Emerging drugs for cancer cachexia

Skeletal muscle mitochondrial uncoupling in a murine cancer cachexia model

Approximately half of all cancer patients present with cachexia, a condition in which disease-associated metabolic changes lead to a severe loss of skeletal muscle mass. Working toward an integrated and mechanistic view of cancer cachexia, we investigated the hypothesis that cancer promotes mitochondrial uncoupling in skeletal muscle. We subjected mice to in vivo phosphorous-31 nuclear magnetic resonance (³¹P NMR) spectroscopy and subjected murine skeletal muscle samples to gas chromatography/mass spectrometry (GC/MS). The mice used in both experiments were Lewis lung carcinoma models of cancer cachexia. A novel ‘fragmented mass isotopomer’ approach was used in our dynamic analysis of ¹³C mass isotopomer data. Our ³¹P NMR and GC/MS results indicated that the adenosine triphosphate (ATP) synthesis rate and tricarboxylic acid (TCA) cycle flux were reduced by 49% and 22%, respectively, in the cancer-bearing mice (p<0.008; t-test vs. controls). The ratio of ATP synthesis rate to the TCA cycle flux (an index of mitochondrial coupling) was reduced by 32% in the cancer-bearing mice (p=0.036; t-test vs. controls). Genomic analysis revealed aberrant expression levels for key regulatory genes and transmission electron microscopy (TEM) revealed ultrastructural abnormalities in the muscle fiber, consistent with the presence of abnormal, giant mitochondria. Taken together, these data suggest that mitochondrial uncoupling occurs in cancer cachexia and thus point to the mitochondria as a potential pharmaceutical target for the treatment of cachexia. These findings may prove relevant to elucidating the mechanisms underlying skeletal muscle wasting observed in other chronic diseases, as well as in aging.

Megestrol acetate for treatment of anorexia-cachexia syndrome

BACKGROUND

This is an updated version of a previously published review in The Cochrane Library (2005, Issue 2) on 'Megestrol acetate for the treatment of anorexia-cachexia syndrome'. Megestrol acetate (MA) is currently used to improve appetite and to increase weight in cancer-associated anorexia. In 1993, MA was approved by the US Food and Drug Administration for the treatment of anorexia, cachexia or unexplained weight loss in patients with AIDS. The mechanism by which MA increases appetite is unknown and its effectiveness for anorexia and cachexia in neoplastic and AIDS (acquired immunodeficiency syndrome) patients is under investigation.

OBJECTIVES

To evaluate the efficacy, effectiveness and safety of MA in palliating anorexia-cachexia syndrome in patients with cancer, AIDS and other underlying pathologies.

SEARCH METHODS

We sought studies through an extensive search of electronic databases, journals, reference lists, contact with investigators and other search strategies outlined in the methods. The most recent search for this update was carried out in May 2012.

SELECTION CRITERIA

Studies were included in the review if they assessed MA compared to placebo or other drug treatments in randomised controlled trials of patients with a clinical diagnosis of anorexia-cachexia syndrome related to cancer, AIDS or any other underlying pathology.

DATA COLLECTION AND ANALYSIS

Two independent review authors conducted data extraction and evaluated methodological quality. We performed quantitative analyses using appetite and quality of life as a dichotomous variable, and analysed weight gain as continuous and dichotomous variables.

MAIN RESULTS

We included 35 trials in this update, the same number but not the same trials as in the previous version of the review. The trials comprised 3963 patients for effectiveness and 3180 for safety. Sixteen trials compared MA at different doses with placebo, seven trials compared different doses of MA with other drug treatments and 10 trials compared different doses of MA. Meta-analysis showed a benefit of MA compared with placebo, particularly with regard to appetite improvement and weight gain in cancer, AIDS and other underlying conditions, and lack of benefit in the same patients when MA was compared to other drugs. There was insufficient information to define the optimal dose of MA, but higher doses were more related to weight improvement than lower doses. Quality of life improvement in patients was seen only when comparing MA versus placebo but not other drugs in both subcategories: cancer and AIDS. Oedema, thromboembolic phenomena and deaths were more frequent in the patients treated with MA. More than 40 side effects were studied.

AUTHORS' CONCLUSIONS

This review shows that MA improves appetite and is associated with slight weight gain in cancer, AIDS and in patients with other underlying pathology. Despite the fact that these patients are receiving palliative care they should be informed of the risks involved in taking MA.