Ghrelin prevents tumour- and cisplatin-induced muscle wasting: characterization of multiple mechanisms involved

The ghrelin receptor agonist HM01 mimics the neuronal effects of ghrelin in the arcuate nucleus and attenuates anorexia-cachexia syndrome in tumor-bearing rats

The gastric hormone ghrelin positively affects energy balance by increasing food intake and reducing energy expenditure. Ghrelin mimetics are a possible treatment against cancer anorexia-cachexia syndrome (CACS). This study aimed to characterize the action of the nonpeptidergic ghrelin receptor agonist HM01 on neuronal function, energy homeostasis and muscle mass in healthy rats and to evaluate its possible usefulness for the treatment of CACS in a rat tumor model. Using extracellular single-unit recordings, we tested whether HM01 mimics the effects of ghrelin on neuronal activity in the arcuate nucleus (Arc). Furthermore, we assessed the effect of chronic HM01 treatment on food intake (FI), body weight (BW), lean and fat volumes, and muscle mass in healthy rats. Using a hepatoma model, we investigated the possible beneficial effects of HM01 on tumor-induced anorexia, BW loss, muscle wasting, and metabolic rate. HM01 (10(-7)-10(-6) M) mimicked the effect of ghrelin (10(-8) M) by increasing the firing rate in 76% of Arc neurons. HM01 delivered chronically for 12 days via osmotic minipumps (50 μg/h) increased FI in healthy rats by 24%, paralleled by increased BW, higher fat and lean volumes, and higher muscle mass. Tumor-bearing rats treated with HM01 had 30% higher FI than tumor-bearing controls and were protected against BW loss. HM01 treatment resulted in higher muscle mass and fat mass. Moreover, tumor-bearing rats reduced their metabolic rate following HM01 treatment. Our studies substantiate the possible therapeutic usefulness of ghrelin receptor agonists like HM01 for the treatment of CACS and possibly other forms of disease-related anorexia and cachexia.

Cytokine Signaling in Skeletal Muscle Wasting

Skeletal muscle wasting occurs in a variety of diseases including diabetes, cancer, Crohn's disease, chronic obstructive pulmonary disease (COPD), disuse, and denervation. Tumor necrosis factor α (TNF-α) is involved in mediating the wasting effect. To date, a causal relationship between TNF-α signaling and muscle wasting has been established in animal models. However, results from clinical trials are conflicting. This is partly due to the fact that other factors such as TNF-like weak inducer of apoptosis (TWEAK) and interleukin 6 (IL-6) are also involved in skeletal muscle wasting. Because muscle wasting is often associated with physical inactivity and reduced food intake, therapeutic interventions will be most effective when multiple approaches are used in conjunction with nutritional support and exercise.

Ghrelin promotes oral tumor cell proliferation by modifying GLUT1 expression

In our study, ghrelin was investigated with respect to its capacity on proliferative effects and molecular correlations on oral tumor cells. The presence of all molecular components of the ghrelin system, i.e., ghrelin and its receptors, was analyzed and could be detected using real-time PCR and immunohistochemistry. To examine cellular effects caused by ghrelin and to clarify downstream-regulatory mechanisms, two different oral tumor cell lines (BHY and HN) were used in cell culture experiments. Stimulation of either cell line with ghrelin led to a significantly increased proliferation. Signal transduction occurred through phosphorylation of GSK-3β and nuclear translocation of β-catenin. This effect could be inhibited by blocking protein kinase A. Glucose transporter1 (GLUT1), as an important factor for delivering sufficient amounts of glucose to tumor cells having high requirements for this carbohydrate (Warburg effect) was up-regulated by exogenous and endogenous ghrelin. Silencing intracellular ghrelin concentrations using siRNA led to a significant decreased expression of GLUT1 and proliferation. In conclusion, our study describes the role for the appetite-stimulating peptide hormone ghrelin in oral cancer proliferation under the particular aspect of glucose uptake: (1) tumor cells are a source of ghrelin. (2) Ghrelin affects tumor cell proliferation through autocrine and/or paracrine activity. (3) Ghrelin modulates GLUT1 expression and thus indirectly enhances tumor cell proliferation. These findings are of major relevance, because glucose uptake is assumed to be a promising target for cancer treatment.

Anamorelin in patients with non-small-cell lung cancer and cachexia (ROMANA 1 and ROMANA 2): results from two randomised, double-blind, phase 3 trials

BACKGROUND

Patients with advanced cancer frequently experience anorexia and cachexia, which are associated with reduced food intake, altered body composition, and decreased functionality. We assessed anamorelin, a novel ghrelin-receptor agonist, on cachexia in patients with advanced non-small-cell lung cancer and cachexia.

