590839 Disclosed is the use of 4-methyl-3-[[4-(3-pyridinyl)-2-pyrimidinyl]amino]-N-[5-(4-methyl-1-H-imidazol-1-yl)-3-(trifluoromethyl)phenyl]benzamide (nilotinib) or a pharmaceutically acceptable saltthereof, for the manufacture of a medicament for treating pulmonary arterial hypertension (PAH) in patients who failed prior PAH therapy.