Growth differentiation factor 15 (GDF-15) inhibition to increase muscle mass and function in cancer cachexia.

e15633 Background: Almost half of cancer deaths are attributed to cancers most frequently associated with cachexia. Cachexia is a complex metabolic disease characterized by anorexia and unintentional weight loss. Skeletal muscle depletion has been recognized as a key feature of the disease, however muscle anabolic therapies have not been successful, suggesting that treatments that target multiple aspects of the disease will be most effective. Growth differentiation factor 15 (GDF-15) is a cytokine that induces anorexia and weight loss and is associated with cachexia in cancer patients. In preclinical cancer cachexia models, GDF-15 inhibition is sufficient to normalize food intake and body weight, including skeletal muscle mass. However, it remains to be determined whether the increased skeletal muscle mass also results in restoration of muscle function. Therefore, we examined the effect of GDF-15 inhibition on muscle mass and function in mouse models of cancer cachexia in comparison with myostatin inhibition, an established muscle anabolic pathway. Methods: Cachectic mouse tumor models were established with subcutaneous implantation of tumor cell lines reported to be GDF-15-dependent; mouse renal cell carcinoma (RENCA) and human ovarian cancer (TOV-21G) cell lines. Mice were treated with anti-GDF-15 (mAB2) or anti-myostatin (RK35) monoclonal antibodies and skeletal muscle function was assessed in vivo via maximum force, maximum rate of contraction and half relax time. In the RENCA tumor model, GDF-15 inhibition fully restored body weight and skeletal muscle mass whereas myostatin inhibition showed only a modest effect. Results: Consistent with the muscle mass improvement, GDF-15 inhibition dramatically increased functional muscle endpoints compared to the partial effect of myostatin inhibition. Interestingly, in the TOV-21G tumor model GDF-15 inhibition only partially restored body weight, however skeletal muscle mass and muscle function were completely normalized. Consistent with the functional assessment, GDF-15 inhibition in the RENCA tumor model decreased the expression of several catabolic genes (i.e. Trim63, Fbxo32, Myh7 and Myh2). The GDF-15 effect is likely to be secondary to the reversal of anorexia since wildtype mice pair-fed to Fc-GDF-15-treated mice demonstrated equivalent muscle mass loss. Conclusions: Taken together these data suggest that GDF-15 inhibition holds potential as an effective therapeutic approach to alleviate multiple aspects of cachexia.