Venetoclax(ABT-199)

Venetoclax (ABT-199; GDC-0199) is a highly selective, orally bioavailable small-molecule inhibitor of Bcl-2, exhibiting sub-nanomolar binding affinity with a Ki of less than 0.01 nM. This compound has been demonstrated to induce autophagy, highlighting its role in modulating programmed cell death pathways. In vitro studies reveal that Venetoclax exhibits potent cytotoxic activity against FL5.12-BCL-2 cells, with an EC50 of 4 nM, while showing markedly reduced efficacy against FL5.12-BCL-XL cells (EC50 = 261 nM), underscoring its selectivity for Bcl-2 over Bcl-XL.The selectivity of Venetoclax is further corroborated in cellular mammalian two-hybrid assays, where it effectively disrupts BCL-2-BIM protein-protein interactions with an EC50 of 3 nM. In contrast, it demonstrates significantly weaker activity against BCL-XL-BCL-XS and MCL-1-NOXA complexes, with EC50 values of 2.2 μM, reinforcing its specificity for Bcl-2-dependent apoptotic regulation.In vivo efficacy studies utilizing xenograft models derived from RS4; 11 cells, a representative model of acute lymphoblastic leukemia (ALL), demonstrate that a single oral dose of Venetoclax (12.5 mg/kg) achieves a maximal tumor growth inhibition (TGImax) of 47% (P < 0.001) and a tumor growth delay (TGD) of 26% (P < 0.05). These results indicate robust anti-tumor activity in a Bcl-2-dependent malignancy.