J M Argilés

Dietary supplementation with a specific combination of high protein, leucine, and fish oil improves muscle function and daily activity in tumour-bearing cachectic mice

Cancer cachexia is characterised by metabolic alterations leading to loss of adipose tissue and lean body mass and directly compromises physical performance and the quality of life of cancer patients. In a murine cancer cachectic model, the effects of dietary supplementation with a specific combination of high protein, leucine and fish oil on weight loss, muscle function and physical activity were investigated. Male CD2F1 mice, 6–7 weeks old, were divided into body weight-matched groups: (1) control, (2) tumour-bearing, and (3) tumour-bearing receiving experimental diets. Tumours were induced by s.c. inoculation with murine colon adenocarcinoma (C26) cells. Food intake, body mass, tumour size and 24 h-activity were monitored. Then, 20 days after tumour/vehicle inoculation, the animals were killed and muscle function was tested ex vivo. Tumour-bearing mice showed reduced carcass, muscle and fat mass compared with controls. EDL muscle performance and total daily activity were impaired in the tumour-bearing mice. Addition of single nutrients resulted in no or modest effects. However, supplementation of the diet with the all-in combination of high protein, leucine and fish oil significantly reduced loss of carcass, muscle and fat mass (loss in mass 45, 52 and 65% of TB-con, respectively (P<0.02)) and improved muscle performance (loss of max force reduced to 55–64% of TB-con (P<0.05)). Moreover, total daily activity normalised after intervention with the specific nutritional combination (50% of the reduction in activity of TB-con (P<0.05)). In conclusion, a nutritional combination of high protein, leucine and fish oil reduced cachectic symptoms and improved functional performance in cancer cachectic mice. Comparison of the nutritional combination with its individual modules revealed additive effects of the single components provided.

Direct effects of doxorubicin on skeletal muscle contribute to fatigue.

Chemotherapy-induced fatigue is a multidimensional symptom. Oxidative stress has been proposed as a working mechanism for anthracycline-induced cardiotoxicity. In this study, doxorubicin (DOX) was tested on skeletal muscle function. Doxorubicin induced impaired ex vivo skeletal muscle relaxation followed in time by contraction impediment, which could be explained by DOX-induced changes in Ca2+ responses of myotubes in vitro. The Ca2+ responses in skeletal muscle, however, could not be explained by oxidative stress.

