Some synthetic apoptosis inducers with high potency in vitro have turned out to be disappointing when used to treat CLL patients: this is the case of the proteasome inhibitor bortezomib, several HDAC inhibitors (MGCD0103 for instance) and antisense oligonucleotides (targeting Bcl-2 or XIAP). This evidence concerns the gene BCL2 and B-cell chronic lymphocytic leukemia.