A plain language summary of the TROPHY-U-01 study: sacituzumab govitecan use in people with locally advanced or metastatic urothelial cancer.

WHAT IS THIS SUMMARY ABOUT?: Sacituzumab govitecan (brand name: TRODELVY®) is a new treatment being studied for people with a type of bladder cancer, called urothelial cancer, that has progressed to a locally advanced or metastatic stage. Locally advanced and metastatic urothelial cancer are usually treated with platinum-based chemotherapy. Metastatic urothelial cancer is also treated with immune checkpoint inhibitors. There are few treatment options for people whose cancer gets worse after receiving these treatments. Sacituzumab govitecan is a suitable treatment option for most people with urothelial cancer because it aims to deliver an anti-cancer drug directly to the cancer in an attempt to limit the potential harmful side effects on healthy cells. This is a summary of a clinical study called TROPHY-U-01, focusing on the first group of participants, referred to as Cohort 1. All participants in Cohort 1 received sacituzumab govitecan. WHAT ARE THE KEY TAKEAWAYS?: All participants received previous treatments for their metastatic urothelial cancer, including a platinum-based chemotherapy and a checkpoint inhibitor. The tumor in 31 of 113 participants became significantly smaller or could not be seen on scans after sacituzumab govitecan treatment; an effect that lasted for a median of 7.2 months. Half of the participants were still alive 5.4 months after starting treatment, without their tumor getting bigger or spreading further. Half of them were still alive 10.9 months after starting treatment regardless of tumor size changes. Most participants experienced side effects. These side effects included lower levels of certain types of blood cells, sometimes with a fever, and loose or watery stools (diarrhea). Side effects led 7 of 113 participants to stop taking sacituzumab govitecan. WHAT WERE THE MAIN CONCLUSIONS REPORTED BY THE RESEARCHERS?: The study showed that sacituzumab govitecan had significant anti-cancer activity. Though most participants who received sacituzumab govitecan experienced side effects, these did not usually stop participants from continuing sacituzumab govitecan. Doctors can help control these side effects using treatment guidelines, but these side effects can be serious. Clinical Trial Registration: NCT03547973 (ClinicalTrials.gov) (TROPHY-U-1).

A Phase 2 Trial of Nab-paclitaxel in Combination With Anti-PD1 Therapy in Advanced Urothelial Cancer.

PURPOSE: Immune checkpoint inhibitor therapy and nab-paclitaxel have each shown efficacy in platinum-refractory advanced urothelial cancer. We conducted a single-arm phase 2 trial of the combination of nab-paclitaxel and pembrolizumab in platinum-refractory or cisplatin-ineligible advanced urothelial cancer (NCT03240016). MATERIALS AND METHODS: Eligible patients had RECIST 1.1 measurable and cisplatin-ineligible or platinum-refractory advanced urothelial cancer. Patients received nab-paclitaxel at starting dose of 125 mg/m2 intravenously on days 1 and 8 and pembrolizumab 200 mg intravenously on day 1 in 21-day cycles until progression, intolerable toxicity, or death. Nab-paclitaxel was permitted to be discontinued after 6 cycles. The nab-paclitaxel starting dose was reduced to 100 mg/m2 after planned interim analysis. Primary end point was overall response rate by RECIST 1.1. Secondary end points included safety/toxicity, duration of response, progression-free survival), and overall survival. RESULTS: Between February 2018 and April 2021, 36 response-evaluable patients were enrolled. There was an equal split of platinum-refractory and cisplatin-ineligible patients. Confirmed overall response rate was 50.0% (18/36) including 3 complete and 15 partial responses; 31/36 patients experienced some tumor shrinkage. At a median follow-up of 19.7 months, median duration of response was 4.4 months (95% CI: 4.0-8.6), median progression-free survival 6.8 months (95% CI: 4.4-not reached), and median overall survival 18.2 months (95% CI: 10.6-not reached). Grade ≥3 adverse events occurred in 21/36 patients including fatigue (n=6) and anemia (n=4). Ten patients had immune-mediated adverse events. CONCLUSIONS: The combination of nab-paclitaxel and pembrolizumab exhibited promising activity in advanced urothelial cancer and warrants further study in this population. After reduction in nab-paclitaxel starting dose, no unanticipated or unexpected toxicities emerged.

