Profiling in various mIDH1 over-expressing U87 cells and HCT116 cells reveals that olutasidenib potently inhibits 2-HG production by multiple IDH1-R132 mutants (R132H, R132C, R132G, R132L), suggesting olutasidenib could be efficacious against most IDH1-R132 mutant-expressing tumors. Olutasidenib is highly selective for IDH1 isoforms, showing no appreciable inhibition against wild-type IDH1 and IDH2 mutants..