769 Background: Cisplatin-based chemotherapy (CT) prior to radical cystectomy (RC) + perioperative anti-PDL1 improves pathologic complete response rates (pCR) and survival in MIBC with predominant UC. Outcomes are poorer in the 5-10% of MIBC with pure/predominant non-UC histology. Thus, optimizing neoadjuvant therapy for these patients (pts) is critical. Pembro monotherapy has induced promising pCR rates in histologic subtypes (PURE-01 trial). We hypothesized that aMVAC + pembro would be safe and effective for non-UC MIBC and conducted a single-center trial testing this combination in pts with pure/predominant non-UC MIBC. Methods: Pts with resectable MIBC (cT2-4a/N0-1) with pure/predominant non-UC histology and fit for CT and RC were treated with neoadjuvant pembro (200mg q3 weeks x 3) + aMVAC (q2 weeks x 4) with G-CSF. Primary endpoint was pCR rate. Secondary endpoints included toxicity, pathologic downstaging (

Adiposity reduction has cancer-specific and overall health benefits for patients with overweight or obesity. The indiscriminate loss of lean mass accompanying weight loss, however, remains a concern for older patients with cancer. Body composition was evaluated in the Prostate Cancer Active Lifestyle Study, a randomized controlled weight loss trial targeting caloric restriction and increased physical activity among patients with prostate cancer and overweight or obesity on active surveillance. Compared with control individuals, the intervention statistically significantly decreased total fat (-3.4%, 95% CI = -5.3% to -1.5%), android fat (-2.0%, 95% CI = -3.6% to -0.4%), and visceral adipose tissue mass (-613 g, 95% CI = -894 to -331 g) (all 2-sided P < .001), with no difference in lean mass (P = .70) and a statistically significant increase in lean mass to fat ratio (0.40, 95% CI = 0.06 to 0.73; 2-sided P = .02). Weight loss interventions incorporating diet and physical activity among patients with prostate cancer and overweight or obesity can yield statistically significant reductions in adiposity while limiting lean mass loss.

Background: The importance of lymph node dissection (LND) at the time of radical cystectomy for urothelial carcinoma (UC) is widely accepted despite known risks. The therapeutic benefits of LND for variant subtype bladder cancer (VBC), a heterogenous and distinct set of diseases, are not well established. We aim to characterize the impact of LND on overall survival across VBC subtypes. Methods: The National Cancer Database was queried for all cases of variant subtype bladder cancer managed with radical cystectomy between 2004 and 2020, using the International Classification of Disease-O-3 morphological codes. The cases were stratified by receipt of individual variant subtypes. The primary outcome was overall survival associated with pathologic nodal status and receipt of nodal dissection. A Kaplan–Meier analysis and Cox proportional hazards analysis were used for survival analyses. Results: A total of 30,911 patients with VBC that were managed with radical cystectomy were included in our analysis. The pNx rates ranged from 33.1% in the micropapillary subtype, 42.2% in the sarcomatoid subtype, 68.4% in the squamous subtype, 48.9% in the adenocarcinoma subtype, and 56.2% in the neuroendocrine subtype. The median OS was higher in those that received a nodal dissection across subtypes but was statistically significant only for the squamous (71.0 [68.0 vs. 74.0] vs. 37.2 [33.6 vs. 40.9] months p < 0.001) and adenocarcinoma (45.9 [32.9 vs. 59.0] vs. 37.9 [28.6 vs. 47.1] months p = 0.037) subtypes. Using Cox proportional hazards regression, LN dissection was associated with improved OS for the squamous (0.50 (0.44–0.58) p < 0.001) and adenocarcinoma (0.65 [0.45–0.93) p = 0.030) subtypes. Conclusions: The role of LND across VBC subtypes is not clearly defined and warrants further investigation to develop a more risk-adaptive approach. We demonstrate heterogeneity with respect to the OS benefit associated with LND at the time of surgery. Among certain VBC subtypes, LND may not offer a significant therapeutic benefit, while LND in squamous and adenocarcinoma VBCs is correlated with improved survival.

