Safety, tolerability and pharmacokinetics of intravenous ghrelin for cancer-related anorexia/cachexia: a randomised, placebo-controlled, double-blind, double-crossover study

Update on clinical trials of growth factors and anabolic steroids in cachexia and wasting

This article and others that focused on the clinical features, mechanisms, and epidemiology of skeletal muscle loss and wasting in chronic diseases, which include chronic kidney disease, cancer, and AIDS, were presented at a symposium entitled "Cachexia and Wasting: Recent Breakthroughs in Understanding and Opportunities for Intervention," held at Experimental Biology 2009. The clinical and anabolic efficacy of specific growth factors and anabolic steroids (eg, growth hormone, testosterone, megestrol acetate) in malnutrition and other catabolic states has been the subject of considerable research during the past several decades. Research on the effects of these agents in cachexia or wasting conditions, characterized by progressive loss of skeletal muscle and adipose tissue, focused on patients with AIDS in the early 1990s, when the devastating effects of the loss of body weight, lean body mass, and adipose tissue were recognized as contributors to these patients' mortality. These same agents have also been studied as methods to attenuate the catabolic responses observed in cancer-induced cachexia and in wasting induced by chronic obstructive pulmonary disease, congestive heart failure, renal failure, and other conditions. This article provides an updated review of recent clinical trials that specifically examined the potential therapeutic roles of growth hormone, testosterone, oxandrolone, and megestrol acetate and emerging data on the orexigenic peptide ghrelin, in human cachexia and wasting.

Effects of ghrelin administration after total gastrectomy: a prospective, randomized, placebo-controlled phase II study

BACKGROUND & AIMS

Body weight (BW) loss and reduction of blood ghrelin level are commonly observed after total gastrectomy (TG). A prospective study was designed to elucidate whether exogenous ghrelin administration prevents postoperative BW loss by improving appetite and oral food intake in patients with gastric cancer after undergoing TG.

METHODS

In this randomized phase II study, 21 patients undergoing TG were assigned to a ghrelin (11 patients) or placebo group (10 patients). They received intravenous infusion of synthetic human ghrelin (3 microg/kg) or saline twice daily for 10 days after starting oral food intake following surgery. Changes in BW, appetite visual analog scale score, food intake calories, body composition, basal metabolic rate, and various blood test results were evaluated.

RESULTS

Excluding one patient who developed profound diaphoresis during ghrelin infusion, 20 patients completed the study. Food intake and appetite were significantly higher with ghrelin compared with placebo (average, 13.8 vs 10.4 kcal/kg/day [P = .030] and 5.7 vs 3.9 cm [P = .032], respectively). BW loss was significantly lower in the ghrelin than in the placebo group (-1.4% vs -3.7%; P = .044). Fat mass, lean body mass, and basal metabolic rate decreased significantly in the placebo group; however, the reductions in lean body mass and basal metabolic rate were not significant in the ghrelin group, although that of fat mass was significant.

CONCLUSIONS

Short-term administration of synthetic ghrelin was safe and successfully lessened postoperative BW loss and improved appetite and food intake after TG.

Integrating GHS into the Ghrelin System

Oligopeptide derivatives of metenkephalin were found to stimulate growth-hormone (GH) release directly by pituitary somatotrope cells in vitro in 1977. Members of this class of peptides and nonpeptidyl mimetics are referred to as GH secretagogues (GHSs). A specific guanosine triphosphatate-binding protein-associated heptahelical transmembrane receptor for GHS was cloned in 1996. An endogenous ligand for the GHS receptor, acylghrelin, was identified in 1999. Expression of ghrelin and homonymous receptor occurs in the brain, pituitary gland, stomach, endothelium/vascular smooth muscle, pancreas, placenta, intestine, heart, bone, and other tissues. Principal actions of this peptidergic system include stimulation of GH release via combined hypothalamopituitary mechanisms, orexigenesis (appetitive enhancement), insulinostasis (inhibition of insulin secretion), cardiovascular effects (decreased mean arterial pressure and vasodilation), stimulation of gastric motility and acid secretion, adipogenesis with repression of fat oxidation, and antiapoptosis (antagonism of endothelial, neuronal, and cardiomyocyte death). The array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development.

