








































This is an open access article under the terms of a license that permits non-commercial use, provided the original work is properly cited.  
© 2023 The Authors. Société Internationale d'Urologie Journal, published by the Société Internationale d'Urologie, Canada.

SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023

Key Words Competing Interests Article Information

Liquid biopsy, circulating tumor DNA,  
prostate cancer, personalized medicine,  
next-generation sequencing

None declared. Received on December 3, 2022 
Accepted on June 10, 2023 
This article has been peer reviewed.

Soc Int Urol J. 2023;4(4):273–286

DOI: 10.48083/RFSH8912

273

REVIEW — LIQUID BIOPSY

Utility and Clinical Application of Circulating Tumor 
DNA (ctDNA) in Advanced Prostate Cancer

Louise Kostos,1,2 Heidi Fettke,2,3 Edmond M. Kwan,4,5 Arun A. Azad1,2

1Department of Medical Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia 2Sir Peter MacCallum Department of Oncology, University of Melbourne, 
Melbourne, Australia 3Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Australia 4Vancouver Prostate Centre, Department of Urologic Sciences, 
The University of British Columbia, Vancouver, Canada 5BC Cancer, Vancouver Centre, Vancouver, Canada

Abstract

The treatment landscape for metastatic prostate cancer has undergone significant changes in recent years. The 
availability of next-generation imaging techniques and the emergence of novel therapies have led to earlier and more 
aggressive treatment approaches for patients. However, despite these advancements, drug resistance and progression 
to castration-resistant disease remain inevitable. Understanding the molecular landscape of advanced prostate cancer 
lies at the forefront of being able to deliver personalized therapies and more robustly risk-stratify patients, when 
combined with clinical factors. Advanced prostate cancer is characterized by inter- and intratumoral heterogeneity, 
posing challenges in comprehensively analyzing the genomic tumor profile using a solitary tissue sample. Additionally, 
the disease often manifests as bone-predominant metastatic tumors, making biopsies impractical in many cases. 
Moreover, archival tissue samples from a prostatectomy specimen may not accurately represent the current state of 
the tumor. To overcome these limitations, liquid biopsies using plasma samples have emerged as a minimally invasive 
surrogate approach to obtain real-time information on the genomic tumor profile. Growing evidence confirms the 
excellent concordance of liquid biopsies with tissue samples, making them an attractive alternative to traditional 
tissue biopsies. These assays can provide predictive and prognostic information that may enhance patient discussions 
and influence treatment decisions. This review focuses on the evolution and utility of circulating tumor-derived DNA 
(ctDNA) liquid biopsy assays in metastatic prostate cancer.

Background

Despite recent treatment advances, metastatic prostate cancer (mPC) continues to be a leading global cause of cancer-
related death in men worldwide, with a 5-year survival rate below 30%[1–3]. The treatment landscape for advanced 
disease has become increasingly complex over the past decade, with the availability of multiple systemic therapies 
such as taxanes, androgen receptor pathway inhibitors (ARPIs), poly (ADP-ribose) polymerase inhibitors (PARPi), 
and targeted radioligand therapy. Each of these therapies is administered alongside androgen deprivation therapy 
(ADT). There is an emphasis on early treatment intensification with the introduction of these therapies as doublet and 
even triplet regimens for metastatic hormone-sensitive prostate cancer (mHSPC)[4,5]. While some clinical subgroups 
achieve a clear survival benefit from these approaches, not all patients benefit from treatment intensification. 
Lingering questions remain regarding the optimal timing of treatment intensification or de-intensification, the ideal 
duration of treatment, and the optimal sequencing of available therapies. Therefore, there is an urgent need for novel 
predictive and prognostic biomarkers to assist with risk stratification and inform treatment decisions.

To address this critical unmet need, it is crucial to prioritize the elucidation of the molecular landscape of advanced 
prostate cancer and apply it at an individual patient level. In this context, there is the continuous development of 

http://SIUJ.org


tools for comprehensive molecular tumor profiling to 
guide treatment selection and sequencing. Currently, 
the gold standard approach for molecular biomarker 
assessment is analysis of tumor tissue[6]. However, 
collecting adequate tumor tissue in mPC, which often 
develops with bone lesions and deep abdominal lymph 
nodes, is not always feasible, with invasive biopsies 
often associated with significant procedural morbidities 
and low-quality samples that preclude serial, multisite 
biopsies[7–9]. Moreover, characterizing molecular 
changes during therapy and upon disease progression 
is challenging, potentially leading to the oversight of 
resistance-conferring or novel clinically actionable 
clones[10]. This is especially important considering that 
the lethal clone involved in metastatic dissemination 
may not originate from the dominant foci of the primary 
prostate tumor[11]. 

Liquid biopsy approaches to molecular tumor charac-
terization have gained attention as attractive surrogates 
for tumor biopsy in advanced prostate cancer over the 
past decade. Liquid biopsies commonly detect biomark-
ers such as circulating tumor cells (CTCs), cell-free DNA 
(cf DNA) or RNA (cf RNA), proteins, and extracellular 
vesicles[12]. Among these, plasma cfDNA has garnered 
the most interest because of its ease of sampling and 

established isolation and preparation protocols. The 
proportion of tumor-derived cf DNA is referred to as 
circulating tumor DNA (ctDNA), and although it is 
found in all fluid compartments of the body, it is best 
characterized from plasma. Furthermore, its short half-
life (minutes to hours) and the ability to simultaneously 
profile both local and distant sites make it an ideal 
substrate for providing a comprehensive “snapshot” of 
the tumor[13–15]. 

The Current Landscape of ctDNA in 
Prostate Cancer
Since the initial discovery of the connection between 
cancer and cfDNA in 1994, the field of ctDNA analysis 
in oncology has rapidly expanded, with FDA-approved 
commercia l assays a nd compa nion diagnost ics 
becoming standard-of-practice for genomic profiling 
in many cancer types[13,16,17]. In 2015, Azad et al. 
published the earliest clinical research involving 
genomic analysis of plasma ctDNA in advanced prostate 
cancer. The authors successfully identified somatic 
androgen receptor (AR) point mutations and focal 
copy number gains using targeted next-generation 
sequencing (NGS) and array comparative genomic 
hybridization, respectively[18]. Furthermore, they 
reported an association between plasma-detectable 
AR alterations and primary resistance to the ARPI 
enzalutamide, providing evidence that ctDNA can be 
exploited to identify and understand contemporary 
biomarkers. Subsequent studies have shown that in 
mPC, ctDNA is a high-fidelity substitute for solid 
tumor tissue-derived DNA and is capable of not only 
recapitulating the somatic landscape of a tumor but also 
identifying clinically relevant driver alterations missed 
by a single metastatic biopsy[10,19–21]. Additionally, 
through serial sampling before and during treatment, 
ctDNA has the potential to monitor tumor progression, 
provide prognostic information, and thus dictate 
tailored treatment plans[22,23]. The investigation of 
ctDNA biomarkers to prognosticate mPC and predict 
response to targeted therapies has become widespread, 
with liquid biopsy collection often incorporated into 
clinical trial design[24–27]. 

Technical Considerations for ctDNA 
Analysis
As ctDNA gains significance in guiding precision-based 
care for men with mPC, a myriad of approaches and 
technological platforms is being employed (Table  1). 
Understanding which approach will provide the most 
robust data for a particular research question is crucial 
to translating ctDNA assays into the clinic. Advanced 
prostate cancer can be detected in 60% to 90% of patient 
plasma samples, with the ctDNA fraction varying 

widely among patients[10,21,28]. Consequently, high 
assay sensitivity is essential to avoid excluding patients 
from data analysis and minimize false-negative results 
t hat may compromise biomarker identif ication. 
Currently, ctDNA analysis techniques can be broadly 
categorized as candidate gene approaches (for < 10 loci) 
and high-throughput approaches[13]. Low-throughput 
candidate gene approaches such as digital droplet 
polymerase chain reaction (PCR) assays, have the 
highest sensitivity, enabling the detection of somatic 
mutations below 0.002% allelic frequency[29,30]. These 
approaches are valuable for monitoring treatment 
resistance and minimal residual disease when the 
targets are already known. High-throughput techniques 
such as NGS provide an unbiased approach to genomic 
analysis and are the preferred method for identifying 
mechanisms of treatment resistance and novel genomic 
biomarkers[31]. However, they are typically less sensitive 
and more expensive than candidate gene approaches. 
Recent advances in NGS technology, however, such as 
the inclusion of molecular barcoding, patient-specific 
custom panels, and significant cost reductions for short-
read sequencing have enabled the detection of somatic 
alterations below 0.5% allelic frequency[32]. These 
improvements also allow for the detection of focal copy 
number abnormalities, which are crucial for examining 
the landscape of mPC. Previously, the prostate cancer 
genome was thought to be associated with few focal 
chromosomal gains or losses, but it is now clear that 
focal copy number alterations, such as focal deletions in 
PTEN or focal AR amplifications, play an integral role in 
tumor evolution and disease progression[33].

