Abstract 5320: BRG399, a small molecule modulator of UBE2K demonstrated dose-dependent anti-cancer efficacy in an in vivo model for gastric cancer
Authors: Kazerounian Shiva , O'Hara Mollie , Guven Arcan , Grover Kashni , Pellegrino Nicole , Gray Kayleigh , Bruce Can , Miller Gregory M. , Nastke Maria-Dorothea , Kiebish Michael A. , Grund Eric M. , Sarangarajan Rangaprasad , Narain Niven R. , Gesta Stephane , Vishnudas Vivek K. 
Published: June 2022

Abstract
Gastric cancer is difficult to treat and exhibits poor survival with current therapies (five-year survival for all stages is 32% and 5% for metastatic gastric cancer) demonstrating a clear unmet clinical need. UBE2K was identified as a drug target from the BERG Interrogative Biology® Platform, from an Artificial Intelligence derived in vitro pan-cancer Bayesian network. UBE2K (also known as Huntington Interacting Protein 2 and E2-25K) is one of the ~40 E2 enzymes from the Ubiquitin Proteasome System and belongs to the Class II of E2 enzymes that preferentially catalyze the synthesis of Lys48-linked changes on monoubiquitinated substrates. Recently, high expression of UBE2K in tumors of gastric cancer patients has been shown to associate with poor prognosis. BERG has developed BRG399 as a candidate molecule to modulate UBE2K activity for use in oncology. Here, we evaluated the anti-cancer effect of BRG399 using Hs 746T, a human xenograft in vivo model for gastric cancer. In vitro evaluation of BRG399 potency revealed an IC50 of 44.3nM in Hs 746T cells. For determination of BRG399 potency in vivo, nude mice were inoculated subcutaneously with Hs 746T cell line and tumors were allowed to reach 120mm3. Animals were then randomized into four groups to receive oral administration of vehicle, 75, 100, or 150mg/kg of BRG399 twice per day for 15 days. The result revealed that BRG399 significantly decreased the growth of Hs 746T tumors in a dose-dependent manner. Statistical analysis using a mixed effect linear model of the tumor volumes on the last day of study demonstrated a tumor growth inhibition of 60.3, 71.2 and 85.3% at the three doses, respectively, without any significant effect on body weight. These results are well correlated with the dose-dependent increase of BRG399 in both plasma and tumor tissues. Anti-tumor effect of BRG399 appears to be the result of G2/M arrest, as indicated by a dose-dependent elevation of two cell cycle-dependent biomarkers, CNNB1 and pHH3, in tumor tissue. This is consistent with the role of UBE2K in regulating several components of cell cycle for dictating the precise timing of cell division. Mixed effect multivariable regression modeling was employed to identify the relationship between these two biomarkers and response. This analysis indicated that the level of plasma concentration of BRG399, together with the tumor levels of CNNB1 and pHH3, are significantly and negatively associated with tumor volume, allowing an inference that these biomarkers are indicative and/or involved in the tumor response of BRG399. In summary, these results signify the anti-cancer efficacy of BRG399 and support its potential as a drug candidate for treatment of gastric cancer.
Citation Format: Shiva Kazerounian, Mollie O'Hara, Arcan Guven, Kashni Grover, Nicole Pellegrino, Kayleigh Gray, Can Bruce, Gregory M. Miller, Maria-Dorothea Nastke, Michael A. Kiebish, Eric M. Grund, Rangaprasad Sarangarajan, Niven R. Narain, Stephane Gesta, Vivek K. Vishnudas. BRG399, a small molecule modulator of UBE2K demonstrated dose-dependent anti-cancer efficacy in an in vivo model for gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5320.