Circulating Tumor DNA Alterations in Advanced Urothelial Carcinoma and Association with Clinical Outcomes: A Pilot Study

Predictive and Prognostic Biomarkers and Tumor Antigens for Targeted Therapy in Urothelial Carcinoma

Urothelial carcinoma (UC) is the fourth most prevalent cancer amongst males worldwide. While patients with non-muscle-invasive disease have a favorable prognosis, 25% of UC patients present with locally advanced disease which is associated with a 10-15% 5-year survival rate and poor overall prognosis. Muscle-invasive bladder cancer (MIBC) is associated with about 50% 5 year survival when treated by radical cystectomy or trimodality therapy; stage IV disease is associated with 10-15% 5 year survival. Current therapeutic modalities for MIBC include neoadjuvant chemotherapy, surgery and/or chemoradiation, although patients with relapsed or refractory disease have a poor prognosis. However, the rapid success of immuno-oncology in various hematologic and solid malignancies offers new targets with tremendous therapeutic potential in UC. Historically, there were no predictive biomarkers to guide the clinical management and treatment of UC, and biomarker development was an unmet need. However, recent and ongoing clinical trials have identified several promising tumor biomarkers that have the potential to serve as predictive or prognostic tools in UC. This review provides a comprehensive summary of emerging biomarkers and molecular tumor targets including programmed death ligand 1 (PD-L1), epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), fibroblast growth factor receptor (FGFR), DNA damage response and repair (DDR) mutations, poly (ADP-ribose) polymerase (PARP) expression and circulating tumor DNA (ctDNA), as well as their clinical utility in UC. We also evaluate recent advancements in precision oncology in UC, while illustrating limiting factors and challenges related to the clinical application of these biomarkers in clinical practice.

Honing the Hunt: A Comprehensive Review of Cell-free Tumor DNA to Predict Neoadjuvant Therapy Efficacy in Bladder Cancer

OBJECTIVE

To provide an updated view on the role of cell-free DNA as a predictor of pathological response to neoadjuvant therapy in patients with muscle-invasive bladder cancer.

METHODS

A systematic review was conducted from September 2023 to October 2023. Selected studies from the MEDLINE and clinical trial databases were critically analyzed regarding the clinical efficacy of cell-free DNA as a predictive instrument after neoadjuvant therapy in bladder cancer. The methodological quality assessment was based on the QUADAS-2 tool.

RESULTS

In this systematic review, we analyzed 5 studies encompassing a cumulative patient cohort of 780 individuals diagnosed with muscle-invasive bladder cancer, with a median follow-up ranging from 6 to 23 months. Among these studies, 4 primarily focused on detecting and analyzing circulating tumor DNA in plasma, while 1 study uniquely utilized cell-free tumor DNA in urine samples. The diagnostic accuracy of cell-free DNA in plasma ranges from 79% to 100%, indicating a variable yet significant predictive capability. In contrast, the study utilizing urinary cell-free DNA demonstrated an accuracy of 81% in predicting treatment response post-neoadjuvant chemotherapy.

CONCLUSION

Cell-free DNA is emerging as a valuable biomarker for predicting response to neoadjuvant chemotherapy in patients with muscle-invasive bladder tumors.

Circulating and urinary tumour DNA in urothelial carcinoma - upper tract, lower tract and metastatic disease

Precision medicine has transformed the way urothelial carcinoma is managed. However, current practices are limited by the availability of tissue samples for genomic profiling and the spatial and temporal molecular heterogeneity observed in many studies. Among rapidly advancing genomic sequencing technologies, non-invasive liquid biopsy has emerged as a promising diagnostic tool to reproduce tumour genomics, and has shown potential to be integrated in several aspects of clinical care. In urothelial carcinoma, liquid biopsies such as plasma circulating tumour DNA (ctDNA) and urinary tumour DNA (utDNA) have been investigated as a surrogates for tumour biopsies and might bridge many shortfalls currently faced by clinicians. Both ctDNA and utDNA seem really promising in urothelial carcinoma diagnosis, staging and prognosis, response to therapy monitoring, detection of minimal residual disease and surveillance. The use of liquid biopsies in patients with urothelial carcinoma could further advance precision medicine in this population, facilitating personalized patient monitoring through non-invasive assays.

