A quantitative high-throughput screening of the R132H mutant IDH1 enzyme and the subsequent optimization of the small molecule hit resulted in probe, ML309 (Compound 7), which is capable of potent and selective inhibition of mutant IDH1 (Ki 96 nM vs. 35 μM for Wt IDH) and effectively lowers cell-based production of D-2HG in a U87MG mutant glioblastoma cell line and later it was also shown to inhibit IDH1 R132C with similar selectivity [123]. The gene discussed is IDH1; the disease is glioblastoma.