Targeting Specific Cell Signaling Pathways for the Treatment of Malignant Peritoneal Mesothelioma

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1 The Use of Kinase Inhibitors: Translational Lab Results Targeting Specific Cell Signaling Pathways for the Treatment of Malignant Peritoneal Mesothelioma Sheelu Varghese, Ph.D. H. Richard Alexander, M.D. Division of Surgical Oncology, Department of Surgery and The Marlene and Stewart Greenebaum Cancer Center University of Maryland School of Medicine Baltimore, MD-21201

2 Introduction Approximately 3,000 people are diagnosed with malignant mesothelioma in the US every year; malignant peritoneal mesothelioma (MPM) accounts for 15-20% of all mesothelioma diagnoses. MPM is characterized by large number of tumor nodules within the abdominal cavity; patients afflicted with this cancer have a poor quality-of-life and survival. This cancer is more common in females and young males compared with pleural mesothelioma which is more common in older males. Patients with peritoneal mesothelioma are usually diagnosed with symptoms of severe abdominal distention, pain, and weight loss.

3 Introduction No curative treatment for MPM; surgery and chemotherapy are treatment options but their use is limited to selected patients. The median overall progression free survival of patients with MPM is less than two years. Asbestos exposure is not always associated with peritoneal mesothelioma incidence. The biology of disease progression of MPM is poorly understood and hence there are no effective therapies for this cancer.

4 Our Aims Identify novel genes and cell pathways that promotes MPM tumor progression in patients. Identify novel specific inhibitors for the genes and pathways identified in patients. Study the role of inhibitors on MPM growth both in vitro and in vivo in small animal models. If the experimental studies are promising translate to patient clinical trials.

5 Our Approach We collected fresh patient tumor samples from patients under an IRB approved protocol; consent was obtained from patients to use their tumor tissue for research purposes. Then we generated a global gene expression pattern of the patient tumors. Next, we compared various clinical parameters (for example patient survival or tumor histology) to the gene expression to identify the significance. Identified the genes and pathways highly significantly associated with patient outcome. Conducted studies of these pathways using specific drugs in MPM cells and animal models to test its effects on tumor xenograft growth.

6 Results Actuarial overall survival of MPM patients. The median overall survival was 47.4 months

7 Results Hierarchical Clustering of the Gene Expression Data From 41 MPM Patient Tumors.

8 Results Clustering of the Gene Expression Data from Non-malignant Peritoneum and 41 MPM Patient Tumors. Clustering of Non-malignant peritoneum (NP) and patient tumor (PT) samples Group A (Poor survival) Group B (Good survival) NP PT

9 Results Major Cell Signaling Pathways Activated in MPM Patient Tumors. Inhibition of these pathways may have therapeutic value Genes of the PI3K pathway activated in MPM Other pathways over-expressed in MPM

10 Results New MPM Cell Lines Derived from Patient Tumors Immunohistochemistry showing positive staining for known markers of mesothelioma Electron micrographs of MPM cells

11 Results BEZ235, a Dual-class PI3K and mtor Inhibitor Significantly Inhibited MPM Cell Proliferation

12 Results BEZ235 Significantly Reduced PI3K and mtor Signaling Pathway Proteins in MPM cells in vitro and Tumor Growth in vivo in Mouse Models Meso-1 Xenograft Models Control BEZ235

13 Conclusions Gene expression profiling of the pre-treatment tumor samples predicts survival of MPM patients. Unsupervised clustering of the genes of the MPM identified two groups of patients significantly differ in their survival; age or sex is not a pre-determined factor for survival in MPM patients. We have identified two important pathways, PI3K and mtor signaling pathways, in MPM patients with therapeutic significance. Pathway specific inhibition of the PI3K and mtor signaling inhibited MPM cell proliferation in vitro. Oral delivery of BEZ235 (40mg/kg body weight), a dual-class PI3K and mtor inhibitor significantly suppressed tumor growth in MPM xenograft models.

14 Acknowledgments Funding support from The Marlene and Stewart Greenebaum Cancer Center, The University of Maryland School of Medicine, Baltimore, MD Technical support from Ms. Zhaorong Chen, Marlene and Stewart Greenebaum Cancer Center Mesothelioma Applied Research Foundation Thank You!