Introduction Arsenic is a naturally occurring carcinogen with the potential to contaminate drinking water. Exposure to arsenic through drinking water has been implicated in many malignancies; notably, a strong association exists between arsenic and bladder cancer, with prostate and kidney cancer being implicated as well. Therefore, in 2000, the U.S. Environmental Protection Agency (EPA) proposed a new limit to arsenic levels in water, a proposal that ultimately was accepted in 2001 and limited arsenic from 50 parts per billion (ppb) to 10 ppb.Although this legislation has reduced levels of arsenic in drinking water, there remains concern that the 10ppb cutoff is not stringent enough. Many studies have suggested deleterious effects of arsenic exposure even at low levels. We therefore sought to describe the impact of the EPA legislation, and whether low levels (<10ppb) of arsenic are associated with incident bladder, prostate and kidney cancers within the state of Washington. Methods We conducted a retrospective ecological study to explore the association between arsenic levels in drinking water and the incidence of bladder, prostate and kidney cancers in Washington State. We reviewed all arsenic tests from public water systems (PWS) in Washington between 2000 – 2018, as documented by the Washington State Department of Health. These PWS serve approximately 85% of the state's population and includes water systems serving more than two residences.To estimate average arsenic levels by county, we compared the geographic regions served by each PWS with county boundaries. We then obtained county-specific cancer incidence data for bladder, prostate and kidney cancers diagnosed between 2014 – 2018 from the Washington State Department of Health. These years were selected to account for an adequate latency period following arsenic exposure.We used multivariable Poisson regression to estimate adjusted incidence rate ratios, evaluating potential associations between arsenic exposure and cancer risk. Results Between 2000-2018, we analyzed 46,476 unique arsenic measurements from drinking water across Washington State. County-level annual average arsenic concentrations ranged from 2 ppb - 7.5 ppb, with no counties exceeding the EPA standard of 10 ppb (Figure 1A). The weighted mean arsenic level across all counties was 3.76 ppb (SD 1.06). From 2014-2018, there were 19,342 prostate, 8,073 bladder, and 6,727 kidney cancer cases diagnosed (Figure 1B).We found a statistically significant association between arsenic exposure and the incidence of bladder and prostate cancers (Table 1). Compared to the lowest arsenic exposure quartile, those in the 3rd and 4th quartiles had a 1.15x (95% CI 1.08-1.24) and 1.21x (95% CI 1.09-1.35) higher adjusted risk of bladder cancer, respectively, and a 1.11x (95% CI 1.06-1.16) and 1.20x (95% CI 1.12-1.29) higher risk of prostate cancer. No significant association was observed between arsenic exposure and kidney cancer. Conclusions To our knowledge, this is the first study to assess the impact of the EPA's arsenic regulation (<10 ppb) on the incidence of urologic cancers, and the first in Washington to explore the relationship between low arsenic levels and urologic cancer rates. Although all Washington counties remained below the 10 ppb threshold during the study period, we still observed a dose-dependent association between arsenic exposure and the incidence of prostate and bladder cancers. These findings suggest that the current EPA standard may not be stringent enough; even lower arsenic concentrations in drinking water may be necessary to mitigate the risk of these cancers.

Objectives Upper tract urothelial carcinoma (UTUC) is an aggressive disease that is challenging to biopsy and diagnose, frequently yielding nondiagnostic cytology and tissue specimens. Therefore, UTUC is often late stage when diagnosed, with poor outcomes. Cell-free tumor DNA (cfDNA) may improve UTUC early diagnosis and assessments of heterogeneity, treatment response, and recurrence but has not been studied in the urine from patients with UTUC. This study aimed to detect recurrent, diagnostic UTUC cytogenetic abnormalities by low-pass whole genome sequencing (LPWGS) and to compare urine-derived and plasma cfDNA against abnormalities identified in patient tumor tissue. Methods Cell-free tumor DNA extracted from voided urine and plasma before nephroureterectomy in 4 patients with UTUC was compared with genomic DNA from formalin-fixed, paraffin-embedded tumor tissue after LPWGS. Results Abnormal autosomal genomic regions were highest in tissue (n = 11,843), intermediate in urine (n = 5,072) and lowest in plasma (n = 763), with a high concordance of flagged regions identified in tissue and urine (r = 0.88). Pairwise analysis of whole chromosome gains/losses and subchromosomal alterations between tissue and urine showed nearly identical patterns in all 4 patients (r = 0.88-0.99) in contrast to plasma (r < 0.25). Abnormal genomic regions identified by LPWGS showed a high degree of overlap (100% for tumor tissue, 94% for urine cfDNA) with cBioPortal UTUC-associated genes. Conclusions We demonstrated the superiority of urine vs plasma cfDNA when LPWGS was used to identify UTUC-associated gene abnormalities. Voided urine cfDNA molecular signatures are highly concordant with matched tumor tissue on chromosomal and subchromosomal levels, emphasizing its feasibility as a noninvasive biomarker for UTUC detection and surveillance.