In addition to these pre-analytical assay decisions, 
the selection and design of the bioinformatics workflow 
used to profile ctDNA are crucial. mPC is typically char-
acterized by high levels of copy number abnormalities, 
structural rearrangements, and genomic heterogene-
ity among lesions[34,35]. Therefore, a comprehensive 
approach capable of detecting point mutations, struc-
tural variants, copy number variants, and low-frequency 
subclonal somatic mutations is necessary for robust 
profiling of the prostate cancer genome. 

Application of ctDNA in Metastatic 
Castration-Resistant Prostate Cancer
Most genomic studies have been conducted in patients 
with metastatic castration-resistant prostate cancer 
(mCRPC), initially using tissue samples and more 
recently incorporating plasma cf DNA analysis. Liquid 
biopsies exhibit excellent concordance with tissue 
samples and represent an attractive alternative to 
molecular profiling of the tumor[10,15]. As a peripheral 
blood sample contains ctDNA from multiple sites, 
this liquid biopsy approach has the added benefit 

Abbreviations 
ADT androgen deprivation therapy
AR androgen receptor
ARPI androgen receptor pathway inhibitor
cfDNA cell-free DNA
CNVs copy number variants 
ctDNA circulating tumor DNA
DDR DNA damage response and repair
HRR homologous recombination repair
ICI immune checkpoint inhibitor
IHC Immunohistochemistry
mCRPC metastatic castration-resistant prostate cancer 
mHSPC metastatic hormone-sensitive prostate cancer 
mPC metastatic prostate cancer 
MSI microsatellite instability
NGS next-generation sequencing
OS overall survival
PARPi poly (ADP-ribose) polymerase inhibitors 
PCR polymerase chain reaction
PFS progression-free survival
PSA prostate-specific antigen
SNVs single nucleotide variants
SVs structural variants 
TMB tumor mutational burden

of capturing inter- and intratumoral heterogeneity, 
thereby offering valuable insights to inform treatment 
decisions that would otherwise be missed in a single-site 
metastatic biopsy. The potential clinical applications of 
ctDNA in mCRPC are outlined below (Figure 1).

Pretreatment ctDNA fraction and profile for 
prognostication
The prognostic value of pretreatment ctDNA levels has 
been firmly established in mCRPC, showing that higher 
ctDNA fraction is associated with shorter progression-
free survival (PFS) and overall survival (OS) regardless 
of treatment received[10,18,47]. In a study evaluating 
202 patients with mCRPC receiving first-line treatment 
with the ARPIs enzalutamide or abiraterone acetate, a 
high ctDNA fraction (> 30%) was associated not only 
with increased tumor burden (as indicated by elevated 
plasma levels of prostate-specific antigen [PSA], lactate 
dehydrogenase [LDH], and alkaline phosphatase 
[ALP]) but also with poor response to treatment even 
after adjusting for established clinical prognostic 
factors[48]. Similarly, a high baseline ctDNA fraction 
prior to taxane chemotherapy was associated with 
shorter radiographic PFS and OS, independent of other 
prognostic variables[49]. Furthermore, specific genomic 
abnormalities detected in ctDNA have prognostic 
i mpl icat ions for t reat ment outcomes. Pat ients 
treated with abiraterone acetate or enzalutamide 
who had baseline aberrations in tumor suppressor 
genes (TP53, RB1, or PTEN) exhibited worse survival 
outcomes compared to those who tested negative at 
baseline or showed undetectable levels by cycle 2 of 
treatment[47,48,50,51]. Therefore, a high pretreatment 
ctDNA fraction and the presence of tumor suppressor 
aberrations can facilitate informed discussions with 
patients about their treatment options and expected 
outcomes and potentially support a more aggressive 
approach to systemic therapy.

Longitudinal monitoring of treatment response
Trad it iona l ly, seria l ser u m PSA measu rements 
have been used to monitor response to treatment in 
mCRPC. However, PSA has limitations, as radiographic 
progression can occur in the absence of a PSA rise, 
and heavily pretreated patients with AR-independent 
disease may have no or low levels of PSA, making 
interpretation of potential response challenging[52,53]. 
Serial ctDNA assays offer an alternative method for 
treatment monitoring. An early reduction in cf DNA 
concentration or fraction (within the first 9 weeks) has 
been associated with longer PFS and OS in patients with 
mCRPC patients treated with taxanes, ARPIs, and PARP 
inhibitors[54–57]. This finding was maintained even 
after adjusting for known clinical risk factors. Similarly, 
a lack of response or persistent rise in ctDNA fraction 
has been associated with shorter PFS[57]. 

275274 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

http://SIUJ.org
http://SIUJ.org


sample. Germline alterations can usually be detected 
through simultaneous analysis of leucocyte samples 
extracted from the buffy coat of peripheral blood after 
centrifugation. Determination of HRR status not only 
informs whether the patient can benefit from a PARP 
inhibitor but also predicts a favorable response to plat-
inum chemotherapy[71]. It is important to note that 
clonal hematopoiesis of indeterminate potential involv-
ing DNA repair genes may lead to false-positive results, 
and therefore ctDNA samples should be accompanied by 
a whole blood control to exclude such variants[72]. 

Prostate cancers with PTEN loss are more sensi-
tive to AKT inhibition, as demonstrated by the 
radiographic PFS benefit when combining the AKT 
inhibitor ipatasertib with abiraterone acetate for 
patients with mCRPC and PTEN loss identified through 
tumor immunohistochemistry[73]. PTEN loss is also 
predictive of a poor response to abiraterone acetate while 
retaining sensitivity to docetaxel[74,75]. The prevalence 
of PTEN loss through cf DNA assay is comparable to 
that found in tissue, potentially eliminating the need for 
archival tissue or a fresh biopsy[76].

Prostate cancer is typically considered immunogen-
ically “cold” due to minimal T-cell infiltrates failing to 
generate a significant peripheral antitumor response, 
with limited benefit from immune checkpoint inhibitor 
(ICI) therapy in unselected cohorts[77–79]. However, 
a subset of prostate cancer exhibits an immuno-
genic phenotype that may benefit from such therapy. 

Early detection of treatment resistance
Analysis of genomic alterations in patients with 
mCRPC has identified both primary and acquired 
mutations associated with treatment resistance. With 
the increasing integration of ARPIs earlier on in the 
mPC disease course, resistance and the development 
of aggressive neuroendocrine prostate cancer may 
become more prevalent[52,58]. Therefore, it is crucial 
to use ctDNA biopsies to investigate markers of ARPI 
resistance. The presence and magnitude of AR gene 
amplification have been associated with shorter PFS 
and OS[48,59–61]. Some AR short variants are more 
frequently detected in liquid biopsy samples than 
in tissue biopsies, making ctDNA an ideal tool for 
early detection of treatment-resistant clones[21]. This 
discordance between plasma and tissue is likely due to 
intratumoral heterogeneity in AR gene expression[62] 
and the ability of liquid biopsies to integrate genomic 
information from multiple metastatic sites. ctDNA may 
also be used to predict resistance to PARPi by detecting 
acquired BRCA reversion mutations, which are also 
more frequently detected in liquid biopsy samples 
compared to tissue and are thought to predict a poor 
response to PARPi[21,63]. However, a recent analysis 
of patients with BRCA-mutant mCRPC enrolled in 
the TRITON2 trial suggests this may not be the case, 
as patients who developed a BRCA reversion mutation 
while receiving rucaparib experienced better treatment 
outcomes[64]. In addition to detecting specific genomic 
aberrations, dynamic changes in ctDNA levels during 

TABLE 1. General comparison of ctDNA analysis platforms used in advanced prostate cancer

Approach Detection method
Genomic elements 

tested
Limit of 

detection (VAF)
Variant types 

detected
Estimated 

turnaround time
Cost

Volume of 
plasma required

Strengths Limitations Clinical uses References

High-throughput 

WGS Entire genome 5%–10% 

SNVs, indels, 
CNVs, SVs, fusions, 

rearrangements

4–6 weeks High 10–20 mL
Provides comprehensive genomic 

information, no prior knowledge of 
loci required

High cost, time-consuming, requires 
complex bioinformatic analysis

Comprehensive genomic profiling, 
identification of rare or novel 

alterations
[36–39]

WES Exons 5%–10% 3–4 weeks Moderate 10–20 mL
Focuses on protein-coding regions 
of the genome, no prior knowledge 

of gene required

High cost, time-consuming, misses 
noncoding regions, requires 

bioinformatic analysis

Identification of novel targets 
and mechanisms of treatment 

resistance
[39–42]

Targeted NGS Panel of genes/regions 1%–5% 2–3 weeks Moderate 5–10 mL
Cost-effective and allows focused 

analysis, high sensitivity

High-cost, requires bioinformatic 
analysis, limited to selected targets, 
some methods cannot detect CNVs 

or SVs

Targeted profiling, and monitoring 
of known alterations, i.e., MRD 

detection
[39,42–44]

Candidate gene 

Digital PCR Specific mutations ≤ 0.01% 
SNVs, indels, known 

mutations

1–2 weeks Low 1–5 mL
Cost-effective, highly sensitive and 

precise detection of mutations
Limited to known mutations and loci

Detection of specific mutations 
for treatment allocation, 

monitoring treatment response
[39,45,46]

Conventional PCR Specific genes/regions < 1%–5% 1–2 weeks Low 1–5 mL
Cost-effective and allows targeted 
analysis, no bioinformatic analysis 

required

Limited to known targets, most 
methods only detect SNVs

Targeted mutation analysis [39]

CNVs: copy number variants; ctDNA: circulating tumor DNA; indel: insertion/deletion; MRD: minimal residual disease;  
NGS: next-generation sequencing; PCR: polymerase chain reaction; SNVs: single nucleotide variants; SVs: structural variants; 

VAF: variant allele frequency; WES: whole exome sequencing; WGS: whole genome sequencing.

therapy are also valuable for early detection of a lack of 
treatment response or the development of progressive 
disease. Early reductions in plasma ctDNA levels from 
baseline have been observed in patients prior to clinical 
determinants of treatment response[65], while persistent 
detectable ctDNA have been associated with worse 
outcomes[47,49,66].

