Application of Liquid Biopsies in Cancer Targeted Therapy.

As a growing body of evidence demonstrates intertumoral and intratumoral heterogeneity and clonal evolution, both during carcinogenesis and also throughout treatment resulting in acquired drug resistance, the utility of blood-based assays or "liquid biopsies" is becoming increasingly recognized in clinical practice and trial design. "Liquid biopsies" provide a less invasive approach to the current gold standard of interrogating tumors by tissue biopsies, which are frequently unfeasible, associated with morbidity, and cannot be performed as often

Prostate-specific Membrane Antigen Heterogeneity and DNA Repair Defects in Prostate Cancer.

BackgroundProstate-specific membrane antigen (PSMA; folate hydrolase) prostate cancer (PC) expression has theranostic utility.ObjectiveTo elucidate PC PSMA expression and associate this with defective DNA damage repair (DDR).Design, setting, and participantsMembranous PSMA (mPSMA) expression was scored immunohistochemically from metastatic castration-resistant PC (mCRPC) and matching, same-patient, diagnostic biopsies, and correlated with next-generation sequencing (NGS) and clinical outcome data.Outcome measurements and statistical analysisExpression of mPSMA was quantitated by modified H-score. Patient DNA was tested by NGS. Gene expression and activity scores were determined from mCRPC transcriptomes. Statistical correlations utilised Wilcoxon signed rank tests, survival was estimated by Kaplan-Meier test, and sample heterogeneity was quantified by Shannon's diversity index.Results and limitationsExpression of mPSMA at diagnosis was associated with higher Gleason grade (p=0.04) and worse overall survival (p=0.006). Overall, mPSMA expression levels increased at mCRPC (median H-score [interquartile range]: castration-sensitive prostate cancer [CSPC] 17.5 [0.0-60.0] vs mCRPC 55.0 [2.8-117.5]). Surprisingly, 42% (n=16) of CSPC and 27% (n=16) of mCRPC tissues sampled had no detectable mPSMA (H-score ConclusionsMembranous PSMA expression is upregulated in some but not all PCs, with mPSMA expression demonstrating marked inter- and intrapatient heterogeneity. DDR aberrations are associated with higher mPSMA expression and merit further evaluation as predictive biomarkers of response for PSMA-targeted therapies in larger, prospective cohorts.Patient summaryThrough analysis of prostate cancer samples, we report that the presence of prostate-specific membrane antigen (PSMA) is extremely variable both within one patient and between different patients. This may limit the usefulness of PSMA scans and PSMA-targeted therapies. We show for the first time that prostate cancers with defective DNA repair produce more PSMA and so may respond better to PSMA-targeting treatments

Genomics of lethal prostate cancer at diagnosis and castration resistance.

The genomics of primary prostate cancer differ from those of metastatic castration-resistant prostate cancer (mCRPC). We studied genomic aberrations in primary prostate cancer biopsies from patients who developed mCRPC, also studying matching, same-patient, diagnostic, and mCRPC biopsies following treatment. We profiled 470 treatment-naive prostate cancer diagnostic biopsies and, for 61 cases, mCRPC biopsies, using targeted and low-pass whole-genome sequencing (n = 52). Descriptive statistics were used to summarize mutation and copy number profile. Prevalence was compared using Fisher's exact test. Survival correlations were studied using log-rank test. TP53 (27%) and PTEN (12%) and DDR gene defects (BRCA2 7%; CDK12 5%; ATM 4%) were commonly detected. TP53, BRCA2, and CDK12 mutations were markedly more common than described in the TCGA cohort. Patients with RB1 loss in the primary tumor had a worse prognosis. Among 61 men with matched hormone-naive and mCRPC biopsies, differences were identified in AR, TP53, RB1, and PI3K/AKT mutational status between same-patient samples. In conclusion, the genomics of diagnostic prostatic biopsies acquired from men who develop mCRPC differ from those of the nonlethal primary prostatic cancers. RB1/TP53/AR aberrations are enriched in later stages, but the prevalence of DDR defects in diagnostic samples is similar to mCRPC

Docetaxel Treatment in PTEN- and ERG-aberrant Metastatic Prostate Cancers.