SWI/SNF complexes and cancers

Epigenetics refers to the study of genetic changes that can affect gene expression without altering the underlying DNA sequence, including DNA methylation, histone modification, chromatin remodelling, X chromosome inactivation and non-coding RNA regulation. Of these, DNA methylation, histone modification and chromatin remodelling constitute the three classical modes of epigenetic regulation. These three mechanisms alter gene transcription by adjusting chromatin accessibility, thereby affecting cell and tissue phenotypes in the absence of DNA sequence changes. In the presence of ATP hydrolases, chromatin remodelling alters the structure of chromatin and thus changes the transcription level of DNA-guided RNA. To date, four types of ATP-dependent chromatin remodelling complexes have been identified in humans, namely SWI/SNF, ISWI, INO80 and NURD/MI2/CHD. SWI/SNF mutations are prevalent in a wide variety of cancerous tissues and cancer-derived cell lines as discovered by next-generation sequencing technologies.. SWI/SNF can bind to nucleosomes and use the energy of ATP to disrupt DNA and histone interactions, sliding or ejecting histones, altering nucleosome structure, and changing transcriptional and regulatory mechanisms. Furthermore, mutations in the SWI/SNF complex have been observed in approximately 20% of all cancers. Together, these findings suggest that mutations targeting the SWI/SNF complex may have a positive impact on tumorigenesis and cancer progression.

Risk Classification of Bladder Cancer by Gene Expression and Molecular Subtype

This study evaluated a panel including the molecular taxonomy subtype and the expression of 27 genes as a diagnostic tool to stratify bladder cancer patients at risk of aggressive behavior, using a well-characterized series of non-muscle invasive bladder cancer (NMIBC) as well as muscle-invasive bladder cancer (MIBC). The study was conducted using the novel NanoString nCounter gene expression analysis. This technology allowed us to identify the molecular subtype and to analyze the gene expression of 27 bladder-cancer-related genes selected through a recent literature search. The differential gene expression was correlated with clinicopathological variables, such as the molecular subtypes (luminal, basal, null/double negative), histological subtype (conventional urothelial carcinoma, or carcinoma with variant histology), clinical subtype (NMIBC and MIBC), tumor stage category (Ta, T1, and T2–4), tumor grade, PD-L1 expression (high vs. low expression), and clinical risk categories (low, intermediate, high and very high). The multivariate analysis of the 19 genes significant for cancer-specific survival in our cohort study series identified TP53 (p = 0.0001), CCND1 (p = 0.0001), MKI67 (p < 0.0001), and molecular subtype (p = 0.005) as independent predictors. A scoring system based on the molecular subtype and the gene expression signature of TP53, CCND1, or MKI67 was used for risk assessment. A score ranging from 0 (best prognosis) to 7 (worst prognosis) was obtained and used to stratify our patients into two (low [score 0–2] vs. high [score 3–7], model A) or three (low [score 0–2] vs. intermediate [score 3–4] vs. high [score 5–7], model B) risk categories with different survival characteristics. Mean cancer-specific survival was longer (122 + 2.7 months) in low-risk than intermediate-risk (79.4 + 9.4 months) or high-risk (6.2 + 0.9 months) categories (p < 0.0001; model A); and was longer (122 + 2.7 months) in low-risk than high-risk (58 + 8.3 months) (p < 0.0001; model B). In conclusion, the molecular risk assessment model, as reported here, might be used better to select the appropriate management for patients with bladder cancer.

