Cancer cachexia: pathophysiological mechanisms

Changes in individual drug-independent system parameters during virtual paediatric pharmacokinetic trials: introducing time-varying physiology into a paediatric PBPK model

Although both POPPK and physiologically based pharmacokinetic (PBPK) models can account for age and other covariates within a paediatric population, they generally do not account for real-time growth and maturation of the individuals through the time course of drug exposure; this may be significant in prolonged neonatal studies. The major objective of this study was to introduce age progression into a paediatric PBPK model, to allow for continuous updating of anatomical, physiological and biological processes in each individual subject over time. The Simcyp paediatric PBPK model simulator system parameters were reanalysed to assess the impact of re-defining the individual over the study period. A schedule for re-defining parameters within the Simcyp paediatric simulator, for each subject, over a prolonged study period, was devised to allow seamless prediction of pharmacokinetics (PK). The model was applied to predict concentration-time data from multiday studies on sildenafil and phenytoin performed in neonates. Among PBPK system parameters, CYP3A4 abundance was one of the fastest changing covariates and a 1-h re-sampling schedule was needed for babies below age 3.5 days in order to seamlessly predict PK (<5% change in abundance) with subject maturation. The re-sampling frequency decreased as age increased, reaching biweekly by 6 months of age. The PK of both sildenafil and phenytoin were predicted better at the end of a prolonged study period using the time varying vs fixed PBPK models. Paediatric PBPK models which account for time-varying system parameters during prolonged studies may provide more mechanistic PK predictions in neonates and infants.

Evaluation of Nutritional Status in Cancer Patients Receiving Radiotherapy

OBJECTIVES

The purpose of the present study was to evaluate the nutritional status of cancer patients receiving radiotherapy (RT) and to assess the possible contributions of nutritional support to patients with malnutrition.

METHODS

Prospectively, 207 patients referred to our outpatient radiotherapy department were included. The patients were classified according to tumor site (head/neck, breast, lung, stomach, or colorectal). Nutritional status at the onset, at the end of RT, and 3 and 6 months after irradiation was evaluated with the subjective global assessment (SGA). All of the patients were supported with additional portions of meal or standard enteral feeding formula during and after the irradiation period as long as they were in the moderately or severely malnourished groups, respectively.

RESULTS

At the onset, malnutrition was present in 31% of all patients, and it increased to 43% at the end of RT. This difference predominated in head/neck cancer patients. Malnutrition ratios in head/neck cancer patients at the onset and after RT were 24% and 88%, respectively. By a 6-month follow-up, the ratio of patients with malnutrition decreased to 8%. Nutritional status of all groups was found to improve during the 6-month follow-up period, except for the breast cancer group, which included no patients with severe malnutrition at any time.

CONCLUSION

The results of the present study may be helpful in planning an appropriate nutritional support for cancer patients undergoing radiotherapy according to the irradiation site.

Determination of D-amino acid oxidase activity in tumour cells

BACKGROUND

We evaluated the assay for determining D-amino acid oxidase (DAAO) activity in tumour cells, rat liver and rat kidney for studying the effects of D-amino acid-containing solution on cancer patients.

METHODS AND RESULTS

In this method the amount of ammonia produced by the DAAO activity after removal of endogenous ammonia using a Sephadex G25 column was determined. The highest activity was observed in rat kidney, which was almost eight times that found in rat liver. As compared with host tissues, the DAAO activity in tumour cells was considerably less.

CONCLUSIONS

This DAAO assay may be useful for analysis of various tissue samples as well as tumour cells.

Eicosapentaenoic acid ethyl ester supplementation in cachectic cancer patients and healthy subjects: effects on lipolysis and lipid oxidation

BACKGROUND & AIMS

Recent reports suggest that weight loss in cachectic cancer patients may be inhibited by supplementation of the n-3 fatty acid eicosapentaenoic acid (20:5n-3; EPA), presumably due to inhibition of lipolysis. The aim of the present double-blind, randomized trial was to assess whether short-term oral EPA ethyl ester (EE) supplementation inhibits lipolysis and lipid oxidation in weight-losing cancer patients and in healthy subjects.

METHODS

Seventeen weight-losing, cancer patients of different tumor types, and 16 healthy subjects were randomized to receive EPA-EE (6 g/d) or placebo (oleic acid (OA)-EE; 6 g/d) for seven days. At baseline (day 0) and during supplementation (days 2 and 7) whole-body lipolysis and palmitic acid release were measured in the overnight fasting state using [1, 1, 2, 3, 3-(2)H(5)]glycerol and [1-(13)C]palmitic acid. Palmitate oxidation was determined by measuring(13)CO(2)enrichment in expired breath.

RESULTS

No significant effects of EPA-EE on whole-body lipolysis, palmitic acid release, or palmitate oxidation were detected in cancer patients nor in healthy subjects in comparison with OA-EE. EPA-EE supplementation reduced plasma-free fatty acid and triacylglycerol concentrations significantly in healthy subjects but not in cancer patients.

CONCLUSION

We conclude that supplementation of EPA-EE does not significantly inhibit lipolysis or lipid oxidation in weight-losing cancer patients or in healthy subjects during short-term supplementation when using OA-EE as a placebo supplement.

