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Biomedical subjects

Stephen J Clarke

Publications and source records attributed to Stephen J Clarke.

At least 19 recordsLinked to original sources
PubMed2006

Transcriptional repression of hepatic cytochrome P450 3A4 gene in the presence of cancer.

PURPOSE: Many chemotherapeutic drugs have an inherent lack of safety due to interindividual variability of hepatic cytochrome P450 (CYP) 3A4 drug metabolism. This reduction in CYP3A4 in cancer patients is possibly mediated by cytokines associated with tumor-derived inflammation. We sought to examine this link by using an explant sarcoma in a novel transgenic mouse model of human CYP3A4 regulation. EXPERIMENTAL DESIGN: Engelbreth-Holm-Swarm sarcoma cells were injected into the hindlimb of transgenic CYP3A4/lacZ mice. Hepatic expression of the human CYP3A4 transgene was analyzed by direct measurement of the reporter gene product, beta-galactosidase enzyme activity. Hepatic expression of murine Cyp3a was analyzed at the mRNA, protein, and function levels. The acute phase response was assessed by examining cytokines [interleukin-6 (IL-6) and tumor necrosis factor] in serum, liver, or tumor as well as hepatic expression of serum amyloid protein P. RESULTS: Engelbreth-Holm-Swarm sarcoma elicited an acute phase response that coincided with down-regulation of the human CYP3A4 transgene in the liver as well as the mouse orthologue Cyp3a11. The reduction of murine hepatic Cyp3a gene expression in tumor-bearing mice resulted in decreased Cyp3a protein expression and consequently a significant reduction in Cyp3a-mediated metabolism of midazolam. Circulating IL-6 was elevated and IL-6 protein was only detected in tumor tissue but not in hepatic tissue. CONCLUSIONS: The current study provides a mechanistic link between cancer-associated inflammation and impaired drug metabolism in vivo. Targeted therapy to reduce inflammation may provide improved clinical benefit for chemotherapy drugs metabolized by hepatic CYP3A4 by improving their pharmacokinetic profile.

Adjuvants, Anesthesia↗
PubMed2006

Nutrition intervention using an eicosapentaenoic acid (EPA)-containing supplement in patients with advanced colorectal cancer. Effects on nutritional and inflammatory status: a phase II trial.

GOALS: The aim of the study was to assess the impact of an eicosapentanoic acid-containing protein and energy dense oral nutritional supplement (EPA-ONS) on nutritional and inflammatory status, quality of life (QOL), plasma phospholipids (PPL) and cytokine profile, tolerance of irinotecan-containing chemotherapy and EPA-ONS in patients with advanced colorectal cancer (CRC) receiving chemotherapy. MATERIALS AND METHODS: Patients with advanced CRC having one prior chemotherapy regimen received 480 ml of EPA-ONS daily for 3 weeks before commencing chemotherapy with folinic acid, 5-fluorouracil, irinotecan (FOLFIRI), and continued for 3 cycles of treatment (9 weeks). All assessments including weight, body composition, C-reactive protein (CRP), QOL, dietary intake, PPL and cytokine analyses were performed at baseline, 3 and 9 weeks. RESULTS: Twenty-three patients were enrolled, 20 completed 3 weeks, and 15 completed 9 weeks. The mean EPA-ONS intake was 1.7 tetrapaks (408 ml) daily. There was a significant increase in mean weight (2.5 kg) at 3 weeks (p=0.03). Lean body mass (LBM) was maintained. Protein and energy intake significantly decreased after the commencement of chemotherapy (protein p=0.003, energy p=0.02). There was a significant increase in energy levels (p=0.03), whilst all other QOL measures were maintained. PPL EPA levels increased significantly over the first 3 weeks. Mean CRP increased by 14.9 mg/L over the first 3 weeks (p=0.004), but decreased to baseline levels by the end of the trial. There was a significant correlation between plasma IL-6 and IL-10 concentrations and survival, and between IL-12 and toxicity. CONCLUSION: Dietary counseling and the provision of EPA-ONS may result in maintenance of nutritional status and QOL, however randomized trials are required to evaluate the impact of EPA on toxicity from chemotherapy.

Aged↗
PubMed2006

Relationship of hepatic functional imaging to irinotecan pharmacokinetics and genetic parameters of drug elimination.

