The interplay of mutagenesis and ecDNA shapes urothelial cancer evolution.

Advanced urothelial cancer is a frequently lethal disease characterized by marked genetic heterogeneity1. In this study, we investigated the evolution of genomic signatures caused by endogenous and external mutagenic processes and their interplay with complex structural variants (SVs). We superimposed mutational signatures and phylogenetic analyses of matched serial tumours from patients with urothelial cancer to define the evolutionary dynamics of these processes. We show that APOBEC3-induced mutations are clonal and early, whereas chemotherapy induces mutational bursts of hundreds of late subclonal mutations. Using a genome graph computational tool2, we observed frequent high copy-number circular amplicons characteristic of extrachromosomal DNA (ecDNA)-forming SVs. We characterized the distinct temporal patterns of APOBEC3-induced and chemotherapy-induced mutations within ecDNA-forming SVs, gaining new insights into the timing of these mutagenic processes relative to ecDNA biogenesis. We discovered that most CCND1 amplifications in urothelial cancer arise within circular ecDNA-forming SVs. ecDNA-forming SVs persisted and increased in complexity, incorporating additional DNA segments and contributing to the evolution of treatment resistance. Oxford Nanopore Technologies long-read whole-genome sequencing followed by de novo assembly mapped out CCND1 ecDNA structure. Experimental modelling of CCND1 ecDNA confirmed its role as a driver of treatment resistance. Our findings define fundamental mechanisms that drive urothelial cancer evolution and have important therapeutic implications.

Proteomic and genomic signatures of repeat instability in cancer and adjacent normal tissues.

Repetitive sequences are hotspots of evolution at multiple levels. However, due to difficulties involved in their assembly and analysis, the role of repeats in tumor evolution is poorly understood. We developed a rigorous motif-based methodology to quantify variations in the repeat content, beyond microsatellites, in proteomes and genomes directly from proteomic and genomic raw data. This method was applied to a wide range of tumors and normal tissues. We identify high similarity between repeat instability patterns in tumors and their patient-matched adjacent normal tissues. Nonetheless, tumor-specific signatures both in protein expression and in the genome strongly correlate with cancer progression and robustly predict the tumorigenic state. In a patient, the hierarchy of genomic repeat instability signatures accurately reconstructs tumor evolution, with primary tumors differentiated from metastases. We observe an inverse relationship between repeat instability and point mutation load within and across patients independent of other somatic aberrations. Thus, repeat instability is a distinct, transient, and compensatory adaptive mechanism in tumor evolution and a potential signal for early detection.

Oncogenic Addiction to ERBB2 Signaling Predicts Response to Trastuzumab in Urothelial Cancer.

Urothelial carcinoma (UC) is a common and frequently lethal cancer. Despite the presence of genomic alterations creating dependency on particular signaling pathways, the use of targeted therapies in advanced and metastatic UC has been limited. We performed an integrated analysis of whole-exome and RNA sequencing of primary and metastatic tumors in a patient with platinum-resistant UC. We found a strikingly high ERBB2 mRNA expression and enrichment of downstream oncogenic ERBB2 signaling in this patient's tumors compared with tumors from an unselected group of patients with UC (N=17). This patient had an exceptional sustained response to trastuzumab. Our findings show that oncogenic addiction to ERBB2 signaling potentially predicts response to ERBB2-directed therapy of UC.

The molecular limitations of biomarker research in bladder cancer.