TRIM29 promotes bladder cancer invasion by regulating the intermediate filament network and focal adhesion.

Bladder cancer is a common malignancy whose lethality is determined by invasive potential. We have previously shown that TRIM29, also known as ATDC, is transcriptionally regulated by TP63 in basal bladder cancers where it promotes invasive progression and metastasis, but the molecular events which promote invasion and metastasis downstream of TRIM29 remained poorly understood. Here we identify stimulation of bladder cancer migration as the specific role of TRIM29 during invasion. We show that TRIM29 physically interacts with K14 + intermediate filaments which in turn regulates focal adhesion stability. Further, we find that both K14 and the focal adhesion protein, ZYX are required for bladder cancer migration and invasion. Taken together, these results establish a role for TRIM29 in the regulation of cytoskeleton and focal adhesions during invasion and identify a pathway with therapeutic potential.

Intronic Cis-Element DR8 in hTERT Is Bound by Splicing Factor SF3B4 and Regulates hTERT Splicing in Non-Small Cell Lung Cancer.

Splicing of the hTERT gene to produce the full-length (FL) transcript is necessary for telomerase enzyme activity and telomere-dependent cellular immortality in the majority of human tumors, including non-small cell lung cancer (NSCLC) cells. The molecular machinery to splice hTERT to the FL isoform remains mostly unknown. Previously, we reported that an intron 8 cis-element termed "direct repeat 8" (DR8) promotes FL hTERT splicing, telomerase, and telomere length maintenance when bound by NOVA1 and PTBP1 in NSCLC cells. However, some NSCLC cells and patient tumor samples lack NOVA1 expression. This leaves a gap in knowledge about the splicing factors and cis-elements that promote telomerase in the NOVA1-negative context. We report that DR8 regulates FL hTERT splicing in the NOVA1-negative and -positive lung cancer contexts. We identified splicing factor 3b subunit 4 (SF3B4) as an RNA trans-factor whose expression is increased in lung adenocarcinoma (LUAD) tumors compared with adjacent normal tissue and predicts poor LUAD patient survival. In contrast to normal lung epithelial cells, which continued to grow with partial reductions of SF3B4 protein, SF3B4 knockdown reduced hTERT splicing, telomerase activity, telomere length, and cell growth in lung cancer cells. SF3B4 was also demonstrated to bind the DR8 region of hTERT pre-mRNA in both NOVA1-negative and -positive NSCLC cells. These findings provide evidence that DR8 is a critical binding hub for trans-factors to regulate FL hTERT splicing in NSCLC cells. These studies help define mechanisms of gene regulation important to the generation of telomerase activity during carcinogenesis. IMPLICATIONS: Manipulation of a core spliceosome protein reduces telomerase/hTERT splicing in lung cancer cells and results in slowed cancer cell growth and cell death, revealing a potential therapeutic strategy.

Computerized Decision Support for Bladder Cancer Treatment Response Assessment in CT Urography: Effect on Diagnostic Accuracy in Multi-Institution Multi-Specialty Study.

This observer study investigates the effect of computerized artificial intelligence (AI)-based decision support system (CDSS-T) on physicians' diagnostic accuracy in assessing bladder cancer treatment response. The performance of 17 observers was evaluated when assessing bladder cancer treatment response without and with CDSS-T using pre- and post-chemotherapy CTU scans in 123 patients having 157 pre- and post-treatment cancer pairs. The impact of cancer case difficulty, observers' clinical experience, institution affiliation, specialty, and the assessment times on the observers' diagnostic performance with and without using CDSS-T were analyzed. It was found that the average performance of the 17 observers was significantly improved (p = 0.002) when aided by the CDSS-T. The cancer case difficulty, institution affiliation, specialty, and the assessment times influenced the observers' performance without CDSS-T. The AI-based decision support system has the potential to improve the diagnostic accuracy in assessing bladder cancer treatment response and result in more consistent performance among all physicians.

