Abstract 588: Characterization of oncolytic peptides for local bladder cancer therapy

Background: Bladder cancer is the sixth most common cancer in the United States, with over 80,000 new cases diagnosed each year. While patients often initially respond positively to treatment, it has been found that nearly 75% of patients diagnosed with high-grade non-muscle invasive bladder cancer (NMIBC) will develop a recurrence within ten years. Treatment options for recurrent NMIBC are severely lacking. Antimicrobial peptides (AMPs) are naturally occurring molecules that kill bacteria by forming membrane pores and lysing the cells. While these molecules have been explored for their use in oncology as oncolytic peptides, their low potency and limited therapeutic index have hindered further development. However, intravesical delivery of oncolytic peptides for NMIBC could minimize the current issues by enabling high concentrations at the site of action while limiting systemic exposure. The aim of this research project was to identify potent and selective oncolytic peptides and investigate their functional activity in vitro. Methods: T24 (bladder transitional cell carcinoma) and HUC (normal urothelial cells) were purchased from ATCC and ScienCell, respectively. Bladder cancer organoid models were acquired from Dr. Shen9s laboratory (Columbia University). Proliferation and cytotoxicity measurements were conducted with alamarBlue (Thermo Fisher), CellTiter-Glo 3D (Promega) and xCELLigence RTCA (ACEA Biosciences). Results: We screened a library of ~40 known AMPs for antiproliferative activity in T24 bladder cancer cells, as well as normal human urothelial cells (HUCs). Based on the results of this experiment, six hits were identified and selected for further characterization. These hits were validated in two patient derived organoid models. While results from the phenotypic screen showed lack of selectivity against HUCs, we further investigated the kinetics of cell death to determine the utility of these molecules as intravesical therapies with short residence time within the bladder. It was determined that Temporin-L exhibited the most rapid kinetics of cell death of the six peptide hits analyzed. Furthermore, washout studies revealed that Temporin-L is capable of quickly killing cancer cells with a lasting effect. Conclusion: We identified several reference oncolytic peptides capable of killing bladder cancer cells. Of these peptides, Temporin-L exhibited unique characteristics in its kinetics of cell death and the potential for it to provide temporal selectivity over normal cells. These unique properties may be advantageous in local intravesical therapy for NMIBC due to the availability to control concentration and duration of exposure. Citation Format: Amy Klova, Hiroe Tariga, Suijin Yang, Anastasia Velentza, Jacek Stalewski, Adeela Kamal, Scott McDonnell. Characterization of oncolytic peptides for local bladder cancer therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 588.