Bladder cancer is the fourth most common cancer type in males and approximately 72,500 individuals were diagnosed in the United States in 2012. Patients with superficial (low-grade papillary) tumors generally have a good prognosis with a 5-year survival rate exceeding 90%, but those with muscle-invasive or locally advanced disease at surgical resection have a significant risk of recurrence with 5-year survival rates of 30-60%. The systemic chemotherapy options for bladder cancer are very limited, and no new drugs have been approved in the United States for metastatic bladder cancer in over 20 years. Although a number of newer, molecularly targeting drugs have been developed and approved for multiple cancer types in the last two decades, no such drug has been developed for the treatment of bladder cancer. This is likely due, in part, to the relatively limited molecular understanding of invasive bladder cancers and lack of knowledge about potential genetic drivers of invasive forms of the disease. Hence, it is of priority to discover novel genetic pathways involved in the carcinogenesis of muscle-invasive bladder cancer for the assessment of risk stratification and for the development of novel drugs. We analyzed exomes of 43 muscle-invasive bladder carcinomas and identified two novel significantly mutated genes, NOS3 (18.6%) and UNC5C (16.3%), in addition to previously reported frequently mutated genes like TP53 (37.2%) and KDM6A (18.6%). Both NOS3 and UNC5C are known to be involved in the apoptotic pathways, with NOS3 encoding for endothelial nitric oxide synthase (eNOS), and UNC5C for netrin receptor, a member of the dependence receptor family. When we correlated the mutational profiles with clinicopathological outcomes by stratifying patients according to disease recurrence status and observing for specific clustering of genetic mutations, we found that somatic mutations in six DNA repair genes (ATM, ERCC2, FANCD2, RAD51AP1, PALB2, BRCA2) were significantly associated with enhanced recurrence-free survival (hazard ratio of 0.091 with 95% CI of 0.018 to 0.45; P=0.0034) even after adjustment for pathologic TN staging, suggestive of their mutations as favorable prognostic events in bladder cancer.
Citation Format: Kai Lee Yap, Kazuma Kiyotani, Kenji Tamura, Miran Jang, Magdeline Montoya, Cory Ganshert, Tomoaki Fujioka, Gary Steinberg, Peter O'Donnell, Yusuke Nakamura. Recurrent somatic mutations of nitric oxide synthase NOS3, netrin receptor UNC5C and DNA repair genes in muscle-invasive bladder carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3430. doi:10.1158/1538-7445.AM2014-3430