TROPHY-U-01: A Phase II Open-Label Study of Sacituzumab Govitecan in Patients With Metastatic Urothelial Carcinoma Progressing After Platinum-Based Chemotherapy and Checkpoint Inhibitors.

PURPOSE: Patients with metastatic urothelial carcinoma (mUC) who progress on platinum-based combination chemotherapy (PLT) and checkpoint inhibitors (CPIs) have limited options that offer objective response rates (ORRs) of approximately 10% with a median overall survival (OS) of 7-8 months. Sacituzumab govitecan (SG) is a TROP-2-directed antibody-drug conjugate with an SN-38 payload that has shown preliminary activity in mUC. METHODS: TROPHY-U-01 (ClinicalTrials.gov identifier: NCT03547973) is a multicohort, open-label, phase II, registrational study. Cohort 1 includes patients with locally advanced or unresectable or mUC who had progressed after prior PLT and CPI. Patients received SG 10 mg/kg on days 1 and 8 of 21-day cycles. The primary outcome was centrally reviewed ORR; secondary outcomes were progression-free survival, OS, duration of response, and safety. RESULTS: Cohort 1 included 113 patients (78% men; median age, 66 years; 66.4% visceral metastases; median of three [range, 1-8] prior therapies). At a median follow-up of 9.1 months, the ORR was 27% (31 of 113; 95% CI, 19.5 to 36.6); 77% had decrease in measurable disease. Median duration of response was 7.2 months (95% CI, 4.7 to 8.6 months), with median progression-free survival and OS of 5.4 months (95% CI, 3.5 to 7.2 months) and 10.9 months (95% CI, 9.0 to 13.8 months), respectively. Key grade ≥ 3 treatment-related adverse events included neutropenia (35%), leukopenia (18%), anemia (14%), diarrhea (10%), and febrile neutropenia (10%), with 6% discontinuing treatment because of treatment-related adverse events. CONCLUSION: SG is an active drug with a manageable safety profile with most common toxicities of neutropenia and diarrhea. SG has notable efficacy compared with historical controls in pretreated mUC that has progressed on both prior PLT regimens and CPI. The results from this study supported accelerated approval of SG in this population.

A Randomized Phase II Study of Androgen Deprivation Therapy with or without Palbociclib in RB-positive Metastatic Hormone-Sensitive Prostate Cancer.

PURPOSE: Palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, blocks proliferation in a RB and cyclin D-dependent manner in preclinical prostate cancer models. We hypothesized that cotargeting androgen receptor and cell cycle with palbociclib would improve outcomes in patients with metastatic hormone-sensitive prostate cancer (mHSPC). PATIENTS AND METHODS: A total of 60 patients with RB-intact mHSPC were randomized (1:2) to Arm 1: androgen deprivation (AD) or Arm 2: AD + palbociclib. Primary endpoint was PSA response rate (RR) after 28 weeks of therapy. Secondary endpoints included safety, PSA, and clinical progression-free survival (PFS), as well as PSA and radiographic RR. Tumors underwent exome sequencing when available. Circulating tumor cells (CTC) were enumerated at various timepoints. RESULTS: A total of 72 patients with mHSPC underwent metastatic disease biopsy and 64 had adequate tissue for RB assessment. A total of 62 of 64 (97%) retained RB expression. A total of 60 patients initiated therapy (Arm 1: 20; Arm 2: 40). Neutropenia was the most common grade 3/4 adverse event in Arm 2. Eighty percent of patients (Arm 1: 16/20, Arm 2: 32/40; P = 0.87) met primary PSA endpoint ≤4 ng/mL at 28 weeks. PSA undetectable rate at 28 weeks was 50% and 43% in Arms 1 and 2, respectively (P = 0.5). Radiographic RR was 89% in both arms. Twelve-month biochemical PFS was 69% and 74% in Arms 1 and 2, respectively (P = 0.72). TP53 and PIK3 pathway mutations, 8q gains, and pretreatment CTCs were associated with reduced PSA PFS. CONCLUSIONS: Palbociclib did not impact outcome in RB-intact mHSPC. Pretreatment CTC, TP53 and PIK3 pathway mutations, and 8q gain were associated with poor outcome.