Request for regulatory guidance for cancer cachexia intervention trials

Rome was not built in a day. Likewise, if one considers the evolution of systemic anti-cancer treatment, it took decades to go from acceptance of any therapy at all to single agents achieving isolated tumour responses (without prolongation of survival) to the current use of combination regimens as adjuvant therapy to surgery. Such incremental progress has led to improved quality of life and eventually survival for patients with some types of cancer. Cachexia and skeletal muscle wasting in cancer are significant clinical problems of high medical need for a large proportion of cancer patients and associated with very poor quality of life and very high mortality.1,2 An effective treatment of a complex multifactorial syndrome such as cachexia will likely evolve from a series of steps of discovery and new interventions before a comprehensive multimodal strategy can be identified that improves patient’s quality and quantity of life.3 There are reasons to be optimistic about the possibility that in the future, cachexia may be treated effectively. A number of drugs have already been developed that target key underlying mechanisms, namely, reduced food intake and altered metabolism and regulation of muscle mass, with the latter being split into pro-anabolic and anti-catabolic approaches. However, there is also some reason to be concerned because of the wide variability in current trial design, including different inclusion criteria, endpoints, analysis plans and the definition of best concomitant supportive care. Taken to the extreme, such differences in general approach have resulted in divergent opinions on what to consider a meaningful clinical endpoint by the European Medicines Agency (EMA) versus the US Food and Drug Administration (FDA). A result has been that in the clinical development programmes of some drugs, different endpoint assessments for American versus European regulatory authorities within the same trials using the same source data have been adopted. An example is the case of the POWER 1 and 2 trials testing the selective androgen receptor modulator enobosarm in patients with cancer suffering from muscle wasting.4–6 There has been a considerable influence from regulatory authorities on trial design. In the last 10 years, some regulatory authorities have consistently suggested that the design of randomized controlled trials testing treatments for cachexia should be aimed at demonstrating appropriate risk versus benefit, where benefit is defined as concomitant improvement in skeletal muscle mass (or lean mass) and relevant/meaningful physical function or improved survival. Whilst this is an admirable goal, from recent phase III trial results, this appears to be possibly unachievable with single modality interventions. Equally, it is not defined to whom the change is supposed to be ‘meaningful’: patient, caregiver, doctor, nurse or healthcare provider? The recent phase III trials of enobosarm used a co-primary end-point of lean body mass and stair climb power.4–6 Based on the FDA agreed co-primary responder analysis the trials failed to reach significance, principally because of lack of benefit in terms of the functional end point. In the responder analysis demanded by the FDA, an increase in performance of at least 10% for stair-climb power test was required for a patient to be considered to have benefited clinically [paper submitted]. Preventing a decline in performance was not considered in these analyses. In the analysis suggested by the EMA (which generally aims to assess clinically meaningful change regardless of direction), the same data were analysed using continuous data, and one of the two POWER trials may be considered successful, as both tests for change in lean mass and for stair-climb power showed significant changes over time. The two trials also had to be different, because of different background chemotherapy demanded in the inclusion criteria (i.e. taxane and non-taxane based). It is not clear, whether these are two trials in two orphan-type cancer indications (with different results), or are instead two trials in one indication with inconsistent results. It all depends on your approach to drug development (and maybe also on the regulatory body you talk to), but certainly it is a confusing situation by any standard. Similarly, the phase III (ROMANA) trials of the ghrelin receptor agonist anamorelin have shown significant benefit in terms of lean and fat body mass, but not for hand grip strength.7 These findings are not completely unexpected since whilst in healthy young individuals there is a strong positive correlation between muscle mass and muscle strength/power per se and between changes thereof,8,9 in older, sick individuals, the magnitude of strength generated by a certain unit of mass tends to be lower. These findings suggest that preservation/augmentation of muscle mass does not necessarily always translate into clinical benefits in non-muscular aspects of the cachexia syndrome as other factors may remain unchanged from a unimodal approach (e.g. targeting muscle anabolism). If other aspects of the cachexia syndrome remain unchanged (like systemic inflammation and catabolism or physical inactivity and undernutrition), can unimodal approaches lead to an increase in physical activity and/or preservation of independence? It appears that a more comprehensive approach to the cachexia syndrome is warranted if the reference outcomes of improved physical activity/preservation of independence are to be pursued. Still, preservation of function (and not its improvement) may also be a laudable aim of treatment development in cachexia, and regulatory guidance should permit for that. However, unlike areas such as hypertension where a given change in blood pressure is accepted as a surrogate for clinical events, it has to be recognized that in cachexia, the ‘relevance’ or ‘meaningfulness’ of a change in surrogates such as hand grip strength, stair-climb power, leg extension strength or timed sit-up-and-go is not known. Perhaps direct measures of patients’ daily physical activity would be better? In the related field of COPD-associated body wasting, exercise rehabilitation is well established with extensive guideline recommendations that are evidence-based.10 These guidelines have been developed over time and are multimodal in focus and are explicitly aimed at improving physical functioning and physical activity levels, nutritional status and quality of life. For patients with heart failure, chronic kidney disease, stroke or ageing-related frailty, such multimodal approaches are frequently considered,11–13 but evidence is so far weak compared with what has been achieved in COPD. Novel therapeutic agents under development for cachexia mostly focus on specific aspects of the syndrome (e.g. muscle anabolism, inflammation or appetite stimulation).14 Surely, phase III registration trials should assess safety in general, but efficacy specifically in relation to the target of the drug based on its mechanism of action. It may not be right to discard an intervention as ineffective because it does not yet affect a functional outcome, if, in fact – when inserted into a multimodal intervention that reflects the multifaceted aspect of the cachexia syndrome – the drug shows extended benefits that touch on issues such as health-related quality of life, patient-reported symptoms and tolerance of anti-cancer therapy. In the context of a complex disease process and a desire for multimodal therapies, regulatory advice on co-therapy with nutrition and exercise is also needed. Suggestions as to how best to include in this context supportive care in clinical trials 15 may also be helpful. We understand that this may include additional clinical trials for food products and supportive care approaches and surely this is acceptable, if the rules of the ‘game’ are clear for the good of our patients. Regulators need to be engaged in encouraging the testing of these modalities and their systematic inclusion in trial designs. In heart failure, such activities have already been initiated and aim to shift the development and authorization of medicines from the molecule paradigm to their evaluation in the context of the whole healthcare regimen.16 If a trial of a new agent incorporates these elements and is successful, it cannot lie with the pharmaceutical company to ensure that such adjuncts are available in precisely the same format everywhere in the world. Rather, the approved drug label may need to recommend such adjuncts for optimal effect. Clearly, this is not an easy field for new developments, but the medical need is great and the commercial returns for those who make it may be big. Once drugs are approved, the longer process of incorporating new agents into best clinical practice can begin. It should be clear to pharmaceutical companies, academic trialists and regulators that they may need to be more realistic about what can be achieved in a single step. Maybe also the adaptive licensing approach proposed by EMA 13 can help in this process of developing regulatory pathways. A willingness to consider current data with an open mind and a ‘Notice on Regulatory Guidance’ on cachexia trial design for cancer and beyond that cuts across continents would be a major step forwards to maintain drug development momentum, if there is to be genuine progress at this exciting juncture in the development of cachexia therapy. We want to help make that a reality whichever way we can.

