Molecular Characterization Of Clinically Defined Aggressive Variant Prostate Cancer (Avpca) In Prospectively Collected Tissues And Corresponding Patient Derived Xenografts (Pdx).

5055 Background: AVPCa shares clinical features with small cell carcinoma (SCC) such as resistance to androgen signaling inhibition and frequent visceral metastases. A prospective clinical trial of platinum doublets (NCT00514540; Aparicio, Clin Can Res 2013;19) gave confidence that clinically defined AVPCa also shares chemotherapy sensitivity with SCC, irrespective of morphology. Here we screen for links between the clinical phenotype and molecular profile of AVPCa and corresponding PDX. Methods: 59 PC samples from 40 men (10 with SCC) registered to NCT00514540, and 8 PDX from 6 of them, were stained for RB, p53, AR, NKX3-1, ASCL1, AURKA, UBE2C and Ki67. We examined relationships between markers. We subjected DNA from 36 of the PC samples and all PDX to OncoScan to determine copy number alterations (CNA). We compared findings to reported TCGA data. We examined associated and downstream molecular events in the PDX. Results: The 40 men with tissues available for study were similar to remaining NCT00514540 p...