Multigene Profiling of Circulating Tumor Cells (CTCs) for Prognostic Assessment in Treatment-Naïve Metastatic Hormone-Sensitive Prostate Cancer (mHSPC).

The substantial biological heterogeneity of metastatic prostate cancer has hindered the development of personalized therapeutic approaches. Therefore, it is difficult to predict the course of metastatic hormone-sensitive prostate cancer (mHSPC), with some men remaining on first-line androgen deprivation therapy (ADT) for several years while others progress more rapidly. Improving our ability to risk-stratify patients would allow for the optimization of systemic therapies and support the development of stratified prospective clinical trials focused on patients likely to have the greatest potential benefit. Here, we applied a liquid biopsy approach to identify clinically relevant, blood-based prognostic biomarkers in patients with mHSPC. Gene expression indicating the presence of CTCs was greater in CHAARTED high-volume (HV) patients (52% CTChigh) than in low-volume (LV) patients (23% CTChigh; * p = 0.03). HV disease (p = 0.005, q = 0.033) and CTC presence at baseline prior to treatment initiation (p = 0.008, q = 0.033) were found to be independently associated with the risk of nonresponse at 7 months. The pooled gene expression from CTCs of pre-ADT samples found AR, DSG2, KLK3, MDK, and PCA3 as genes predictive of nonresponse. These observations support the utility of liquid biomarker approaches to identify patients with poor initial response. This approach could facilitate more precise treatment intensification in the highest risk patients.

MEK is a promising target in the basal subtype of bladder cancer.

While many resources exist for the drug screening of bladder cancer cell lines in 2D culture, it is widely recognized that screening in 3D culture is more representative of in vivo response. Importantly, signaling changes between 2D and 3D culture can result in changes to drug response. To address the need for 3D drug screening of bladder cancer cell lines, we screened 17 bladder cancer cell lines using a library of 652 investigational small-molecules and 3 clinically relevant drug combinations in 3D cell culture. Our goal was to identify compounds and classes of compounds with efficacy in bladder cancer. Utilizing established genomic and transcriptomic data for these bladder cancer cell lines, we correlated the genomic molecular parameters with drug response, to identify potentially novel groups of tumors that are vulnerable to specific drugs or classes of drugs. Importantly, we demonstrate that MEK inhibitors are a promising targeted therapy for the basal subtype of bladder cancer, and our data indicate that drug screening of 3D cultures provides an important resource for hypothesis generation.

Intraobserver Variability in Bladder Cancer Treatment Response Assessment With and Without Computerized Decision Support.

We evaluated the intraobserver variability of physicians aided by a computerized decision-support system for treatment response assessment (CDSS-T) to identify patients who show complete response to neoadjuvant chemotherapy for bladder cancer, and the effects of the intraobserver variability on physicians' assessment accuracy. A CDSS-T tool was developed that uses a combination of deep learning neural network and radiomic features from computed tomography (CT) scans to detect bladder cancers that have fully responded to neoadjuvant treatment. Pre- and postchemotherapy CT scans of 157 bladder cancers from 123 patients were collected. In a multireader, multicase observer study, physician-observers estimated the likelihood of pathologic T0 disease by viewing paired pre/posttreatment CT scans placed side by side on an in-house-developed graphical user interface. Five abdominal radiologists, 4 diagnostic radiology residents, 2 oncologists, and 1 urologist participated as observers. They first provided an estimate without CDSS-T and then with CDSS-T. A subset of cases was evaluated twice to study the intraobserver variability and its effects on observer consistency. The mean areas under the curves for assessment of pathologic T0 disease were 0.85 for CDSS-T alone, 0.76 for physicians without CDSS-T and improved to 0.80 for physicians with CDSS-T (P = .001) in the original evaluation, and 0.78 for physicians without CDSS-T and improved to 0.81 for physicians with CDSS-T (P = .010) in the repeated evaluation. The intraobserver variability was significantly reduced with CDSS-T (P < .0001). The CDSS-T can significantly reduce physicians' variability and improve their accuracy for identifying complete response of muscle-invasive bladder cancer to neoadjuvant chemotherapy.