PURPOSE: The marked variability of irinotecan (Ir) clearance warrants individualized dosing based on hepatic drug handling. The aims of this trial were to identify parameters from functional hepatic nuclear imaging (HNI) that correlate with (1) Ir pharmacology, and (2) single-nucleotide polymorphisms (SNPs) for the ABCB1 (P-glycoprotein) and UGT-1A1 genes, known to influence Ir handling. METHODS: Patients underwent genotyping for ABCB1 SNPs and UTUGT-1A1*28 carriage and HNI with 99mTc-DIDA (acetanilidoiminodiacetic acid)/99mTc-DISIDA (disofenin) and MIBI (99mTc-sestamibi) scans, probes for biliary transport proteins ABCC1 and -2, and ABCB1 function. HNI data were analyzed by noncompartmental and deconvolutional analysis to provide hepatic extraction and biliary excretion parameters. Patients received Ir, fluorouracil, and folinic acid using a weekly x2, every-3-weeks schedule. Plasma was taken for Ir and SN-38 analysis on day 1, cycle 1. RESULTS: Of the 21 patients accrued, Ir pharmacokinetics data were obtained from 16 patients. 99mTc-DIDA/DISIDA percent retention at 1 hour (1-hour RET) correlated to baseline serum bilirubin (P = .008). Both 99mTc-DIDA/DISIDA and MIBI 1-hour RET correlated with SN-38 area under the curve (AUC; P < .01). On multiple regression analysis, SN-38 AUC = -215 + 18.68 x bilirubin + 4.27 x MIBI 1-hour RET (P = .009, R2 = 44.2%). HNI parameters did not correlate with Ir toxicity or UGT1A1*28 carriage. MIBI excretion was prolonged in patients with the ABCB1 exon 26 TT variant allele relative to wild-type (P = .015). CONCLUSION: Functional imaging of hepatic uptake and excretory pathways may have potential to predict Ir pharmacokinetics. Evaluation of a larger cohort as well as polymorphisms in other biliary transporters and UGT1A1 alleles is warranted.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2006

Altered deoxyuridine and thymidine in plasma following capecitabine treatment in colorectal cancer patients.

AIMS: To investigate the relationship between changes in plasma deoxynucleoside concentrations and response and toxicity in patients treated with capecitabine. METHODS: Twenty-six patients received 2 g capecitabine twice daily orally for 2 weeks of a 3-week cycle. Blood samples were collected on day 0 (baseline), day 8, day 15 and day 22 of the first cycle for the determination of plasma thymidine (TdR) and deoxyuridine (UdR) concentrations. Patients were reviewed weekly during the first cycle, then 3-weekly for toxicity assessment. Response was assessed according to Response Evaluation Criteria in Solid Tumours (RECIST) criteria. RESULTS: The plasma UdR and UdR/TdR ratios were significantly elevated (P < 0.001) compared with baseline (49.3 +/- 20.8 nmol l(-1)) for the entire 3-week treatment period. In contrast, the plasma TdR concentrations of these patients were significantly reduced only on day 8 (P < 0.01) compared with baseline (12.1 +/- 3.83 nmol l(-1)), but returned gradually to basal levels by day 15. There were no significant correlations demonstrated between pretreatment or maximal post-treatment plasma nucleoside ratio and either toxicity or response. The TSER genotype frequencies of homozygous TSER*2, TSER*3 and heterozygous TSER*2/*3 were 7.7%, 42.3% and 50%, respectively. These preliminary data also indicate no direct relationship between thymidylate synthase (TS) genotype and plasma nucleoside levels. CONCLUSIONS: Capecitabine mimics continuous infusion of 5-FU to achieve sustained cellular TS inhibitory effects and suggests the antiproliferative mechanism of capectabine is at least partly due to TS inhibition through its active metabolite FdUMP. Although plasma UdR and TdR concentrations and the UdR/TdR ratio can provide some pharmacodynamic indication of TS inhibition, they are unlikely to predict therapeutic response or toxicity accurately following capecitabine treatment in cancer patients.

Antimetabolites, Antineoplastic↗
PubMed2006

Advances in the adjuvant treatment of colorectal cancer.

