A method for preparing partially hydrated -N-{4-[3-chloro-4-(2-pyridinylmethoxy) anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide as a maleate salt comprising the steps of: i) heating -N- {4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide and maleic acid to 50°C-60°C in a water:n-propanol solution and maintaining the mixture at 50-60°C for a minimum of 15 min.; ii) cooling said solution over at least one hour to 40°C and maintaining the cooled solution at 40°C for 12 hours; iii) further cooling the cooled solution to room temperature, 25°C, over a minimum of 4 hours and maintaining the further cooled solution at room temperature, 25°C, for at least 2 hours; iv) filtering the mixture obtained in step iii) to obtain crystalline -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate salt, wherein the crystalline -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate salt is -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate monohydrate; v) drying the -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate monohydrate from step iv) under vacuum at a temperature greater than 30°C for 12 to 48 hours to obtain crystalline, anhydrous -N- {4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl} -4-(dimethylamino)-2-butenamide maleate; and vi) exposing the crystalline, anhydrous -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate to 75% relative humidity at an ambient temperature (20-25°C) for 22 days, to form crystalline, partially hydrated -N-{4-[3-chloro-4-(2-pyridinylmethoxy) anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate. i) heating -N- {4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide and maleic acid to 50°C-60°C in a water:n-propanol solution and maintaining the mixture at 50-60°C for a minimum of 15 min.; ii) cooling said solution over at least one hour to 40°C and maintaining the cooled solution at 40°C for 12 hours; iii) further cooling the cooled solution to room temperature, 25°C, over a minimum of 4 hours and maintaining the further cooled solution at room temperature, 25°C, for at least 2 hours; iv) filtering the mixture obtained in step iii) to obtain crystalline -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate salt, wherein the crystalline -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate salt is -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate monohydrate; v) drying the -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate monohydrate from step iv) under vacuum at a temperature greater than 30°C for 12 to 48 hours to obtain crystalline, anhydrous -N- {4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl} -4-(dimethylamino)-2-butenamide maleate; and vi) exposing the crystalline, anhydrous -N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate to 75% relative humidity at an ambient temperature (20-25°C) for 22 days, to form crystalline, partially hydrated -N-{4-[3-chloro-4-(2-pyridinylmethoxy) anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide maleate.