Although our in vitro experiments do not provide direct evidence to what extent endogenous BAFF provides survival signals to CLL cells, in particular when considering that, as discussed above, the extent of “bioactive” BAFF in CLL patients is yet unclear, these results demonstrate that BAFF confers resistance of CLL cells to all three small molecule inhibitors. Here, TNFSF13B is linked to B-cell chronic lymphocytic leukemia.