METHODS

ROMANA 1 and ROMANA 2 were randomised, double-blind, placebo-controlled phase 3 trials done at 93 sites in 19 countries. Patients with inoperable stage III or IV non-small-cell lung cancer and cachexia (defined as ≥5% weight loss within 6 months or body-mass index <20 kg/m(2)) were randomly assigned 2:1 to anamorelin 100 mg orally once daily or placebo, with a computer-generated randomisation algorithm stratified by geographical region, cancer treatment status, and weight loss over the previous 6 months. Co-primary efficacy endpoints were the median change in lean body mass and handgrip strength over 12 weeks and were measured in all study participants (intention-to-treat population). Both trials are now completed and are registered with ClinicalTrials.gov, numbers NCT01387269 and NCT01387282.

FINDINGS

From July 8, 2011, to Jan 28, 2014, 484 patients were enrolled in ROMANA 1 (323 to anamorelin, 161 to placebo), and from July 14, 2011, to Oct 31, 2013, 495 patients were enrolled in ROMANA 2 (330 to anamorelin, 165 to placebo). Over 12 weeks, lean body mass increased in patients assigned to anamorelin compared with those assigned to placebo in ROMANA 1 (median increase 0·99 kg [95% CI 0·61 to 1·36] vs -0·47 kg [-1·00 to 0·21], p<0·0001) and ROMANA 2 (0·65 kg [0·38 to 0·91] vs -0·98 kg [-1·49 to -0·41], p<0·0001). We noted no difference in handgrip strength in ROMANA 1 (-1·10 kg [-1·69 to -0·40] vs -1·58 kg [-2·99 to -1·14], p=0·15) or ROMANA 2 (-1·49 kg [-2·06 to -0·58] vs -0·95 kg [-1·56 to 0·04], p=0·65). There were no differences in grade 3-4 treatment-related adverse events between study groups; the most common grade 3-4 adverse event was hyperglycaemia, occurring in one (<1%) of 320 patients given anamorelin in ROMANA 1 and in four (1%) of 330 patients given anamorelin in ROMANA 2.

INTERPRETATION

Anamorelin significantly increased lean body mass, but not handgrip, strength in patients with advanced non-small-cell lung cancer. Considering the unmet medical need for safe and effective treatments for cachexia, anamorelin might be a treatment option for patients with cancer anorexia and cachexia.

FUNDING

Helsinn Therapeutics.

Mechanisms of anorexia-cachexia syndrome and rational for treatment with selective ghrelin receptor agonist

Cancer cachexia is a multi-organ, multifactorial and often irreversible syndrome affecting many patients with cancer. Cancer cachexia is invariably associated with weight loss, mainly from loss of skeletal muscle and body fat, conditioning a reduced quality of life due to asthenia, anorexia, anaemia and fatigue. Treatment options for treating cancer cachexia are limited. The approach is multimodal and may include: treatment of secondary gastrointestinal symptoms, nutritional treatments, drug, and non-drug treatments. Nutritional counselling and physical training may be beneficial in delaying or preventing the development of anorexia-cachexia. However, these interventions are limited in their effect, and no definitive pharmacological treatment is available to address the relevant components of the syndrome. Anamorelin is a first-in-class, orally active ghrelin receptor agonist that binds and stimulates the growth hormone secretagogue receptor centrally, thereby mimicking the appetite-enhancing and anabolic effects of ghrelin. It represents a new class of drug and an additional treatment option for this patient group, whose therapeutic options are currently limited. In this review we examine the mechanisms of anamorelin by which it contrasts catabolic states, its role in regulation of metabolism and energy homeostasis, the data of recent trials in the setting of cancer cachexia and its safety profile.

Anamorelin hydrochloride for the treatment of cancer-anorexia-cachexia in NSCLC

INTRODUCTION

Cancer anorexia-cachexia syndrome (CACS) is associated with increased morbidity and mortality. Anamorelin is a novel, orally active ghrelin receptor agonist in clinical development for the treatment of CACS in NSCLC. The aim of this review is to summarize preclinical and clinical studies evaluating anamorelin as a potential promising treatment for CACS in NSCLC.

AREAS COVERED

Pharmacodynamics, pharmacokinetics and metabolism, clinical efficacy, safety and tolerability of anamorelin for the treatment of CACS in NSCLC were reviewed. Anamorelin administration may lead to increases in food intake, body weight and lean body mass, and a stimulatory effect on growth hormone secretion in NSCLC patients. Anamorelin is well tolerated with no dose-limiting toxicities identified to date.

EXPERT OPINION

Targeting ghrelin receptors presents the advantage of potentially addressing multiple mechanisms of CACS simultaneously including appetite, muscle protein balance, adipose tissue metabolism, energy expenditure and inflammation. Clinical data suggest that anamorelin is well tolerated and it effectively increases appetite, body weight and lean mass in patients with advanced NSCLC. Long-term safety remains unknown at this time. The potential synergistic effects of anamorelin with nutritional support or exercise as well as its efficacy/safety in other tumor types are also unknown.