Mucositis was the dose-limiting toxicity and the MTD was 60 mg/m(2). C(max) of Idarubicin and idarubicinol were 7.7+/-2.0 and 26.3+/-9.7 ng/ml at 40 mg/m(2) and increased to 14.8+3.0 and 47.4+12.6 ng/ml at 70 mg/m(2). AUCt(0-264) of idarubicin and idarubicinol increased from 423.2+/-111.6 and 2581+/-606 hng/ml at 40 mg/m(2) to 732.8+/-140.2 and 4590+/-1258 hng/ml at 70 mg/m(2). Conversion rates after HD-Ida and HD-TM were 28.6 and 38.5%, respectively. No episodes of cardiac toxicity were observed. We conclude that HD-Ida followed by HD-TM is feasible and devoid of cardiac toxicity. Moreover, the activity of HD-Ida after a epirubicin-containing regimen suggests incomplete cross-resistance between the two drugs.

Severe 5-fluorouracil toxicity associated with a marked alteration of pharmacokinetics of 5-fluorouracil and its catabolite 5-fluoro-5,6-dihydrouracil: a case report

OBJECTIVE

To describe the altered pharmacokinetics of 5-fluorouracil (5-FU) and its major catabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) in a 52-year-old woman affected by a severe 5-FU toxicity.

METHODS

Toxicities were rated according to World Health Organization. 5-FU and 5-FDHU plasma concentrations and dihydropyrimidine dehydrogenase (DPD) activity of peripheral blood mononuclear cells (PBMC) were measured by HPLC analysis.

RESULTS

After a single cycle of 5-FU therapy the patient developed grade 4 diarrhea and stomatitis, grade 3 vomiting, neutropenia, and dermatitis. Compared to a control population, 5-FU AUC, elimination half-life, and C(max) were markedly increased (24.75 vs. 9.25 +/- 0.63 h microg/ml, >5 vs. 0.36 +/- 0.05 h, and 58.54 vs. 37.2 +/- 4.03 microg/ml, respectively) whereas systemic clearance was decreased (12 vs. 51.29 +/- 2.97 l/h/m2); also 5-FDHU AUC (3.3 vs. 12.35 +/- 0.7 h microg/ml) and C(max) (3.4 vs. 4.56 +/- 0.15 microg/ml), which was reached with delay, were reduced. Surprisingly, the PBMC DPD activity (110.8 pmol/min/mg protein) and urinary uracil (68.32 micromol/g urinary creatinine) were within normal range.

CONCLUSIONS

Our results show the altered 5-FU and 5-FDHU pharmacokinetics in a severe 5-FU toxicity case due to an impairment of the hepatic DPD activity and suggest the necessity of a pharmacological evaluation of 5-FU treated patients.

Gemcitabine, epirubicin and paclitaxel: pharmacokinetic and pharmacodynamic interactions in advanced breast cancer

BACKGROUND

The objectives of this study were to investigate the disposition of gemcitabine, epirubicin, paclitaxel, 2',2'-difluorodeoxyuridine and epirubicinol, and characterize the pharmacokinetic and pharmacodynamic profile of treatment in patients with breast cancer.

PATIENTS AND METHODS

The drug dispostion in 15 patients who received gemcitabine 1000 mg/m2, epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (GEP) on day 1 of a 21-day cycle, was compared with that of patients treated with epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (EP, n = 6) and epirubicin 90 mg/m2 alone (n = 6). Drug and metabolite levels in plasma and urine were assessed by high-performance liquid chromatography and parameters of drug exposure were related to hematological toxicity by a sigmoid-maximum effect (Emax) model.