Metastatic bladder cancer (BLCA) is an aggressive disease complicated by the emergence of variant histological subtypes and variable responses to treatment. Understanding the heterogeneity that exists both between these histological subtypes and within individual BLCA tumors is imperative in advancing precision medicine for BLCA. The University of Washington/Fred Hutchinson Cancer Center metastatic BLCA rapid autopsy program is a first-of-its-kind program collecting both primary and metastatic tumor samples from advanced BLCA patients, with a focus on aggressive variant subtype tumors. To explore intra-tumoral heterogeneity of both tumor and stromal compartments, single-nucleus RNA sequencing, in combination with matching bulk DNA and RNA sequencing, was performed on 15 tumors from 9 patients. The resulting dataset totaled 39,888 cells across a variety of histological subtypes: conventional urothelial carcinoma (UC), UC with squamous differentiation (UCSD), and plasmacytoid UC (PUC). Our unique snRNAseq dataset, the first in either metastatic or variant subtype BLCA, was used to dissect genomic and transcriptomic heterogeneity within BLCA tumors. On a genomic level, we observe subclonal copy number variations (CNVs) in BLCA driver genes in almost all (8/9) patients. Furthermore, we observe varying levels of intra-tumoral transcriptomic heterogeneity, where metastatic survival time is positively associated with tumor heterogeneity. Despite this heterogeneity, particular pathways define the epithelial transcriptomics of variant histological subtypes, including the upregulation of cell cycle and DNA repair upregulated in PUC tumors, which is validated in both bulk RNA sequencing and immunohistochemistry of a larger UW/FH BLCA rapid autopsy cohort. Investigation of the tumor microenvironment revealed that PUC tumors may be more immune-hot than UC, with increased B- and T-cell infiltration, while UCSD tumors have immunosuppressive microenvironments enriched in tissue-associated macrophages. Interestingly, these differences across subtypes are supported by changes in inter-cellular signaling between epithelial and fibroblast cells and the immune cells. These findings lay the groundwork for development of precision medicines for histological subtypes in BLCA by revealing heterogeneity and immune microenvironments that underlie disease aggressiveness and therapeutic resistance. Samantha L. Schuster, Pushpa Itagi, Sonali Arora, Thomas Persse, Patricia C. Galipeau, John K. Lee, Robert B. Montgomery, Jonathan L. Wright, Petros Grivas, Funda Vakar-Lopez, Andrew C. Hsieh, Hung-Ming Lam, Gavin Ha. Histological subtypes of metastatic bladder cancer have distinct tumor microenvironments and high intratumoral heterogeneity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB468.

831 Background: Long non-coding RNA (lncRNA)-based genomic profiling has suggested utility to identify a distinct tumor subgroup corresponding to a favorable prognosis in patients with bladder cancer. Here, we further evaluate a genomic classifier in a cohort of patients undergoing radical cystectomy (RC). Methods: Transcriptome-wide expression profiling using Decipher Bladder was performed on TURBT samples from a cohort of patients with high grade, clinically organ confined (cTa-T2N0M0) UC who subsequently underwent RC without any neoadjuvant therapy (n=226). LncRNA-based luminal favorable status was determined using a previously developed genomic classifier. The primary endpoint was overall survival (OS) following surgery. Secondary endpoints included cancer-specific mortality and upstaging at RC. Results: In the study, 134 patients were clinical NMIBC (cTa/Tis/T1) and 92 patients were cT2. We identified 60 patients with luminal favorable subtype, all of which showed robust gene expression patterns associated with less aggressive bladder cancer biology. On MVA, patients with the luminal favorable subtype (vs. without) were significantly associated with lower odds of upstaging to pT3+ disease (OR [95% CI] 0.32 [0.12-0.82], p = 0.02), any upstaging (OR [95% CI] 0.41 [0.20-0.83], p = 0.01), and any upstaging and/or pN+ (OR [95% CI] 0.50 [0.25-1.00], p = 0.05). Luminal favorable bladder cancer was significantly associated with better OS (HR 0.33 [95% CI 0.15-0.74], p=0.007). Conclusions: This study validates the performance of the genomic classifier for identifying urothelial carcinomas with a luminal favorable subtype, harboring less aggressive tumor biology.

