The present invention relates to certain 2-(2,4,5-substituted-anilino)pyrimidine compounds and pharmaceutically acceptable salts thereof which may be useful in the treatment or prevention of a disease or medical condition mediated through certain mutated forms of epidermal growth factor receptor (for example the L858R activating mutant, the Exonl9 deletion activating mutant and the T790M resistance mutant). Such compounds and salts thereof may be useful in the treatment or prevention of a number of different cancers. The invention also relates to pharmaceutical compositions comprising said compounds and salts thereof, especially useful polymorphic forms of these compounds and salts, intermediates useful in the manufacture of said compounds and to methods of treatment of diseases mediated by various different forms of EGFR using said compounds and salts thereof.本発明は、上皮細胞増殖因子受容体の特定の変異型（例えば、Ｌ８５８Ｒ活性化変異体、Ｅｘｏｎ１９欠失活性化変異体及びＴ７９０Ｍ耐性変異体）が介在する疾患又は病状の治療又は予防に有用であり得る、特定の２－（２，４，５－置換－アニリノ）ピリミジン化合物及びその薬学的に許容される塩に関する。このような化合物及びその塩は、様々な癌の治療又は予防に有用な場合がある。本発明は、前記化合物及びその塩、これらの化合物及び塩の特に有用な多様な多形、前記化合物の製造に有用な中間体、及び前記化合物及びその塩を用いた、種々の形態のＥＧＦＲが介在する疾患の治療方法にも関する。
