3.7. Data analysis 4. Results 4.1. Discovery and preparation of NPB001-05 4.2. Effect of NPB001-05 on growth of Bcr-Abl positive and negative cells, primary cultures and normal human peripheral blood mononuclear cells (PBMCs) 4.3. NPB001-05 inhibits proliferation of leukemic cell lines independent of Bcr-Abl mutational status 4.4. NPB001-05 inhibits autophosphorylation of wt and resistant Bcr-Abl 4.5. Effect of NPB001-05 on CML clinical samples 4.6. NPB001-05 blocks cell cycle progressing and induces apoptosis of Bcr-Abl positive cells 4.7. In-vitro profiling of NPB001-05 on different kinases 5. Discussion 6. Acknowledgements 7. References ABSTRACTThe deregulated activity of the Bcr-Abl tyrosine kinase provides a rational basis for the development therapeutics in all phases of Chronic Myelogenous Leukemia (CML). Although a well studied imatinib therapy has clinical success against CML, resistance to imatinib due to mutations in the kinase domain, especially T315I poses a major problem for the ultimate success of CML therapy by this agent. Herein we describe an NPB001-05, derived from extract of Piper betle leafs, which is highly active in specifically inhibiting Bcr-Abl expressing cells. NPB001-05 inhibited the proliferation of BaF3 cells ectopically expressing wild type Bcr-Abl phenotype and 12 different imatinib-resistant mutations of clinical relevance (average IC 50 5.7 µg/ml). Moreover, NPB001-05 was highly inhibitory to wild type P210 Bcr-Abl and P210 Bcr-Abl-T315I kinase activity and abrogated the autophosphorylating enzyme in time-and dose-dependent manner. NPB001-05 was non-toxic on normal cells, but was inhibitory to CML patient derived peripheral blood mononuclear cells. Treatment with NPB001-05 caused apoptosis induction and G 0 G 1 cell cycle arrest in both Bcr-Abl wild type and T315I mutant cell lines.