Regulation of skeletal-muscle-protein turnover in cancer-associated cachexia

Cancer is frequently associated with anorexia, weight loss, negative nitrogen balance, and skeletal-muscle wasting. Depletion of skeletal-muscle mass is critical to overall survival of the patient, can prolong rehabilitation to normal function after recovery, and decreases quality of life in a palliative-care setting. The biochemical and physiologic bases of cancer-associated muscle wasting have been most fully investigated in animal models. These studies provide evidence for suppressed protein synthesis and activated proteolysis in cancer-associated muscle wasting and indicate a need for both anabolic and anticatabolic therapies. Several humoral factors of host or tumor origin are implicated in altered muscle-protein metabolism, including cytokines, metabolites of arachidonic acid, and a proteolysis-inducing glycoprotein; their interrelationships are less well characterized. Several catabolic mediators may share common downstream mechanisms because they ultimately activate the ATP-, ubiquitin-, and proteasome-dependent intracellular proteolytic system. Although important gaps in our current understanding remain, data available from animal studies can be used as a basis to develop relevant studies in human subjects.

Nutritional support of the cancer patient: issues and dilemmas

Malnutrition in cancer patients results from multifactorial events and is associated with an alteration of quality of life and a reduced survival. A simple nutritional assessment program and early counselling by a dietitian are essential to guide nutritional support and to alert the physician to the need for enteral (EN) or parenteral nutrition (PN). A daily intake of 20-35 kcal/kg, with a balanced contribution of glucose and lipids, and of 0.2-0.35 g nitrogen/kg is recommended both for EN and PN, with an adequate provision of electrolytes, trace elements and vitamins. EN, always preferable for patients with an intact digestive tract, and PN are both safe and effective methods of administering nutrients. The general results in clinical practice suggest no tumor growth during nutritional support. The indiscriminate use of conventional EN and PN is not indicated in well-nourished cancer patients or in patients with mild malnutrition. EN or PN is not clinically efficacious for patients treated with chemotherapy or radiotherapy, unless there are prolonged periods of GI toxicity, as in the case of bone marrow transplant patients. Severely malnourished cancer patients undergoing major visceral surgery may benefit from perioperative nutritional support, preferably via enteral access. Nutritional support in palliative care should be based on the potential risks and benefits of EN and PN, and on the patient's and family's wishes. Research is currently directed toward the impact of nutritional pharmacology on the clinical outcome of cancer patients. Glutamine-supplemented PN is probably beneficial in bone marrow transplant patients. Immune diets are likely to reduce the rate of infectious complications and the length of hospital stay after GI surgery. Further studies are needed to determine the efficacy of such novel approaches in specific populations of cancer patients, and should also address the question of the overall cost-benefit ratio of nutritional pharmacology, and the effect of nutritional support on length and quality of life.

Contribution of diet, tumour volume and patient-related factors to weight loss in patients with colorectal liver metastases

BACKGROUND

One of the difficulties in assessing the contribution of tumour-related factors to cancer cachexia is measurement of the extent of disease where dissemination to multiple organ sites has occurred.

METHODS

In this study the extent of tumour (both tumour volume and increase in marker levels), diet and patient-related factors (appetite, metabolic hormones, immune activation, liver function and quality of life) were compared in patients with colorectal liver metastases who had lost at least 1 kg in body-weight (weight loss) and patients who had not lost 1 kg in body weight (stable weight) during the preceding month.

RESULTS

Forty patients (22 men; 14 with weight loss) were studied. Liver metastasis volume was significantly greater in patients who lost weight than in those whose weight was stable (median (interquartile range) 1179 (245-1517) versus 119 (23-523) ml; P = 0.003). The prevalence of patients with raised levels of serum immune products was significantly greater in the weight loss group for soluble interleukin (IL) 2 receptor alpha (sIL2ralpha) (P = 0.03) and IL-6 (P = 0.05), but not for soluble tumour necrosis factor receptor 1 (sTNFr1) or neopterin. There were significant correlations between serum C-reactive protein and sIL2ralpha (rs = 0.68, P < 0.0001) and IL-6 (rs = 0.46, P = 0.008) but not sTNFr1 or neopterin levels. Significant differences in appetite, nausea, diet, energy intake, liver function tests and serum levels of metabolic hormones were not detected.

CONCLUSION

Weight loss in patients with colorectal liver metastases was not explained by changes in diet, quality of life, or hormones, but activation of the innate and incomplete activation of the acquired immune systems may be involved. Agents that attenuate either the acute-phase inflammatory response or T lymphocyte IL-2 receptor upregulation might reduce weight loss in patients with metastatic disease.

Relation between depression and circulating immune products in patients with advanced colorectal cancer

We have previously suggested that colorectal liver metastases might produce 'toxins' that reduce both quality of life (QoL) and survival. In this study we assessed whether QoL in patients with such metastases was related to immune activation, as determined by increased serum levels of interleukin 6 (IL6), soluble tumour necrosis factor receptor 1 (sTNFr1), soluble interleukin 2 receptor alpha (sIL2r alpha) or the interferon-gamma marker neopterin. Serum IL6, sTNFr1, sIL2r alpha, neopterin, alkaline phosphatase and carcinoembryonic antigen levels, liver metastasis volume, and QoL (Hospital Anxiety and Depression [HAD] scale, Rotterdam Symptom Checklist [RSC], and Sickness Impact Profile [SIP]) were measured in 43 patients. There were significant positive correlations between serum sIL2r alpha and HAD depression score (r = 0.66, P = 0.0001), RSC physical symptom score (r = 0.46, P < 0.01), and SIP score (r = 0.47, P = 0.009). Multiple regression analysis suggested that serum sIL2r alpha level was a significant independent predictor of HAD depression score. Although survival was shorter (logrank test P < 0.05) where sIL2r alpha, sTNFr1 and IL6 levels were higher, the ability of sIL2r alpha to predict HAD depression score was independent of survival.