Facilitating selection of personalized treatment
One of the most important advantages of ctDNA 
analysis is the ability to identify potentially actionable 
genomic aberrat ions, enabl i ng t he del iver y of 
personalized treatment plans (Table 2). Detecting AR 
gene amplifications from the outset may assist clinicians 
in providing tailored treatment plans, potentially 
favoring taxane chemotherapy due to the known 
resistance to ARPIs[67]. 

With the introduction of PARPi such as olaparib 
and rucaparib for patients with homologous recombi-
nation repair (HRR) gene mutations[68,69], guidelines 
now recommend testing all patients with mCRPC for 
somatic and germline pathogenic HRR aberrations, 
including BRCA1 and BRCA2[70]. Typically, this testing 
is conducted on tissue samples, which often suffer from 
compromised DNA quality as they are archival pretreat-
ment samples. However, ctDNA analysis provides an 
easily accessible alternative for HRR status testing, 
showing excellent concordance with tissue samples 
for HRR-related gene mutations[21,56], although this 
depends on tumor content (ie, ctDNA fraction) in the 

Biomarkers detectable in cfDNA assays can help iden-
tify these patients and provide a rationale for treatment. 
A recent analysis found that patients with mCRPC and 
a tumor mutational burden (TMB) of greater than 10 
mutations per megabase respond better to ICI therapy 
than chemotherapy[80]. Similarly, patients with mCRPC 
whose tumors harbor CDK12 mutations[81,82] and high 
microsatellite instability (MSI)[83] have shown vulner-
ability to ICI therapy. Both CDK12 mutations and MSI 
can be detected using plasma ctDNA platforms, showing 
high concordance with matched tissue samples[84,85].

Somatic mutations in genes responsible for regulat-
ing the Wnt signaling pathway are found in up to 20% of  
patients with mCRPC[43,86]. Activating mutations in 
the Wnt pathway, such as CTNNB1, are associated with 
resistance to ARPI, and CTNNB1 mutations occur more 
frequently in mCRPC cfDNA samples that have progressed 
on enzalutamide[50,87]. Consequently, the Wnt pathway 
has become an attractive target for therapeutic intervention, 
leading to extensive preclinical research into Wnt pathway 
inhibitors[88]. Despite the interest and development of 
several novel agents, Wnt-pathway–directed therapies are 
yet to be approved for clinical use.

Finally, the transition to AR-independent mPC is 
driven by lineage plasticity and can result in neuroen-
docrine differentiation. Confirming neuroendocrine 
features requires a repeat biopsy, which can be chal-
lenging due to tumor heterogeneity and the associ-
ated morbidity of metastatic biopsies. Neuroendocrine 

277276 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

http://SIUJ.org
http://SIUJ.org


of tumor suppressor gene alterations in tissue samples is 
associated with early relapse and worse outcomes[95,96].  
In plasma samples, baseline alterations in DNA damage 
response and repair (DDR) genes and loss-of-function 
alterations in TP53 are likewise associated with poorer 
PFS and OS[35]. Untreated mHSPC patients with 
somatic DDR mutations had significantly shorter OS 
and a shorter time to ADT failure[35], while the pres-
ence of germline DDR alterations predicted shorter 

time to developing castration-resistant disease[98,99]. 
Such findings can assist clinicians with risk stratifica-
tion and deciding when to intensify upfront treatment 
for patients with mHSPC. Patients with poor prognos-
tic factors present at baseline, such as a high ctDNA  
fraction and/or DDR or tumor suppressor alterations, 
may be considered for a more aggressive treatment 
regimen or enrolment in clinical trials. Conversely, the 
absence of detectable ctDNA at baseline or the absence 

prostate cancer is enriched with tumor suppressor 
gene alterations (such as TP53, PTEN, RB1), heralding 
an aggressive disease phenotype resistant to standard 
therapeutic approaches[89,90]. cf DNA methylation 
assays matched with tissue samples have shown high 
concordance for identifying neuroendocrine features, 
potentially serving as a future surrogate for tissue biop-
sies in cases where neuroendocrine transformation is 
suspected. 

ctDNA analysis is now being integrated into clinical 
trials, both as a supplementary test conducted alongside 
treatment and, more recently, as a means of determining 
treatment. There are two ongoing biomarker-directed 
clinical trials (ProBio and PC-BETS) using ctDNA anal-
ysis to guide treatment allocation in mCRPC[91–93].

Metastatic Hormone-Sensitive Prostate 
Cancer
The benefits of ctDNA in mHSPC are less established 
compared with mCRPC, primarily because of the 

TABLE 2. 

Examples of the clinical significance of specific ctDNA findings in advanced prostate cancer 

Disease setting ctDNA finding Clinical significance 

mHSPC

Baseline ctDNA fraction
• Higher pretreatment ctDNA fraction is predictive of ADT failure, shorter metastasis-free 

survival and OS[35,94]. 

Baseline tumor suppressor 
gene alterations

• Associated with early relapse and worse survival outcomes[95,96].
• Abiraterone acetate + ADT less effective compared to patients without tumor suppressor 

gene alterations[97].

Baseline DDR alterations
• Somatic DDR mutation associated with shorter PFS and OS[35]. 
• Germline DDR alterations predictive of a shorter time to developing castration-resistant 

disease[98,99].

Baseline AR aberrations
• Any AR aberration was associated with poor OS compared to patients without detectable AR 

alterations[100].

SPOP mutation • Predictive of a favorable response to ARPIs and improved survival outcomes[101,102].

mCRPC

ctDNA fraction

• Higher ctDNA fraction correlates with shorter PFS as well as OS regardless of treatment 
received[10,13,47–49]. 

• An early reduction in cfDNA concentration or ctDNA fraction associated with longer PFS and 
OS[54–57,103].

• A lack of response or continued rise in ctDNA fraction has been associated with shorter 
PFS[47,49,57,66]. 

Baseline tumor suppressor 
gene alterations

• Patients treated with ARPIs had worse survival outcomes compared to those without tumor 
suppressor gene alterations at baseline, or who reverted to undetectable by cycle 2 of 
treatment[47,48,50,51]. 

AR amplification
• The presence, as well as magnitude, of AR gene amplification, has been associated with 

shorter PFS as well as OS[48,59–61]. 

HRR alterations
• Presence of HRR mutation/s predicts sensitivity to PARPi as well as platinum 

chemotherapy[71]. 

CTNNB1 mutation
• Wnt pathway activating mutations (such as CTNNB1) are associated with resistance to 

ARPI[50,87]. 

PTEN loss
• Prostate cancers with PTEN loss on IHC are more sensitive to AKT inhibition[73]. PTEN loss 

is also predictive for poor response to abiraterone acetate, while sensitivity to docetaxel is 
retained[74,75]. 

CDK12 mutation, high-MSI, 
high TMB

• A TMB of > 10 mutations per megabase[80], CDK12 mutations[81,82] and high MSI[83] predict 
sensitivity to ICI therapy. 

AR: androgen receptor; ARPI: androgen receptor pathway inhibitor; ctDNA: circulating tumor DNA; DDR: DNA damage response and repair;  
HRR: homologous recombination repair; IHC: Immunohistochemistry; mCRPC: metastatic castration-resistant prostate cancer; mHSPC: metastatic 
hormone-sensitive prostate cancer; MSI: microsatellite instability; OS: overall survival; PFS: progression-free survival; TMB: tumor mutational burden. 

AR: androgen receptor; ctDNA: circulating tumor DNA; NGS: next-generation sequencing. “Created with BioRender.com”. Reproduced  with permission. 

FIGURE 1. 

Advantages, limitations, and clinical applications of ctDNA in advanced prostate cancer

lower cf DNA yield and ctDNA fraction observed in 
lower-volume, less heavily pretreated disease and due 
to decreases in the abundance of ctDNA in plasma 
following administration of ADT[35].

ctDNA as a prognostic tool to guide upfront 
treatment intensification

Kohli et al. demonstrated that baseline ctDNA fraction 
also holds prognostic value in mHSPC, with higher 
pretreatment ctDNA fractions predicting shorter OS. 
The combination of ctDNA fraction, volume of disease, 
and serum ALP levels was also more prognostic of 
survival than clinical factors alone, with low-volume 
metastatic disease and low ctDNA fraction associated 
with the longest OS[35]. A higher ctDNA fraction was 
also predictive of ADT failure and shorter metastasis-
free survival[35,94]. 