PURPOSE: Urothelial carcinoma of the bladder (UCB) is a common malignancy with limited systemic treatment options in advanced stages. Despite recent advances in immunotherapy, the majority of patients do not respond to these treatments. There is an unmet need for developing robust biomarkers to inform treatment decisions and identify patients who are likely to respond. METHODS: A MEDLINE/PubMed literature search was performed, focusing on tissue-based and circulating biomarkers, and their potential in muscle-invasive UCB. RESULTS: UCB is a heterogeneous disease that consists of several clonal and subclonal populations, each with a mix of truncal and private genomic alterations. This inter- and intra-tumoral heterogeneous landscape results in the development of treatment resistance. Tumor heterogeneity also constitutes a barrier to the development of robust markers of response and resistance to chemotherapy and immunotherapy. Defects in DNA repair genes and a high tumor mutational burden independently confer sensitivity to cisplatin-based chemotherapy and checkpoint inhibitors. Oncogenic alterations such as FGFR3 mutations and fusions are associated with response to FGFR3 inhibitors. Several emerging potential biomarkers, including gene expression-based molecular subtypes, T-cell receptor clonality, and tissue- or blood-based immune-gene profiling, require prospective testing and validation. Tissue-based biomarkers such as PD-L1 immunohistochemistry have several limitations due to discordance in assay methodology and trial designs. Novel liquid-biopsy techniques are promising as potential biomarkers. CONCLUSIONS: Validated biomarkers that capture the complexity of the biology of both the tumor and the tumor microenvironment are needed in muscle-invasive UCB. Standardization of methods is critical to developing reliable biomarkers to guide clinical management.

Characterization of metastatic urothelial carcinoma via comprehensive genomic profiling of circulating tumor DNA.

BACKGROUND: Biomarker-guided clinical trials are increasingly common in metastatic urothelial carcinoma (mUC), yet patients for whom contemporary tumor tissue is not available are not eligible. Technological advancements in sequencing have made cell-free circulating DNA (cfDNA) next-generation sequencing (NGS) readily available in the clinic. The objective of the current study was to determine whether the genomic profile of mUC detected by NGS of cfDNA is similar to historical tumor tissue NGS studies. A secondary objective was to determine whether the frequency of genomic alterations (GAs) differed between lower tract mUC (mLTUC) and upper tract mUC (mUTUC). METHODS: Patients from 13 academic medical centers in the United States who had a diagnosis of mUC between 2014 and 2017 and for whom cfDNA NGS results were available were included. cfDNA profiling was performed using a commercially available platform (Guardant360) targeting 73 genes. RESULTS: Of 369 patients with mUC, 294 were diagnosed with mLTUC and 75 with mUTUC. A total of 2130 GAs were identified in the overall mUC cohort: 1610 and 520, respectively, in the mLTUC and mUTUC cohorts. In the mLTUC cohort, frequently observed GAs were similar between cfDNA NGS and historical tumor tissue studies, including tumor protein p53 (TP53) (P = 1.000 and .115, respectively), AT-rich interaction domain 1A (ARID1A) (P = .058 and .058, respectively), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) (P = .058 and .067, respectively), erb-b2 receptor tyrosine kinase 2 (ERBB2) (P = .565 and .074, respectively), and fibroblast growth factor receptor 3 (FGFR3) (P = .164 and .014, respectively). No significant difference was observed with regard to the frequency of GAs between patients with mLTUC and mUTUC. CONCLUSIONS: Among patients with mUC for whom no tumor tissue was available, cfDNA NGS was able to identify a similar profile of GAs for biomarker-driven clinical trials compared with tumor tissue. Despite the more aggressive clinical course, cases of mUTUC demonstrated a circulating tumor DNA genomic landscape that was similar to that of mLTUC. Cancer 2018;124:2115-24. © 2018 American Cancer Society.

A combinatorial genetic strategy for exploring complex genotype-phenotype associations in cancer.

Available genetically defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Here, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

FGFR Inhibition in Urothelial Carcinoma.

