Figure 2. Target engagement and efficacy of PHGDH inhibitors.

All data points are the average of 3 biological replicates. Error bars represent standard deviations. a, NCT-502 reduces intracellular serine concentrations in MDA-MB-231 cells expressing PHGDH in medium lacking serine and glycine. Inactive compound (PHGDH-inactive) has no effect on intracellular serine concentrations. b, NCT-502 treatment in media lacking serine and glycine decreases the concentrations of serine and glycine only in MDA-MB-231 cells expressing PHGDH, while sparing all other amino acids except for aspartate. c, NCT-503 does not affect the intracellular concentration of aspartate in MDA-MB-468 cells in complete RPMI. d, PHGDH inhibitors reduce M+3 serine produced from U-¹³C glucose while sparing the labeling of the glycolytic intermediates M+3 dihydroxyacetone phosphate (DHAP) and M+3 3-phosphoglycerate. e, C234S PHGDH is less sensitive to NCT-503 inhibition than wild type PHGDH in vitro. f, Expression of C234S PHGDH in MDA-MB-468 cells increases glucose-mediated serine flux in the presence of NCT-503. g, Intracellular synthesis of M+3-serine from U-¹³C glucose following washout of NCT-502 demonstrates PHGDH inhibitor reversibility. *, p<0.05, Student’s t-test.