Blood-based liquid biopsy: insights into early detection, prediction, and treatment monitoring of bladder cancer

Bladder cancer (BC) is a clinical challenge worldwide with late clinical presentation, poor prognosis, and low survival rates. Traditional cystoscopy and tissue biopsy are routine methods for the diagnosis, prognosis, and monitoring of BC. However, due to the heterogeneity and limitations of tumors, such as aggressiveness, high cost, and limited applicability of longitudinal surveillance, the identification of tumor markers has attracted significant attention in BC. Over the past decade, liquid biopsies (e.g., blood) have proven to be highly efficient methods for the discovery of BC biomarkers. This noninvasive sampling method is used to analyze unique tumor components released into the peripheral circulation and allows serial sampling and longitudinal monitoring of tumor progression. Several liquid biopsy biomarkers are being extensively studied and have shown promising results in clinical applications of BC, including early detection, detection of microscopic residual disease, prediction of recurrence, and response to therapy. Therefore, in this review, we aim to provide an update on various novel blood-based liquid biopsy markers and review the advantages and current limitations of liquid biopsy in BC therapy. The role of blood-based circulating tumor cells, circulating tumor DNA, cell-free RNA, exosomes, metabolomics, and proteomics in diagnosis, prognosis, and treatment monitoring, and their applicability to the personalized management of BC, are highlighted.

Cell-Free DNA, MicroRNAs, Proteins, and Peptides as Liquid Biopsy Biomarkers in Prostate Cancer and Bladder Cancer

Liquid biopsy, as a novel noninvasive tool for biomarker discovery, has gained a lot of attention and represents a significant innovation in precision medicine. Due to its minimally invasive nature, liquid biopsy has fewer complications and can be scheduled more frequently to provide individualized snapshots of the disease at successive time points. This is particularly valuable in providing simultaneous measurements of tumor burden during treatment and early detection of tumor recurrence or drug resistance. Blood-based liquid biopsy is an attractive, minimally invasive alternative, which has shown promise in diagnosis, risk stratification, disease monitoring, and more. Urine has gained popularity due to its less invasive sampling, the ability to easily repeat samples, and the ability to track tumor evolution in real time, making it a powerful tool for diagnosis and treatment monitoring, especially in urologic cancers. In this review, we provide a detailed discussion on the potential clinical applications of prostate cancer (PCa) and bladder cancer (BCa), with cell-free DNA (cfDNA), microRNAs (miRNAs), proteins, and peptides as liquid biopsy biomarkers.

Profiling of extracellular vesicles of metastatic urothelial cancer patients to discover protein signatures related to treatment outcome

The prognosis of metastatic urothelial carcinoma (mUC) patients is poor, and early prediction of systemic therapy response would be valuable to improve outcome. In this exploratory study, we investigated protein profiles in sequential plasma‐isolated extracellular vesicles (EVs) from a subset of mUC patients treated within a Phase I trial with vinflunine combined with sorafenib. The isolated EVs were of exosome size and expressed exosome markers CD9, TSG101 and SYND‐1. We found, no association between EVs/ml plasma at baseline and progression‐free survival (PFS). Protein profiling of EVs, using an antibody‐based 92‐plex Proximity Extension Assay on the Oncology II^® platform, revealed a heterogeneous protein expression pattern. Qlucore bioinformatic analyses put forward a protein signature comprising of SYND‐1, TNFSF13, FGF‐BP1, TFPI‐2, GZMH, ABL1 and ERBB3 to be putatively associated with PFS. Similarly, a protein signature from EVs that related to best treatment response was found, which included FR‐alpha, TLR 3, TRAIL and FASLG. Several of the markers in the PFS or best treatment response signatures were also identified by a machine learning classification algorithm. In conclusion, protein profiling of EVs isolated from plasma of mUC patients shows a potential to identify protein signatures that may associate with PFS and/or treatment response.

