Development and Application of Liquid Biopsies in Metastatic Prostate Cancer

PURPOSE Cell-free DNA (cfDNA) and circulating tumor cell (CTC)–based liquid biopsies have emerged as potential tools to predict responses to androgen receptor (AR)–directed therapy in metastatic prostate cancer. However, because of complex mechanisms and incomplete understanding of genomic events involved in metastatic prostate cancer resistance, current assays (eg, CTC AR-V7) demonstrate low sensitivity and remain underutilized. The recent discovery of AR enhancer amplification in > 80% of patients with metastatic disease and its association with disease resistance presents an opportunity to improve on current assays. We hypothesized that tracking AR/enhancer genomic alterations in plasma cfDNA would detect resistance with high sensitivity and specificity. PATIENTS AND METHODS We developed a targeted sequencing and analysis method as part of a new assay called Enhancer and Neighboring Loci of Androgen Receptor Sequencing (EnhanceAR-Seq). We applied EnhanceAR-Seq to plasma collected from 40 patients with metastatic prostate cancer treated with AR-directed therapy to monitor AR/enhancer genomic alterations and correlated these events with therapy resistance, progression-free survival (PFS), and overall survival (OS). RESULTS EnhanceAR-Seq identified genomic alterations in the AR/enhancer locus in 45% of cases, including a 40% rate of AR enhancer amplification. Patients with AR/enhancer alterations had significantly worse PFS and OS than those without (6-month PFS, 30% v 71%; P = .0002; 6-month OS, 59% v 100%; P = .0015). AR/enhancer alterations in plasma cfDNA detected 18 of 23 resistant cases (78%) and outperformed the CTC AR-V7 assay, which was also run on a subset of patients. CONCLUSION cfDNA-based AR locus alterations, including of the enhancer, are strongly associated with resistance to AR-directed therapy and significantly worse survival. cfDNA analysis using EnhanceAR-Seq may enable more precise risk stratification and personalized therapeutic approaches for metastatic prostate cancer.

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Fundamentals of liquid biopsies in metastatic prostate cancer: from characterization to stratification

Current Opinion in Oncology ◽

10.1097/cco.0000000000000655 ◽

2020 ◽

Vol 32 (5) ◽

pp. 527-534

Author(s):

Lisanne F. van Dessel ◽

John W.M. Martens ◽

Martijn P. Lolkema

Keyword(s):

Prostate Cancer ◽

Metastatic Prostate Cancer ◽

Liquid Biopsies

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Validation of Cell-Free RNA and Circulating Tumor Cells for Molecular Marker Analysis in Metastatic Prostate Cancer

Biomedicines ◽

10.3390/biomedicines9081004 ◽

2021 ◽

Vol 9 (8) ◽

pp. 1004

Author(s):

Michael Ladurner ◽

Manuel Wieser ◽

Andrea Eigentler ◽

Martin Seewald ◽

Gabriele Dobler ◽

...

Keyword(s):

Gene Expression ◽

Prostate Cancer ◽

Tumor Cells ◽

Circulating Tumor Cells ◽

Expression Analysis ◽

Metastatic Prostate Cancer ◽

Single Cells ◽

Liquid Biopsies ◽

Poor Overall Survival ◽

Monitoring Therapy

Since tissue material is often lacking in metastatic prostate cancer (mPCa), there is increasing interest in using liquid biopsies for treatment decision and monitoring therapy responses. The purpose of this study was to validate the usefulness of circulating tumor cells (CTCs) and plasma-derived cell-free (cf) RNA as starting material for gene expression analysis through qPCR. CTCs were identified upon prostate-specific membrane antigen and/or cytokeratin positivity after enrichment with ScreenCell (Westford, Massachusetts, USA) filters or the microfluidic ParsortixTM (Guildford, Surrey, United Kingdom) system. Overall, 50% (28/56) of the patients had ≥5 CTCs/7.5 mL of blood. However, CTC count did not correlate with Gleason score, serum PSA, or gene expression. Notably, we observed high expression of CD45 in CTC samples after enrichment, which could be successfully eliminated through picking of single cells. Gene expression in picked CTCs was, however, rather low. In cfRNA from plasma, on the other hand, gene expression levels were higher compared to those found in CTCs. Moreover, we found that PSA was significantly increased in plasma-derived cfRNA of mPCa patients compared to healthy controls. High PSA expression was also associated with poor overall survival, indicating that using cfRNA from plasma could be used as a valuable tool for molecular expression analysis.

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