Recent deep learning frameworks in histopathology, particularly multiple instance learning (MIL) combined with pathology foundational models (PFMs), have shown strong performance. However, PFMs exhibit limitations on certain cancer or specimen types due to domain shifts - these cancer types were rarely used for pretraining or specimens contain tissue-based artifacts rarely seen within the pretraining population. Such is the case for transurethral resection of bladder tumor (TURBT), which are essential for diagnosing muscle-invasive bladder cancer (MIBC), but contain fragmented tissue chips and electrocautery artifacts and were not widely used in publicly available PFMs. To address this, we propose a simple yet effective domain-adaptive self-supervised adaptor (DA-SSL) that realigns pretrained PFM features to the TURBT domain without fine-tuning the foundational model itself. We pilot this framework for predicting treatment response in TURBT, where histomorphological features are currently underutilized and identifying patients who will benefit from neoadjuvant chemotherapy (NAC) is challenging. In our multi-center study, DA-SSL achieved an AUC of 0.77+/-0.04 in five-fold cross-validation and an external test accuracy of 0.84, sensitivity of 0.71, and specificity of 0.91 using majority voting. Our results demonstrate that lightweight domain adaptation with self-supervision can effectively enhance PFM-based MIL pipelines for clinically challenging histopathology tasks. Code is Available at https://github.com/zhanghaoyue/DA_SSL_TURBT.

865 Background: The detection of tumor-associated urinary DNA (uDNA) as a biomarker for non-muscle invasive bladder cancer (NMIBC) has shown promise, but is significantly limited in sensitivity due to replication errors inherent in next-generation sequencing (NGS). Duplex sequencing is an ultrasensitive/accurate sequencing technology which may provide a solution to this problem. We present a pilot study applying duplex sequencing technique to uDNA in NMIBC for use as a biomarker of recurrence. Methods: Urine samples from a total of 30 patients with NMIBC were collected following complete transurethral resection of bladder tumor and prior to intravesical therapy (pre-tx) and following six weeks of intravesical therapy (post-tx). Detection of ten commonly mutated NMIBC genes was carried out using next generation duplex sequencing. Results were correlated with recurrence of tumor. Results: Median age for our cohort was 71 [41, 88] and 80% were male. A total of 16 (53.3%) of the cohort experienced a recurrence within the first year, with a median time to recurrence of 10 months. Tumor-associated uDNA was successfully detected to variant allele fraction (VAF) below 0.001. Presence of any pathogenic variant in the pre-tx urine >0.006 VAF was associated with a 72.7% sensitivity and 78.9% specificity for recurrence within one year. The highest VAF of pathogenic variant in uDNA trended with time-to-relapse. Post-tx uDNA assessment did not correlate with recurrence. Further analysis is limited by small sample size. Conclusions: This pilot study demonstrates potential utility of ultrasensitive duplex sequencing on NMIBC uDNA in the detection of recurrence.

