Modulation of BCR/ABL GRB2 Interaction

Bcr/Abl is a chimeric oncogene implicated in the pathogenesis of Philadelphia chromosome (Ph1)positive human leukemias. Worldwide there are approximately 60,000 patients with the Bcr/Abltranslocation, with very limited therapy available. Bone marrow transplantation is the only treatmentthat results in long term survival. However, it is effective for only a subset of patients and is extremelyexpensive. Recent data has identified a protein termed GRB2 as a direct effector of Bcr/Abl. In turnGRB2 may mediate oncogenic transformation by constitutive activation of the normal Ras protein. Wepropose to develop a cell based assay for the detection of modulators of the Bcr/Abl-GRB2 complex.For this purpose Bcr/Abl and GRB2 specific antibodies will be paired to format a capture assay to detectcompounds that disrupt the Bcr/Abl-GRB2 complex. In Phase I, the capture assay will be formatted froma bench assay into a cell based screen compatible with our automated screening. A pilot screen of 1000fungal extracts will be carried out to test screen/extract compatibility and reproducibility of the assayin an automated format. In Phase II, we propose to screen over 100,000 fungal extracts. Over the last6 years we have developed a proprietary, state-of-the-art, high-throughput screening technology. Ourunique primary screening system employs live cells and robotic systems with a screening capacity inexcess of 150,000 assays per week. This technology is ideally suited to the proposed search for sucha modulator. Complete automation not only allows the primary screen to be cost-effective, but hasproved essential to obtain highly reproducible data form a cell-based high-throughput screen.