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Medline ® Abstract for Reference 27

of 'Treatment of relapsed or refractory chronic lymphocytic leukemia'

The clinically active BTK inhibitor PCI-32765 targets B-cell receptor- and chemokine-controlled adhesion and migration in chronic lymphocytic leukemia.
de Rooij MF, Kuil A, Geest CR, Eldering E, Chang BY, Buggy JJ, Pals ST, Spaargaren M
Blood. 2012 Mar;119(11):2590-4. Epub 2012 Jan 25.
Small-molecule drugs that target the B-cell antigen receptor (BCR) signalosome show clinical efficacy in the treatment of B-cell non-Hodgkin lymphoma. These agents, including the Bruton tyrosine kinase (BTK) inhibitor PCI-32765, display an unexpected response in patients with chronic lymphocytic leukemia (CLL): a rapid and sustained reduction of lymphadenopathy accompanied by transient lymphocytosis, which is reversible upon temporary drug deprivation. We hypothesized that this clinical response reflects impaired integrin-mediated adhesion and/or migration. Here, we show that PCI-32765 strongly inhibits BCR-controlled signaling and integrinα(4)β(1)-mediated adhesion to fibronectin and VCAM-1 of lymphoma cell lines and primary CLL cells. Furthermore, PCI-32765 also inhibits CXCL12-, CXCL13-, and CCL19-induced signaling, adhesion, and migration of primary CLL cells. Our data indicate that inhibition of BTK by PCI-32765 overcomes BCR- and chemokine-controlled integrin-mediated retention and homing of malignant B cells in their growth- and survival-supporting lymph node and bone marrow microenvironment, which results in clinically evident CLL regression.
Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.