Highlights
•Efficient generation of a biobank of patient-derived bladder cancer organoids
•Organoids recapitulate the histological and molecular spectrum of human bladder cancer
•Bladder tumor organoids display clonal evolution in culture and as xenografts
•Drug response of organoids can be validated in xenografts
Summary
Bladder cancer is the fifth most prevalent cancer in the U.S., yet is understudied, and few laboratory models exist that reflect the biology of the human disease. Here, we describe a biobank of patient-derived organoid lines that recapitulates the histopathological and molecular diversity of human bladder cancer. Organoid lines can be established efficiently from patient biopsies acquired before and after disease recurrence and are interconvertible with orthotopic xenografts. Notably, organoid lines often retain parental tumor heterogeneity and exhibit a spectrum of genomic changes that are consistent with tumor evolution in culture. Analyses of drug response using bladder tumor organoids show partial correlations with mutational profiles, as well as changes associated with treatment resistance, and specific responses can be validated using xenografts in vivo. Our studies indicate that patient-derived bladder tumor organoids represent a faithful model system for studying tumor evolution and treatment response in the context of precision cancer medicine.
Introduction
Most bladder cancers are urothelial carcinomas, with the majority of these being non-muscle-invasive bladder cancers, which usually have a relatively favorable prognosis but are associated with considerable morbidity and high cost for managing treatment (Kamat et al., 2016, Knowles and Hurst, 2015, Lerner et al., 2016). These non-muscle-invasive tumors can be classified as low-grade or high-grade and encompass multiple growth patterns, including papillary tumors and carcinoma in situ (CIS), a flattened layer of dysplastic cells that is presumed to represent a common precursor of muscle-invasive bladder cancer. In contrast, muscle-invasive bladder cancers have a relatively poor prognosis (Kamat et al., 2016, Prasad et al., 2011).
Treatment regimens for bladder cancer and their efficacy vary depending on clinical stage and associated risk factors (Kamat et al., 2016, Lerner et al., 2016, Prasad et al., 2011, Resnick et al., 2013). The front-line treatment for non-muscle-invasive bladder cancer is transurethral resection (TUR), with or without subsequent intravesical delivery (into the bladder lumen) of chemotherapy, such as mitomycin C, or bacillus Calmette-Guerin (BCG) (Redelman-Sidi et al., 2014), depending on disease stage, grade, and other clinical characteristics. In the case of muscle-invasive bladder cancer, a current standard of care is cisplatin-based neoadjuvant chemotherapy followed by radical cystectomy (Grossman et al., 2003, Herr et al., 1998, International Collaboration of Trialists et al., 2011). Although approximately 50% of patients who undergo cystectomy are alive after 5 years, the procedure affects quality of life and is consequently disfavored by many patients.
Several lines of evidence suggest that the distinct clinical outcomes of non-muscle-invasive versus muscle-invasive bladder tumors can be attributed to their different molecular profiles (Dyrskjøt et al., 2003, Hurst et al., 2012, Lauss et al., 2010). For example, gain-of-function mutations of FGFR3 are more prevalent in low-grade non-muscle-invasive bladder cancers, whereas loss or mutation of TP53 is more frequent in high-grade muscle-invasive bladder cancers (Knowles and Hurst, 2015). However, molecular studies have shown that the relationship between these general categories of bladder cancer is complex (Lindgren et al., 2012). Moreover, an analysis of non-muscle-invasive bladder cancer has identified multiple subtypes associated with disease outcome and clinical response, with the worst outcomes observed in patients with TP53 and ERBB2 (HER2) mutations (Hedegaard et al., 2016). Therefore, there is a need to develop models for both non-muscle-invasive and muscle-invasive bladder cancer to elucidate the biologic function of recurrent somatic mutations and their role in mediating transformation and promoting disease progression as a prelude to the development of rational treatment strategies.
Recently, several studies have shown the value of three-dimensional organoid culture systems for modeling varied aspects of cancer biology (Drost and Clevers, 2017, Weeber et al., 2017). In particular, patient-derived organoids derived from colorectal, pancreatic, liver, breast, and prostate cancers can model key features of parental tumors and can also be used to investigate drug response (Boj et al., 2015, Broutier et al., 2017, Gao et al., 2014, Sachs et al., 2018, van de Wetering et al., 2015). Notably, a recent study on the establishment of patient-derived tumor organoid lines from a wide range of tumor types has also described the generation of eight bladder tumor organoid lines, which have not been extensively characterized (Pauli et al., 2017). Here, we report the generation and detailed analysis of 22 patient-derived bladder cancer organoid lines and demonstrate their histopathological and molecular concordance with their corresponding parental tumors. We show that these organoid lines frequently retain tumor heterogeneity and display changes in their mutational profiles during culture and xenografting that are consistent with clonal evolution. Furthermore, we demonstrate the utility of these patient-derived organoid lines as a model system for investigating tumor evolution and its role in modulating drug response….