Ghrelin gene products and the regulation of food intake and gut motility

A breakthrough using "reverse pharmacology" identified and characterized acyl ghrelin from the stomach as the endogenous cognate ligand for the growth hormone (GH) secretagogue receptor (GHS-R) 1a. The unique post-translational modification of O-n-octanoylation at serine 3 is the first in peptide discovery history and is essential for GH-releasing ability. Des-acyl ghrelin, lacking O-n-octanoylation at serine 3, is also produced in the stomach and remains the major molecular form secreted into the circulation. The third ghrelin gene product, obestatin, a novel 23-amino acid peptide identified from rat stomach, was found by comparative genomic analysis. Three ghrelin gene products actively participate in modulating appetite, adipogenesis, gut motility, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. Knockdown or knockout of acyl ghrelin and/or GHS-R1a, and overexpression of des-acyl ghrelin show benefits in the therapy of obesity and metabolic syndrome. By contrast, agonism of acyl ghrelin and/or GHS-R1a could combat human anorexia-cachexia, including anorexia nervosa, chronic heart failure, chronic obstructive pulmonary disease, liver cirrhosis, chronic kidney disease, burn, and postsurgery recovery, as well as restore gut dysmotility, such as diabetic or neurogenic gastroparesis, and postoperative ileus. The ghrelin acyl-modifying enzyme, ghrelin O-Acyltransferase (GOAT), which attaches octanoate to serine-3 of ghrelin, has been identified and characterized also from the stomach. To date, ghrelin is the only protein to be octanylated, and inhibition of GOAT may have effects only on the stomach and is unlikely to affect the synthesis of other proteins. GOAT may provide a critical molecular target in developing novel therapeutics for obesity and type 2 diabetes.

An update on promising agents for the treatment of cancer cachexia

PURPOSE OF REVIEW

There are no published conclusive phase III controlled clinical trials nor general consensus about treatment approaches despite several years of coordinated efforts in basic and clinical research. Consequently, practice guidelines for the prevention and treatment of cancer-related muscle wasting are lacking. The purpose of this review is to supply an update on the promising agents and/or combined approaches for the treatment of cancer cachexia.

RECENT FINDINGS

The choice for cancer cachexia treatment in clinical practice is very limited: the only approved drugs in Europe are progestagens. Several drugs with a strong rationale have failed or have not shown univocal results in clinical trials: they include eicosapentaenoic acid, cannabinoids, bortezomib and anti-tumor necrosis factor (TNF)-alpha monoclonal antibody. Several emerging drugs have shown promising results but are still under clinical investigation [thalidomide, selective cyclooxygenase (COX)-2 inhibitors, ghrelin mimetics, oxandrolone, olanzapine]. Moreover, increasing knowledge of cachexia pathophysiology and preliminary clinical findings seem to suggest that a combined treatment approach may be the most effective option.

SUMMARY

A number of promising new agents are currently being developed but are not as yet regarded as standard of care. They include: selective COX-2 inhibitors, ghrelin mimetics, oxandrolone, selective androgen receptor modulators (ostarine), olanzapine, anti-IL-6 antibody and an innovative approach of multitargeted combined treatment. The data reported seem to suggest that the most effective treatment for cancer cachexia may be a combination regimen rather than single-agent treatments. This is in keeping with the general consensus that cancer cachexia is a multifactorial process and, hence, a potentially effective approach should be multimodal.

Randomized phase III clinical trial of five different arms of treatment in 332 patients with cancer cachexia

PURPOSE

A phase III, randomized study was carried out to establish the most effective and safest treatment to improve the primary endpoints of cancer cachexia-lean body mass (LBM), resting energy expenditure (REE), and fatigue-and relevant secondary endpoints: appetite, quality of life, grip strength, Glasgow Prognostic Score (GPS) and proinflammatory cytokines.

PATIENTS AND METHODS

Three hundred thirty-two assessable patients with cancer-related anorexia/cachexia syndrome were randomly assigned to one of five treatment arms: arm 1, medroxyprogesterone (500 mg/day) or megestrol acetate (320 mg/day); arm 2, oral supplementation with eicosapentaenoic acid; arm 3, L-carnitine (4 g/day); arm 4, thalidomide (200 mg/day); and arm 5, a combination of the above. Treatment duration was 4 months.

RESULTS

Analysis of variance showed a significant difference between treatment arms. A post hoc analysis showed the superiority of arm 5 over the others for all primary endpoints. An analysis of changes from baseline showed that LBM (by dual-energy X-ray absorptiometry and by L3 computed tomography) significantly increased in arm 5. REE decreased significantly and fatigue improved significantly in arm 5. Appetite increased significantly in arm 5; interleukin (IL)-6 decreased significantly in arm 5 and arm 4; GPS and Eastern Cooperative Oncology Group performance status (ECOG PS) score decreased significantly in arm 5, arm 4, and arm 3. Toxicity was quite negligible, and was comparable between arms.

CONCLUSION

The most effective treatment in terms of all three primary efficacy endpoints and the secondary endpoints appetite, IL-6, GPS, and ECOG PS score was the combination regimen that included all selected agents.

