Ductal (PDC), acinar (PAC) and neuroendocrine (PNC) carcinomas of the prostate: A comparative comprehensive genomic profiling (CGP) study.

Abstract

5064 Background: PDC, PAC and PNC are histologic subtypes of prostate cancer (PC). We queried whether these subsets would share similar genomic alterations (GA) reflecting their disease biology and clinical features. Methods: CGP was performed using a hybrid capture-based assay on 61 PDC, 4,132 PAC and 217 PNC. Tumor mutational burden (TMB) was determined on 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. Results: The age, GA per tumor and TP53 GA of PDC, PAC and PNC were similar (Table). RB1 GA were predominant in PNC. TMPRSS2:ERG fusions were most frequent in PNC, intermediate in PAC and lowest in PDC. AR GA were more often identified in PAC than PDC or PNC whereas PTEN GA were most frequent in PDC than PAC or PNC. Targetable GA were identified in all 3 groups when focused on BRCA2 (PARP inhibitors) and PIK3CA (MTOR inhibitors). ATM GA (PARP inhibitors) were more common in PAC than PDC or PNC. BRAF GA (BRAF/MEK inhibitors) were more frequent in PDC and PAC than PNC. CDK12 GA potentially associated with immunotherapy (IO) benefit were similar in PDC and PAC and low in PNC. Low frequencies of MSI-High and low median TMB levels were similar in all 3 groups. Conclusions: The pathologic features of PDC, PAC and PNC have been classically maintained as representative of 3 different tumor types with potentially contrasting histogenesis. In the current CGP based study, all 3 tumor types did not display significant differences in genomic signatures other than the high RB1 GA. CGP may reveal biomarkers that could direct patients to targeted (PARP, MTOR and BRAF/MEK inhibitors) or immunotherapies ( CDK12 GA, MSI-High or high TMB status) especially in PDC and PAC. [Table: see text]