[Liquid biopsy to indvidualise therapy in advanced bladder cancer]

Biomarker development is focussing more and more on the analysis of body fluids ("liquid biopsy") due to its advantages compared to tissue analysis. In addition to proteins and lipoproteins, circulating tumour cells (CTCs), extracellular vesicles (EVs) and cell-free nucleic acids (DNA, RNA) can be investigated from body fluids. Treatment of muscle-invasive balder cancer (MIBC) is still challenging. Therefore, new biomarkers are warranted to estimate the metastatic risk, to detect metastatic spread at an early time point and to select the most effective systemic therapy in a given patient. This review gives an overview of liquid biopsy from blood in patients with advanced MIBC and considers CTCs, EVs as well as circulating DNA (ctDNA) and non-coding RNA (ncRNA) and their role for prognostic evaluation and selecting treatment.

Longitudinal Evaluation of Circulating Tumor DNA Using Sensitive Amplicon-Based Next-Generation Sequencing to Identify Resistance Mechanisms to Immune Checkpoint Inhibitors for Advanced Urothelial Carcinoma

Serial evaluation of circulating tumor DNA may allow noninvasive assessment of drivers of resistance to immune checkpoint inhibitors (ICIs) in advanced urothelial cancer (aUC). We used a novel, amplicon-based next-generation sequencing assay to identify genomic alterations (GAs) pre- and post-therapy in 39 patients with aUC receiving ICI and 6 receiving platinum-based chemotherapy (PBC). One or more GA was seen in 95% and 100% of pre- and post-ICI samples, respectively, commonly in TP53 (54% and 54%), TERT (49% and 59%), and BRCA1/BRCA2 (33% and 33%). Clearance of ≥1 GA was seen in 7 of 9 patients responding to ICI, commonly in TP53 (n = 4), PIK3CA (n = 2), and BRCA1/BRCA2 (n = 2). A new GA was seen in 17 of 20 patients progressing on ICI, frequently in BRCA1/BRCA2 (n = 6), PIK3CA (n = 3), and TP53 (n = 3), which seldom emerged in patients receiving PBC. These findings highlight the potential for longitudinal circulating tumor DNA evaluation in tracking response and resistance to therapy.

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

Cancer of the urinary bladder is a neoplasm with considerable importance in veterinary medicine, given its high incidence in several domestic animal species and its life-threatening character. Bladder cancer in companion animals shows a complex and still poorly understood biopathology, and this lack of knowledge has limited therapeutic progress over the years. Even so, important advances concerning the identification of tumour markers with clinical applications at the diagnosis, prognosis and therapeutic levels have recently been made, for example, the identification of pathological BRAF mutations. Those advances are now facilitating the introduction of targeted therapies. The present review will address such advances, focusing on small animal oncology and providing the reader with an update on this field. When appropriate, comparisons will be drawn with bladder cancer in human patients, as well as with experimental models of the disease.

Serial ctDNA analysis predicts clinical progression in patients with advanced urothelial carcinoma

BACKGROUND

Targeted sequencing of circulating tumour DNA (ctDNA) is a promising tool to monitor dynamic changes in the variant allele frequencies (VAF) of genomic alterations and predict clinical outcomes in patients with advanced urothelial carcinoma (UC).

METHODS

We performed targeted sequencing of 182 serial ctDNA samples from 53 patients with advanced UC.

RESULTS

Serial ctDNA-derived metrics predicted the clinical outcomes in patients with advanced UC. Combining serial ctDNA aggregate VAF (aVAF) values with clinical factors, including age, sex, and liver metastasis, improved the performance of prognostic models. An increase of the ctDNA aVAF by ≥1 in serial ctDNA samples predicted disease progression within 6 months in 90% of patients. The majority of patients with aVAFs ≤0.7 in three consecutive ctDNA samples achieved durable clinical responses (≥6 months).

CONCLUSIONS

Serial ctDNA analysis predicts disease progression and enables dynamic monitoring to guide precision medicine in patients with advanced UC.