TP63 isoform expression is linked with distinct clinical outcomes in cancer.

BACKGROUND: Half of muscle-invasive bladder cancer patients will relapse with metastatic disease and molecular tests to predict relapse are needed. TP63 has been proposed as a prognostic biomarker in bladder cancer, but reports associating it with clinical outcomes are conflicting. Since TP63 is expressed as multiple isoforms, we hypothesized that these conflicting associations with clinical outcome may be explained by distinct opposing effects of differential TP63 isoform expression. METHODS: Using RNA-Seq data from The Cancer Genome Atlas (TCGA), TP63 isoform-level expression was quantified and associated with clinical covariates (e.g. survival, stage) across 8,519 patients from 29 diseases. A comprehensive catalog of TP63 isoforms was assembled using gene annotation databases and de novo discovery in bladder cancer patients. Quantifications and un-annotated TP63 isoforms were validated using quantitative RT-PCR and a separate bladder cancer cohort. FINDINGS: DNp63 isoform expression was associated with improved bladder cancer patient survival in patients with a luminal subtype (HR = 0.89, CI 0.80-0.99, Cox p = 0.034). Conversely, TAp63 isoform expression was associated with reduced bladder cancer patient survival in patients with a basal subtype (HR = 2.35, CI 1.64-3.37, Cox p < 0.0001). These associations were observed in multiple TCGA disease cohorts and correlated with epidermal differentiation (DNp63) and immune-related (TAp63) gene signatures. INTERPRETATION: These results comprehensively define TP63 isoform expression in human cancer and suggest that TP63 isoforms are involved in distinct transcriptional programs with opposing effects on clinical outcome.

ATDC is required for the initiation of KRAS-induced pancreatic tumorigenesis.

Pancreatic adenocarcinoma (PDA) is an aggressive disease driven by oncogenic KRAS and characterized by late diagnosis and therapeutic resistance. Here we show that deletion of the ataxia-telangiectasia group D-complementing (Atdc) gene, whose human homolog is up-regulated in the majority of pancreatic adenocarcinoma, completely prevents PDA development in the context of oncogenic KRAS. ATDC is required for KRAS-driven acinar-ductal metaplasia (ADM) and its progression to pancreatic intraepithelial neoplasia (PanIN). As a result, mice lacking ATDC are protected from developing PDA. Mechanistically, we show ATDC promotes ADM progression to PanIN through activation of ß-catenin signaling and subsequent SOX9 up-regulation. These results provide new insight into PDA initiation and reveal ATDC as a potential target for preventing early tumor-initiating events.

ATDC mediates a TP63-regulated basal cancer invasive program.

Basal subtype cancers are deadly malignancies but the molecular events driving tumor lethality are not completely understood. Ataxia-telangiectasia group D complementing gene (ATDC, also known as TRIM29), is highly expressed and drives tumor formation and invasion in human bladder cancers but the factor(s) regulating its expression in bladder cancer are unknown. Molecular subtyping of bladder cancer has identified an aggressive basal subtype, which shares molecular features of basal/squamous tumors arising in other organs and is defined by activation of a TP63-driven gene program. Here, we demonstrate that ATDC is linked with expression of TP63 and highly expressed in basal bladder cancers. We find that TP63 binds to transcriptional regulatory regions of ATDC and KRT14 directly, increasing their expression, and that ATDC and KRT14 execute a TP63-driven invasive program. In vivo, ATDC is required for TP63-induced bladder tumor invasion and metastasis. These results link TP63 and the basal gene expression program to ATDC and to aggressive tumor behavior. Defining ATDC as a molecular determinant of aggressive, basal cancers may lead to improved biomarkers and therapeutic approaches.

