Abstract 1999: Diagnostic utility of the NETest in neuroendocrine transformed prostate cancer
Authors: Rahbar Kambiz , Kidd Mark , Drozdov Ignat , Kitz Alexandra , Malczewska Anna , Bodei Lisa , Rajwa Pawel , Bernemann Christof , Modlin Irvin 
Published: September 2020

Background: Neuroendocrine differentiation and the development of an aggressive phenotype are key features of castration-resistant prostate cancer (CRPC) disease. Current blood-based biomarkers cannot detect these treatment-refractory cancer variants.

Aims: Evaluate the utility of the NETest, a blood-based 51-marker gene neuroendocrine detection tool, as a CRPC diagnostic and examine which functional gene clusters (hallmarks) differentiate CRPC from PCa.

Methods: NETest gene identification in CRPC: Publicly available CRPC RNAseq dataset (cBIO Portal: dbGap phs000909.v.p1, tissue samples: n=47, including 15 neuroendocrine CRPC). Blood gene expression: Prostate cancers (PCa): (n=50) CRPC, (n=40) hormone-sensitive PCa (n=75), and benign prostatic hyperplasia (BPH) (n=41). NETest assay: PCR (51 genes): Expression normalized and categorized into functional classifiers. 51 markers algorithmically assessed and scored: 0-100. Cut-off 40 for progressive disease. PSA: ECLIA diagnostic assay: cut-off 4ng/L, &gt;10ng/ml=critical value. Statistics: ANOVA, AUROC analyses and sensitivity/specificity metrics. Data is mean±SEM.

Results: RNA tissue seq: Captured all 51 NETest genes (100%). Thirty-three (65%) genes were detected as upregulated in CRPC tumors (1.09-1425 fold elevated over normal tissue). Blood-PCR: In CRPC, detected in 49/51 (96%) NETest genes. Gene expression was significantly upregulated (p&lt;0.01) in CRPC vs. PCa for somatostatin receptors (2-fold), inflammasome and fibrosome (1.9-fold), proliferome (1.6-fold) and RAF-RAS signaling (1.4-fold). NETest scores were elevated in CRPC (80±2.4) (ANOVA, p&lt;0.0001) vs. PCa (36±2) and BPH (36±3). The AUC differentiating CRPC from PCa was 0.92 (p&lt;0.0001). The cut-off of 40 imparted diagnostic sensitivities and specificities of 94% and 87%, respectively. PSA: PSA was elevated in CRPC (27±59ng/ml). This was not different to PCa (8.1±8ng/ml, p=0.43) but was increased vs. BPH (6.8±1.2ng/ml, p&lt;0.005). The AUC for CRPC vs. PCA was 0.60 (p=0.10). PSA&gt;10ng/ml occurred in 63% of CRPC, 55% of PCA (p=NS) and 24% of BPH (p&lt;0.05). The AUC for NETest (0.92) was significantly better (p&lt;0.0001) than PSA (0.6).

Conclusion: The NETest detects neuroendocrine neoplasia genes in the blood and accurately identifies genomic hallmarks of castration-resistant prostate cancer. It performs significantly better than PSA. This multi-gene NETest liquid biopsy is likely to have clinical utility in the diagnosis of CRPC and provide a basis to stratify patients for CRPC-based therapies.

Citation Format: Kambiz Rahbar, Mark Kidd, Ignat Drozdov, Alexandra Kitz, Anna Malczewska, Lisa Bodei, Pawel Rajwa, Christof Bernemann, Irvin Modlin. Diagnostic utility of the NETest in neuroendocrine transformed prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1999.