RESULTS

Paclitaxel administration significantly increased the epirubicinol area under the concentration-time curve, from 357+/-146 (epirubicin) to 603+/-107 (EP) and 640+/-81 h x ng/ml (GEP), and reduced the renal clearance of epirubicin and epirubicinol by 38 and 52.2% and 34.5 and 53% in GEP- and EP-treated patients, respectively, compared with epirubicin alone. Gemcitabine had no apparent effect on paclitaxel and epirubicin pharmacokinetics, and renal clearance of epirubicin and epirubicinol. The only pharmacokinetic/pharmacodynamic relationship observed was between neutropenia and the time spent above the threshold plasma level of 0.1 micromol/l (tC0.1) of paclitaxel, with the time required to obtain a 50% decrease in neutrophil count (Et50) of GEP being 7.8 h, similar to that of EP.

CONCLUSIONS

Paclitaxel and/or its vehicle, Cremophor EL, interferes with the disposition and renal excretion of epirubicin and epirubicinol; gemcitabine has no affect on epirubicin and paclitaxel plasma pharmacokinetics and renal excretion of epirubicin, while neutropenia is not enhanced by gemcitabine.

Acetylcholinesterase blockade does not account for the adverse cardiovascular effects of the antitumor drug irinotecan: a preclinical study

This study investigates the mechanisms that account for the adverse cardiovascular effects of the antitumor drug irinotecan. The activities of irinotecan, its active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), and camptothecin were assayed in urethane-anesthetized rats to determine their effects on heart rate and blood pressure. In vitro experiments were performed to assess the effects of test drugs on acetylcholinesterase activity. Intravenous irinotecan (10 micromol/kg) decreased heart rate and blood pressure, but SN-38, camptothecin, or intracerebroventricular irinotecan had no effect. The bradycardic and hypotensive responses induced by irinotecan were abolished by bilateral vagotomy or atropine. Physostigmine caused a transient bradycardia, followed by a tachycardic response, and promoted a marked increment of blood pressure. Vagotomy or atropine prevented the bradycardic action of physostigmine, whereas the tachycardic and hypertensive responses were sensitive to atropine, but not to vagotomy. Five minutes after irinotecan administration (10 micromol/kg i.v.), its concentration in plasma and atrial tissue accounted for 2.29 +/- 0.19 micromol/L and 1.08 +/- 0.16 micromol/kg, respectively. The in vitro activity of human erythrocyte acetylcholinesterase was significantly inhibited by irinotecan (-21.5% at 100 microM) or physostigmine (-84.8% at 1 microM), whereas SN-38 or camptothecin had no effect. Rat atrial acetylcholinesterase was also significantly inhibited in vitro by irinotecan (-16.9% at 100 microM). The present results indicate that irinotecan exerts depressant effects on both heart rate and arterial blood pressure. A direct activation of cholinergic receptors or an interaction with central nervous sites does not appear to account for these inhibitory actions, whereas a blockade of acetylcholinesterase seems to occur at concentrations of irinotecan that may not be relevant in clinical settings.

Design, synthesis, and characterization of the antitumor activity of novel ceramide analogues

A deficiency in apoptosis is one of the key events in the proliferation and resistance of malignant cells to antitumor agents; for these reasons, the search for apoptosis-inducing drugs represents a valuable approach for the development of novel anticancer therapies. In this study we report the first example of conformationally restrained analogues of ceramide (compounds 1-4), where the polar portion of the molecule has been replaced by a thiouracil (1, 3) or uracil (2, 4) ring. The evaluation of their biologic activity on CCRF-CEM human leukemia cells demonstrated that the most active was compound 1 followed by compound 2 (mean 50% inhibition of cell proliferation [IC(50)] 1.7 and 7.9 microM, respectively), while compounds 3 and 4 were inactive, as were uracil, thiouracil, and 5,6-dimethyluracil, the pyrimidine moieties of compounds 1-4. For comparison, the IC(50) of the reference substance, the cell-permeable C2-ceramide, was 31.6 microM. Compounds 1 and 2 and C2-ceramide were able to trigger apoptosis, as shown by the occurrence of DNA and nuclear fragmentation, and to release cytochrome c from treated cells. The treatment of female CD-1 nu/nu athymic mice bearing a WiDr human colon xenograft with the most active compound 1 at 2, 10, 50, and 200 mg/kg ip daily for 10 days resulted in an antitumor effect that was equivalent at 50 mg/kg or superior (200 mg/kg) to that of cyclophosphamide, 20 mg/kg ip daily, delivered on the same schedule, with markedly lower systemic toxicity. In conclusion, the present study demonstrates that the new ceramide analogues 1 and 2 are characterized by in vitro and in vivo antitumor activity and low toxicity.