Ghrelin and its therapeutic potential for cachectic patients

The discovery of ghrelin has resulted in the development of approaches to appetite, enabling a better understanding of the mechanisms regulating appetite through molecular analyses. Ghrelin is a 28-amino acid peptide that was isolated from the stomach only a decade ago, and has recently been investigated as a potential therapeutic endogenous agent. This peptide increases appetite, adjusts energy balance, suppresses inflammation, and enhances the release of growth hormone from the pituitary gland. Although many bioactive substances such as peptide YY, leptin, adiponectin and obestatin are involved in appetite control, ghrelin is the only known peptide to signal starvation information from a peripheral organ to the central nervous system, contributing to an increase in appetite. Clinical trials have revealed the effectiveness of ghrelin in increasing lean body mass and activity in cachectic patients. As shown in clinical research on humans and basic research using animal models, cachexia often occurs in response to excess release of proinflammatory cytokines and induces further appetite loss, which aggravates the physiological status of underlying diseases. Ghrelin functions as a protector against the vicious cycle of the cachectic paradigm through orexigenic, anabolic and anti-inflammatory effects, so administration of ghrelin may be able to improve quality of life in cachectic patients. We show here a significant role of ghrelin in the pathophysiology of cachectic diseases and the possibility of clinical applications.

Ghrelin reverses experimental diabetic neuropathy in mice

Ghrelin, an acylated peptide produced in the stomach, increases food intake and growth hormone secretion, suppresses inflammation and oxidative stress, and promotes cell survival and proliferation. We investigated the pharmacological potential of ghrelin in the treatment of polyneuropathy in uncontrolled streptozotocin (STZ)-induced diabetes in mice. Ghrelin or desacyl-ghrelin was administered daily for 4 weeks after STZ-induced diabetic polyneuropathy had developed. Ghrelin administration did not alter food intake, body weight gain, blood glucose levels, or plasma insulin levels when compared with mice given saline or desacyl-ghrelin administration. Ghrelin administration ameliorated reductions in motor and sensory nerve conduction velocities in diabetic mice and normalized their temperature sensation and plasma concentrations of 8-isoprostaglandin alpha, an oxidative stress marker. Desacyl-ghrelin failed to have any effect. Ghrelin administration in a mouse model of diabetes ameliorated polyneuropathy. Thus, ghrelin's effects represent a novel therapeutic paradigm for the treatment of this otherwise intractable disorder.

Cancer cachexia: medical management

BACKGROUND

Cachexia is a complex metabolic syndrome associated with many chronic or end-stage diseases, especially cancer, and is characterized by loss of muscle with or without loss of fat mass. The management of cachexia is a complex challenge that should address the different causes underlying this clinical event with an integrated or multimodal treatment approach targeting the different factors involved in its pathophysiology.

MATERIALS AND METHODS

The purpose of this article was to review the current medical treatment of cancer-related cachexia, in particular focusing on combination therapy and ongoing research.

RESULTS

Among the treatments proposed in the literature for cancer-related cachexia, some proved to be ineffective, namely, cyproheptadine, hydrazine, metoclopramide, and pentoxifylline. Among effective treatments, progestagens are currently considered the best available treatment option for cancer-related cachexia, and they are the only drugs approved in Europe. Drugs with a strong rationale that have failed or have not shown univocal results in clinical trials so far include eicosapentaenoic acid, cannabinoids, bortezomib, and anti-TNF-alpha MoAb. Several emerging drugs have shown promising results but are still under clinical investigation (thalidomide, selective cox-2 inhibitors, ghrelin mimetics, insulin, oxandrolone, and olanzapine).

CONCLUSIONS

To date, despite several years of co-ordinated efforts in basic and clinical research, practice guidelines for the prevention and treatment of cancer-related muscle wasting are lacking, mainly because of the multifactorial pathogenesis of the syndrome. From all the data presented, one can speculate that one single therapy may not be completely successful in the treatment of cachexia. From this point of view, treatments involving different combinations are more likely to be successful.

Ghrelin receptor modulators and their therapeutic potential

Background: Ghrelin is a peptide produced predominantly in the stomach and intestines, and is a natural growth hormone (GH) secretagogue-receptor ligand. It is able to stimulate GH release, but it also exhibits an important role in conditions related to processes regulating nutrition, body composition and growth, and heart, liver, thyroid or kidney dysfunction. Drug discovery efforts initially focused on ghrelin-receptor agonists, known as GH secretagogues, to be used as anabolic agents, but none of them reached the market. Discussion: The latest developments in this field are constituted by the discovery of new nonpeptidic compounds endowed with interesting properties: oxindole agonists are able to exert an increase in the fat-free mass, while ghrelin was reported to increase the fat mass gain, and triazole- and 2,4-diaminopyrimidine-based antagonists were shown to be able to reduce food intake, without inhibition of GH secretion stimulated by an agonist to the ghrelin receptor. Other antagonist compounds (quinazolinones) were discovered as antiobesity/antidiabetic agents. Moreover, inverse agonists have been discovered that are able to reduce weight gain. Conclusions: Taking into account the great number of pathological conditions related to ghrelin, and the discovery of several compounds able to modulate the ghrelin receptor, its importance in the field of medicinal chemistry research is set to increase significantly.

