The invention relates to hydrochloride, hydrobromide, hemi-citrate, acetate, p-tosylate, L-tartrate, hemi-succinate, and mesylate salt forms of 3-(4-bromo-2,6-difluoro-benzyloxy)-5-[3-(4-pyrrolidin-1-yl-butyl)-ureido]-isothiazole-4-carboxylic acid amide having the following formula:The invention also relates to pharmaceutical compositions containing the hydrochloride, hydrobromide, hemi-citrate, acetate, p-tosylate, L-tartrate, hemi-succinate, and mesylate salts of formula I. The invention further relates to methods of treating hyperproliferative diseases, such as cancers, in mammals, especially humans by administering the above salts and to methods of preparing the crystal forms of the above salts.