The development of pre-clinical models to study and identify novel biomarkers in muscle invasive bladder cancer

Bladder cancer is the 4th commonest malignancy in the United Kingdom and worldwide there are nearly 400,000 new cases every year with over 150,000 deaths. The gold standard treatment for muscle invasive bladder cancer is radical cystectomy with neoadjuvant chemotherapy. Despite this the overall survival at 5 years is only around 50%. To improve outcomes new pre-clinical models of greater physiological relevance are needed and the ability to translate research from the laboratory to clinical practice needs to be improved. The tyrosine kinase HER2 is an attractive therapeutic target in bladder cancer and has the potential to be used in clinical practice. The hypothesis of this thesis was that HER2 would be a prognostic biomarker in patients with bladder cancer requiring radical cystectomy and that it has a critical role in bladder cancer cell invasiveness. To test this the aims were firstly to create a novel three dimensional cell culture to be used as a more physiological method of studying the invasiveness of bladder cancer. Secondly a tissue micro-array and associated database of cystectomy patients was created for biomarker discovery and to investigate the role of HER2 and its family members as biomarkers in patients with bladder cancer treated with cystectomy. The novel three dimensional organotypic model was successfully optimized and its ability to reproduce invasive characteristics confirmed with primary invasive cancer cells harvested from a cystectomy patient. Lenti-viral knockdown of HER2 failed to affect the invasive nature of the T24 cell line. The TMA consisted of 226 cystectomy patients treated over a 10-year period with a median follow up of 49 months. The 5-year overall survival was 48.8% with a cancer specific survival of 62.1% and 27.4% of patients received neo-adjuvant chemotherapy. 17% of patients overexpressed HER2 and HER2 was an independent risk factor for worse overall survival with a hazard ratio of 1.66. Other biomarkers screened for included Nrf-2, which this TMA suggests predicts response to cisplatin based chemotherapy, AIMP3 which may predict resistance to radiation when down regulated and b-HCG, which demonstrated a potential role as a marker of recurrence when measured in blood serum. In conclusion, HER2 appears to be prognostic of poor outcome in this cohort but is not critical for bladder cancer invasion in the organotypic model. The process of testing this has created two valuable models for biomarker discovery that will be used in future research.