Introduction Cell-free DNA (cfDNA) has emerged as a promising liquid biopsy biomarker for various malignancies. In particular, voided urine cfDNA has shown potential as a biomarker within urothelial bladder cancer. With a specificity of 99.3% and sensitivity of 86.7% for detecting bladder cancer, urine cfDNA has proven superior to plasma cfDNA, making it the preferred biomarker in this context.Despite these advancements, studies of cfDNA within upper tract urothelial carcinoma (UTUC) are limited. The existing literature on UTUC cfDNA predominantly focuses on plasma-derived cfDNA, leaving voided urine cfDNA relatively unexplored. While it seems logical to extrapolate the benefits of urine cfDNA from bladder cancer to UTUC, this area has yet to be thoroughly investigated.Therefore, we utilized low-pass whole genome sequencing (LP-WGS) to detect genomic alterations in cfDNA from both urine and plasma samples of UTUC patients, with the goal of establishing urine cfDNA as a reliable biomarker for UTUC. Methods We prospectively enrolled four patients with known or suspected UTUC undergoing radical nephroureterectomy. We collected peripheral blood and voided urine samples from all patients preoperatively. CfDNA was isolated from urine and plasma using standard protocols. Genomic DNA was extracted from radical nephroureterectomy specimens and established as tissue DNA.Next-generation sequencing using LP-WGS was performed on all samples (urine, plasma, tissue) to a minimum depth of 0.1x. Sequenced reads were matched against the human reference genome (hg19). Via a custom-developed clinically validated bioinformatics pipeline, copy number alterations (CNAs) were identified – which are genomic regions of provided samples that deviated from the reference genome. CNAs of urine and plasma were matched against tissue samples, and differences in CNAs at the chromosomal and sub-chromosomal level were identified amongst all three samples. Statistical z-scores for CNAs were utilized to determine the magnitude of detected CNAs in urine and plasma cfDNA. Results Four patients underwent radical nephroureterectomy; final pathology was pT1N0 (n=2) and pT2Nx (n=2). All patients had preoperative voided urine cfDNA, preoperative plasma cfDNA and tumor tissue DNA available for analysis.At the chromosomal level, we observed that CNAs in urine cfDNA closely mirrored that of tissue. In contrast, there was low concordance between CNAs in plasma cfDNA and tissue. This discrepancy is illustrated in Figure 1. Pearson correlation coefficients of CNAs between urine cfDNA and tissue ranged from 0.873 to 0.997, indicating strong concordance. Conversely, the correlation coefficients for CNAs between plasma cfDNA and tissue were much lower, ranging from -0.242 to 0.213.On a sub-chromosomal level, a similar pattern of concordance was observed between urine cfDNA and tissue, with comparable aberrations detected in plasma cfDNA and tissue. Amplifications, deletions, and arm level gains/losses identified in tissue specimens were duplicated to a high level in matched urine cfDNA. Conclusions In this pilot study, we demonstrated that for upper tract urothelial carcinoma, copy number alterations (CNAs) of urine cfDNA closely mirrored that of tissue, on both the chromosomal and sub-chromosomal level. Conversely, this relationship between plasma cfDNA and tissue was not seen. Our findings also serve as proof of concept that UTUC can be detected in urine supernatant using LP-WGS. Taken together, these data suggest that urine cfDNA has the potential to serve as an accurate biomarker for UTUC, offering a less invasive yet equally informative approach to UTUC diagnosis and surveillance.

Muscle-invasive bladder cancer (MIBC) with histologic subtypes represents a clinical challenge because of poor responses to conventional therapies and under-representation in clinical trials. This single-center phase 2 trial evaluated the combination of neoadjuvant pembrolizumab and accelerated methotrexate, vinblastine, doxorubicin, and cisplatin (aMVAC) chemotherapy in patients with pure or predominant nonurothelial histologies. Seventeen patients were enrolled, with squamous differentiation being the most common variant. The primary endpoint, a pathologic complete response (pCR), was achieved in nine of 17 patients (53%), with an additional patient achieving ypTisN0 (downstaging rate 59%) and another achieving a clinical complete response. Grade ≥3 toxicities were observed in 47% of patients, primarily attributable to aMVAC. At median follow-up of 35 mo (range 11-48) the estimated 2-yr event-free survival (EFS) and overall survival rates were 64% (95% confidence interval 32-84%) and 79% (95% confidence interval 47-93%), respectively. Preliminary biomarker analysis did not reveal significant correlations between immune-cell subsets at baseline and pCR or EFS. These findings suggest that chemoimmunotherapy is a very promising approach for MIBC with histology subtypes. Larger studies are warranted to further refine therapeutic strategies.

