Abstract 4180: RS-41, a multi-targeted kinase inhibitor, induces cell cycle arrest and apoptosis in p53 mutant and wild type models of upper gastrointestinal cancers

Introduction: Upper Gastrointestinal Cancers (UGCs) are a leading cause of cancer-related mortality and account for approximately 1.1 million deaths worldwide. UGCs respond poorly to conventional chemotherapy due to constitutive over activity of multiple oncogenic signaling mechanisms, including the epidermal growth factor receptor (EGFR), ERBB2/HER-2, Aurora kinases, and JAK-STAT pathways. In addition, presence of mutant P53 further imparts resistance to conventional chemotherapeutic agents. Therefore, novel small molecule inhibitors that target multiple kinases associated with oncogenic progression could pave the way for improved chemotherapy and better therapeutic outcomes. In this study, we characterized the anticancer activity of RS-41, an investigational 4-phenylbenzamidopyrrolo[2,3-d]-pyrimidin-4-amine multi-kinase inhibitor, in P53 mutant and wild type models of UGC. Methods: Target kinase inhibition and selectivity screening assays were performed to determine potency and selectivity of kinase inhibition for RS-41. In addition, MTT-cell viability assay, clonogenic cell survival assay, cell cycle analyses, and western blot analyses were done to evaluated the effect of RS-41 treatment on cell viability, survival, cell cycle progression, and expression of apoptotic markers in P53 mutant (FLO-1) and P53 wild type (AGS) UGC cells, respectively. Results: The kinase selectivity screening assay characterized RS-41 for its selectivity against a panel of 90 human kinases. The kinase screening analyses showed that RS-41 selectively inhibits AURKA (IC50-0.96±0.03µM), JAK2 (IC50-1.21±0.17µM), and EGFR (IC50-5.92±0.75µM) kinases, respectively. The cell viability data indicate that treatment with RS-41 mediates significant (P≤0.05) inhibition of FLO-1 and AGS UGC cell viability. The clonogenic cell survival data showed that treatment with RS-41 for 24 hrs. suppresses subsequent formation of colonies in both FLO-1 and AGS UGC cells. The cell cycle data exhibited a marked increase (P≤0.05) in the percentage of FLO-1 and AGS cells in the sub-G1-phase (cell death) after treatment with RS-41 for 24 and 72 hrs., respectively. The western blotting data further confirmed induction of apoptosis in FLO-1 and AGS cells as evidenced by an increase in expression of various markers of apoptosis (P73/P53, cleaved PARP, and/or cleaved caspase 3) following treatment with RS-41 for 24 and 72 hrs. Conclusions: Our in vitro data indicate that inhibition of various oncogenic kinases with RS-41 is an effective therapeutic strategy for inducing apoptosis in both P53 mutant and wild type UGC cells. Our study suggests that RS-41 is a promising multi-kinase inhibitor with a potential to further enhance chemotherapeutic options for treatment of UGC. Citation Format: Tanvi Visal, Shraddha Patel, Priya Pancholi, Samhita Bapat, Amruta Samant, Dhvanir Kansara, Sonali Kurup, Vikas Sehdev. RS-41, a multi-targeted kinase inhibitor, induces cell cycle arrest and apoptosis in p53 mutant and wild type models of upper gastrointestinal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4180. doi:10.1158/1538-7445.AM2017-4180