A surgical orthotopic approach for studying the invasive progression of human bladder cancer.

The invasion of bladder cancer into the sub-urothelial muscle and vasculature are key determinants leading to lethal metastatic progression. However, the molecular basis is poorly understood, partly because of the lack of uncomplicated and reliable models that recapitulate the biology of locally invasive disease. We developed a surgical grafting technique, characterized by a simple, rapid, reproducible and high-efficiency approach, to recapitulate the pathobiological events of human bladder cancer invasion in mice. This technique consists of a small laparotomy and direct implantation of human cancer cells into the bladder lumen. Unlike other protocols, it does not require debriding of the urothelial lining, injection into the bladder wall, specialized imaging equipment, bladder catheterization or costly surgical equipment. With minimal practice, the procedure can be executed in <10 min. Tumors develop with a high take rate, and most cell lines exhibit local invasion within 4 weeks of implantation.

Diagnostic Accuracy of CT for Prediction of Bladder Cancer Treatment Response with and without Computerized Decision Support.

RATIONALE AND OBJECTIVES: To evaluate whether a computed tomography (CT)-based computerized decision-support system for muscle-invasive bladder cancer treatment response assessment (CDSS-T) can improve identification of patients who have responded completely to neoadjuvant chemotherapy. MATERIALS AND METHODS: Following Institutional Review Board approval, pre-chemotherapy and post-chemotherapy CT scans of 123 subjects with 157 muscle-invasive bladder cancer foci were collected retrospectively. CT data were analyzed with a CDSS-T that uses a combination of deep-learning convolutional neural network and radiomic features to distinguish muscle-invasive bladder cancers that have fully responded to neoadjuvant treatment from those that have not. Leave-one-case-out cross-validation was used to minimize overfitting. Five attending abdominal radiologists, four diagnostic radiology residents, two attending oncologists, and one attending urologist estimated the likelihood of pathologic T0 disease (complete response) by viewing paired pre/post-treatment CT scans placed side-by-side on an internally-developed graphical user interface. The observers provided an estimate without use of CDSS-T and then were permitted to revise their estimate after a CDSS-T-derived likelihood score was displayed. Observer estimates were analyzed with multi-reader, multi-case receiver operating characteristic methodology. The area under the curve (AUC) and the statistical significance of the difference were estimated. RESULTS: The mean AUCs for assessment of pathologic T0 disease were 0.80 for CDSS-T alone, 0.74 for physicians not using CDSS-T, and 0.77 for physicians using CDSS-T. The increase in the physicians' performance was statistically significant (P < .05). CONCLUSION: CDSS-T improves physician performance for identifying complete response of muscle-invasive bladder cancer to neoadjuvant chemotherapy.

3-D Cell Culture System for Studying Invasion and Evaluating Therapeutics in Bladder Cancer.

Bladder cancer is a significant health problem. It is estimated that more than 16,000 people will die this year in the United States from bladder cancer. While 75% of bladder cancers are non-invasive and unlikely to metastasize, about 25% progress to an invasive growth pattern. Up to half of the patients with invasive cancers will develop lethal metastatic relapse. Thus, understanding the mechanism of invasive progression in bladder cancer is crucial to predict patient outcomes and prevent lethal metastases. In this article, we present a three-dimensional cancer invasion model which allows incorporation of tumor cells and stromal components to mimic in vivo conditions occurring in the bladder tumor microenvironment. This model provides the opportunity to observe the invasive process in real time using time-lapse imaging, interrogate the molecular pathways involved using confocal immunofluorescent imaging and screen compounds with the potential to block invasion. While this protocol focuses on bladder cancer, it is likely that similar methods could be used to examine invasion and motility in other tumor types as well.