Additionally, several prognostic genomic aberra-
tions exist in mHSPC, and ctDNA analysis is a useful 
method for identifying them (see Table 2). The presence 

279278 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

http://SIUJ.org
http://SIUJ.org


References

1. Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer Statistics, 2021. 
2021;71(1):7–33. doi: 10.3322/caac.21654. PMID: 33433946.

2. H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et 
al. Global Cancer Statistics 2020: GLOBOCAN estimates of incidence 
and mortality worldwide for 36 cancers in 185 countries. CA Cancer J 
Clin.2021;71(3):209–249. doi: 10.3322/caac.21660. PMID: 33538338.

3. Rebello RJ, Oing C, Knudsen KE, Loeb S, Johnson DC, Reiter RE, et 
al. Prostate cancer. Nat Rev Dis Primers.2021;7(1):9. doi: 10.1038/
s41572-020-00243-0. PMID: 33542230.

4. Smith MR, Hussain M, Saad F, Fizazi K, Sternberg CN, Crawford 
ED, et al.; ARASENS Trial Investigators. Darolutamide and survival 
in metastatic, hormone-sensitive prostate cancer. N Engl J 
Med.2022;386(12):1132–1142. doi: 10.1056/NEJMoa2119115. PMID: 
35179323; PMCID: PMC9844551. 

5. Fizazi K, Foulon S, Carles J, Roubaud G, McDermott R, Fléchon A, et 
al.; PEACE-1 investigators. Abiraterone plus prednisone added to 
androgen deprivation therapy and docetaxel in de novo metastatic 
castration-sensitive prostate cancer (PE ACE-1): a multicentre, 
open-label, randomised, phase 3 study with a 2 × 2 factorial 
design. Lancet.2022;399(10336):1695–1707. doi: 10.1016/S0140-
6736(22)00367-1. PMID: 35405085.

6. Finzel A, Sadik H, Ghitti G, Laes JF. The combined analysis of 
solid and liquid biopsies provides additional clinical information 
to improve patient care. J Cancer Metastasis Treat.2018;4:21. doi: 
10.20517/2394-4722.2018.10.

7. Hussain M, Corcoran C, Sibilla C, Fizazi K, Saad F, Shore N, et al. Tumor 
genomic testing for >4,000 men with metastatic castration-resistant 
prostate cancer in the phase III trial PROfound (Olaparib). Clin Cancer 
Res.2022;28(8):1518–1530. doi: 10.1158/1078-0432.CCR-21-3940. 
PMID: 35091440.

8. Holmes MG, Foss E, Joseph G, Foye A, Beckett B, Motamedi D, et al. 
CT-guided bone biopsies in metastatic castration-resistant prostate 
cancer: factors predictive of maximum tumor yield. J Vasc Interv 
Radiol.2017;28(8):1073–81.e1. doi: 10.1016/j.jvir.2017.04.019. PMID: 
28549709.

9. Lorente D, Omlin A, Zafeiriou Z, Nava-Rodrigues D, Pérez-López R, 
Pezaro C, et al. Castration-resistant prostate cancer tissue acquisition 
from bone metastases for molecular analyses. Clin Genitourin 
Cancer.2016;14(6):485–493. doi: 10.1016/j.clgc.2016.04.016. PMID: 
27246360; PMCID: PMC5132155.

10. Wyatt AW, Annala M, Aggarwal R, Beja K, Feng F, Youngren J, et al. 
Concordance of circulating tumor DNA and matched metastatic tissue 
biopsy in prostate cancer. J Natl Cancer Inst.2017;109(12):djx118. doi: 
10.1093/jnci/djx118. PMID: 29206995; PMCID: PMC6440274.

11. Haffner MC, Mosbruger T, Esopi DM, Fedor H, Heaphy CM, Walker 
DA, et al. Tracking the clonal origin of lethal prostate cancer. J Clin 
Invest.2013;123(11):4918 – 4922. doi: 10.1172/JCI70354. PMID: 
24135135; PMCID: PMC3809798.

12. Soda N, Rehm BHA, Sonar P, Nguyen NT, Shiddiky MJA. Advanced 
liquid biopsy technologies for circulating biomarker detection. J Mater 
Chem B.2019;7(43):6670 – 6704. doi: 10.1039/c9tb01490j. PMID: 
31646316.

13. Fettke H, Kwan EM, Azad AA. Cell-free DNA in cancer: current insights. 
Cell Oncol (Dordr).2019;42(1):13–28. doi: 10.1007/s13402-018-0413-5. 
PMID: 30367445.

14. Kustanovich A, Schwartz R, Peretz T, Grinshpun A. Life and death of 
circulating cell-free DNA. Cancer Biol Ther.2019;20(8):1057–1067. 
doi: 10.1080/15384047.2019.1598759. PMID: 30990132; PMCID: 
PMC6606043.

15. Herberts C, Annala M, Sipola J, Ng SWS, Chen XE, Nurminen A, et 
al. Deep whole-genome ctDNA chronology of treatment-resistant 
prostate cancer. Nature.2022;608(7921):199 –208. doi: 10.1038/
s41586-022-04975-9. PMID: 35859180.

16. Sorenson GD, Pribish DM, Valone FH, Memoli VA, Bzik DJ, Yao SL. 
Soluble normal and mutated DNA sequences from single-copy genes 
in human blood. Cancer Epidemiol Biomarkers Prev.1994;3(1):67–71.

17. Bando H, Nakamura Y, Taniguchi H, Shiozawa M, Yasui H, Esaki T, et al. 
Effects of metastatic sites on circulating tumor DNA in patients with 
metastatic colorectal cancer. JCO Precis Oncol.2022(6):e2100535. doi: 
10.1200/PO.21.00535. PMID: 35544728.

18. Azad AA, Volik SV, Wyatt AW, Haegert A, Le Bihan S, Bell RH, et al. 
Androgen receptor gene aberrations in circulating cell-free DNA: 
biomarkers of therapeutic resistance in castration-resistant prostate 
cancer. Clin Cancer Res.2015;21(10):2315–2324. doi: 10.1158/1078-
0432.CCR-14-2666. PMID: 25712683.

19. Chi KN, Barnicle A, Sibilla C, Lai Z, Corcoran C, Williams JA, et al. 
Concordance of BRCA1, BRCA2 (BRCA), and ATM mutations identified 
in matched tumor tissue and circulating tumor DNA (ctDNA) in men 
with metastatic castration-resistant prostate cancer (mCRPC) 
screened in the PROfound study. J Clin Oncol.2021;39(6_suppl):26. 
doi: 10.1200/JCO.2021.39.6_suppl.26.

20. Dong X, Zheng T, Zhang M, Dai C, Wang L, Wang L, et al. Circulating 
cell-free DNA-based detection of tumor suppressor gene copy 
number loss and its clinical implication in metastatic prostate cancer. 
Front Oncol.2021;11:720727. doi: 10.3389/fonc.2021.720727. PMID: 
34504797; PMCID: PMC8422845.

21. Tukachinsky H, Madison RW, Chung JH, Gjoerup OV, Severson 
EA, Dennis L, et al. Genomic analysis of circulating tumor DNA in 
3,334 patients with advanced prostate cancer identifies targetable 
BRCA alterations and AR resistance mechanisms. Clin Cancer 
Res.2021;27(11):3094–3105. doi: 10.1158/1078-0432.CCR-20-4805. 
PMID: 33558422; PMCID: PMC9295199.

22. Geeurickx E, Hendrix A. Targets, pitfalls and reference materials 
for liquid biopsy tests in cancer diagnostics. Mol Aspects 
Med.2020;72:100828. doi: 10.1016/j.mam.2019.10.005. PMID: 
31711714.

of poor prognostic aberrations may potentially spare the 
patient from unnecessary treatment toxicity. However, 
prospective data evaluating ctDNA as a prognostic tool 
to guide treatment decisions in mHSPC (alongside clin-
ical parameters) is needed before ctDNA can be adopted 
into mainstream practice.

Genomic aberrations to guide the choice of 
systemic therapy in metastatic hormone-
sensitive prostate cancer
Baseline tumor suppressor gene a lterations are 
associated with worse outcomes with AR PIs in 
mHSPC[97]. Furthermore, the phase 3 TITAN trial, 
where patients received apalutamide or placebo in 
combination with ADT for mHSPC, found that any AR 
aberration combined with detectable ctDNA at baseline 
is associated with poor OS[100]. In such cases, the 
addition of docetaxel as part of triplet therapy may be 
particularly important. Conversely, an SPOP mutation, 
which occurs in approximately 5% of patients with 
mHSPC, predicts a favourable response to ARPIs and 
improved survival outcomes[101]. 

