Simple and Efficient Stratification of Invasive Bladder Cancer Patients

Intrinsic Molecular Subclassification of Urothelial Carcinoma of the Bladder: Are We Finally there?

Bladder cancer is a highly prevalent disease throughout the world usually encountered in older patients, and associated with substantial morbidity, mortality, and cost. The treatment of bladder cancer has remained unchanged for the last several decades. However, in recent years the availability of comprehensive genomic data from The Cancer Genome Atlas and other large projects have considerably improved our understanding of the pathogenesis of these tumors. These studies demonstrated that bladder cancers can be grouped into 2 broad categories namely basal and luminal molecular subtypes with recognizable subgroups in each of these categories. Clinical data suggest that invasive basal cancers are more sensitive to neoadjuvant chemotherapy (NAC), such that most patients with basal cancers who are aggressively managed with NAC have excellent outcomes. Patients with luminal cancers do not appear to derive much clinical benefit from NAC, but some may appear to be sensitive to anti-programmed death-ligand 1 (PDL1) antibodies and possibly other immune checkpoint inhibitors. It is hoped that future studies will also identify biomarkers such as immunohistochemical markers which may be used to predict therapeutic response of these tumors. This will contribute substantially toward efficient and cost-effective diagnosis and management of these neoplasms.

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.