Metastatic bladder cancer (mBLCA) exhibits significant heterogeneity at the genomic, transcriptomic, molecular, and epigenetic levels, contributing to challenges in diagnosis, prognosis, and treatment. While 75% of mBLCA cases are urothelial carcinomas, 25% show divergent differentiation with variant histological features. This work characterizes intra-patient and inter-patient heterogeneity through comprehensive genomic and transcriptomic analyses of a rapid autopsy cohort of 20 patients with multiple tumors, matched normal tissue, and cell-free DNA (cfDNA). Our findings provide critical insights into tumor heterogeneity, clonal evolution, metastatic seeding, and the tumor microenvironment. Using bioinformatics tools, we reconstructed clonal evolution trees from whole-genome sequencing (WGS) analysis of tumors and inferred migration patterns to determine metastatic seeding. COSMIC mutational signatures were examined to correlate histological subtypes with clinical history. Single-nucleus RNA sequencing (snRNA-seq) revealed cell types and transcriptional heterogeneity using the human protein atlas and known marker annotations. To investigate alterations and clonality in tumors and their matched cfDNA, we used custom methodologies to evaluate mutations, CNAs, SVs, and rearrangements. The clonal evolution trees and bulk RNA-seq highlight cisplatin resistance in the plasmacytoid urothelial carcinoma subtype, driven by upregulation of the DNA damage response pathway. Significant mutational heterogeneity (∼20-30% subclonal) emerges in later stages of tumor evolution, potentially contributing to therapy resistance. Additionally, a substantial proportion (60-70%) of structural variants arise later in tumor progression, particularly in driver genes. snRNA-seq revealed distinct clusters of epithelial cells, macrophages, fibroblasts, and other cell types. cfDNA analysis captured over 80% of subclonal deleterious tumor mutations in BLCA driver genes. Nucleosome profiling of cfDNA helps distinguish mBLCA from healthy samples and identify key transcription factors to differentiate between variants. This comprehensive study of mBLCA, leveraging a rapid autopsy dataset, uncovers critical insights into variant histologies across multiple omics layers. Integrating cfDNA analysis captures intra-patient and inter-patient tumor heterogeneity, providing a holistic view of clonal dynamics. By elucidating the patterns of clonal evolution, this work advances our understanding of tumor progression and establishes a foundation for precision therapies targeting adaptive and evolving clones. Pushpa Itagi, Samantha Schuster, Sonali Arora, Patricia Galipeau, Thomas Persse, Funda Vakar-Lopez, John K. Lee, Petros Grivas, Robert Montgomery, Jonathan Wright, Hung-Ming Lam, Andrew Hsieh, Gavin Ha. Deciphering heterogeneity and tumor evolution in bladder cancer using multi-omics and liquid biopsies from rapid autopsies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1241.

INTRODUCTION AND OBJECTIVES:Transurethral Resection of Bladder Tumor (TURBT) is a diagnostic staging procedure for bladder cancer (BC). Its pathologic interpretation may be limited by cautery artifact, lack of spatial orientation of tumor specimens, inter-pathologist variance in identifying subtypes, and sampling bias. Accurately identifying subtype histology (SH) on TURBT is critical for clinical decisions. We compared the agreement between TURBT and radical cystectomy (RC) pathology in patients with SH BC. METHODS:We examined TURBT and RC pathology of patients who underwent RC at our institution. We included patients with pure SH and mixed histologies in either TURBT or RC specimens. Cohen's kappa coefficient was used to determine the degree of agreement between TURBT and RC. RESULTS:From 1135 RC performed, 650 (57%) patients had SH in either TURBT or RC; 225 patients were (y)pT0 at the time of RC and 36 patients had rare histologies, leaving 389 patients for analysis. 172 (44%) patients had an exact match between TURBT and RC. We found a high level of agreement between TURBT and RC in pure non-UC histology (kappa range: 0.82-0.98). In contrast, we found substantial (sarcomatoid; kappa 0.70), moderate (squamous, glandular, plasmacytoid, small cell/neuroendocrine; kappa range: 0.42-0.55) and fair (micropapillary; kappa 0.38) concordance between TURBT and RC in patients with UC mixed with SH. CONCLUSIONS:We found variable levels of agreement of SH detection between TURBT and RC. Agreement was high in pure non-UC histology. Further, we found that NAT, completeness of TURBT, and >50% SH at TURBT are associated with the persistence of SH at RC. Future efforts are needed to develop reproducible diagnostic tools for accurate characterization of SH in UC.