Challenges and Limitations of ctDNA 
Profiling
One significant limitation of ctDNA profiling in prostate 
cancer is the variability in ctDNA shed into the plasma, 
potentially resulting in undetectable plasma tumor 
content. Unfortunately, up to half of mPC patients have 
low plasma tumor fraction (< 20%), and the dynamics of 
ctDNA release mechanisms and relative contributions 
from different lesions are still not fully understood[59,76]. 
These samples pose challenges, as the high background 
signal can hinder the sensitive and specific detection 
of copy number variants, the identification of loss of 
heterozygosity (either by copy-loss or copy-neutral 
mechanisms), and the filtering of non-neoplastic somatic 
mutations arising from hematopoietic stem cells[72].  
It is unlikely that ctDNA biopsies will completely replace 
genomic analysis of solid tissue, especially in earlier-
disease stages where tumor burden is lower. Additional 
approaches such as methylation or tumor-informed 
sequencing are required to overcome the limitations of 
low ctDNA fraction. Incorporating ctDNA with current 
conventional methods will significantly advance our 

understanding of the biological processes underlying 
treatment resistance and response. Indeed, recent 
studies on PARP inhibitors in mCRPC have combined 
ctDNA analysis with tumor tissue testing to detect 
HRR alterations[104,105]. Continued advancements 
in DNA processing, sequencing technologies, and 
downstream bioinformatics ana lysis w ill enable 
the increasing integration of ctDNA into precision-
oncology initiatives for mPC. However, due to the 
substantial infrastructural, technological, and financial 
requirements of ctDNA analysis, particularly for 
high-throughput assays, global access to ctDNA 
platforms at both the research and clinical levels is 
still limited. Furthermore, there is considerable lack 
of harmonization in the post-analytical stage, further 
complicating the implementation of ctDNA assays into 
the clinic (Figure 1). Significant efforts are still required 
to establish best practices for variant interpretation 
and reporting[106,107]. These considerations must be 
addressed before widespread clinical implementation of 
ctDNA profiling in mPC can occur.

Conclusion
The increasing complexity of optimal treatment 
selection and sequencing in mPC is compounded by 
the integration of multiple novel therapies. Clinicians 
urgently need the ability to molecularly profile patients 
to gain predictive and prognostic insights that will 
guide treatment decisions. The high concordance 
between ctDNA and tumor tissue samples, combined 
with its minimally invasive and easily accessible nature, 
makes ctDNA a highly attractive alternative to tissue 
biopsy for assessing a tumor’s molecular profile. By 
employing serial sampling, ctDNA can capture clonal 
heterogeneity across metastatic sites and track lineage 
plasticity as it develops, enabling early detection of 
resistant clones before they manifest clinically. However, 
before widespread adoption of ctDNA can be realized, 
several limitations must be addressed. These include 
improving the sensitivity of analysis techniques to detect 
aberrations at low allele frequencies and streamlining 
variant interpretation pipelines. Furthermore, extensive 
clinical validation with large sample sizes and eventual 
cost subsidization are prerequisites for the broad use of 
ctDNA in clinical practice. 

281280 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

http://SIUJ.org
http://SIUJ.org


44. Newman AM, Bratman SV, To J, Wynne JF, Eclov NC, Modlin LA, et al. 
An ultrasensitive method for quantitating circulating tumor DNA with 
broad patient coverage. Nat Med.2014;20(5):548–554. doi: 10.1038/
nm.3519. PMID: 24705333; PMCID: PMC4016134.

45. Du M, Huang CC, Tan W, Kohli M, Wang L. Multiplex digital PCR to 
detect amplifications of specific androgen receptor loci in cell-free 
DNA for prognosis of metastatic castration-resistant prostate cancer. 
Cancers (Basel).2020;12(8):2139. doi: 10.3390/cancers12082139. 
PMID: 32752286; PMCID: PMC7465398.

46. Ma Y, Luk A, Young FP, Lynch D, Chua W, Balakrishnar B, et al. Droplet 
digital PCR based androgen receptor variant 7 (AR-V7) detection from 
prostate cancer patient blood biopsies. Int J Mol Sci.2016;17(8). doi: 
10.3390/ijms17081264. PMID: 27527157; PMCID: PMC5000662.

47. Jayaram A, Wingate A, Wetterskog D, Wheeler G, Sternberg CN, 
Jones R, et al. Plasma tumor gene conversions after one cycle 
abiraterone acetate for metastatic castration-resistant prostate 
cancer: a biomarker analysis of a multicenter international trial. Ann 
Oncol.2021;32(6):726–735. doi: 10.1016/j.annonc.2021.03.196. PMID: 
33794293.

48. Annala M, Vandekerkhove G, Khalaf D, Taavitsainen S, Beja K, 
Warner EW, et al. Circulating tumor DNA genomics correlate with 
resistance to abiraterone and enzalutamide in prostate cancer. Cancer 
Discov.2018;8(4):444–457. doi: 10.1158/2159-8290.CD-17-0937. PMID: 
29367197.

49. Mehra N, Dolling D, Sumanasuriya S, Christova R, Pope L, Carreira S, 
et al. Plasma Cell-free DNA concentration and outcomes from taxane 
therapy in metastatic castration-resistant prostate cancer from two 
phase III trials (FIRSTANA and PROSELICA). Eur Urol.2018;74(3):283–
291. doi: 10.1016/j.eururo.2018.02.013. PMID: 29500065; PMCID: 
PMC6090941.

50. Wyatt AW, Azad AA, Volik SV, Annala M, Beja K, McConeghy B, et al. 
Genomic alterations in cell-free DNA and enzalutamide resistance in 
castration-resistant prostate cancer. JAMA Oncol.2016;2(12):1598–
1606. doi: 10.1001/jamaoncol.2016.0494. PMID: 27148695; PMCID: 
PMC5097690.

51. Torquato S, Pallavajjala A, Goldstein A, Toro PV, Silberstein JL, Lee 
J, et al. Genetic alterations detected in cell-free DNA are associated 
with enzalutamide and abiraterone resistance in castration-resistant 
prostate cancer. JCO Precis Oncol.2019;3:PO.18.00227. doi: 10.1200/
PO.18.00227. PMID: 31131348; PMCID: PMC6532665.

52. Beltran H, Hruszkewycz A, Scher HI, Hildesheim J, Isaacs J, Yu EY, et 
al. The role of lineage plasticity in prostate cancer therapy resistance. 
Clin Cancer Res.2019;25(23):6916–6924. doi: 10.1158/1078-0432.
CCR-19-1423. PMID: 31363002; PMCID: PMC6891154.

53. Bryce AH, Chen YH, Liu G, Carducci MA, Jarrard DM, Garcia JA, et 
al. Patterns of cancer progression of metastatic hormone-sensitive 
prostate cancer in the ECOG3805 CHA ARTED trial. Eur Urol 
Oncol.2020;3(6):717–724. doi: 10.1016/j.euo.2020.07.001. PMID: 
32807727; PMCID: PMC7738423.

54. Sumanasuriya S, Seed G, Parr H, Christova R, Pope L, Bertan C, et 
al. Elucidating prostate cancer behaviour during treatment via 
low-pass whole-genome sequencing of circulating tumour DNA. Eur 
Urol.2021;80(2):243–253. doi: 10.1016/j.eururo.2021.05.030. PMID: 
34103179; PMCID: PMC8329366.

55. Goodall J, Assaf ZJ, Shi Z, Seed G, Zhang L, Lauffer B, et al. Circulating 
tumor DNA (ctDNA) dynamics associate with treatment response 
and radiological progression-free survival (rPFS): analyses from a 
randomized phase II trial in metastatic castration-resistant prostate 
cancer (mCRPC). J Clin Oncol.2020;38(15_suppl):5508. doi: 10.1200/
JCO.2020.38.15_suppl.5508.

56. Goodall J, Mateo J, Yuan W, Mossop H, Porta N, Miranda S, 
et al.; TOPARP-A investigators. Circulating cell-free DNA to 
guide prostate cancer treatment with PARP inhibition. Cancer 
Discov.2017;7(9):1006–1017. doi: 10.1158/2159-8290.CD-17-0261. 
PMID: 28450425; PMCID: PMC6143169.

57. Annala M, Fu S, Bacon JV W, Sipola J, Iqbal N, Ferrario C, et al. 
Cabazitaxel versus abiraterone or enzalutamide in poor prognosis 
metastatic castration-resistant prostate cancer: a multicentre, 
randomised, open-label, phase II trial. Ann Oncol.2021;32(7):896–905. 
doi: 10.1016/j.annonc.2021.03.205. PMID: 33836265.

58. Bluemn EG, Coleman IM, Lucas JM, Coleman RT, Hernandez-Lopez S, 
Tharakan R, et al. Androgen receptor pathway-independent prostate 
cancer is sustained through FGF signaling. Cancer Cell.2017;32(4):474–
489.e6. doi: 10.1016/j.ccell.2017.09.003. PMID: 29017058; PMCID: 
PMC5750052.

59. Fettke H, Kwan EM, Docanto MM, Bukczynska P, Ng N, Graham LK, et 
al. Combined cell-free DNA and RNA profiling of the androgen receptor: 
clinical utility of a novel multianalyte liquid biopsy assay for metastatic 
prostate cancer. Eur Urol.2020;78(2):173 –180. doi: 10.1016/j.
eururo.2020.03.044. PMID: 32487321; PMCID: PMC8216705.