Beneficial immune modulatory effects of a specific nutritional combination in a murine model for cancer cachexia.

The majority of patients with advanced cancer are recognised by impaired immune competence influenced by several factors, including the type and stage of the tumour and the presence of cachexia. Recently, a specific nutritional combination containing fish oil, specific oligosaccharide mixture, high protein content and leucine has been developed aimed to support the immune system of cancer patients in order to reduce the frequency and severity of (infectious) complications. In a recently modified animal model cachexia is induced by inoculation of C26 tumour cells in mice. In a pre-cachectic state, no effect was observed on contact hypersensitivity, a validated in vivo method to measure Th1-mediated immune function, after adding the individual nutritional ingredients to the diet of tumour-bearing mice. However, the complete mixture resulted in significantly improved Th1 immunity. Moreover, in a cachectic state, the complete mixture reduced plasma levels of pro-inflammatory cytokines and beneficially affected ex vivo immune function. Accordingly, the combination of the nutritional ingredients is required to obtain a synergistic effect, leading to a reduced inflammatory state and improved immune competence. From this, it can be concluded that the specific nutritional combination has potential as immune-supporting nutritional intervention to reduce the risk of (infectious) complications in cancer patients.

Dose-dependent effects of leucine supplementation on preservation of muscle mass in cancer cachectic mice

Cancer cachexia, which is characterized by muscle wasting, is associated with increased morbidity and mortality. Because muscle protein synthesis may be increased and protein breakdown reduced by leucine supplementation, we used the C26 tumor-bearing cachectic mouse model to assess the effects of dietary supplementation with leucine on muscle weight and the markers of muscle protein breakdown (mRNA of atrogin and murf). Male CD2F1 mice were subcutaneously inoculated with tumor cells (tumor-bearing mice; TB) or were sham injected (control; C). They were fed standard diets or diets supplemented with leucine [1 gr (TB1Leu) or 8 gr (TB8Leu) supplemented leucine per kg feed]; TB and C received 8.7% Leu/g protein, TB1Leu received 9.6% Leu/g protein and TB8Leu received 14.6 Leu/g protein. After 21 days, the following were determined: body weights, plasma amino-acid concentrations, tumor size and muscle mass of the gastrocnemius (mG), tibialis anterior (mTA), extensor digitorum longus (mEDL) and soleus (mS) muscles. In tumor-bearing (TB) mice, carcass and skeletal muscle masses decreased, and levels of atrogin and murf mRNA in the mEDL increased. Muscle-mass loss was counteracted dose-dependently by leucine supplementation: relative to TB, the mass of the mG was +23% in TB8Leu, and +22% in mTA (p<0.05). However, leucine supplementation did not change atrogin and murf mRNA levels. Total plasma amino acid concentrations increased in TB, especially for taurine, lysine, arginine and alanine (p<0.05). Leucine supplementation attenuated the increase in total plasma amino-acid concentrations (p<0.05). Irrespective of changes in muscle protein breakdown markers, leucine supplementation reduced muscle wasting in tumor-bearing cachectic mice and attenuated changes in plasma amino acids.

Differences in food intake of tumour‐bearing cachectic mice are associated with hypothalamic serotonin signalling

Anorexia is a common symptom among cancer patients and contributes to malnutrition and strongly impinges on quality of life. Cancer‐induced anorexia is thought to be caused by an inability of food intake‐regulating systems in the hypothalamus to respond adequately to negative energy balance during tumour growth. Here, we show that this impaired response of food‐intake control is likely to be mediated by altered serotonin signalling and by failure in post‐transcriptional neuropeptide Y (NPY) regulation.

Open source in cachexia

It is the concept of freely sharing technological information so it can be improved through multiple insights and viewpoints. Because the technology is ‘open source’, the amount of work involved is decreased as many individuals add multiple contributions. The central theme of open research is to disentangle the methodology freely available via the Internet and any data or results extracted or derived from them. This permits a massively distributed collaboration, and anyone can participate at any level of the project. Open ‘science’ is the application of open source methods to science (Figure 1). Open science removes the traditional hierarchy of research and encourages scientists of all levels—student or professor—to engage and contribute. Ideally, complete data release and collaboration happen in real time, to prevent duplication of effort and to maximize useful interaction between participants.