Abstract 5557: Systematic mapping of drug sensitivity in hematological malignancies identifies vulnerability of chronic lymphocytic leukemia with mutant p53
Authors: Sellner Leopold , Oles Malgorzata , Slabicki Mikolaj , Blume Carolin , Hüllein Jennifer , Stolz Tatjana , Lukas Marina , Sill Martin , Oakes Christopher C. , Dietrich Sascha , Merkel Olaf , Jauch Anna , Hensel Manfred , Rossi Davide , Zirlik Katja , Dürig Jan , Ringshausen Ingo , Herling Marco , Seiffert Martina , Dreger Peter , Kalle Christof von , Ho Anthony D. , Glimm Hanno , Huber Wolfgang , Zenz Thorsten 
Published: May 2015

Abstract
Introduction: The impact of mutations and pathway deregulation for drug sensitivity is only partly understood. Here we systematically investigated heterogeneity of drug response and genetic lesions in leukemia and lymphoma using primary tumor cells in order to identify pathway dependencies which can be exploited by rational treatment approaches. Methods: Primary leukemia / lymphoma cells obtained from peripheral blood were characterized with an ex vivo high-throughput drug screening platform in two steps: In an initial screen 2221 different compounds were tested for cytotoxicity on a limited cohort (n=20). 67 promising compounds targeting different pathways were selected for further validation on a larger cohort (n=111; 97 chronic lymphocytic leukemia (CLL), 5 T-prolymphocytic leukemia (T-PLL), 6 non-CLL B-Non-Hodgkin-Lymphoma (B-NHL), mononuclear cells of 3 healthy donors). Heat inactivated human serum was supplemented to mimic micro-environmental conditions. Cell viability was assessed by quantification of ATP (CellTiterGlo®) 48 and 72 hours after drug application. To understand heterogeneous pathway dependencies, drug sensitivity was regressed on genetic profiles. Genetic characterization was performed by FISH, targeted sequencing of recurrent aberrations (BRAF, MYD88, NOTCH1, SF3B1, TP53) as well as whole exome sequencing. Results: We initially focused on the impact of compounds interfering with or dependent on the p53 pathway. Nutlin-3 and fludarabine induced cell death more efficiently in cells with wild-type (n=80) than in CLL with mutated p53 (n=17; Nutlin-3 10µM: 51±18 vs 80±18; fludarabine 10µM: 40±36 vs 67±23 [% viability of untreated control], both p&lt;0.001). Furthermore inhibitors with related targets (e.g. B-cell receptor pathway) showed similar response profiles across patients. Based on the sensitivity data we built a hierarchy of compounds with preferential sensitivity for specific genetic subgroups. We identified compounds with increased activity in groups with high risk aberrations (e.g. TP53 mutation, NOTCH1 mutation, 11q deletion, unmutated IGHV). Validation of the top hit with increased response of TP53-mutated CLL (compound A 10µM wt vs mutTP53: 58±31 vs 37±18 [% viability of untreated control], p&lt;0.01) confirmed genotype-specific cytotoxicity across concentration ranges (0.1-10µM). Other compounds inhibiting the same target support our observation. The effect was reproducible in co-culture of CLL cells with HS-5 stroma cells (66±16 vs 32±13 [% viability of untreated control], p&lt;0.05). Conclusion: Our data provide a comprehensive map of genetically determined drug sensitivity in lymphoid malignancies. The work offers a novel functional classification of lymphoma based on drug sensitivity and identifies synthetic lethal interaction for TP53 mutant CLL.
Citation Format: Leopold Sellner, Malgorzata Oles, Mikolaj Slabicki, Carolin Blume, Jennifer Hüllein, Tatjana Stolz, Marina Lukas, Martin Sill, Christopher C. Oakes, Sascha Dietrich, Olaf Merkel, Anna Jauch, Manfred Hensel, Davide Rossi, Katja Zirlik, Jan Dürig, Ingo Ringshausen, Marco Herling, Martina Seiffert, Peter Dreger, Christof von Kalle, Anthony D. Ho, Hanno Glimm, Wolfgang Huber, Thorsten Zenz. Systematic mapping of drug sensitivity in hematological malignancies identifies vulnerability of chronic lymphocytic leukemia with mutant p53. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5557. doi:10.1158/1538-7445.AM2014-5557