PI3K inhibitor copanlisib and the BCL2 inhibitor venetoclax are cytotoxic for MCL and MZL cells when combined and act via downregulating BCLXL or MCL1. (A) Four cell lines were exposed for 24 hours to copanlisib (30 nM, 300 nM), venetoclax (0.3 μM, 3 μM), or the combination of the 2 agents. (B) Three MCL and 2 MZL primary cells were exposed for 48 hours to copanlisib (100 or 200 nM), venetoclax (100 or 200 nM), or the combination of the 2 agents. The y-axis indicates the percentage of live cells, defined as Annexin V and 7AAD⁻, compared with dimethyl sulfoxide (DMSO)–treated cells. (C) Two cell lines exposed to copanlisib (30 nM, 300 nM), venetoclax (0.3 μM, 3 μM), or the combination of the 2 agents for 24 hours. cPARP, cleaved PARP; SMZL, splenic MZL.