BTK and B-cell chronic lymphocytic leukemia: Notably, treatment of CLL cells with the PI3Kδ inhibitor, Idelalisib or BTK inhibitor, Ibrutinib which are currently FDA approved for CLL69, abrogated increases in GCS transcription and synergised with the first generation Bcl-2/Bcl-xl inhibitor ABT-7377,67,68.