The present invention provides an acid addition salt of N-ethyl-N'-[2-methoxy-4-(5-methyl-4-{[(1S)-1-pyridin-3-ylbutyl]amino}pyrimidin-2-yl)phenyl]urea and uses thereof including a method for the treatment of a hyperproliferation-related disorder. The present invention also provides a pharmaceutical composition comprising an acid addition salt of N-ethyl-N'-[2-methoxy-4-(5-methyl-4-{[(1S)-1-pyridin-3-ylbutyl]amino}pyrimidin-2-yl)phenyl]urea.