ABPP of Ibrutinib Resistance in B Cell Malignancies

Ibrutinib,a novel Bruton'styrosine kinase inhibitor, demonstrated high response rates in B-cell lymphomas but a growing number of ibrutinib treated patients relapse with resistance, fulminant progression and accelerated mortality. Using chemical proteomics and a high-throughput ex vivo assay in a reconstructed tumor microenvironment (TME), we determined the molecular basis for ibrutinib activity and mechanism of acquired ibrutinib resistance. Reciprocal activation of PI3K-AKT-mTOR and integrin β1 signaling were identified as a signaling hub of kinome for ibrutinib resistance, resulting in enforced TME-lymphoma interactions, promoting mantle cell lymphoma (MCL) growth and drug resistance. Combinatorial disruption of BCR signaling and ibrutinib resistance associated pathways led to release of MCL cells from TME, reversal of drugresistance and enhanced anti-MCL activity in murine and patient-derived xenograft models. This study integrated TME-mediated de-novo and acquired drug resistance mechanisms and provides the rationale for novel combination therapeutic strategy against MCL and other B cell malignancies.