PIK3CA gene alterations in bladder cancer: Analysis of correlative series of transurethral resection (TUR)—Correlation with grade histology and tumor size.

4584 Background: PI3K pathway involvement in bladder cancer is well documented and activating mutations of the gene have been identified, particularly in tumors of low grade and stage. We have analyzed hot spot mutations and copy number in PIK3CA gene as well as mRNA expression levels in tumor tissue of pts with urothelial cell carcinoma (UCC). Methods: 90 pts were analyzed. In 85 pts, fresh tissue from tumor and adjacent normal tissue was collected. All pts signed an informed consent and basic demoghrapics data were collected. Histology confirmation of UCC was required. PIK3CA alterations were analyzed by quantative-PCR. Results: Patient«s characteristics were: median age 73 years, Ta 45.5%, T1 41.1%, T2 12.2%; high-grade histology 43.4%, low-grade 51,1%, PULMP 4,4%. With a median follow-up of 10.0 months, 21% tumor recurrences were observed. 13% normal tissue and 51,8% tumor samples harbored alterations in PIK3CA gene, including alterations affecting the helical domain (mutations 65%, amplifications 60%...