Current therapies for CLL include the combination fludarabine-cyclophosphamide-rituximab, as well as the newer compounds ibrutinib (Bruton's tyrosine kinase [BTK] inhibitor), idelalisib (phosphatidylinositol 3-kinase δ [PI3-Kδ] inhibitor), and venetoclax (Bcl-2 inhibitor) (12, 16). Here, BTK is linked to B-cell chronic lymphocytic leukemia.