Oncolytic Immunotherapy for Bladder Cancer Using Coxsackie A21 Virus: Using a Bladder Tumor Precision-Cut Slice Model System to Assess Viral Efficacy

Abstract

Oncolytic viruses are anticancer agents that selectively target and kill cancer cells by direct lysis, while at the same time stimulating a tumor antigen-specific adaptive immune response. These promising therapeutic agents target multiple cancers and have already proven to be an effective treatment option for solid malignancies. One such agent, T-Vec (Talimogene laherparepvec) has been licensed and is in routine clinical use for treatment of malignant melanoma. Non-muscle invasive bladder cancer (NMIBC) is an ideal potential target for oncolytic immunotherapy as locally instilled live biological therapy using Bacille Calmette-Guerin (BCG) is already well established in the clinical setting. Coxsackievirus A21 (CVA21) is a novel intercellular adhesion molecule-1 (ICAM-1)-targeted immunotherapeutic virus. We have investigated CVA21-induced cytotoxicity in a panel of human bladder cancer cell lines, revealing a range of sensitivities largely correlating with expression of the viral receptor ICAM-1. CVA21 in combination with low doses of mitomycin-C enhanced CVA21 viral replication and oncolysis by increasing surface expression levels of ICAM-1. In addition to cell lines and an animal model a key component of our studies into oncolytic immunotherapy for bladder cancer was the use of a bladder tumor precision slice preclinical model system which represents tumor architecture, heterogeneity, and the complexity of a tumor in vitro. Results seen in cell lines were reflected in the tumor slice model whereby levels of virus protein expression and induction of apoptosis were enhanced with prior exposure to mitomycin-C. In this chapter we demonstrate the utility of the precision cut tumor slice model as a unique organotypic model to test oncolytic viruses. We will describe how to prepare and slice the tumor using a vibrating microtome together with the optimum culture and conditions for treatment.