BACKGROUND: There have been numerous advances in the adjuvant therapy of colon cancer in the last two decades. METHODS: This review outlines the historical perspectives of adjuvant treatment as well as current and emerging standards of care. RESULTS: Although previous regimens included a variety of equivalent schedules of 5-fluorouracil and folinic acid, integration of newer drugs such as oxaliplatin are offering significant improvements in disease-free survival. The use of targeted agents such as bevacuzimab creates the potential to further increase cure rates in the adjuvant setting. The current low rate of referral of eligible patients for chemotherapy in Australia is also discussed. CONCLUSION: Adjuvant therapy for colon cancer is making major strides as we attempt to cure more patients.

Antineoplastic Agents↗
PubMed2006

Evaluation of nutritional and inflammatory status of advanced colorectal cancer patients and its correlation with survival.

The purpose of this study was to evaluate novel inflammatory and nutritional prognostic factors in patients with advanced colorectal cancer (ACRC). All ACRC patients attending the clinic for palliative treatment were eligible for study. Demographics, including performance status (PS), C-reactive protein (CRP), albumin (Alb), Glasgow prognostic score (GPS), weight, weight history, body mass index (BMI), and nutritional status using the patient-generated subjective global assessment (PGSGA), were collected and correlated with survival. At a median follow-up of 29.8 mo, with a minimum follow-up of 15.7 mo, the median survival was 9.9 mo (0.8-21.8 mo). Fifteen (29%) patients were newly diagnosed (stage IV colorectal cancer), and 36 (71%) had received prior chemotherapy. Although the median BMI was 27 kg/m2 (range = 17-41 kg/m2), 28 of 50 (56%) were nutritionally at risk. In fact, 19 patients (38%) were critically in need of nutrition intervention (PGSGA score of > or =9). Thirty-three of 48 patients (69%) had an elevated CRP (>10 mg/l with a median of 21.1 mg/L), and 7 patients (15%) had both a CRP of >10 mg/l and hypoalbuminemia (< 35 g/l). A significant positive correlation was found between PGSGA score and CRP (P = 0.003; r = 0.430). Using univariate analysis, significantly worse survival was found for patients with poorer PS (P = 0.001), high GPS (P = 0.04), low Alb (P = 0.017), elevated serum alkaline phosphatase (SAP; P = 0.018), PGSGA score of > 9 (P = 0.001), and PGSGA group B/C (P = 0.02). Using the Cox proportional hazard model for multivariate survival analysis, type of treatment (hazard ratio, HR = 1.48; 95% confidence interval, CI = 1.11-1.79; P = 0.005), PS (HR = 2.37; 95% CI = 1.11-5.09; P = 0.026), GPS (HR = 2.27; 95% CI = 1.09-4.73; P = 0.028), and SAP (HR = 0.44; 95% CI = 0.18-1.07; P =0.069) remained significant predictors of survival. These preliminary data suggest that the type of treatment, PS, GPS, and SAP are important predictors of survival in ACRC.

Adult↗
PubMed2006

Predicting the toxicity of weekly docetaxel in advanced cancer.

OBJECTIVES: To determine the safety profile of 40 mg/m(2) docetaxel administered weekly to a mixed population of advanced cancer patients and identify predictors of toxicity and survival following treatment with weekly docetaxel in this population. PATIENTS AND METHODS: 68 patients with advanced cancer were enrolled into the study. Various patient characteristics, including inflammatory and nutritional status, docetaxel pharmacokinetics and liver function were investigated. Predictors of treatment-related toxicity and survival were analysed using multivariate logistic regression and Cox proportional hazards analysis, respectively. RESULTS: 27 patients (40%) experienced grade 3 or 4 toxicity, mainly gastrointestinal toxicities (20%), leukopenia (16%) and neutropenia (12%), during the first 8 weeks of docetaxel treatment. Docetaxel pharmacokinetics were the only predictive factor for haematological toxicity. The odds of severe haematological toxicity were approximately 9-fold higher for patients with reduced docetaxel clearance (e.g. <30 L/h). The odds of non-haematological toxicity were about 3-fold higher for patients with elevated levels of inflammatory markers: alpha(1)-acid glycoprotein (AAGP) >1.5 g/L or C-reactive protein >10 mg/L). Multivariate analysis indicated that weight loss, liver dysfunction and elevated levels of AAGP were independently significant predictors of survival. CONCLUSION: This is the first description of factors predictive of the toxicity and survival following weekly administration of docetaxel. Patients with reduced clearance of docetaxel and elevated markers of inflammation experienced worse adverse effects, while patients with weight loss, liver dysfunction and elevated markers of inflammation had worse survival.

