Huang, Xiaoyi

260 Background: The purpose of this study was to evaluate cell free nucleic acid based biomarkers for prognosis in mCRPC stage. Methods: Uniformly collected blood from mCRPC patients was processed for plasma which was used for exosomal RNA extraction. RNA sequencing was applied to examine microRNA (miRNA) profiles initially in a discovery cohort of 23 mCRPC patients. The sequences from fastq files were mapped to human miRBase (release 19) for known miRNA read counts. A software package (miRDeep2) was used for novel miRNA prediction. Cox regression was used for association of candidate miRNAs with overall survival (OS), defined as time from development of mCRPC to death or last follow up after adjusting for Gleason Score (GS) and time on androgen deprivation (AD) for hormone sensitive disease. miRNAs significantly associated with OS (FDR<0.05) were then validated in an independent cohort of 100 mCRPC subjects using univariate Cox regression. Results: RNA sequencing generated >10 million mappable reads per specimen in the discovery cohort. Among these reads ~50% were known miRNAs which included 1237 unique RNA sequences. Due to low abundance of most RNA transcripts, only miRNAs (n=250) with >/= 32 reads (on average) were analyzed. Four mRNAs (miR-1290, -1246, -375 and a predicted miRNA on chr. 12) were associated with OS(FDR<0.05). These were evaluated as prognotic markers in the independent cohort (N=100) using real time RT-PCR. Median time on AD for this cohort prior to progression to mCRPC was 35.7 (range: 3.5-136) months; median GS was 7; median follow up after mCRPC development was 12.5 (1-41) months at which time 28 patients had died. Elevated expression for miR-1290 and -375 were associated with shorter OS after adjusting for GS and AD time with a Hazard Ratio (HR) for miR-375 of 1.19 (CI: 1.006-1.18); (p=0.04) and a HR for miR1290 of 1.58 (CI:1.01-2.4); (p=0.04). A stronger association with shorter OS was observed for elevated expression of both miRs-HR of 2.02 (CI: 1.1-3.6) (p=0.01). Conclusions: Blood-based nucleic acid assays are easily accessible for biomarker development in mCRPC. Results from this study suggest specific exosomal miRs are of prognostic value in mCRPC and should be validated in larger cohorts.

Abstract PURPOSE: Cell free circulating microvesicles (in particular, exosomes) contain proteins and nuclei acids that may serve as biomarkers for disease diagnosis and prognosis. The goal of this study was to identify exosomal microRNAs that may predict clinical outcome of patients with castrate resistant prostate cancer (CRPC). EXPERIMENTAL DESIGN: In discovery stage, we performed RNA sequencing using plasma exosomal RNAs derived from 36 patients with CRPC. We mapped the sequence reads to known miRbase (Release 19, 2043 entries) and normalized the miRNA abundance by sequence counts per million mappable reads. We applied Cox regression analysis to identify the miRNAs that were associated with overall survival of CRPC. In validation stage, we first examined an exosomal small RNA sequencing dataset consisting of 192 individuals with various health conditions. We used Normfinder and Bestkeeper to select most stably expressed miRNAs as candidates for normalization references. We then applied real-time qRT-PCR assays to test selected candidate reference miRNAs and survival-related miRNAs in additional 100 CRPC patients. From validated miRNAs, we constructed multivariate models to predict overall survival for this group of patients. RESULTS RNA sequencing generated over 6 million mappable reads per patient in the initial discovery cohort. Among these reads, ∼45% were mapped to known miRNAs for a total of 483 known and 275 novel miRNAs with normalized read counts ≥ 5. The median follow-up time for the 36 CRPC patients was 35.6 months during which 10 patients had died. Cox regression analysis identified four microRNAs (miR-1290, -1246, -375 and a predicted miRNA at chromosome 12) that were associated with overall survival (FDR&lt;0.05). Of six selected candidate miRNAs, miR-30a/e-5p performed the best in their stability as endogenous references for real-time qRT-PCR. When normalized by these internal controls, we confirmed two of the three known miRs (miR-1290 and -375) showing significant association with overall survival in the validation cohort (p&lt;0.001) with a median follow up time of 12.5 (range: 1-41) months at which time 28 patients had died. The median overall survival for patients with high (N=21) and low (N=40) expression in both miR-1290 and -375 was 7.2 (1-26.7) months and 15.3 (1-41) months, respectively (p&lt;0.05). The miR-1290/-375-based prediction model consistently showed better predictive performance with AUC=72% than clinical variable-based model with AUC=64%. CONCLUSIONS: Plasma exosomal miRNAs provide an easily accessible resource for biomarker development in prognosis of advanced prostate cancer. Exosomal miR-1290 and miR-375 are associated with overall survival in CRPC patients. miR-30a/e-5p, especially the geometric mean of miR-30a/e-5p, are qualified endogenous references for real-time qPCR. Further confirmation of these findings is needed for prognostic and predictive biomarker in development of CRPC stage. Citation Format: Xiaoyi Huang, Tiezheng Yuan, Meihua Liang, Meijun Du, Shu Xia, Rachel Louise Dittmar, Zhifu Sun, Yan Lu, Stephen N. Thibodeau, Lisa Boardman, Manish Kohli, Liang Wang. Exosomal miR-1290 and miR-375 as prognostic markers in metastatic castrate resistant prostate cancer. [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 574. doi:10.1158/1538-7445.AM2014-574