An orally bioavailable, selective inhibitor of Bruton's agammaglobulinemia tyrosine kinase (BTK), with potential antineoplastic activity. Upon administration, spebrutinib targets and covalently binds to BTK, thereby preventing its activity. By irreversibly inhibiting BTK, administration of this agent may lead to an inhibition of B cell receptor (BCR) signaling and may inhibit cell proliferation of B-cell malignancies. BTK, a cytoplasmic tyrosine kinase and member of the Tec family of kinases, plays an important role in B lymphocyte development, activation, signaling, proliferation and survival.