Abstract: Sets of biomarker genes useful for monitoring exposure and response to anti-tumor agents that inhibit IMPDH and related biomolecules are disclosed along with methods for identifying such sets of genes, methods of using such sets to identify additional therapeutic agents as well as methods for stratifying patients into groups that are sensitive or resistant to such therapeutic agents. Methods of screening patients for recurrence of disease by monitoring changes in gene expression associated with malignancy are also described. The nucleotide sequence of such biomarkers are presented.