To validate whether the detection method reflects the neomorphic activity of the IDH mutant enzyme, we treated tumor cell lines (TS603, HT‐1080, U251, and RD) with the IDH mutant enzyme inhibitor ivosidenib (650 nm) for 48 h to selectively inhibit the neomorphic activity of the IDH mutant enzyme. Here, IDH1 is linked to neoplasm.