BACKGROUND AND OBJECTIVE: The 2024 US Food and Drug Administration approval of erdafitinib for the treatment of metastatic urothelial carcinoma (mUC) with FGFR3 alterations ushered in the era of targeted therapy for bladder cancer. In this review, we summarize the effects of FGFR pathway alterations in oncogenesis, clinical data supporting FGFR inhibitors in the management of bladder cancer, and the challenges that remain. METHODS: Original articles relevant to FGFR inhibitors in urothelial cancer between 1995 and 2024 were systematically identified in the PubMed and MEDLINE databases using the search terms "FGFR" and "bladder cancer". An international expert panel with extensive experience in FGFR inhibitor treatment was convened to synthesize a collaborative narrative review. KEY FINDINGS AND LIMITATIONS: Somatic FGFR3 alterations are found in up to 70% of low-grade non-muscle-invasive bladder cancers; these activate downstream signaling cascades and culminate in cellular proliferation. Beyond a link to lower-grade/lower-stage tumors, there is little consistency regarding whether these alterations confer prognostic risks for cancer recurrence or progression. FGFR3-altered tumors have been linked to a non-inflamed tumor microenvironment, but paradoxically do not seem to impact the response to systemic immunotherapy. Several pan-FGFR inhibitors have been investigated in mUC. With the introduction of novel intravesical drug delivery systems, FGFR inhibitors are poised to transform the therapeutic landscape for early-stage UC. CONCLUSIONS AND CLINICAL IMPLICATIONS: With deepening understanding of the biology of bladder cancer, novel diagnostics, and improved drug delivery methods, we posit that FGFR inhibition will lead the way in advancing precision treatment of bladder cancer.

Novel Use of Circulating Tumor DNA to Identify Muscle-invasive and Non-organ-confined Upper Tract Urothelial Carcinoma.

BACKGROUND: Optimal patient selection for neoadjuvant chemotherapy prior to surgical extirpation is limited by the inaccuracy of contemporary clinical staging methods in high-risk upper tract urothelial carcinoma (UTUC). OBJECTIVE: To investigate whether the detection of plasma circulating tumor DNA (ctDNA) can predict muscle-invasive (MI) and non-organ-confined (NOC) UTUC. DESIGN, SETTING, AND PARTICIPANTS: Plasma cell-free DNA was prospectively collected from chemotherapy-naïve, high-risk UTUC patients undergoing surgical extirpation and sequenced using a 152-gene panel and low-pass whole-genome sequencing. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: To test for concordance, whole-exome sequencing was performed on matching tumor samples. The performance of ctDNA for predicting MI/NOC UTUC was summarized using the area under a receiver-operating curve, and a variant count threshold for predicting MI/NOC disease was determined by maximizing Youden's J statistic. Kaplan-Meier methods estimated survival, and Mantel-Cox log-rank testing assessed the association between preoperative ctDNA positivity and clinical outcomes. RESULTS AND LIMITATIONS: Of 30 patients enrolled prospectively, 14 were found to have MI/NOC UTUC. At least one ctDNA variant was detected from 21/30 (70%) patients, with 52% concordance with matching tumor samples. Detection of at least two panel-based molecular alterations yielded 71% sensitivity at 94% specificity to predict MI/NOC UTUC. Imposing this threshold in combination with a plasma copy number burden score of >6.5 increased sensitivity to 79% at 94% specificity. Furthermore, the presence of ctDNA was strongly prognostic for progression-free survival (PFS; 1-yr PFS 69% vs 100%, p < 0.001) and cancer-specific survival (CSS; 1-yr CSS 56% vs 100%, p = 0.016). CONCLUSIONS: The detection of plasma ctDNA prior to extirpative surgery was highly predictive of MI/NOC UTUC and strongly prognostic of PFS and CSS. Preoperative ctDNA demonstrates promise as a biomarker for selecting patients to undergo neoadjuvant chemotherapy prior to nephroureterectomy. PATIENT SUMMARY: Here, we show that DNA from upper tract urothelial tumors can be detected in the blood prior to surgical removal of the kidney or ureter. This circulating tumor DNA can be used to predict that upper tract urothelial carcinoma is invasive into the muscular lining of the urinary tract and may help identify those patients who could benefit from chemotherapy prior to surgery.

The evolution of metastatic upper tract urothelial carcinoma through genomic-transcriptomic and single-cell protein markers analysis.