The emerging treatment landscape of advanced urothelial carcinoma

PURPOSE OF REVIEW

Urothelial carcinoma (UC) is one of the most common malignancies in the Western world. Historically, patients with advanced disease have had a poor prognosis and progress within months of completing upfront platinum-based chemotherapy. In the last two years, the treatment landscape for metastatic UC (mUC) has significantly shifted with the emergence of contemporary immunotherapy and targeted agents. The purpose of this review is to highlight the current and emerging systemic treatment options for mUC of the bladder.

RECENT FINDINGS

PD-1/PD-L1 immune checkpoint inhibitors (ICIs) have demonstrated activity in the postplatinum and platinum-ineligible settings. Additionally, they have become a standard maintenance treatment option after avelumab demonstrated increased overall survival in patients with stable disease or better after first line platinum-based chemotherapy. Novel targeted therapies and antibody-drug conjugates (ADCs) have been granted Food and Drug Administration approval for subsequent line therapy based on promising results in phase II and III trials.

SUMMARY

There has been a considerable increase in the variety of effective therapies for mUC, including the utility of ICIs, novel targeted agents, and ADCs. Platinum-based chemotherapy remains an effective first-line option. As the role of novel therapies continues to shift toward earlier in the disease course, there remains an important need to develop feasible, globally accessible predictive biomarkers that can aid in patient selection and inform sequencing of therapeutic options.

Immune checkpoint inhibitors in advanced upper and lower tract urothelial carcinoma: a comparison of outcomes

OBJECTIVES

To compare clinical outcomes between patients with locally advanced (unresectable) or metastatic urothelial carcinoma (aUC) in the upper and lower urinary tract receiving immune checkpoint inhibitors (ICIs).

PATIENTS AND METHODS

We performed a retrospective cohort study collecting clinicopathological, treatment, and outcome data for patients with aUC receiving ICIs from 2013 to 2020 across 24 institutions. We compared the objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) between patients with upper and lower tract UC (UTUC, LTUC). Uni- and multivariable logistic and Cox regression were used to assess the effect of UTUC on ORR, OS, and PFS. Subgroup analyses were performed stratified based on histology (pure, mixed) and line of treatment (first line, subsequent line).

RESULTS

Out of a total of 746 eligible patients, 707, 717, and 738 were included in the ORR, OS, and PFS analyses, respectively. Our results did not contradict the hypothesis that patients with UTUC and LTUC had similar ORRs (24% vs 28%; adjusted odds ratio [aOR] 0.73, 95% confidence interval [CI] 0.43-1.24), OS (median 9.8 vs 9.6 months; adjusted hazard ratio [aHR] 0.93, 95% CI 0.73-1.19), and PFS (median 4.3 vs 4.1 months; aHR 1.01, 95% CI 0.81-1.27). Patients with mixed-histology UTUC had a significantly lower ORR and shorter PFS vs mixed-histology LTUC (aOR 0.20, 95% CI 0.05-0.91 and aHR 1.66, 95% CI 1.06-2.59), respectively).

CONCLUSION

Overall, patients with UTUC and LTUC receiving ICIs have comparable treatment response and outcomes. Subgroup analyses based on histology showed that those with mixed-histology UTUC had a lower ORR and shorter PFS compared to mixed-histology LTUC. Further studies and evaluation of molecular biomarkers can help refine patient selection for immunotherapy.

Spectrum of FGFR2/3 Alterations in Cell-Free DNA of Patients with Advanced Urothelial Carcinoma

Detecting genomic alterations (GAs) in advanced urothelial carcinoma (aUC) can expand treatment options by identifying candidates for targeted therapies. Erdafitinib is FDA-approved for patients with platinum-refractory aUC with activating mutation or fusion in FGFR2/3. We explored the prevalence and spectrum of FGFR2/3 GAs identified with plasma cfDNA NGS testing (Guardant360) in 997 patients with aUC. FGFR2/3 GAs were detected in 201 patients (20%) with characterized activating GAs in 141 (14%). Our results indicate the Guardant360-based FGFR2/3 GA detection rate is similar to those described from previous studies employing tumor tissue testing, suggesting that plasma-based cfDNA NGS may non-invasively identify candidates for anti-FGFR targeted therapies.