Increased serum levels of ghrelin at diagnosis mediate body weight loss in non-small cell lung cancer (NSCLC) patients

OBJECTIVE

Ghrelin is an orexigenic peptide implicated in body weight regulation, while cachexia is a multifactorial effect of non-small cell lung cancer (NSCLC) presented in patients with advanced disease. The aim of this study was to detect the role of ghrelin in cachexia and systemic inflammation of advanced NSCLC patients as well as its role as a diagnostic and prognostic tool.

METHODS

Ghrelin serum levels were measured in 101 inoperable NSCLC patients before receiving any therapy (75 patients with weight loss and 26 without weight loss) and 60 healthy control volunteers. Epidemiological, anthropometrical and laboratory data were assessed for all participants (patients and healthy volunteers).

RESULTS

NSCLC patients presented significantly higher ghrelin serum levels than healthy individuals, adjusted for sex, age and BMI (0.5+/-0.4 ng/ml vs. 0.4+/-0.3 ng/ml, P<0.001). NSCLC patients with weight loss presented significantly increased ghrelin serum levels (0.56+/-0.24 ng/ml vs. 0.52+/-0.44 ng/ml, P=0.017), compared to NSCLC patients without weight loss.

CONCLUSIONS

Ghrelin serum levels are significantly increased in NSCLC patients, mainly in the subgroup of patients diagnosed with cachexia, indicating a possible implication in the pathogenesis of lung cancer. Further studies are needed to determine its potential role as predictive and prognostic marker.

Ghrelin increases hunger and food intake in patients with restricting-type anorexia nervosa: a pilot study

Ghrelin increases hunger sensation and food intake in various patients with appetite loss. Anorexia nervosa (AN) begins with psychological stress-induced anorexia and some patients cannot increase their food intake partly because of malnutrition-induced gastrointestinal dysfunction. The effects of ghrelin on appetite, food intake and nutritional parameters in anorexia nervosa (AN) patients were examined. Five female restricting- type AN patients (age: 14-35 y; body mass index: 10.2-14.6 kg/m(2)) had persistently complained of gastrointestinal symptoms and failed to increase body weight. They were hospitalized for 26 days (6 days' pretreatment, 14 days' ghrelin-treatment, and 6 days' post-treatment) and received an intravenous infusion of 3 microg/kg ghrelin twice a day. Ghrelin infusion improved epigastric discomfort or constipation in 4 patients, whose hunger scores evaluated by visual analogue scale questionnaires also increased significantly after ghrelin infusion. Daily energy intake during ghrelin infusion increased by 12-36 % compared with the pre-treatment period. Serum levels of total protein and triglyceride as nutritional parameters significantly increased after ghrelin treatment. There were no serious adverse effects including psychological symptoms. We found that ghrelin decreases gastrointestinal symptoms and increases hunger sensation and daily energy intake without serious adverse events in AN patients. Although the present study had major limitations of the lack of a randomized, placebo-controlled group, non-blindness of the investigators and the small number of patients recruited, it would contribute to further investigations for therapeutic potential of ghrelin in AN patients.

Long-term effects of ghrelin and ghrelin receptor agonists on energy balance in rats

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), is the only circulating agent to powerfully promote a positive energy balance. Such action is mediated predominantly by central nervous system pathways controlling food intake, energy expenditure, and nutrient partitioning. The ghrelin pathway may therefore offer therapeutic potential for the treatment of catabolic states. However, the potency of the endogenous hormone ghrelin is limited due to a short half-life and the fragility of its bioactivity ensuring acylation at serine 3. Therefore, we tested the metabolic effects of two recently generated GHS-R agonists, BIM-28125 and BIM-28131, compared with ghrelin. All agents were administered continuously for 1 mo in doses of 50 and 500 nmol x kg(-1) x day(-1) using implanted subcutaneous minipumps in rats. High-dose treatment with single agonists or ghrelin increased body weight gain by promoting fat mass, whereas BIM-28131 was the only one also increasing lean mass significantly. Food intake increased during treatment with BIM-28131 or ghrelin, whereas no effects on energy expenditure were detected. With the lower dose, only BIM-28131 had a significant effect on body weight. This also held true when the compound was administered by subcutaneous injection three times/day. No symptoms or signs of undesired effects were observed in any of the studies or treated groups. These results characterize BIM-28131 as a promising GHS-R agonist with an attractive action profile for the treatment of catabolic disease states such as cachexia.