A novel PCR-based blood assay for the detection and monitoring of prostate cancer

The PROSTest, a proprietary, patented liquid biopsy assay for the detection of prostate cancer (PCa), is one of a series of tests developed by Wren for precision oncology. It uses machine learning algorithms to convert cancer-related gene expression in blood into a single readout to differentiate patients with PCa from those with non-cancerous symptomatic patients. The algorithm output is a score ranging from 0-100, with a cut-off of 50, where patients with scores ≥50 were shown to have PCa. The assay was analytically validated under CLIA and clinically qualified in a multiple clinical studies. The assay is highly reproducible with intra- and inter-assay variability of <2% and can detect as little as 1 cancer cell/ml of blood. In head-to-head comparisons, the PROSTest was significantly more accurate than PSA for detecting a PCa (PROSTest: 93% vs. 74% for PSA, p<0.0001, n=288). In individuals with no cancer (n=153), positive PSAs (>4ng/mL) occur in ~25%; all were PROSTest-negative. PROSTest is also highly accurate for detecting minimal residual disease (also known as biochemical recurrence). The PROSTest is significantly more accurate (p<0.002, n=167) than 68Ga-PET-PSMA imaging for detecting MRD especially in patients with low PSA (<0.5ng/ml) where PROSTest was positive in 93% positive vs 62% by PET-imaging (p=0.0002, n=45).