Abstract 1441: Systems-level interrogation of resistance mechanisms to immunotherapy through pooled shRNA screens

Abstract

Abstract Despite the impressive clinical efficacy of immunotherapy in some patients, many still do not respond or progress following an initial response. The molecular mechanisms underlying the tumor resistance in those non-responders remain largely undefined. To address this issue, we set out to perform high-throughput unbiased pooled shRNA screens to identify critical genes that confer immune resistance. Patient-derived melanoma cells were transduced with barcoded pooled lentiviral shRNA libraries that targeted the human kinome, followed by exposure to cytotoxicity mediated by autologous tumor infiltrating lymphocytes. Tumor cells were then subject to genomic deep sequencing and integrated analysis to identify depleted barcodes and corresponding genes. One identified candidate of particular interest is Aurora Kinase A (AURKA), a cell cycle regulator that has previously been shown to contribute to tumorigenesis and correlate with poor prognosis for cancer patients. Importantly, our independent screening with a bioactive compound library also implicated Aurora Kinase as an immune resistance candidate against T cell immunotherapy. Further studies showed that suppression of Aurora kinase activity with a pan inhibitor - AMG900, exhibited a synergistic cytotoxic effect with tumor infiltrating lymphocyte-mediated killing on autologous tumor cells from patients. Furthermore, our Nanostring analysis of tumor biopsies from patients that received adoptive T cell therapy revealed significantly increased expression of AURKA in tumors from non-responding patient when compared with responder counterparts. These results have substantiated the validity of our pooled shRNA screening platform. Further investigations are ongoing to elucidate the underpinnings of Aurora kinase-mediated tumor resistance to immunotherapy and to functionally and physiologically validate other putative targets we have identified. Citation Format: Zhe Wang, Shruti Malu, Weiyi Peng, Jodi McKenzie, Rina Mbofung, Leila Williams, Sahil Seth, Tim Heffernan, Patrick Hwu. Systems-level interrogation of resistance mechanisms to immunotherapy through pooled shRNA screens. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1441.