Efficacy and safety of rucaparib in previously treated, locally advanced or metastatic urothelial carcinoma from a phase 2, open-label trial (ATLAS)

BACKGROUND

ATLAS evaluated the efficacy and safety of the PARP inhibitor rucaparib in patients with previously treated locally advanced/unresectable or metastatic urothelial carcinoma (UC).

METHODS

Patients with UC were enrolled independent of tumor homologous recombination deficiency (HRD) status and received rucaparib 600 mg BID. The primary endpoint was investigator-assessed objective response rate (RECIST v1.1) in the intent-to-treat and HRD-positive (loss of genome-wide heterozygosity ≥10%) populations. Key secondary endpoints were progression-free survival (PFS) and safety. Disease control rate (DCR) was defined post-hoc as the proportion of patients with a confirmed complete or partial response (PR), or stable disease lasting ≥16 weeks.

RESULTS

Of 97 enrolled patients, 20 (20.6%) were HRD-positive, 30 (30.9%) HRD-negative, and 47 (48.5%) HRD-indeterminate. Among 95 evaluable patients, there were no confirmed responses. However, reductions in the sum of target lesions were observed, including 6 (6.3%) patients with unconfirmed PR. DCR was 11.6%; median PFS was 1.8 months (95% CI, 1.6-1.9). No relationship was observed between HRD status and efficacy endpoints. Median treatment duration was 1.8 months (range, 0.1-10.1). Most frequent any-grade treatment-emergent adverse events were asthenia/fatigue (57.7%), nausea (42.3%), and anemia (36.1%). Of 64 patients with data from tumor tissue samples, 10 (15.6%) had a deleterious alteration in a DNA damage repair pathway gene, including four with a deleterious BRCA1 or BRCA2 alteration.

CONCLUSIONS

Rucaparib did not show significant activity in unselected patients with advanced UC regardless of HRD status. The safety profile was consistent with that observed in patients with ovarian or prostate cancer.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov (NCT03397394). Date of registration: 12 January 2018. This trial was registered in EudraCT (2017-004166-10).

Circulating Cell-Free DNA in Liquid Biopsies as Potential Biomarker for Bladder Cancer: A Systematic Review

Bladder cancer (BC) is among the most frequent cancer types in the world and is the most lethal urological malignancy. Presently, diagnostic and follow-up methods for BC are expensive and invasive. Thus, the identification of novel predictive biomarkers for diagnosis, progression, and prognosis of BC is of paramount importance. To date, several studies have evidenced that cell-free DNA (cfDNA) found in liquid biopsies such as blood and urine may play a role in the particular scenario of urologic tumors, and its analysis may improve BC diagnosis report about cancer progression or even evaluate the effectiveness of a specific treatment or anticipate whether a treatment would be useful for a specific patient depending on the tumor characteristics. In the present review, we have summarized the up-to-date studies evaluating the value of cfDNA as potential diagnostic, prognostic, or monitoring biomarker for BC in several biofluids.

Tumor heterogeneity and the potential role of liquid biopsy in bladder cancer

Bladder cancer (BC) is a heterogeneous disease that characterized by genomic instability and a high mutation rate. Heterogeneity in tumor may partially explain the diversity of responses to targeted therapies and the various clinical outcomes. A combination of cytology and cystoscopy is the standard methodology for BC diagnosis, prognosis, and disease surveillance. However, genomics analyses of single tumor‐biopsy specimens may underestimate the mutational burden of heterogeneous tumors. Liquid biopsy, as a promising technology, enables analysis of tumor components in the bodily fluids, such as blood and urine, at multiple time points and provides a minimally invasive approach that can track the evolutionary dynamics and monitor tumor heterogeneity. In this review, we describe the multiple faces of BC heterogeneity at the genomic and transcriptional levels and how they affect clinical care and outcomes. We also summarize the outcomes of liquid biopsy in BC, which plays a potential role in revealing tumor heterogeneity. Finally, we discuss the challenges that must be addressed before liquid biopsy can be widely used in clinical treatment.

