A combination of BR101801 and venetoclax enhances antitumor effect in DLBCL cells via c-Myc/Bcl-2/Mcl-1 triple targeting

Double hit diffuse large B-cell lymphoma (DLBCL) with rearrangement and overexpression of both c-Myc and Bcl-2 responds poorly to standard R-CHOP therapy. In a recent phase I study, Venetoclax (ABT-199) targeting Bcl-2 also exhibited disappointing response rates in patients with relapsed/refractory DLBCL, suggesting that targeting only Bcl-2 is not sufficient for achieving successful efficacy due to the concurrent oncogenic function of c-Myc expression and drug resistance following an increase in Mcl-1. Therefore, co-targeting c-Myc and Mcl-1 could be a key combinatorial strategy to enhance the efficacy of Venetoclax. In this study, BR101801 a novel drug for DLBCL, effectively inhibited DLBCL cell growth/proliferation, induced cell cycle arrest, and markedly inhibited G0/G1 arrest. The apoptotic effect of BR101801 was also observed by increased Cytochrome C, cleaved PARP, and Annexin V-positive cell populations. This anti-cancer effect of BR101801 was confirmed in animal models, where it effectively inhibited tumor growth by reducing the expression of both c-Myc and Mcl-1. Furthermore, BR101801 exhibited a significant synergistic antitumor effect even in late xenograft models when combined with Venetoclax. Our data strongly suggest that c-Myc/Bcl-2/Mcl-1 triple targeting through a combination of BR101801 and Venetoclax could be a potential clinical option for double-hit DLBCL.