60. Jayaram A, Wingate A, Wetterskog D, Conteduca V, Khalaf D, 
Sharabiani MTA, et al. Plasma androgen receptor copy number status 
at emergence of metastatic castration-resistant prostate cancer: a 
pooled multicohort analysis. JCO Precis Oncol.2019;3:PO.19.00123. 
doi: 10.1200/PO.19.00123. PMID: 32923850; PMCID: PMC7446348.

61. Tolmeijer SH, Boerrigter E, Schalken JA, Geerlings MJ, van Oort 
IM, van Erp NP, et al. A systematic review and meta-analysis on the 
predictive value of cell-free DNA-based androgen receptor copy 
number gain in patients with castration-resistant prostate cancer. 
JCO Precis Oncol.2020;4:714–729. doi: 10.1200/PO.20.00084. PMID: 
35050750.

62. Kumar A, Coleman I, Morrissey C, Zhang X, True LD, Gulati R, et 
al. Substantial interindividual and limited intraindividual genomic 
diversity among tumors from men with metastatic prostate cancer. Nat 
Med.2016;22(4):369–378. doi: 10.1038/nm.4053. PMID: 26928463; 
PMCID: PMC5045679.

23. Crocetto F, Russo G, Di Zazzo E, Pisapia P, Mirto BF, Palmieri A, et al. 
Liquid biopsy in prostate cancer management-current challenges and 
future perspectives. Cancers (Basel).2022;14(13):3272. doi: 10.3390/
cancers14133272. PMID: 35805043; PMCID: PMC9265840.

24. Dhiantravan N, Emmett L, Joshua AM, Pattison DA, Francis RJ, 
Williams S, et al. UpFrontPSMA: a randomized phase 2 study 
of sequential (177) Lu-PSMA-617 and docetaxel vs docetaxel in 
metastatic hormone-naïve prostate cancer (clinical trial protocol). BJU 
Int.2021;128(3):331–342. doi: 10.1111/bju.15384. PMID: 33682320.

25. Maughan BL, Nussenzveig R, Swami U, Gupta S, Agarwal N. Prospective 
trial of nivolumab (Nivo) plus radium-223 (RA) in metastatic castration-
resistant prostate cancer (mCRPC) evaluating circulating tumor DNA 
(ctDNA) levels as a biomarker of response. J Clin Oncol.2020;38(6_
suppl):TPS267. doi: 10.1200/JCO.2020.38.6_suppl.TPS267. 

26. Agarwal N, Azad A, Fizazi K, Mateo J, Matsubara N, Shore ND, et al.; 
for the TALAPRO-3 investigational group. Talapro-3: a phase 3, double-
blind, randomized study of enzalutamide (ENZA) plus talazoparib (TALA) 
versus placebo plus enza in patients with DDR gene mutated metastatic 
castration-sensitive prostate cancer (mCSPC). J Clin Oncol.2022;40(6_
suppl):TPS221. doi: 10.1200/JCO.2022.40.6_suppl.TPS221.

27. Clarke NW, Armstrong AJ, Thier y-Vuillemin A, Oya M, Shore 
N, Loredo E, et al.; for the PROpel Investigators. Abiraterone and 
olaparib for metastatic castration-resistant prostate cancer. NEJM 
Evidence.2022;1(9):EVIDoa2200043. doi: 10.1056/EVIDoa2200043.

28. Fettke H, Kwan EM, Bukczynska P, Steen JA, Docanto M, Ng 
N, et al. Independent prognostic impact of plasma NCOA 2 
alterations in metastatic castration-resistant prostate cancer. 
Prostate.2021;81(13):992–1001. doi: 10.1002/pros.24194. PMID: 
34254334.

29. Hussung S, Follo M, Klar RFU, Michalczyk S, Fritsch K, Nollmann F, et 
al. Development and clinical validation of discriminatory multitarget 
digital droplet PCR assays for the detection of hot spot KRAS and 
NRAS mutations in cell-free DNA. J Mol Diagn.2020;22(7):943–956. 
doi: 10.1016/j.jmoldx.2020.04.206. PMID: 32376474. 

30. Odegaard JI, Vincent JJ, Mortimer S, Vowles JV, Ulrich BC, Banks KC, 
et al. Validation of a plasma-based comprehensive cancer genotyping 
assay utilizing orthogonal tissue- and plasma-based methodologies. 
Clin Cancer Res.2018;24(15):3539–3549. doi: 10.1158/1078-0432.
CCR-17-3831. PMID: 29691297.

31. Chan HT, Chin Y M, Low SK. Circulating tumor DNA-based 
genomic profiling assays in adult solid tumors for precision 
oncology: recent advancements and future challenges. Cancers 
(Basel).2022;14(13):3275. doi: 10.3390/cancers14133275. PMID: 
35805046; PMCID: PMC9265547.

32. Fet tke H, Steen JA, Kwan EM, Bukcz ynska P, Keer thikumar 
S, Goode D, et al. Analy tical validation of an error-corrected 
ultr a-sensitive c tDN A nex t- gener ation sequencing assay. 
BioTechniques.2020;69(2):133–140. doi: 10.2144/btn-2020-0045. 
PMID: 32654508.

33. Ulz P, Belic J, Graf R, Auer M, Lafer I, Fischereder K, et al. Whole-
genome plasma sequencing reveals focal amplifications as a driving 
force in metastatic prostate cancer. Nat Comm.2016;7(1):12008. doi: 
10.1038/ncomms12008. PMID: 27328849; PMCID: PMC4917969.

34. Baca SC, Garraway LA. The genomic landscape of prostate cancer. 
Front Endocrinol (Lausanne).2012;3:69. doi: 10.3389/fendo.2012.00069. 
PMID: 22649426; PMCID: PMC3355898.

35. Kohli M, Tan W, Zheng T, Wang A, Montesinos C, Wong C, et al. 
Clinical and genomic insights into circulating tumor DNA-based 
alterations across the spectrum of metastatic hormone-sensitive and 
castrate-resistant prostate cancer. EBioMedicine.2020;54:102728. 
doi: 10.1016/j.ebiom.2020.102728. PMID: 32268276; PMCID: 
PMC7186589.

36. van Dessel LF, van Riet J, Smits M, Zhu Y, Hamberg P, van der Heijden 
MS, et al. The genomic landscape of metastatic castration-resistant 
prostate cancers reveals multiple distinct genotypes with potential 
clinical impact. Nat Commun.2019;10(1):5251. doi: 10.1038/s41467-
019-13084-7. PMID: 31748536; PMCID: PMC6868175.

37. Crumbaker M, Chan EKF, Gong T, Corcoran N, Jaratlerdsiri W, Lyons 
RJ, et al. The impact of whole genome data on therapeutic decision-
making in metastatic prostate cancer: a retrospective analysis. 
Cancers (Basel).2020;12(5):1178. doi: 10.3390/cancers12051178. PMID: 
32392735; PMCID: PMC7280976.

38. Quigley DA, Dang HX, Zhao SG, Lloyd P, Aggarwal R, Alumkal JJ, et 
al. Genomic hallmarks and structural variation in metastatic prostate 
cancer. Cell.2018;174(3):758–769.e9. doi: 10.1016/j.cell.2018.06.039. 
PMID: 30033370; PMCID: PMC6425931.

39. Vnencak-Jones C, Berger M, Pao W. 2016. Types of molecular 
tumor testing. My Cancer Genome. Accessed June 25, 2023. 
https://www.mycancergenome.org/content/molecular-medicine/
types-of-molecular-tumor-testing/ 

40. Beltran H, Eng K, Mosquera JM, Sigaras A, Romanel A, Rennert H, et 
al. Whole-exome sequencing of metastatic cancer and biomarkers of 
treatment response. JAMA Oncol.2015;1(4):466–474. doi: 10.1001/
jamaoncol.2015.1313. PMID: 26181256; PMCID: PMC4505739.

41. Ramesh N, Sei E, Tsai PC, Bai S, Zhao Y, Troncoso P, et al. Decoding the 
evolutionary response to prostate cancer therapy by plasma genome 
sequencing. Genome Biol.2020;21(1):162. doi: 10.1186/s13059-020-
02045-9. PMID: 32631448; PMCID: PMC7336456.

42. Han X, Wang J, Sun Y. Circulating tumor DNA as biomarkers for cancer 
detection. Genomics Proteomics Bioinformatics.2017;15(2):59–72. doi: 
10.1016/j.gpb.2016.12.004. PMID: 28392479; PMCID: PMC5414889.

43. Beltran H, Yelensky R, Frampton GM, Park K, Downing SR, MacDonald 
T Y, et al. Targeted nex t-generation sequencing of advanced 
prostate cancer identifies potential therapeutic targets and 
disease heterogeneity. Eur Urol.2013;63(5):920–926. doi: 10.1016/j.
eururo.2012.08.053. PMID: 22981675; PMCID: PMC3615043.

