Effect of the Bruton Tyrosine Kinase (Btk)-inhibitors spebrutinib (CC-292) and acalabrutinib (ACP-196) on macrophage´s phenotype and functions.

JOSE LUIS MARIN FRANCO; VERGARA-RUBIO, MARICEF; BEZARES FERNANDO; COLADO ANA; JANCIC CAROLINA; RISNIK DENISE; ELÍAS, ESTEBAN E.; GAMBERALE ROMINA; CORDINI, GREGORIO; GENOULA, MELANIE; FERNANDEZ GRECCO HORACIO; CABREJO, MARÍA; GIORDANO MIRTA; BALBOA LUCIANA; BORGE MERCEDES

Cologne

Congreso; XIth International Workshop of the German CLL Study Group, 2018; 2018

Ibrutinib is a first-in-class Btk inhibitor used in the treatment of CLL and other B-cell malignancies. Besides its effects on leukemic B-cells, ibrutinib also affects functions on T cells, NK cells and macrophages. While some of these effects might be explained by inhibition of Btk, which is expressed in myeloid cells, ibrutinib also inhibits other off-target kinases such us Itk, Tec, Bmx and Lyn. Second generation Btk-inhibitors with higher selectivity have been developed and are being evaluated in clinical trials. We have described that ibrutinib impairs macrophage-phagocytosis of rituximab-coated CLL cells (Haematologica. 2015 Apr;100(4):e140-2), macrophage´s M1 polarization, response to TLR`s ligands and also response to Mycobacterium tuberculosis (Mtb) (manuscript under review). Here we aimed to evaluate the effect of second-generation Btk inhibitors, spebrutinib (CC-292/AVL-292) and acalabrutinib (ACP-196), on macrophages´ phenotype and functions.First we compared the effect of Btk-inhibitors on macrophage-phagocytosis of rituximab-coated CLL cells, a central mechanism of action of anti-CD20 mAbs. To this aim, CLL cells were labeled with CFSE, coated with rituximab (10 µg/ml) and then cultured with human macrophages. Btk inhibitors were used at concentrations that can be achieved in patients´ plasma during treatment (0.03-1 µM). The percentage of CFSE positive macrophages was determined by flow cytometry. While we confirmed that ibrutinib reduces rituximab-coated CLL cells phagocytosis, we found that spebrutinib and acalabrutinib did not affect the phagocytosis assay (n=7, p