Background Loss of PTEN is a common genomic aberration in castration-resistant prostate cancer (CRPC) and is frequently concurrent with ERG rearrangements, causing resistance to next-generation hormonal treatment (NGHT) including abiraterone. The relationship between PTEN loss and docetaxel sensitivity remains uncertain.Objective To study the antitumor activity of docetaxel in metastatic CRPC in relation to PTEN and ERG aberrations.Design setting and participants Single-centre, retrospective analysis of PTEN loss and ERG expression using a previously described immunohistochemistry (IHC) binary classification system. Patients received docetaxel between January 1, 2006 and July 31, 2016.Outcome measurements and statistical analysis Response correlations were analyzed using Pearson's χ2 tests and independent-sample t tests. Overall (OS) and progression-free survival (PFS) were analyzed using univariate and multivariate (MVA) Cox regression and Kaplan-Meier methods.Results and limitations Overall, 215 patients were eligible. Established metastatic CRPC prognostic factors were well balanced between PTEN loss (39%) and normal patients (61%). PTEN loss was associated with shorter median OS (25.4 vs 34.7 mo; hazard ratio [HR] 1.66, 95% confidence interval [CI] 1.18-2.13; p = 0.001). There were no differences in median PFS (8.0 vs 9.1 mo; univariate HR 1.20, 95% CI 0.86-1.68; p = 0.28) and PSA response (53.4% vs 50.6%; p = 0.74). PTEN loss was an independent prognostics factor in MVA. ERG status was available for 100 patients. ERG positivity was not associated with OS or PFS. Limitations include the retrospective nature and the single-centre analysis.Conclusions Our findings suggest that metastatic CRPC with PTEN loss might benefit more from docetaxel than from NGHT.Patient summary In this study we found that metastatic prostate cancer with loss of the PTEN switch may benefit more from docetaxel than from abiraterone

Genomic Analysis of Three Metastatic Prostate Cancer Patients with Exceptional Responses to Carboplatin Indicating Different Types of DNA Repair Deficiency.

Platinum-based regimens have not been proved to increase survival from advanced prostate cancer (PCa). Incontrovertible evidence that a proportion of prostate cancers have homologous recombination DNA (HRD) repair defects, and that such genomic aberrations are synthetically lethal with both poly(ADP)-ribose polymerase inhibition and platinum, has increased interest in the utilisation of these drugs against a subset of these diseases. Here in we report three patients with advanced castration-resistant PCa with HRD defects having exceptional responses to carboplatin

RB1 Heterogeneity in Advanced Metastatic Castration-Resistant Prostate Cancer.

Purpose Metastatic castration-resistant prostate cancer (mCRPC) is a lethal but clinically heterogeneous disease, with patients having variable benefit from endocrine and cytotoxic treatments. Intrapatient genomic heterogeneity could be a contributing factor to this clinical heterogeneity. Here, we used whole-genome sequencing (WGS) to investigate genomic heterogeneity in 21 previously treated CRPC metastases from 10 patients to investigate intrapatient molecular heterogeneity (IPMH).Experimental Design: WGS was performed on topographically separate metastases from patients with advanced metastatic prostate cancer. IPMH of the RB1 gene was identified and further evaluated by FISH and IHC assays.Results WGS identified limited IPMH for putative driver events. However, heterogeneous genomic aberrations of RB1 were detected. We confirmed the presence of these RB1 somatic copy-number aberrations, initially identified by WGS, with FISH, and identified novel structural variants involving RB1 in 6 samples from 3 of these 10 patients (30%; 3/10). WGS uncovered a novel deleterious RB1 structural lesion constituted of an intragenic tandem duplication involving multiple exons and associating with protein loss. Using RB1 IHC in a large series of mCRPC biopsies, we identified heterogeneous expression in approximately 28% of mCRPCs.Conclusions mCRPCs have a high prevalence of RB1 genomic aberrations, with structural variants, including rearrangements, being common. Intrapatient genomic and expression heterogeneity favors RB1 aberrations as late, subclonal events that increase in prevalence due to treatment-selective pressures

HER3 Is an Actionable Target in Advanced Prostate Cancer.