HER2 is an oncogenic driver in multiple cancers and a predictive biomarker for HER2-targeted therapies. Although HER2-directed therapies like fam-trastuzumab deruxtecan are approved for HER2-positive breast and other solid tumors, the landscape of HER2 expression in advanced prostate cancer and urothelial carcinoma remains inadequately characterized. We evaluated HER2 protein expression in metastatic prostate cancer and urothelial carcinoma using a validated IHC assay on tissue microarrays constructed from the University of Washington Tissue Acquisition Necropsy Program. HER2 expression was scored using standardized gastric cancer criteria. Genomic analysis of ERBB2 alterations was conducted on a subset of samples. HER2 expression heterogeneity and its relationship with other surface markers were also evaluated. In the prostate cancer cohort (n = 52 patients, 1-19 tumors per patient), HER2 expression was low, with no 3+ expression observed and only five (10%) patients exhibiting 2+ expression. Low-level ERBB2 copy-number gains were observed in some tumors but did not correlate with HER2 protein expression (P = 0.2). In urothelial carcinoma (n = 20, 2-6 tumors per patient), HER2 expression was more frequent, with ≥2+ expression observed in six (30%) cases and 3+ expression observed in three (15%) cases in at least one tumor. Urothelial carcinoma samples showed less heterogeneity, with more consistent expression across metastases. HER2 overexpression is rare and heterogeneous in metastatic prostate cancer, limiting its utility as a therapeutic target. HER2 expression is more prevalent and uniform in urothelial carcinoma. These findings underscore the importance of comprehensive HER2 assessment in advanced urothelial carcinoma and suggest that success of HER2-directed therapies in prostate cancer will require careful case selection. SIGNIFICANCE:This study demonstrates that HER2 is rarely overexpressed in metastatic prostate cancer but is more common and consistent in urothelial carcinoma. These findings highlight the need for HER2 testing in urothelial cancer and suggest that HER2-targeted therapies in prostate cancer will require careful patient selection.

Background: Active surveillance (AS) is increasingly used to monitor patients with lower risk prostate cancer (PCa). The Prostate Cancer Active Lifestyle Study (PALS) was a randomized controlled trial to determine whether weight loss improves obesity biomarkers on the causal pathway to progression in patients with PCa on AS. Methods: Overweight/obese men (body mass index >25 kg/m2) diagnosed with PCa who elected AS were recruited. The intervention was a 6-month, individually delivered, structured diet and exercise program adapted from the Diabetes Prevention Program with a 7% weight loss goal from baseline. Control participants attended one session reviewing the US Dietary and Physical Activity Guidelines. The primary outcome was change in glucose regulation from baseline to the end of the 6-month intervention, which was measured by fasting plasma glucose, C-peptide, insulin, insulin-like growth factor 1, insulin-like growth factor binding protein-3, adiponectin, and homeostatic model assessment for insulin resistance. Results: Among 117 men who were randomized, 100 completed the trial. The mean percentage weight loss was 7.1% and 1.8% in the intervention and control arms, respectively (adjusted between-group mean difference, -6.0 kg; 95% confidence interval, -8.0, -4.0). Mean percentage changes from baseline for insulin, C-peptide, and homeostatic model assessment for insulin resistance in the intervention arm were -23%, -16%, and -25%, respectively, compared with +6.9%, +7.5%, and +6.4%, respectively, in the control arm (all p for intervention effects <= .003). No significant between-arm differences were detected for the other biomarkers. Conclusions: Overweight/obese men with PCa undergoing AS who participated in a lifestyle-based weight loss intervention successfully met weight loss goals with this reproducible lifestyle intervention and experienced improvements in glucose-regulation biomarkers associated with PCa progression.

