Cell penetrating peptides as a therapeutic strategy in chronic lymphocytic leukemia.

PP2A is a serine/threonine phosphatase critical to a number of physiological and developmental processes. In this manuscript, we show that a peptide, specifically blocking the caspase- 9/PP2A interaction, DPT-C9h, induces apoptosis in primary tumour B cells isolated from peripheral blood mononuclear cells or bone marrow of chronic lymphocytic leukemia (CLL) patients, but not on B cells obtained from healthy donors (HD). Moreover, in both CLL patients and HD, DPT-C9h does not induce apoptosis on T- and NKcells and monocytes. Our results strongly suggest that DPT-C9h peptide has tumour specificity and that caspase-9/PP2Ac interaction constitutes a novel therapeutic approach for the treatment in CLL patients.