The novel p300 inhibitor B029‐2 targets p300/CBP, reducing the expression of serine synthesis enzymes (such as PSPH and PSAT1) by lowering H3K18Ac and H3K27Ac levels in gene promoter regions, thereby decreasing amino acid synthesis in liver cancer cells and resulting in significant anti‐tumour effects.293. The gene discussed is EP300; the disease is liver cancer.