The invention relates to the stabilized amorphous form of the methanesulfonic acid addition salt of 4-(4-methylpiperazin-1-ylmethyl)-N-[4-methyl-3-(4-(pyridin-3-yl)-pyrimidin-2-ylamino)-phenyl]-benzamide, pharmaceutical compositions such as capsules or tablets containing this form, the use of such form in diagnostic methods or, preferably, for the therapeutic treatment of warm-blooded animals, especially humans, and the use of formulation principles stabilizing the amorphous form of Imatinib mesylate as an intermediate for the preparation of pharmaceutical compositions.
