SYK and B-cell chronic lymphocytic leukemia: To further underscore the robustness of the assay, it should be noted that apoptosis was initially described in the case of ibrutinib or other signaling inhibitors (e.g. SYK inhibitors) only when these drugs were tested ex vivo on CLL cells in the absence of stromal support and/or at much higher concentration not attainable in vivo [45–49].