Pharmacogenetics of anticancer drugs in non-Hodgkin lymphomas

The variability of tumour responses to chemotherapeutic agents is a topic of major interest in current oncology research. Advances in the knowledge of molecular pathology of cancer make available strategies by which tumour cells can be profiled for their genetic background in order to select anticancer agents that might selectively kill cells in a molecular context that matches the mechanism of action of drugs. The next generation of anticancer treatments might thus be tailored on the basis of the numerous molecular alterations identified in tumour cells of a particular patient. However, to exploit these alterations, it is necessary to understand how they influence the cellular pathways that control the sensitivity or, conversely, resistance to chemotherapeutic agents. The aim of this article is to outline major genetic abnormalities in non-Hodgkin lymphomas that can be used to streamline anticancer drug selection and to underscore the major role of pharmacogenetics, which studies the interactions between genetic background and drug activity, to the prediction of likelihood of response and identification of potential new targets for pharmacological intervention.

Drug distribution and pharmacokinetic/pharmacodynamic relationship of paclitaxel and gemcitabine in patients with non-small-cell lung cancer

BACKGROUND

Gemcitabine and paclitaxel are two of the most active agents in non-small-cell lung cancer (NSCLC), and pharmacologic investigation of the combination regimens including these drugs may offer a valuable opportunity in treatment optimization. The present study investigates the pharmacokinetics and pharmacodynamics of paclitaxel and gemcitabine in chemotherapy-naive patients with advanced NSCLC within a phase I study.

PATIENTS AND METHODS

Patients were given i.v. paclitaxel 100 mg/m2 by one-hour infusion followed by gemcitabine 1,500, 1,750 and 2,000 mg/m2 by 30-min administration. Plasma levels of paclitaxel, gemcitabine and its metabolite 2',2'-difluorodeoxyuridine (dFdU) were determined by high-performance liquid chromatography (HPLC). Concentration-time curves were modeled by compartmental and non-compartmental methods and pharmacokinetic/pharmacodynamic (PK/PD) relationships were fitted according to a sigmoid maximum effect (Emax) model.

RESULTS

Paclitaxel pharmacokinetics did not change as a result of dosage escalation of gemcitabine from 1,500 to 2,000 mg/m2. A nonproportional increase in gemcitabine peak plasma levels (Cmax, from 18.56 +/- 4.94 to 40.85 +/- 14.85 microg/ml) and area under the plasma concentration-time curve (AUC, from 9.99 +/- 2.75 to 25.01 +/- 9.87 h x microg/ml) at 1,500 and 2,000 mg/m, respectively, was observed, suggesting the occurrence of saturation kinetics at higher doses. A significant relationship between neutropenia and time of paclitaxel plasma levels > or = 0.05 micromol/l was observed, with a predicted time of 10.4 h to decrease cell count by 50%. A correlation was also observed between percentage reduction of platelet count and gemcitabine Cmax, with a predicted effective concentration to induce a 50% decrease of 14.3 microg/ml.

CONCLUSION

This study demonstrates the lack of interaction between drugs, the nonproportional pharmacokinetics of gemcitabine at higher doses and the Emax relationship of paclitaxel and gemcitabine with neutrophil and platelet counts, respectively. In addition, gemcitabine 1,500 mg/m2 is the recommended dosage in combination with paclitaxel 100 mg/m2 for future phase II studies, due to its predictable kinetic behaviour and less severe thrombocytopenia than expected.