It has been recognized for decades that ERBB signaling is important in prostate cancer, but targeting ERBB receptors as a therapeutic strategy for prostate cancer has been ineffective clinically. However, we show here that membranous HER3 protein is commonly highly expressed in lethal prostate cancer, associating with reduced time to castration resistance (CR) and survival. Multiplex immunofluorescence indicated that the HER3 ligand NRG1 is detectable primarily in tumor-infiltrating myelomonocytic cells in human prostate cancer; this observation was confirmed using single-cell RNA sequencing of human prostate cancer biopsies and murine transgenic prostate cancer models. In castration-resistant prostate cancer (CRPC) patient-derived xenograft organoids with high HER3 expression as well as mouse prostate cancer organoids, recombinant NRG1 enhanced proliferation and survival. Supernatant from murine bone marrow-derived macrophages and myeloid-derived suppressor cells promoted murine prostate cancer organoid growth in vitro, which could be reversed by a neutralizing anti-NRG1 antibody and ERBB inhibition. Targeting HER3, especially with the HER3-directed antibody-drug conjugate U3-1402, exhibited antitumor activity against HER3-expressing prostate cancer. Overall, these data indicate that HER3 is commonly overexpressed in lethal prostate cancer and can be activated by NRG1 secreted by myelomonocytic cells in the tumor microenvironment, supporting HER3-targeted therapeutic strategies for treating HER3-expressing advanced CRPC. SIGNIFICANCE: HER3 is an actionable target in prostate cancer, especially with anti-HER3 immunoconjugates, and targeting HER3 warrants clinical evaluation in prospective trials

Clinical Utility of Circulating Tumour Cell Androgen Receptor Splice Variant-7 Status in Metastatic Castration-resistant Prostate Cancer.

Abstract Background Detection of androgen receptor splice variant-7 (AR-V7) mRNA in circulating tumour cells (CTCs) is associated with worse outcome in metastatic castration-resistant prostate cancer (mCRPC). However, studies rarely report comparisons with CTC counts and biopsy AR-V7 protein expression. Objective To determine the reproducibility of AdnaTest CTC AR-V7 testing, and associations with clinical characteristics, CellSearch CTC counts, tumour biopsy AR-V7 protein expression and overall survival (OS). Design, setting, and participants CTC AR-V7 status was determined for 227 peripheral blood samples, from 181 mCRPC patients with CTC counts (202 samples; 136 patients) and matched mCRPC biopsies (65 samples; 58 patients). Outcome measurements and statistical analysis CTC AR-V7 status was associated with clinical characteristics, CTC counts, and tissue biopsy AR-V7 protein expression. The association of CTC AR-V7 status and other baseline variables with OS was determined. Results and limitations Of the samples, 35% were CTC+/AR-V7+. CTC+/AR-V7+ samples had higher CellSearch CTC counts (median CTC; interquartile range [IQR]: 60, 19–184 vs 9, 2–64; Mann-Whitney test p Conclusions Studies reporting the prognostic relevance of CTC AR-V7 status must account for CTC counts. Discordant CTC AR-V7 results and AR-V7 protein expression in matched, same-patient biopsies are reported. Patient summary Liquid biopsies that determine circulating tumour cell androgen receptor splice variant-7 status have the potential to impact treatment decisions in metastatic castration-resistant prostate cancer patients. Robust clinical qualification of these assays is required before their routine use

Prostate-specific Antigen Decline After 4 Weeks of Treatment with Abiraterone Acetate and Overall Survival in Patients with Metastatic Castration-resistant Prostate Cancer.