Adult↗
PubMed2005

Rapid quantitation of plasma 2'-deoxyuridine by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry and its application to pharmacodynamic studies in cancer patients.

A novel method employing high-performance liquid chromatograph-mass spectrometry (LC-MS) has been developed and validated for the quantitation of plasma 2'-deoxyuridine (UdR). It involves a plasma clean-up step with strong anion-exchange solid-phase extraction (SAX-SPE) followed by HPLC separation and atmospheric pressure chemical ionization mass spectrometry detection (APCI-MS) in a selected-ion monitoring (SIM) mode. The ionization conditions were optimised in negative ion mode to give the best intensity of the dominant formate adduct [M+HCOO]- at m/z 273. Retention times were 7.5 and 12.5 min for 2'-deoxyuridine and 5-iodo-2'-deoxyuridine, an iodinated analogue internal standard (IS), respectively. Peak area ratios of 2'-deoxyuridine to IS were used for regression analysis of the calibration curve. The latter was linear from 5 to 400 nmol/l using 1 ml sample volume of plasma. The average recovery was 81.5% and 78.6% for 2'-deoxyuridine and 5-iodo-deoxyuridine, respectively. The method provides sufficient sensitivity, precision, accuracy and selectivity for routine analysis of human plasma 2'-deoxyuridine concentration with the lowest limit of quantitation (LLOQ) of 5 nmol/l. Clinical studies in cancer patients treated with the new fluoropyrimidine analogue capecitabine (N4-pentoxycarbonyl-5'-5-fluorocytidine) have shown that plasma 2'-deoxyuridine was significantly elevated after 1 week of treatment, consistent with inhibition of thymidylate synthase (TS). These findings suggest that the mechanism of antiproliferative toxicity of capecitabine is at least partly due to TS inhibitory activity of its active metabolite 5-fluoro-2'-deoxyuridine monophosphate (FdUMP). Monitoring of plasma UdR concentrations have the potential to help clinicians to guide scheduling of capecitabine or other TS inhibitors in clinical trials. Marked differences of plasma 2'-deoxyuridine between human and rodents have also been confirmed. In conclusion, the LC-MS method developed is simple, highly selective and sensitive and permits pharmacodynamic studies of TS inhibitors in several species.

Atmospheric Pressure↗
PubMed2005

A phase I/II study of pemetrexed and vinorelbine in patients with non-small cell lung cancer.

PURPOSE: Pemetrexed and vinorelbine are active antineoplastic agents in non-small cell lung cancer (NSCLC). Phase I objectives include maximum tolerated dose (MTD) and recommended phase II dose determination, and pharmacokinetics of the pemetrexed-vinorelbine doublet in locally advanced or metastatic solid tumor patients (pts). Phase II objectives include tumor response evaluation, efficacy, and toxicity for first-line treatment of advanced NSCLC. EXPERIMENTAL DESIGN: Phase I pts received pemetrexed (day 1, 300-700 mg/m2) and vinorelbine (days 1 and 8, 15-30 mg/m2) every 21 days. Pharmacokinetics determined at cycle 1. Beginning with dose-level 3, folic acid and Vitamin B12 supplementation were given. RESULTS: Thirty-one phase I pts were enrolled. MTD was pemetrexed 700 mg/m2 and vinorelbine 30 mg/m2; and recommended phase II dose was pemetrexed 500 mg/m2 and vinorelbine 30 mg/m2. When administered in combination, pemetrexed and vinorelbine pharmacokinetics were consistent with single-agent administration. Thirty-seven (36 chemonaive) phase II NSCLC pts received pemetrexed-vinorelbine. Evaluable tumor response was 40%, with intent-to-treat 38%. One drug-related death occurred from febrile neutropenia with Staphylococcal infection. Grade 3/4 hematologic toxicities were neutropenia (65%) and febrile neutropenia (11%), while prevalent grade 3/4 non-hematologic toxicity was fatigue (27%). CONCLUSION: The pemetrexed-vinorelbine combination is well tolerated and shows activity as first-line treatment in advanced NSCLC patients.

Adult↗
PubMed2005

Management of chemotherapy-induced nausea, vomiting, oral mucositis, and diarrhoea.

