Mouse Models of Muscle-invasive Bladder Cancer: Key Considerations for Clinical Translation Based on Molecular Subtypes

Context: In the past few years, research has suggested that molecular subtypes in muscle-invasive bladder cancer (MIBC) may be exploited to accelerate developments in clinical disease management and novel therapeutics. Objective: To review MIBC mouse models from a molecular subtype perspective, their advantages and limitations, and their applications in translational medicine, based on a PubMed search for publications from January 2000 to February 2018. Evidence acquisition: Publications relevant to MIBC mouse models and their molecular subtypes were identified in a literature review. Evidence synthesis: We classified the models according to the technique used for their establishment. For xenotransplant and allograft models, the inoculated cells and inoculated locations are the major determinants of molecular subtypes. Although the cell lines used in xenotransplant models can cover most of the basal-squamous and luminal subtypes, allograft models offer a more realistic environment in which to reconstruct aspects of the associated stromal and immune features. Autochthonous models, using genetic and/or chemical stimuli to induce disease progression, can also generate models with basal-squamous and luminal subtypes, but further molecular characterisation is needed since other mutational variants may be introduced in these models. Conclusions: We identified preclinical MIBC models with different subtype specifications and assessed their promise and current limitations. These models are versatile tools that can reproduce the molecular complexity of MIBC and support novel therapeutic development. Patient summary: Understanding which models of muscle-invasive bladder cancer most accurately represent the clinical situation is important for the development of novel drugs and disease management strategies. We review the different models currently available and their relevance to different clinical subtypes. An ability to map preclinical mouse models to the different molecular subtypes of bladder cancer should help researchers to develop novel therapeutic strategies for bladder cancer.