Fused bicyclic pyrimidine compounds of formula (I): wherein R1, R3, R4, X1, X2, Y, Z, A, B, C, D, n, and the two bonds are defined herein. Also disclosed are a method for inhibiting Aurora kinase activity and a method for treating cancer with these compounds.本發明係有關於一種式(I)之稠合雙環嘧啶化合物:;其中,R1、R3、R4、X1、X2、Y、Z、A、B、C、D、n、以及兩個 鍵結定義於本文中。本發明亦揭露一種抑制極光激酶活性的方法,以及一種以這些化合物治療癌症的方法。