283282 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

https://www.mycancergenome.org/content/molecular-medicine/types-of-molecular-tumor-testing/
https://www.mycancergenome.org/content/molecular-medicine/types-of-molecular-tumor-testing/
http://SIUJ.org
http://SIUJ.org


82. Wu YM, Cieślik M, Lonigro RJ, Vats P, Reimers MA, Cao X, et al.; 
PCF/SU2C International Prostate Cancer Dream Team. Inactivation 
of CDK12 delineates a distinct immunogenic class of advanced 
prostate cancer. Cell.2018;173(7):1770–1782.e14. doi: 10.1016/j.
cell.2018.04.034. PMID: 29906450; PMCID: PMC6084431.

83. Abida W, Cheng ML, Armenia J, Middha S, Autio KA, Vargas HA, 
et al. Analysis of the prevalence of microsatellite instability in 
prostate cancer and response to immune checkpoint blockade. JAMA 
Oncol.2019;5(4):471–478. doi: 10.1001/jamaoncol.2018.5801. PMID: 
30589920; PMCID: PMC6459218.

84. Willis J, Lefterova MI, Artyomenko A, Kasi PM, Nakamura Y, Mody 
K, et al. Validation of microsatellite instability detection using 
a comprehensive plasma-based genotyping panel. Clin Cancer 
Res.2019;25(23):7035–7045. doi: 10.1158/1078-0432.CCR-19-1324. 
PMID: 31383735.

85. Warner E, Herberts C, Fu S, Yip S, Wong A, Wang G, et al. BRCA2, ATM, 
and CDK12 defects differentially shape prostate tumor driver genomics 
and clinical aggression. Clin Cancer Res.2021;27(6):1650–1662. doi: 
10.1158/1078-0432.CCR-20-3708. PMID: 33414135.

86. Robinson D, Van Allen EM, Wu YM, Schultz N, Lonigro RJ, Mosquera 
JM, et al. Integrative clinical genomics of advanced prostate cancer. 
Cell.2015;161(5):1215–1228. doi: 10.1016/j.cell.2015.05.001.

87. Isaacsson Velho P, Fu W, Wang H, Mirkheshti N, Qazi F, Lima FAS, et al. 
Wnt-pathway activating mutations are associated with resistance to 
first-line abiraterone and enzalutamide in castration-resistant prostate 
cancer. Eur Urol.2020;77(1):14–21. doi: 10.1016/j.eururo.2019.05.032. 
PMID: 31176623; PMCID: PMC6893106.

88. Zhang Z, Cheng L, Li J, Farah E, Atallah NM, Pascuzzi PE, et al. 
Inhibition of the Wnt/β-catenin pathway overcomes resistance 
to enzalutamide in castration-resistant prostate cancer. Cancer 
Res.2018;78(12):3147–3162. doi: 10.1158/0008-5472.CAN-17-3006. 
PMID: 29700003; PMCID: PMC6004251.

89. Beltran H, Prandi D, Mosquera JM, Benelli M, Puca L, Cyrta J, et al. 
Divergent clonal evolution of castration-resistant neuroendocrine 
prostate cancer. Nat Med.2016;22(3):298–305. doi: 10.1038/nm.4045. 
PMID: 26855148; PMCID: PMC4777652.

90. Conteduca V, Ku SY, Fernandez L, Dago-Rodriquez A, Lee J, Jendrisak 
A, et al. Circulating tumor cell heterogeneity in neuroendocrine 
prostate cancer by single cell copy number analysis. NPJ Precis 
Oncol. 2021;5 (1):76. doi: 10.1038/s41698- 021- 00211-1. PMID: 
34385567; PMCID: PMC8361159.

91. Chi KN, Mukherjee S, Saad F, Winquist E, Ong M, Kolinsky MP, 
et al. Prostate cancer biomarker enrichment and treatment 
selection (PC-BETS) study: a Canadian cancer trials group phase II 
umbrella trial for metastatic castration-resistant prostate cancer 
(mCRPC). J Clin Oncol.2020;38(15_suppl):5551. doi: 10.1200/
JCO.2020.38.15_suppl.5551.

92. De Laere B, Crippa A, Discacciati A, Larsson B, Oldenburg J, 
Mortezavi A, et al.; ProBio Investigators. Clinical trial protocol for 
ProBio: an outcome-adaptive and randomised multiarm biomarker-
driven study in patients with metastatic prostate cancer. Eur Urol 
Focus.2022;8(6):1617–1621. doi: 10.1016/j.euf.2022.03.005. PMID: 
35317973.

93. Crippa A, De Laere B, Discacciati A, Larsson B, Connor JT, Gabriel EE, 
et al. The ProBio trial: molecular biomarkers for advancing personalized 
treatment decision in patients with metastatic castration-resistant 
prostate cancer. Trials.2020;21(1):579. doi: 10.1186/s13063-020-
04515-8. PMID: 32586393; PMCID: PMC7318749.

94. Vandekerkhove G, Struss WJ, Annala M, Kallio HML, Khalaf D, Warner 
EW, et al. Circulating tumor DNA abundance and potential utility in de 
novo metastatic prostate cancer. Eur Urol.2019;75(4):667–675. doi: 
10.1016/j.eururo.2018.12.042. PMID: 30638634.

95. Hamid AA, Gray KP, Shaw G, MacConaill LE, Evan C, Bernard B, et 
al. Compound genomic alterations of TP53, PTEN, and RB1 tumor 
suppressors in localized and metastatic prostate cancer. Eur 
Urol.2019;76(1):89 –97. doi: 10.1016/j.eururo.2018.11.045. PMID: 
30553611.

96. Schweizer MT, Ha G, Gulati R, Brown LC, McKay RR, Dorff T, 
et al. CDK12-mutated prostate cancer: clinical outcomes with 
standard therapies and immune checkpoint blockade. JCO Precis 
Oncol.2020;4:382–392. doi: 10.1200/po.19.00383. PMID: 32671317; 
PMCID: PMC7363399.

97. Velez MG, Kosiorek HE, Egan JB, McNatty AL, Riaz IB, Hwang SR, et 
al. Differential impact of tumor suppressor gene (TP53, PTEN, RB1) 
alterations and treatment outcomes in metastatic, hormone-sensitive 
prostate cancer. Prostate Cancer Prostatic Dis.2022 Sep;25(3):479-
483. doi: 10.1038/s41391-021-00430-4. PMID: 34294873; PMCID: 
PMC9385473. 

98. Wei Y, Wu J, Gu W, Wang J, Lin G, Qin X, et al. Prognostic value 
of germline DNA repair gene mutations in de novo metastatic and 
castration-sensitive prostate cancer. Oncologist.2020;25(7):e1042–
e1050. doi: 10.1634/theoncologist.2019-0495. PMID: 32190957; 
PMCID: PMC7356812.

99. Annala M, Struss WJ, Warner EW, Beja K, Vandekerkhove G, Wong A, 
et al. Treatment outcomes and tumor loss of heterozygosity in germline 
DNA repair-deficient prostate cancer. Eur Urol.2017;72(1):34–42. doi: 
10.1016/j.eururo.2017.02.023. PMID: 28259476.

100. Agarwal N, Lucas J, Aguilar-Bonavides C, Thomas S, Gormley M, 
Chowdhury S, et al. Genomic aberrations associated with overall 
survival (OS) in metastatic castration-sensitive prostate cancer 
(mCSPC) treated with apalutamide (APA) or placebo (PBO) plus 
androgen deprivation therapy (ADT) in TITAN. J Clin Oncol.2022;40(16_
suppl):5066. doi: 0.1200/JCO.2022.40.16_suppl.5066.

63. Quigley D, Alumkal JJ, Wyatt AW, Kothari V, Foye A, Lloyd P, et 
al. Analysis of circulating cell-free DNA identifies multiclonal 
heterogeneit y of BRCA 2 reversion mutations associated with 
resistance to PARP inhibitors. Cancer Discov.2017;7(9):999–1005. 
doi: 10.1158/2159-8290.CD-17-0146. PMID: 28450426; PMCID: 
PMC5581695.

64. Loehr A, Hussain A, Patnaik A, Bryce AH, Castellano D, Font A, et al. 
Emergence of BRCA reversion mutations in patients with metastatic 
castration-resistant prostate cancer after treatment with rucaparib. 
Eur Urol.2022;83(3):200–209. doi: 10.1016/j.eururo.2022.09.010. 
PMID: 36243543.

65. Tolmeijer SH, Boerrigter E, Sumiyoshi T, Ng S, Kwan EM, 
Annala M, et al. On-treatment plasma ctDNA fraction and 
treatment outcomes in metastatic castration-resistant prostate 
cancer. J Clin Oncol. 2022;4 0 (16 _ suppl):5 051. doi: 10.120 0/
JCO.2022.40.16_suppl.5051.

66. Conteduca V, Casadei C, Scarpi E, Brighi N, Schepisi G, Lolli C, et al. 
Baseline plasma tumor DNA (ctDNA) correlates with PSA kinetics in 
metastatic castration-resistant prostate cancer (mCRPC) treated with 
abiraterone or enzalutamide. Cancers (Basel).2022;14(9):2219. doi: 
10.3390/cancers14092219. PMID: 35565349; PMCID: PMC9102454.