The molecular characteristics of metastatic upper tract urothelial carcinoma (UTUC) are not well understood, and there is a lack of knowledge regarding the genomic and transcriptomic differences between primary and metastatic UTUC. To address these gaps, we integrate whole-exome sequencing, RNA sequencing, and Imaging Mass Cytometry using lanthanide metal-conjugated antibodies of 44 tumor samples from 28 patients with high-grade primary and metastatic UTUC. We perform a spatially-resolved single-cell analysis of cancer, immune, and stromal cells to understand the evolution of primary to metastatic UTUC. We discover that actionable genomic alterations are frequently discordant between primary and metastatic UTUC tumors in the same patient. In contrast, molecular subtype membership and immune depletion signature are stable across primary and matched metastatic UTUC. Molecular and immune subtypes are consistent between bulk RNA-sequencing and mass cytometry of protein markers from 340,798 single cells. Molecular subtypes at the single-cell level are highly conserved between primary and metastatic UTUC tumors within the same patient.

Urine Biopsy as Dynamic Biomarker to Enhance Clinical Staging of Bladder Cancer in Radical Cystectomy Candidates.

PURPOSE: There is significant interest in identifying complete responders to neoadjuvant chemotherapy (NAC) before radical cystectomy (RC) to potentially avoid removal of a pathologically benign bladder. However, clinical restaging after NAC is highly inaccurate. The objective of this study was to develop a next-generation sequencing-based molecular assay using urine to enhance clinical staging of patients with bladder cancer. METHODS: Urine samples from 20 and 44 patients with bladder cancer undergoing RC were prospectively collected for retrospective analysis for molecular correlate analysis from two clinical trials, respectively. The first cohort was used to benchmark the assay, and the second was used to determine the performance characteristics of the test as it correlates to responder status as measured by pathologic examination. RESULTS: First, to benchmark the assay, known mutations identified in the tissue (MT) of patients from the Accelerated Methotrexate, Vinblastine, Doxorubicin, Cisplatin trial (ClinicalTrials.gov identifier: NCT01611662, n = 16) and a cohort from University of California-San Francisco (n = 4) were cross referenced against mutation profiles from urine (MU). We then determined the correlation between MU persistence and residual disease in pre-RC urine samples from a second prospective clinical trial (The pT0 trial; ClinicalTrials.gov identifier: NCT02968732). Residual MU status correlated strongly with residual disease status (pT0 trial; n = 44; P = .0092) when MU from urine supernatant and urine pellet were assessed separately and analyzed in tandem. The sensitivity, specificity, PPV, and NPV were 91%, 50%, 86%, and 63% respectively, with an overall accuracy of 82% for this second cohort. CONCLUSION: MU are representative of MT and thus can be used to enhance clinical staging of urothelial carcinoma. Urine biopsy may be used as a reliable tool that can be further developed to identify complete response to NAC in anticipation of safe RC avoidance.

The Cytidine Deaminase APOBEC3G Contributes to Cancer Mutagenesis and Clonal Evolution in Bladder Cancer.

Mutagenic processes leave distinct signatures in cancer genomes. The mutational signatures attributed to APOBEC3 cytidine deaminases are pervasive in human cancers. However, data linking individual APOBEC3 proteins to cancer mutagenesis in vivo are limited. Here, we showed that transgenic expression of human APOBEC3G promotes mutagenesis, genomic instability, and kataegis, leading to shorter survival in a murine bladder cancer model. Acting as mutagenic fuel, APOBEC3G increased the clonal diversity of bladder cancer, driving divergent cancer evolution. Characterization of the single-base substitution signature induced by APOBEC3G in vivo established the induction of a mutational signature distinct from those caused by APOBEC3A and APOBEC3B. Analysis of thousands of human cancers revealed the contribution of APOBEC3G to the mutational profiles of multiple cancer types, including bladder cancer. Overall, this study dissects the mutagenic impact of APOBEC3G on the bladder cancer genome, identifying that it contributes to genomic instability, tumor mutational burden, copy-number loss events, and clonal diversity. SIGNIFICANCE: APOBEC3G plays a role in cancer mutagenesis and clonal heterogeneity, which can potentially inform future therapeutic efforts that restrict tumor evolution. See related commentary by Caswell and Swanton, p. 487.

