Additionally, ARQ 531 inhibits CLL cell survival and suppresses BCR-mediated activation of C481S BTK and PLCγ2 mutants, which facilitate clinical resistance to ibrutinib.<b>Significance:</b> This study characterizes a rationally designed kinase inhibitor with efficacy in models recapitulating the most common mechanisms of acquired resistance to ibrutinib.
We have also made the novel and clinically relevant discovery that inhibition of HDAC induces the BTK-targeting miRs in ibrutinib-sensitive and resistant CLL to effectively reduce both wild-type and C481S-mutant BTK.