67. Conteduca V, Jayaram A, Romero-Laorden N, Wetterskog D, Salvi S, 
Gurioli G, et al. Plasma androgen receptor and docetaxel for metastatic 
castration-resistant prostate cancer. Eur Urol.2019;75(3):368–373. 
doi: 10.1016/j.eururo.2018.09.049. PMID: 30773204; PMCID: 
PMC6377278.

68. Abida W, Patnaik A, Campbell D, Shapiro J, Bryce AH, McDermott 
R, et al.; TRITON2 investigators. Rucaparib in men with metastatic 
castration-resistant prostate cancer harboring a BRCA1 or BRCA2 
gene alteration. J Clin Oncol.2020;38(32):3763–3772. doi: 10.1200/
JCO.20.01035. PMID: 32795228; PMCID: PMC7655021.

69. de Bono J, Mateo J, Fizazi K, Saad F, Shore N, Sandhu S, et al. 
Olaparib for metastatic castration-resistant prostate cancer. N Engl J 
Med.2020;382(22):2091–2102. doi: 10.1056/NEJMoa1911440. PMID: 
32343890.

70. National Comprehensive Cancer Network (NCCN). Prostate Cancer 
V1.2023 2022. Available at: https://www.nccn.org/professionals/
physician_gls/pdf/prostate.pdf. Accessed June 25, 2023.

71. Mota JM, Barnett E, Nauseef JT, Nguyen B, Stopsack KH, Wibmer 
A, et al. Platinum-based chemotherapy in metastatic prostate cancer 
with DNA repair gene alterations. JCO Precis Oncol.2020;4:355–366. 
doi: 10.1200/po.19.00346. PMID: 32856010; PMCID: PMC7446522.

72. Jensen K, Konnick EQ, Schweizer MT, Sokolova AO, Grivas P, Cheng 
HH, et al. Association of clonal hematopoiesis in DNA repair genes 
with prostate cancer plasma cell-free DNA testing interference. JAMA 
Oncol.2021;7(1):107–110. doi: 10.1001/jamaoncol.2020.5161. PMID: 
33151258; PMCID: PMC7645740.

73. Sweeney C, Bracarda S, Sternberg CN, Chi KN, Olmos D, Sandhu S, et al. 
Ipatasertib plus abiraterone and prednisolone in metastatic castration-
resistant prostate cancer (IPATential150): a multicentre, randomised, 
double-blind, phase 3 trial. Lancet.2021;398(10295):131–142. doi: 
10.1016/S0140-6736(21)00580-8. PMID: 34246347.

74. Ferraldeschi R, Nava Rodrigues D, Riisnaes R, Miranda S, Figueiredo 
I, Rescigno P, et al. PTEN protein loss and clinical outcome from 
castration-resistant prostate cancer treated with abiraterone acetate. 
Eur Urol.2015;67(4):795–802. doi: 10.1016/j.eururo.2014.10.027. PMID: 
25454616; PMCID: PMC4410287. 

75. Rescigno P, Lorente D, Dolling D, Ferraldeschi R, Rodrigues DN, 
Riisnaes R, et al. Docetaxel treatment in PTEN- and ERG-aberrant 
metastatic prostate cancers. Eur Urol Oncol.2018;1(1):71–77. doi: 
10.1016/j.euo.2018.02.006. PMID: 29911685; PMCID: PMC5995869.

76. Kwan EM, Dai C, Fettke H, Hauser C, Docanto MM, Bukczynska P, 
et al. Plasma cell–free DNA profiling of PTEN-PI3K-AKT pathway 
aberrations in metastatic castration-resistant prostate cancer. JCO 
Precis Oncol.2021:(5):PO.20.00424. doi: 10.1200/PO.20.00424. PMID: 
34250422; PMCID: PMC8232889. 

77. May KF Jr, Gulley JL, Drake CG, Dranoff G, Kantoff PW. Prostate 
cancer immunotherapy. Clin Cancer Res.2011;17(16):5233–5238. 
doi: 10.1158/1078-0432.CCR-10-3402. PMID: 21700764; PMCID: 
PMC3263933.

78. Sharma P, Pachynski RK, Narayan V, Fléchon A, Gravis G, Galsky MD, 
et al. Nivolumab plus ipilimumab for metastatic castration-resistant 
prostate cancer: preliminary analysis of patients in the CheckMate 
650 trial. Cancer Cell.2020;38(4):4 89 – 499.e3. doi: 10.1016/j.
ccell.2020.08.007. PMID: 32916128.

79. Beer TM, Kwon ED, Drake CG, Fizazi K, Logothetis C, Gravis G, et 
al. Randomized, double-blind, phase III trial of ipilimumab versus 
placebo in asymptomatic or minimally symptomatic patients with 
metastatic chemotherapy-naive castration-resistant prostate cancer. 
J Clin Oncol.2017;35(1):40–47. doi: 10.1200/JCO.2016.69.1584. PMID: 
28034081.

80. Graf RP, Fisher V, Weberpals J, Gjoerup O, Tierno MB, Huang RSP, et 
al. Comparative effectiveness of immune checkpoint inhibitors vs 
chemotherapy by tumor mutational burden in metastatic castration-
resistant prostate cancer. JAMA Netw Open.2022;5(3):e225394. doi: 
10.1001/jamanetworkopen.2022.5394. PMID: 35357449; PMCID: 
PMC8972027.

81. Gongora ABL, Marshall CH, Velho PI, Lopes CDH, Marin JF, Camargo 
AA, et al. Extreme responses to a combination of DNA-damaging 
therapy and immunotherapy in CDK12-altered metastatic castration-
resistant prostate cancer: a potential therapeutic vulnerability. Clin 
Genitourin Cancer.2022;20(2):183–188. doi: 10.1016/j.clgc.2021.11.015. 
PMID: 35027313.

285284 SIUJ.ORG SIUJ  •  Volume 4, Number 4  •  July 2023SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY Utility and Clinical Application of Circulating Tumor DNA (ctDNA) in Advanced Prostate Cancer

https://www.nccn.org/professionals/physician_gls/pdf/prostate.pdf
https://www.nccn.org/professionals/physician_gls/pdf/prostate.pdf
http://SIUJ.org
http://SIUJ.org


101. Nizialek E, Lim SJ, Wang H, Isaacsson Velho P, Yegnasubramanian S, 
Antonarakis ES. Genomic profiles and clinical outcomes in primary 
versus secondary metastatic hormone-sensitive prostate cancer. 
Prostate.2021;81(9):572– 579. doi: 10.1002/pros.24135. PMID: 
33955569.

102. Swami U, Graf RP, Nussenzveig RH, Fisher V, Tukachinsky H, Schrock 
AB, et al. SPOP mutations as a predictive biomarker for androgen 
receptor axis–targeted therapy in de novo metastatic castration-
sensitive prostate cancer. Clin Cancer Res.2022;28(22):4917–4925. 
doi: 10.1158/1078-0432.CCR-22-2228. PMID: 36088616.

103. Tolmeijer SH, Boerrigter E, Sumiyoshi T, Kwan EM, Ng S, Annala M, 
et al. Early on-treatment changes in circulating tumor DNA fraction 
and response to enzalutamide or abiraterone in metastatic castration-
resistant prostate cancer. Clin Cancer Res.2023;CCR-22-2998. doi: 
10.1158/1078-0432.CCR-22-2998. PMID: 36996325.

104. Loehr A, Patnaik A, Campbell D, Shapiro J, Bryce AH, McDermott R, 
et al. Response to rucaparib in BRCA-mutant metastatic castration-
resistant prostate cancer identified by genomic testing in the TRITON2 
study. Clin Cancer Res.2021;27(24):6677–6686. doi: 10.1158/1078-
0432.CCR-21-2199. PMID: 34598946; PMCID: PMC8678310.

105. Chi KN, Barnicle A, Sibilla C, Lai Z, Corcoran C, Barrett JC, et al. 
Detection of BRCA1, BRCA 2, and ATM alterations in matched 
tumor tissue and circulating tumor DNA in patients with prostate 
cancer screened in PROfound. Clin Cancer Res.2023;29(1):81–91. 
doi: 10.1158/1078-0432.CCR-22-0931. PMID: 36043882; PMCID: 
PMC9811161. 

106. Taavitsainen S, Annala M, Ledet E, Beja K, Miller PJ, Moses M, et al. 
Evaluation of commercial circulating tumor DNA test in metastatic 
prostate cancer. JCO Precis Oncol.2019;3:PO.19.00014. doi: 10.1200/
PO.19.00014. PMID: 32914020; PMCID: PMC7446428.

107. Kwan EM, Wyatt AW, Chi KN. Towards clinical implementation of 
circulating tumor DNA in metastatic prostate cancer: opportunities for 
integration and pitfalls to interpretation. Front Oncol.2022;12:1054497. 
doi: 10.3 389/fonc.2022.105 4 4 97. PMID: 36 4 39 4 51; PMCID: 
PMC9685669.

286 SIUJ  •  Volume 4, Number 4  •  July 2023 SIUJ.ORG

REVIEW — LIQUID BIOPSY

http://SIUJ.org

