The primary objective of this study will be to assess how effective Xilonix is in the treatment of patients with symptomatic colorectal cancer. By blocking a substance that helps tumours grow and spread, Xilonix therapy may not only slow tumour growth, but also may improve symptoms of muscle loss, fatigue, appetite loss, and pain in patients with colorectal cancer. The effectiveness of the therapy will be measured by assessing the change in these symptoms for patients treated with Xilonix versus those treated with placebo. Reversal of muscle loss will be assessed with a type of X-ray called a DEXA scanner. Improvement in pain, appetite loss, and fatigue will be measured with a questionnaire that is completed by patients enrolled on the trial.