The past 10 years have seen substantial advances in molecularly targeted therapies for treatment of patients with cancer; however, chemotherapy will continue to be used. Therefore, the toxic effects of chemotherapy must be readily managed-especially nausea, vomiting, mucositis, and diarrhoea. For moderately to highly emetogenic chemotherapy, standard prophylactic treatment is an antagonist for 5-hydroxytryptamine 3 receptors (5-HT3R) combined with dexamethasone for the acute phase, and dexamethasone with another agent for prevention of the delayed phase. Palonoestron (a 5-HT3R antagonist) and aprepitant (an antagonist for the protachykinin 1 receptor) have been introduced for the prevention of emesis. Other agents such as cannabinoids, gabapentin, and olanzapine might also be effective. There is no standard prophylactic regimen for chemotherapy-induced mucositis. The most common treatment is optimum care of the mouth by use of mouthwashes. Keratinocyte growth factor, molgromastim, and transforming growth factor beta3 may also reduce chemotherapy-induced mucositis. Severe diarrhoea is another potentially fatal complication of chemotherapy and is most common in patients treated with irinotecan. Several interventions have been assessed for prevention and treatment of diarrhoea such as high-dose loperamide, non-absorbable antibiotics, budesonide, thalidomide, and fish oils, but only loperamide is used routinely. Symptom management has become a focus of clinical research, and development of personalised medicine should identify patients at increased risk of toxic effects because of molecular or biochemical factors, thus leading to changes in dose, early intervention, or use of alternative therapies.

Anti-Inflammatory Agents↗
PubMed2005

Nutritional assessment in cancer: comparing the Mini-Nutritional Assessment (MNA) with the scored Patient-Generated Subjective Global Assessment (PGSGA).

The evaluation of nutritional status in cancer patients is often neglected in spite of the fact that poor nutritional status may adversely affect prognosis and treatment tolerance. In day-to-day oncology practice, a sensitive but simply applied nutritional assessment tool is needed to identify at-risk patients. Several tools exist; however, none has been universally accepted. The aim of this study was to compare two potential tools, the Mini-Nutritional Assessment (MNA) and the scored Patient Generated Subjective Global Assessment (PGSGA). The MNA is more simply applied and does not require a trained dietitian. The PGSGA has been previously validated in cancer patients. One hundred fifty-seven newly diagnosed cancer patients were assessed using both tools. Of these, 126 were reassessed at 4-6 wk, and 104 were reassessed at Weeks 8-12 after initial assessment. A significant negative correlation was found between the tools at all three time periods (at baseline r = -0.76; P < 0.001). Taking the PGSGA as the most accepted nutritional assessment tool, at baseline the MNA demonstrated a sensitivity of 97% and specificity of 54%. At 4-6 wk MNA sensitivity was 79% and specificity was 69%. At 8-12 wk MNA sensitivity was 93% and specificity was 82%. When comparing the tools in elderly patients alone (>65 yr), similar results were obtained. Both tools were able to correctly classify patients as malnourished, although the MNA lacks specificity. Therefore, the PGSGA should be the tool of choice for nutritional assessment in cancer patients.

Adult↗
PubMed2004

Factors affecting cytochrome P-450 3A activity in cancer patients.

PURPOSE: The purpose is to identify the demographic, physiologic, and inheritable factors that influence CYP3A activity in cancer patients. EXPERIMENTAL DESIGN: A total of 134 patients (62 females; age range, 26 to 83 years) underwent the erythromycin breath test as a phenotyping probe of CYP3A. Genomic DNA was screened for six variants of suspected functional relevance in CYP3A4 (CYP3A4*1B, CYP3A4*6, CYP3A4*17, and CYP3A4*18) and CYP3A5 (CYP3A5*3C and CYP3A5*6). RESULTS: CYP3A activity (AUC(0-40 min)) varied up to 14-fold in this population. No variants in the CYP3A4 and CYP3A5 genes were a significant predictor of CYP3A activity (P > 0.2954). CYP3A activity was reduced by approximately 50% in patients with concurrent elevations in liver transaminases and alkaline phosphatase or elevated total bilirubin (P < 0.001). In a multivariate analysis, CYP3A activity was not significantly influenced by age, sex, and body size measures (P > 0.05), but liver function combined with the concentration of the acute-phase reactant, alpha-1 acid glycoprotein, explained approximately 18% of overall variation in CYP3A activity (P < 0.001). CONCLUSIONS: These data suggest that baseline demographic, physiologic, and chosen genetic polymorphisms have a minor impact on phenotypic CYP3A activity in patients with cancer. Consideration of additional factors, including the inflammation marker C-reactive protein, as well as concomitant use of other drugs, food constituents, and complementary and alternative medicine with inhibitory and inducible effects on CYP3A, is needed to reduce variation in CYP3A and treatment outcome to anticancer therapy.