Immunotherapy in the Treatment of Localized Genitourinary Cancers.

Importance: A true revolution in the management of advanced genitourinary cancers has occurred with the discovery and adoption of immunotherapy (IO). The therapeutic benefits of IO were recently observed not to be solely confined to patients with disseminated disease but also in select patients with localized and locally advanced genitourinary neoplasms. Observations: KEYNOTE-057 demonstrated the benefit of pembrolizumab monotherapy for treating high-risk nonmuscle invasive bladder cancer unresponsive to bacillus Calmette-Guérin (BCG), resulting in recent US Food and Drug Administration approval. Furthermore, a current phase 3 trial (Checkmate274) demonstrated a disease-free survival benefit with the administration of adjuvant nivolumab vs placebo in muscle-invasive urothelial carcinoma after radical cystectomy. In addition, the recent highly publicized phase 3 KEYNOTE 564 trial demonstrated a recurrence-free survival benefit of adjuvant pembrolizumab in patients with high-risk localized/locally advanced kidney cancer. Conclusions and Relevance: The adoption and integration of IO in the management of localized genitourinary cancers exhibiting aggressive phenotypes are becoming an emerging therapeutic paradigm. Clinical oncologists and scientists should become familiar with these trials and indications because they are likely to dramatically change our treatment strategies in the months and years to come.

Combinatorial genetic strategy accelerates the discovery of cancer genotype-phenotype associations.

Available genetically-defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Herein, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

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.

Loss of function mutations in CDKN1A are permissive for APOBEC3-induced mutagenesis in urothelial carcinoma.

Mutagenic mechanisms that shape the genomic landscape and dysfunction of DNA repair converge to promote bladder tumorigenesis. A recent study by Arnoff and El-Deiry highlights the unique interactions between CDKN1A loss of function mutations, which play a key role in cell cycle regulation, modulating DNA repair, and inducing cell apoptosis and senescence, and APOBEC3-induced mutagenesis, the predominant contributor of mutations in urothelial carcinoma.

Recurrent exon-deleting activating mutations in AHR act as drivers of urinary tract cancer.

Bladder cancer has a high recurrence rate and low survival of advanced stage patients. Few genetic drivers of bladder cancer have thus far been identified. We performed in-depth structural variant analysis on whole-genome sequencing data of 206 metastasized urinary tract cancers. In ~ 10% of the patients, we identified recurrent in-frame deletions of exons 8 and 9 in the aryl hydrocarbon receptor gene (AHRΔe8-9), which codes for a ligand-activated transcription factor. Pan-cancer analyses show that AHRΔe8-9 is highly specific to urinary tract cancer and mutually exclusive with other bladder cancer drivers. The ligand-binding domain of the AHRΔe8-9 protein is disrupted and we show that this results in ligand-independent AHR-pathway activation. In bladder organoids, AHRΔe8-9 induces a transformed phenotype that is characterized by upregulation of AHR target genes, downregulation of differentiation markers and upregulation of genes associated with stemness and urothelial cancer. Furthermore, AHRΔe8-9 expression results in anchorage independent growth of bladder organoids, indicating tumorigenic potential. DNA-binding deficient AHRΔe8-9 fails to induce transformation, suggesting a role for AHR target genes in the acquisition of the oncogenic phenotype. In conclusion, we show that AHRΔe8-9 is a novel driver of urinary tract cancer and that the AHR pathway could be an interesting therapeutic target.

Tumor-Infiltrating Myeloid Cells Confer De Novo Resistance to PD-L1 Blockade through EMT-Stromal and Tgfß-Dependent Mechanisms.

SIGNIFICANCE: Most patients with bladder cancer do not respond to ICB targeting of the PD-L1 signaling axis. Our modeling applied a de novo resistance signature to show that tumor-infiltrating myeloid cells promote poor treatment response in a TGFß-dependent mechanism.

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.