All PI3K isoforms - α, β, γ and δ - are expressed in all the MCL cell lines tested...More interestingly, the combination of copanlisib and volasertib induced synergistic effects in ibrutinib-resistant, venetoclax-resistant, and ibrutinib-venetoclax dual-resistant cell lines in vitro. Moreover, combined treatment with copanlisib (6mg/kg/2d) and volasertib (5mg/kg/week) significantly enhanced anti-MCL activity in the same PDX model, compared to that of either single-agent treatment...