Background The availability of multiple new treatments for metastatic castration-resistant prostate cancer (mCRPC) mandates earlier treatment switches in the absence of a response. A decline in prostate-specific antigen (PSA) is widely used to monitor treatment response, but is not validated as an intermediate endpoint for overall survival (OS).Objective To evaluate the association between early PSA decline and OS following abiraterone acetate (AA) treatment.Design, setting, and participants We identified mCRPC patients treated with AA before or after docetaxel at the Royal Marsden NHS Foundation Trust between 2006 and 2014. Early PSA decline was defined as a 30% decrease in PSA at 4 wk relative to baseline, and early PSA rise as a 25% increase.Outcome measurements and statistical analysis Association with OS was analyzed using multivariate Cox regression and log-rank analyses. Spearman's rho correlation coefficient (r) was calculated to evaluate the association between PSA changes at 4 wk and 12 wk.Results and limitations There were 274 patients eligible for this analysis. A 30% PSA decline at 4 wk was associated with longer OS (25.8 vs 15.1 mo; hazard ratio [HR] 0.47, p<0.001), and a 25% PSA rise at 4 wk with shorter OS (15.1 vs 23.8 mo; HR 1.7, p=0.001) in both univariate and multivariable models. The percentage PSA decline at 4 wk was significantly correlated with the percentage PSA change at 12 wk (r=0.82; p<0.001). Patients achieving a 30% PSA decline at 4 wk were 11.7 times more likely to achieve a 50% PSA decrease at 12 wk (sensitivity 90.9%, specificity 79.4%). Limitations include the retrospective design of this analysis.Conclusions Patients not achieving 30% PSA decline after 4 wk of AA have a lower likelihood of achieving PSA response at 12 wk and significantly inferior OS. Prospective multicentre validation studies are needed to confirm these findings.Patient summary Prostate-specific antigen (PSA) is commonly used to evaluate response to treatment in metastatic castration-resistant prostate cancer. Expert recommendations discourage reliance on PSA changes earlier than 12 wk after treatment initiation. Our data suggest that early PSA changes are associated with survival in patients receiving abiraterone acetate

Consensus Statement on Circulating Biomarkers for Advanced Prostate Cancer

Context: In advanced prostate cancer (PC), there is increasing investigation of circulating biomarkers, including quantitation and characterization of circulating tumour cells and cell-free nucleic acids, for therapeutic monitoring and as prognostic and predictive biomarkers. However, there is a lack of consensus and standardisation regarding analyses, reporting, and integration of results into specific clinical contexts. A consensus meeting on circulating biomarkers was held to address these topics. Objective: To present a report of the consensus statement on circulating biomarkers in advanced PC. Evidence acquisition: Four important areas of controversy in the field of circulating biomarkers in PC management were identified: known clinical utility of circulating biomarkers; unmet clinical needs for circulating biomarkers in PC care; most pressing blood-based molecular assays required; and essential steps for developing circulating biomarker assays. A panel of 18 international PC experts in the field of circulating biomarkers developed the programme and consensus questions. The panel voted publicly but anonymously on 50 predefined questions developed following a modified Delphi process. Evidence synthesis: Voting was based solely on panellist opinions of the predefined topics and therefore not on a standard literature review or meta-analysis. The outcomes of the voting had varying degrees of support, as reflected in the wording of this article and in the detailed voting results provided in the Supplementary material. Conclusions: The expert voting results presented can guide the future development of circulating biomarkers for PC care. Notably, the consensus meeting highlighted the importance of reproducibility and variability studies, among other significant areas in need of trials specifically designed to address them. Patient summary: A panel of international experts met to discuss and vote on the use of different blood-based prostate cancer tests, and how they can be used to guide treatment and disease monitoring to deliver more precise and better patient care