Adult↗
PubMed2004

Population pharmacokinetics of weekly docetaxel in patients with advanced cancer.

AIMS: Previous pharmacokinetic studies of the 3-weekly regimen (100 mg m(-2) every 3 weeks) of docetaxel have shown that docetaxel clearance is affected by liver function, body surface area, age, serum alpha1-acid glycoprotein and cytochrome P450 3A4 (CYP3A4) activity. However, the pharmacokinetics of a weekly docetaxel (40 mg m(-2) week(-1)) schedule are not well characterized. The aims of this study were (a) to investigate the pharmacokinetics of docetaxel (40 mg m(-2) week(-1)) using sparse concentration-time data collected from patients with advanced cancer and (b) to utilize a population pharmacokinetic approach to identify patient covariates that significantly influence the clearance of docetaxel when administered according to this regimen. METHODS: A two-compartment pharmacokinetic model was used to describe the docetaxel concentration-time data from 54 patients with advanced cancer. The mean population and individual posterior Bayesian estimates of docetaxel clearance were estimated using P-PHARM. The relationships between docetaxel clearance and 21 covariates were investigated. This included estimates of CYP3A4 function in each patient using the erythromycin breath test (1/tmax). Significant covariates were included into the final population pharmacokinetic model. Pharmacokinetic models were validated using a data splitting approach with a dataset consisting of 16 patients. RESULTS: Significant relationships were found between docetaxel clearance and 1/tmax (erythromycin breath test parameter) and several of the liver function enzymes and CL was best described by the equation; CL = 21.51 + 217 (1/tmax) - 0.13 (ALT). This final population pharmacokinetic model provided both precise and unbiased predictions of docetaxel concentrations in a validation group of patients and an estimate of the population mean (95% confidence interval) clearance of docetaxel was 30.13 l h(-1) (12.54, 46.04 l h(-1)) with an intersubject variability 30%. CONCLUSIONS: A population pharmacokinetic model has been developed and validated for weekly docetaxel (40 mg m(-2)) in patients with advanced cancer. These results indicate that CYP3A4 activity and hepatic function have an impact on the pharmacokinetics of docetaxel when administered weekly.

Adult↗
PubMed2004

Population pharmacokinetics of raltitrexed in patients with advanced solid tumours.

AIMS: To investigate the population pharmacokinetics of raltitrexed in patients with advanced solid tumours and to identify patient covariates contributing to the interpatient variability in the pharmacokinetics of raltitrexed. METHODS: Patient covariate and concentration-time data were collected from patients receiving 0.1-4.5 mg m(-2) raltitrexed during the early clinical trials of raltitrexed. Data were fitted using nonlinear mixed effects modelling to generate population mean estimates for clearance (CL) and central volume of distribution (V). The relationship between individual estimates of the pharmacokinetic parameters and patient covariates was examined and the influence of significant covariates on the population parameter estimates and their variance was investigated using stepwise multiple linear regression. The performance of the developed model was tested using an independent validation dataset. All patient data were pooled in the total cohort to refine the population pharmacokinetic model for raltitrexed. RESULTS: three-compartment pharmacokinetic model was used to fit the concentration-time data of raltitrexed. Estimated creatinine clearance (CL(CR)) was found to influence significantly the CL of raltitrexed and explained 35% of variability in this parameter, whilst body weight (WT) and serum albumin concentrations (ALB) accounted for 56% of the variability in V. Satisfactory prediction (mean prediction error 0.17 micro g l(-1) and root mean square prediction error 4.99 micro g l(-1)) of the observed raltitrexed concentrations was obtained in the model validation step. The final population mean estimates were 2.17 l h(-1)[95% confidence interval (CI) 2.06, 2.28] and 6.36 l (95% CI 6.02, 6.70) for CL and V, respectively. Interpatient variability in the pharmacokinetic parameters was reduced (CL 28%, V 25%) when influential covariates were included in the final model. The following covariate relationships with raltitrexed parameters were described by the final population model: CL (l h(-1)) = 0.54 + 0.02 CL(CR) (ml min(-1)) and V (l) = 6.64 + 0.08 WT (kg) - 0.16 ALB (g l(-1)). CONCLUSIONS: A population pharmacokinetic model has been developed for raltitrexed in patients with advanced cancer. Pharmacokinetic parameters of raltitrexed are markedly influenced by the patient's renal function, body weight and serum albumin levels, which may be taken into account in dose individualization. The use of influential covariates to guide anticancer dosage selection may result in less variability in drug exposure and potentially a better clinical outcome.