Abstract Background: Bladder Cancer is a highly prevalent cancer with staggering mortality of about 20%. Metastatic BLCA (mBLCA) with variant histologies are aggressive and have a poor prognosis. The extent and impact of tumor heterogeneity in these variant subtypes are not fully understood. This work explores the intricate characterization of intra-patient and inter-patient tumor heterogeneity through genomic and transcriptomic analyses, drawing insights from a unique rapid autopsy cohort comprising 20 patients. The resulting revelations provide critical perspectives on heterogeneity and clonal evolution in mBLCA, underscoring the essential role of understanding these dynamics for the development of personalized treatment strategies. Approach: Our research focuses on the genetic and molecular characteristics of these tumors, including the vast landscape of tumor heterogeneity, clonal evolution, genomic alterations, mutational signatures, and structural variants. Within the tumor microenvironment, we identified diverse cell populations with distinct genetic profiles. A detailed examination of mutational signatures sheds light on the specific processes underlying genetic alterations, while the investigation of structural variants elucidates their consequential role in cancer development and progression. Advanced bioinformatics tools are deployed to process and interpret the vast genomic and transcriptomic datasets, facilitating the identification of clonal populations, their genetic features, and the trajectory of clonal evolution. Furthermore, statistical models are employed to discern correlations between mutational signatures, treatment responses, and clinical outcomes. Summary: The study unveils substantial inter-patient heterogeneity and discernible differences in mutational signatures, revealing intriguing correlations with treatment responses. These variations are intricately connected to underlying genomic alterations, copy number alterations, and gene expression patterns, offer a detailed perspective on the molecular landscape of mBLCA. Conclusion: This multi-omics exploration stands as the most extensive study of its kind, leveraging rapid autopsy samples of metastatic variant histology BLCA. The research provides unprecedented resolution of genomic alterations and intra- and inter-patient tumor heterogeneity. The exploration of clonal evolution enhances our appreciation of the temporal dynamics of tumor progression, establishing a robust foundation for future therapeutic interventions precisely targeting evolving tumor clones. As we advance into an era of personalized medicine, these findings pave the way for tailored therapeutic strategies in the challenging landscape of metastatic variant histology Bladder Cancer. Citation Format: Pushpa Itagi, Sonali Arora, Thomas Persse, Michael Yang, Patricia Galipeau, Yixin Lin, Funda Vakar-Lopez, John K. Lee, Petros Grivas, Robert B. Montgomery, Jonathan L. Wright, Hung-Ming Lam, Andrew Hsieh, Gavin Ha. Elucidating tumor evolution and heterogeneity in metastatic bladder cancer from rapid autopsies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1610.

TPS357 Background: Inherited (germline) pathogenic and likely pathogenic variants (gPV) in key genes associated with increased risk of prostate cancer (PrCa) now warrant more attentive prostate cancer screening in NCCN guidelines—e.g., BRCA2, HOXB13, ATM, BRCA1, MSH2, MSH6, PMS2, CHEK2 and TP53. In the case of BRCA2 and others, there is association with more aggressive PrCa. Despite this, early detection guidelines lack specific recommendations for carriers of these risk genes. Data from the international IMPACT study of a targeted PrCa screening program used a PSA threshold to biopsy of >3.0ng/mL and supports initiating screening at the age of 40y. However, questions remain, such as optimal PSA threshold for biopsy and management of suspected cancer risk genes. In the PATROL study, we offer a prospective early detection study for people at risk for PrCa due to known or suspected cancer risk genes, which also serves as infrastructure for engaging people at-risk for PrCa wishing to be proactive and as a framework to investigate novel biomarkers of early detection. Methods: PATROL is a multicenter, prospective study for people who are at known or suspected increased risk for PrCa due to carrying a gPV (e.g., BRCA2) to participate in a PrCa early detection study. The primary endpoint is to determine the positive predictive value of predefined age-directed PSA thresholds and prostate-specific imaging for biopsy. Other exploratory endpoints include characterizing clinico-pathologic characteristics of diagnosed PrCa, and understanding the impact of screening on patient-reported outcomes (e.g., anxiety and decisional regret). Biospecimens to be collected include germline DNA, urine, and tumor tissue to evaluate emerging clinical and research biomarkers. Key eligibility includes: people ≥40y who carry a gPV in an eligible gene, who have no prior diagnosis of PrCa, who do not have another active malignancy, and who provide informed consent. Study procedures include annual physical exam, PSA, and imaging per treating physician. In addition, study will collect annual clinical data, blood and urine, archival biopsy tissue, biomarkers (e.g., SelectMDx). Participants will undergo prostate biopsy per protocol recommendations: for any clinical concern, PSA >1.0 ng/mL if <50y; PSA >1.5 ng/mL if 50-59y; PSA >2.0 ng/mL if =/>60y). If PrCa is diagnosed, clinical care will be determined by the participant and their treating physician. If opting for active surveillance, study procedures will continue to be collected annually for 10 yrs or until definitive treatment. If/when opting for definitive treatment, study procedures will continue to be collected for one additional year. Long-term clinical PrCa outcomes will be collected annually until the study closes. Clinical trial information: NCT04472338 .