Novel Targeted Therapy for CLL

DESCRIPTION (provided by applicant): Of the nearly 84,000 cases of leukemia in the Western world, B-cell chronic lymphocytic leukemia (B-CLL) is the most common and accounts for approximately 30% of all adult leukemia cases. It is characterized by the rele ntless accumulation of monoclonal mature B cells. Tumor cells from B-CLL patients show increased survival rates that have been shown to be due to inhibited apoptosis and alterations of genes involved in cell cycle control and cell survival. When evaluating the signaling pathways that are aberrantly activated in B-CLL cells, it was demonstrated that the kinase Akt is constitutively activated and the overstimulation of Akt results in activation of the NFkB pathway that leads to increased production of NO and inhibited apoptosis. It has been known for many years that a genetic predisposition for B-CLL exists given that B-CLL occurs more commonly in people with at least one first degree relative with CLL. Among chromosomal aberrations that have been documented i n B-CLL cases is a deletion at 11q that includes a portion of the PPP2R1B gene, which encodes the A2 constant regulatory subunit of Protein Phosphatase 2a (PP2a). PP2a is a commonly known tumor suppressor that is underexpressed as a result of the 11q delet ion leading to decreased PP2a activity in B-CLL cells. The role of PP2a in deactivation of Akt, the mitogen activated protein kinases (MAPK) p38, JNK, and ERK, as well as Nuclear Factor kB (through IkK) is well established. Reduced PP2a activity in B-CLL c ells would be expected to lead to aberrant signaling through Akt, production of inducible Nitric Oxide Synthase (iNOS), and other effects demonstrated in malignant B-CLL cells. Therefore, pharmacological activation of PP2a may provide a novel approach to d evelopment of B-CLL therapeutics. Cognosci has developed novel therapeutic peptides with potent anti-inflammatory activity in vitro and in vivo. In mechanistic studies we recently demonstrated that these peptides suppress phosphorylation and the accompanyi ng activation of important inflammatory signaling proteins including p38, JNK, and ERK MAPKs as well as IkK, IkB, and NFkB. Upon analysis of the mechanism of action of the Cognosci compounds, we found that compound treatment results in activation of PP2a a nd suppression of signal transduction pathways and production of cytokines, iNOS and its product NO. During a preliminary evaluation of several COG compounds in primary CD19+/CD5+ B-CLL cells from patients, we discovered that one of these compounds, (COG11 2) is highly and preferentially cytotoxic for human CLL cells with an EC50 of 224 nM and an EC50 for normal B-cells of gt20 uM. We propose to determine the effect of COG112 treatment on the phosphorylation state of key signal transduction proteins and PP2a activity in B-CLL cells. We will also evaluate COG112 for anti-CLL activity in the E5-TCL1 transgenic mouse model of CLL. PUBLIC HEALTH RELEVANCE: Of the nearly 84,000 cases of leukemia in the Western world, B-cell chronic lymphocytic leukemia (B-CLL) is the most common and accounts for approximately 30% of all adult leukemia cases. It is characterized by the relentless accumulation of monoclonal mature B cells. Tumor cells from B-CLL patients show increased survival rates that have been shown to be due to inhibited apoptosis and alterations of genes involved in cell cycle control and cell survival. When evaluating the signaling pathways that are aberrantly activated in B-CLL cells, it was demonstrated that the kinase Akt is constitutively activated and the overstimulation of Akt results in activation of the NFkB pathway that leads to increased production of NO and inhibited apoptosis. It has been known for many years that a genetic predisposition for B-CLL exists given that B-CLL occurs more commonly in peo ple with at least one first degree relative with CLL. Among chromosomal aberrations that have been documented in B-CLL cases is a deletion at 11q that includ