Disclosed are methods of treating hyperproliferative disorders such as cancer, methods of arresting the cell cycle in cancer cells, methods of inhibiting glutathione synthesis in cancer cells, and associated compounds for use and uses in medicaments. In certain embodiments, the methods, uses and compounds are provided with reference to compounds of the structural formula (I), in which X1, X2, Z1, Z2, the ring system denoted by "a", R1, L1, L2, Q, L3, R3, L4, R4, L5, and R5 are as described herein. In certain embodiments, compounds disclosed herein are especially active against cancers having a mutant KRAS gene.