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.

5-fluorouracil administered as a 48-hour chronomodulated infusion in combination with leucovorin and cisplatin: a randomized phase II study in metastatic colorectal cancer

OBJECTIVE

The primary objective of this trial was to determine the objective response of two regimens with CDDP administered every 2 weeks immediately before or after an 'optimal' 48-hour chronomodulated infusion of 5-fluorouracil (5-FU) modulated with leucovorin (LV) in metastatic colorectal cancer patients. Secondary endpoints were toxicity, 5-FU and its metabolites, plasma pharmacokinetics and progression-free and overall survival.

METHODS

Metastatic colorectal cancer patients with measurable disease who were chemotherapy-naive or pretreated only with a 5-FU-bolus-based chemotherapy were eligible for this study. The study was designed as a randomized phase II clinical trial.

RESULTS

Eighty-three patients were entered into the study. Forty-two were randomized to CDDP given before 5-FU and 41 to CDDP given after 5-FU. Patient characteristics were similar among the two groups. Toxicities were also similar among the two arms and the most frequent WHO grade III-IV toxicities were stomatitis (14%) and neutropenia (39-50%). Plasma pharmacokinetic profiles of 5-FU and 5-FUH2 were not significantly affected by the sequence of CDDP and 5-FU administration. Antitumor activity was similar in the two arms and was very promising both in pretreated patients (response rate 29%; 95% confidence interval 15-46%) and in chemotherapy-naive patients (response rate 56%, complete response 9%, 95% confidence interval 40-71%). Median survival of the patients with and without pretreatment was 12 and 16 months, respectively.

CONCLUSIONS

These results do not suggest a sequence dependence of the synergism between CDDP and 5-FU. However, they challenge the need of oxaliplatin to improve 5-FU/LV activity in advanced colorectal cancer. In fact, our results with an 'optimal' 5-FU dose and scheduling are very similar to those obtained with oxaliplatin plus 5-FU/LV. However, only a randomized phase III study will be able to give an answer to the hypotheses raised by this study.

In-vitro evidence of autocrine secretion of vascular endothelial growth factor by endothelial cells from human placental blood vessels

Vascular endothelial growth factor (VEGF), a highly specific mitogen for vascular endothelial cells, is involved in placental vascular growth and remodelling. The aim of this study was to investigate whether placental endothelial cells secrete VEGF in an autocrine manner and if this secretion is correlated with endothelial cell growth. Blood vessels, excised from the apical surface of three human placentae, were sectioned into 40 fragments per placenta and cultured in fibrin gel matrix for 27 days. Immunohistochemical detection of placental endothelial cells was performed by positive staining with anti-human factor VIII-associated antigen and negative staining with anti-human alpha-actin and desmin. To investigate the production and autocrine action of VEGF, VEGF concentrations in culture media were measured and the effect of an anti-VEGF neutralizing antibody on endothelial cell growth was observed. The results demonstrate that soluble VEGF is secreted by placental endothelial cells reaching a plateau from day 24 (68.74 +/- 7.52 pg/ml) to day 27 (67.20 +/- 6.28 pg/ml). Furthermore, VEGF concentrations in media collected on days 6, 12, 18, 21 and 27 of culture were found to be directly correlated to the sprouting parameter of endothelial cells, as calculated by image analysis on the same day ( P < 0.001, r (2) = 0.95 ). The use of 10 and 100 ng/ml of a neutralizing antibody against human VEGF suppressed cell proliferation, compared to that observed in the untreated controls, by 74.8 +/- 7.3 and 89.4 +/- 3.9% respectively. In conclusion, this study reports the first evidence of autocrine secretion of VEGF by human placental endothelial cells and demonstrates the involvement of VEGF in endothelial cell growth within a fibrin gel culture.

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.

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.