A genomic blood test (NETest) identifies neuroendocrine transformation of prostate cancer.

Abstract

e17511 Background: Neuroendocrine-like differentiation (NELD) and an aggressive phenotype are key features of castration-resistant prostate cancer (CRPC). Current blood-based biomarkers cannot detect these treatment-refractory variants. Our aim was to evaluate the NETest, a blood-based 51-marker gene neuroendocrine detection tool, as a CRPC-diagnostic versus prostate cancer (PCA). Methods: In silico evaluation: NETest gene identification in the TCGA-PRAD ( n= 500 PCA) and CRPC RNAseq datasets (cBIOPortal: dbGap-phs000909.v.p1, tissue samples: n= 47, including 15 CRPC). Blood gene expression: PCA: n= 50, CRPC: n= 40, hormone-sensitive PCA: n= 75 and benign prostatic hyperplasia (BPH: n= 41). NETest assay: Normalized gene expression, algorithmically assessed and scored: 0-100. Cut-off 20. PSA: ECLIA diagnostic assay: cut-off 4ng/L, > 10ng/ml = actionable value. Statistics: ANOVA, AUROC analyses and sensitivity/specificity metrics. Data is mean±SEM. Results: RNAseq: Two (4%) of the 51 NETest genes were identified in TCGA-PCA. In contrast, all 51 NETest genes (100%) were identified in CRPC tumors. Thirty-three (65%) were detected as upregulated (1.09-1425-fold vs. normal tissue). Blood-PCR: 49/51 (96%) NETest genes detected in CRPC blood. NELD-gene expression was significantly upregulated ( > 2-fold, p< 0.01) in CRPC vs. PCA ( TPH1, PNMA2, SSTR etc). NETest scores were elevated in CRPC (79±2.8) (ANOVA, p< 0.0001) vs. PCA (22±2) and BPH (23±3). The AUC differentiating CRPC from PCA was 0.93 ( p< 0.0001). NETest was elevated in 94% of CRPC vs. 13% PCA and 15% BPH (both p< 0.001). The diagnostic sensitivities and specificities were 94% and 87%, respectively. PSA: PSA was elevated in CRPC (220±372ng/ml). This was different to PCA (14±20ng/ml, p< 0.0001) and BPH (10.3±5.7ng/ml, p< 0.003). The AUC for CRPC vs. PCA/BPH was 0.70 ( p= 0.10). PSA > 10ng/ml occurred in 70% of CRPC, 60% of PCA ( p= NS) and 39% of BPH ( p< 0.05). The AUC for NETest (0.93) was significantly better than PSA (z-statistic: 4.63, p< 0.0001). Conclusions: The NETest is a liquid biopsy that detects neuroendocrine neoplasia genes in the blood and accurately identifies NELD in castration-resistant prostate cancer. We anticipate that the NETest could be used to provide real-time information relevant to the evolving neuroendocrine status of a PCA during therapy.