The invention relates to the use of the CXCR4 antagonist 6-{4-[1-(Propan-2- yl)piperidin-4-yl]-1,4-diazepan-1-yl}-N-(pyridin-4-yl)pyridine-2-carboxamide or a pharmaceutically acceptable salt thereof in the treatment of cancers of the breast, bladder, colon, rectum and liver.