Adult↗
PubMed2003

Inflammatory response: an unrecognised source of variability in the pharmacokinetics and pharmacodynamics of cancer chemotherapy.

An important limitation in the use of chemotherapy in cancer treatment is that cytotoxic agents have small margins of safety compared with other drugs. The largely unpredictable pharmacokinetics of cytotoxic agents contribute significantly to differences in toxicity and efficacy between individuals. Over the past few decades, evidence has accumulated that the inflammatory response to conditions such as infection, degenerative disease, and cancer can greatly affect the disposition of drugs. A more recent finding is that the presence of an inflammatory response identifies patients with more aggressive disease and may also compromise the pharmacodynamics of anticancer drugs. In this review, we discuss the changes in the pharmacokinetics of drugs caused by the presence of inflammation. Also, we discuss the modulating role of inflammatory mediators on the pharmacokinetics and pharmacodynamics of cytotoxic agents. We argue that, overall, these factors identify inflammatory response as a potentially important factor in the interindividual variability of response and toxic effects to cancer chemotherapy.

Animals↗
PubMed2003

Baseline nutritional assessment in advanced cancer patients receiving palliative chemotherapy.

Depletion of nutritional reserves and significant weight loss can lead to an increased risk of morbidity, reduced chemotherapy response, and shorter survival in patients with cancer. Weight loss and malnutrition are recognized to result from multifactorial processes, which if assessed and managed appropriately may lead to improved treatment outcome. Numerous methodologies are used for the assessment of nutritional status. However, it remains unclear which of these tools is the most appropriate in the setting of cancer chemotherapy. The aim of this study was to investigate the use of various fundamental assessment tools that could be applied to the routine clinical evaluation of nutritional status in patients with advanced solid malignancies before treatment with palliative chemotherapy. We investigated the interrelationships between biochemical indices, anthropometric measures, and a nutritional screening tool, the Mini-Nutritional Assessment, in 73 patients. Many of these measures were highly interrelated, but the baseline history of weight loss in these patients was strongly correlated to the Mini-Nutritional Assessment (MNA) score (P < 0.0005). In turn, baseline weight loss and the MNA score were strongly correlated to serum C-reactive protein (a marker of acute-phase response). In some patients, malnutrition was linked to disease- or treatment-related upper digestive tract morbidity. Testing for the serum concentration of C-reactive protein at baseline may identify a subset of patients for whom a decline in nutritional status is linked to the presence of an active inflammatory response, a recognized precursor of cachexia

Adult↗
PubMed2002

Pemetrexed: single-agent and combination phase I study overview.

Pemetrexed is a novel folic acid antimetabolite that exerts its activity by the inhibition of multiple enzyme targets. It has been evaluated in a series of phase I clinical trials that explored different administration schedules. The schedule that has been carried forward into phase II trials involves the administration of pemetrexed as a 10-minute intravenous infusion every 21 days with no standard pretreatment with folic acid or vitamin B(12). When given in this manner, the dose-limiting toxicities were neutropenia and thrombocytopenia. Other toxicities included mucositis, rash, and fatigue. The recommended phase II dose was 600 mg/m(2) administered intravenous every 21 days, although this was subsequently modified to 500 mg/m(2) when several early patients experienced toxicities requiring dose reduction in phase II studies. On the basis of preclinical studies suggesting additive or synergistic effects, pemetrexed has also been evaluated in phase I studies in combination with several other agents including cisplatin, carboplatin, oxaliplatin, irinotecan, the taxanes, and anthracyclines. Encouraging anticancer activity has been observed in many of these studies.

Antimetabolites, Antineoplastic↗