Cancer cachexia is a multifactorial syndrome characterized by an ongoing loss of skeletal muscle mass, which negatively impacts quality of life and portends a poor prognosis. Numerous molecular substrates and mechanisms underlie the dysregulation of skeletal muscle synthesis and degradation observed in cancer cachexia, including pro-inflammatory cytokines (TNF-α, IL-1 and IL-6), and the NF-kB, IGF1-AKT-mTOR, and myostatin/activin-SMAD pathways. Recent preclinical and clinical studies have demonstrated that anti-cachexia drugs (such as MABp1 and soluble receptor antagonist of myostatin/activin) not only prevent muscle wasting but may also prolong overall survival. In this review, we focus on the significance of cachexia signalling in cancer patients and highlight promising drugs targeting tumor cachexia in clinical development.