Tumor heterogeneity in muscle-invasive bladder cancer

Muscle-invasive bladder cancer (MIBC), a highly heterogeneous disease, shows genomic instability and a high mutation rate. Clinical outcomes are variable and responses to conventional chemotherapy differ among patients (due to inter-patient tumor heterogeneity and inter-tumor heterogeneity) and even within each individual tumor (intra-tumor heterogeneity). Emerging evidence indicates that tumor heterogeneity may play an important role in cancer progression, resistance to therapy, and metastasis. Comprehensive molecular subtyping classifies MIBC into distinct categories that have potential to guide prognosis, patient stratification, and treatment. Genomic characterization of time-series analyses at the single cell level, and of cell-free circulating tumor DNA or circulating tumor cells, are emerging technologies that enable dissection of the complex clonal architecture of MIBC. This review provides insight into the clinical significance of the molecular mechanisms underlying heterogeneity, focusing on inter- and intra-tumor heterogeneity, with special emphasis on molecular classification and methods used to analyze the complex patterns involved.

Targetable gene fusions and aberrations in genitourinary oncology

Gene fusions result from either structural chromosomal rearrangement or aberrations caused by splicing or transcriptional readthrough. The precise and distinctive presence of fusion genes in neoplastic tissues and their involvement in multiple pathways central to cancer development, growth and survival make them promising targets for personalized therapy. In genitourinary malignancies, rearrangements involving the E26 transformation-specific family of transcription factors have emerged as very frequent alterations in prostate cancer, especially the TMPRSS2-ERG fusion. In renal malignancies, Xp11 and t(6;11) translocations are hallmarks of a distinct pathological group of tumours described as microphthalmia-associated transcription factor family translocation-associated renal cell carcinomas. Novel druggable fusion events have been recognized in genitourinary malignancies, leading to the activation of several clinical trials. For instance, ALK-rearranged renal cell carcinomas have shown responses to alectinib and crizotinib. Erdafitinib has been tested for the treatment of FGFR-rearranged bladder cancer. Other anti-fibroblast growth factor receptor 3 (FGFR3) compounds are showing promising results in the treatment of bladder cancer, including infigratinib and pemigatinib, and all are currently in clinical trials.

Circulating tumor cells as Trojan Horse for understanding, preventing, and treating cancer: a critical appraisal

Circulating tumor cells (CTCs) are regarded as harbingers of metastases. Their ability to predict response to therapy, relapse, and resistance to treatment has proposed their value as putative diagnostic and prognostic indicators. CTCs represent one of the zeniths of cancer evolution in terms of cell survival; however, the triggers of CTC generation, the identification of potentially metastatic CTCs, and the mechanisms contributing to their heterogeneity and aggressiveness represent issues not yet fully deciphered. Thus, prior to enabling liquid biopsy applications to reach clinical prime time, understanding how the above mechanistic information can be applied to improve treatment decisions is a key challenge. Here, we provide our perspective on how CTCs can provide mechanistic insights into tumor pathogenesis, as well as on CTC clinical value. In doing so, we aim to (a) describe how CTCs disseminate from the primary tumor, and their link to epithelial-mesenchymal transition (EMT); (b) trace the route of CTCs through the circulation, focusing on tumor self-seeding and the possibility of tertiary metastasis; (c) describe possible mechanisms underlying the enhanced metastatic potential of CTCs; (d) discuss how CTC could provide further information on the tissue of origin, especially in cancer of unknown primary origin. We also provide a comprehensive review of meta-analyses assessing the prognostic significance of CTCs, to highlight the emerging role of CTCs in clinical oncology. We also explore how cell-free circulating tumor DNA (ctDNA) analysis, using a combination of genomic and phylogenetic analysis, can offer insights into CTC biology, including our understanding of CTC heterogeneity and tumor evolution. Last, we discuss emerging technologies, such as high-throughput quantitative imaging, radiogenomics, machine learning approaches, and the emerging breath biopsy. These technologies could compliment CTC and ctDNA analyses, and they collectively represent major future steps in cancer detection, monitoring, and management.

