NCIt definition : The maleate form of acalabrutinib, an orally available inhibitor of Bruton's tyrosine
kinase (BTK) with potential antineoplastic activity. Upon administration, acalabrutinib
inhibits the activity of BTK and prevents the activation of the B-cell antigen receptor
(BCR) signaling pathway. This prevents both B-cell activation and BTK-mediated activation
of downstream survival pathways. This leads to an inhibition of the growth of malignant
B cells that overexpress BTK. BTK, a member of the src-related BTK/Tec family of cytoplasmic
tyrosine kinases, is overexpressed in B-cell malignancies; it plays an important role
in B lymphocyte development, activation, signaling, proliferation and survival.;