| abstract |
The present invention relates to compounds of formula I which function as inhibitors of rearranged during transfection (RET) kinase enzyme activity, Wherein HET, bonds a, b, c and d, X 1 , X 2 , X 3 , X 4 , R 2 and R 3 are each as defined herein. The invention also relates to processes for preparing these compounds, pharmaceutical compositions comprising them and their use in the treatment of proliferative diseases such as cancer and other diseases or conditions in which RET kinase activity is involved. |