Venetoclax can sensitize CLL cells to BTKis, and ibrutinib, as well as the other BTKis, can inhibit the expression of two different BCL2-family antiapoptotic proteins, myeloid cell leukemia-1 (MCL-1) and B-cell lymphoma-extra large (BCL-XL), further sensitizing CLL cells to BCL-2 inhibition [139,140]. This evidence concerns the gene MCL1 and B-cell chronic lymphocytic leukemia.