The increase in lactate levels shown in Fig. 3 may be an important observation associated with the inhibition of mutant IDH1. It has been reported that the activity of lactate dehydrogenase A (LDH-A) is downregulated in mutant IDH1 glioma cells44, which is opposite to the typical upregulation of LDH-A in most other cancers. This evidence concerns the gene IDH1 and central nervous system cancer.