TC-E 5008 is a potent mutant IDH1 inhibitor with Ki values of 190 nM and 120 nM for R132H and R132C IDH1 mutants, respectively. TC-E 5008 exhibits very weak activity against WT-IDH1 with a Ki value of 12.3 μM. TC-E 5008 has anti-proliferative activity on multiple ER positive breast cancer cell lines.