Recently, we found that nalfurafine hydrochloride (our development code TRK-820), which is used as a treatment for pruritus in dialysis and chronic liver diseases refractory to existing therapies, increased food intake in normal animals, increased body weight and prolonged life in a B16/F10 cell transplantation model mouse, and improved food intake, body weight gain and muscle weakness in an A549 cell transplanted non-small cell lung cancer model mice and may be a potential therapeutic agent for cancer cachexia. . In addition, genetic analysis of the hypothalamus of A549 cell transplantation model mice revealed that TRK-820 increased peptides involved in hyperphagia and suppressed dopamine-related genes. These results suggest that TRK-820 suppresses the effects of dopamine in the hypothalamus, causing activation of the hyperphagic system, leading to increased food intake and consequent weight gain. This presentation will discuss the therapeutic effects of TRK-820 on cancer cachexia and the details of the mechanisms currently known.