Emerging biomarkers in urothelial carcinoma: Challenges and opportunities

Advanced urothelial carcinoma (UC) is a very important cause of cancer-related morbidity and mortality with, until recently, only a few available therapeutic options. The treatment landscape has dramatically changed in recent years with the introduction of immune checkpoint inhibitors and the development of novel targeted agents, such as erdafitinib, and antibody-drug conjugates, such as enfortumab vedotin. Cost-effective utilization of this rapidly expanding therapeutic armamentarium can be further optimized via the identification and validation of reliable prognostic and predictive biomarkers that inform prognostication and patient selection. In this review, we aim to summarize examples of recent developments in the rapidly expanding field of emerging biomarkers in UC, outlining challenges and opportunities.

Liquid biopsy in the clinical management of bladder cancer: current status and future developments

Introduction: The use of liquid biopsy on the blood from solid malignancies provides a convenient way of detecting actionable mutations, monitoring treatment response, detecting early recurrence and prognosticating outcomes. The aim of this review is to discuss the current status and future direction of serum biomarkers in the clinical management of urinary bladder cancer.Areas covered: This review provides an overview of blood liquid biopsy and bladder cancer using methods of circulating tumors cells, circulating RNA, serum metabolites and cell-free DNA. Recent clinical studies and advances in methodology are emphasized. We performed a literature search using PMC/PubMed with keywords including 'liquid biopsy', 'circulating tumor DNA', 'cell-free DNA', 'biomarkers', 'bladder cancer' 'precision medicine'. Additional articles were obtained from the cited references of key articles. An emphasis was placed on recent studies published since 2018.Expert opinion: Liquid biopsies represent a potential biomarker using cell-free DNA, metabolomic profiles of altered cellular metabolism, circulating cancer cells and RNA. Despite displaying tremendous clinical promise, the current status of the blood liquid biopsies has not reached fruition. However, future investigations should lead the evolution of liquid biomarker into clinical utility for the management of bladder cancer.

Circulating Tumor Cell and Circulating Tumor DNA Assays Reveal Complementary Information for Patients with Metastatic Urothelial Cancer

Despite considerable advances in the management of urothelial carcinoma (UC), better risk stratification and enhanced detection of minimal residual disease are still urgent priorities to prolong survival while avoiding the morbidity of overtreatment. Circulating tumor cells and DNA (CTCs, ctDNA) are two biologically distinct "liquid biopsies" that may potentially address this need, although they have been understudied in UC to date and their relative utility is unknown. To this end, matched CTC and ctDNA samples were collected for a head-to-head comparison in a pilot study of 16 patients with metastatic UC. CTCs were defined as cytokeratin- and/or EpCAM-positive using the RareCyte direct imaging platform. ctDNA was assayed using the PlasmaSelect64 probe-capture assay. 75% of patients had detectable CTCs, and 73% had detectable somatic mutations, with no correlation between CTC count and ctDNA. 91% of patients had tissue confirmation of at least one plasma mutation and, importantly, several clinically actionable mutations were detected in plasma that were not found in the matching tumor. A ctDNA fraction of >2% was significantly associated with worse overall survival (p=0.039) whereas CTC detection was not (p=0.46). Notably, using a predefined gene panel for ctDNA detection had a high but not complete detection rate in metastatic UC, similar to what has been described for a custom tissue-personalized assay approach. In sum, both liquid biopsies show promise in UC and deserve further investigation. PATIENT SUMMARY: New "liquid biopsy" blood tests are emerging for urothelial cancer aimed at early detection and avoiding overtreatment. Our results suggest that two such tests provide complementary information: circulating tumor cells may be best for studying the biological features of a person's cancer, whereas circulating tumor DNA may be better for early detection.