BR-001 (BR001) is a potent, selective, allosteric inhibitor of EED subunit of PRC2 complex, disrupts EED-H3K27me3 interaction (IC50=4.5 nM).BR-001 directly binds to EED in the H3K27me3-binding pocket, BR-001 significantly increases the thermal stability of EED in thermal shift assay.BR-001 is selective for EED, has no activity against 371 wild-type kinases.BR-001 significantly reduced the cellular H3K27me3 level and also exhibited a strong antiproliferative effect in Karpas 422 cells.BR-001 inhibited proliferation of DLBCL cells and tumor growth, and upregulated target genes expression.BR-001 has potent antitumor efficacy in vivo, modulates immune response to suppress syngeneic CT26 colon tumor.