WK500B is a BCL6 inhibitor that binds to BCL6 within cells, obstructing the BCL6 repression complex and reactivating target genes of BCL6, which leads to the death of DLBCL cells and induces apoptosis and cell cycle arrest. In animal models, WK500B inhibits the formation of germinal centers (GC) and the growth of DLBCL tumors without toxic side effects. Moreover, WK500B demonstrates strong efficacy and favorable pharmacokinetic properties, indicating significant development potential.