Targeted DNA and RNA Sequencing of Paired Urothelial and Squamous Bladder Cancers Reveals Discordant Genomic and Transcriptomic Events and Unique Therapeutic Implications.

BACKGROUND: Integrated molecular profiling has identified intrinsic expression-based bladder cancer molecular subtypes. Despite frequent histological diversity, robustness of subtypes in paired conventional (urothelial) and squamous components of the same bladder tumor has not been reported. OBJECTIVE: To assess the impact of histological heterogeneity on expression-based bladder cancer subtypes. DESIGN, SETTING, AND PARTICIPANTS: We performed clinically applicable, targeted DNA and/or RNA sequencing (multiplexed DNA and RNA sequencing [mxDNAseq and mxRNAseq, respectively]) on 112 formalin-fixed paraffin-embedded (FFPE) bladder cancer samples, including 12 cases with paired urothelial/squamous components and 21 bladder cancer cell lines. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Unsupervised hierarchical and consensus clustering of target gene expression enabled derivation of basal/luminal molecular subtyping. RESULTS AND LIMITATION: Across 21 bladder cancer cell lines, our custom mxRNAseq panel was highly concordant with whole transcriptome sequencing, and assessed targets robustly determined expression-based basal/luminal subtypes from The Cancer Genome Atlas data (in silico) and internally sequenced FFPE tissues. Frequent deleterious TP53 (56%) and activating hotspot PIK3CA (30%) somatic mutations were seen across 69 high-quality tissue samples. Potentially targetable focal ERBB2 (6%) or EGFR (6%) amplifications were also identified, and a novel subgene copy-number detection approach is described. Combined DNA/RNA analysis showed that focally amplified samples exhibit outlier EGFR and ERBB2 expression distinct from subtype-intrinsic profiles. Critically, paired urothelial and squamous components showed divergent basal/luminal status in three of 12 cases (25%), despite identical putatively clonal prioritized somatic genomic alterations. Limitations include lack of profiled paired normal tissues for formal somatic alteration determination, and the need for formal analytical and clinical validation. CONCLUSIONS: Our results support the feasibility of clinically relevant integrative bladder cancer profiling and challenge the intrinsic nature of expression subtypes in histologically diverse bladder cancers. PATIENT SUMMARY: A targeted RNA sequencing assay is capable of assessing gene expression-based subtypes in individual components of clinical bladder cancer tissue specimens. Different histological components of the same tumor may yield divergent expression profiles, suggesting that expression-based subtypes should be interpreted with caution in heterogeneous cancers.

GM-CSF Mediates Mesenchymal-Epithelial Cross-talk in Pancreatic Cancer.

UNLABELLED: Pancreatic ductal adenocarcinoma (PDA) is characterized by a dense stroma consisting of a prevalence of activated fibroblasts whose functional contributions to pancreatic tumorigenesis remain incompletely understood. In this study, we provide the first identification and characterization of mesenchymal stem cells (MSC) within the human PDA microenvironment, highlighting the heterogeneity of the fibroblast population. Primary patient PDA samples and low-passage human pancreatic cancer-associated fibroblast cultures were found to contain a unique population of cancer-associated MSCs (CA-MSC). CA-MSCs markedly enhanced the growth, invasion, and metastatic potential of PDA cancer cells. CA-MSCs secreted the cytokine GM-CSF that was required for tumor cell proliferation, invasion, and transendothelial migration. Depletion of GM-CSF in CA-MSCs inhibited the ability of these cells to promote tumor cell growth and metastasis. Together, these data identify a population of MSCs within the tumor microenvironment that possesses a unique ability, through GM-CSF signaling, to promote PDA survival and metastasis. SIGNIFICANCE: The role of stroma in pancreatic cancer is controversial. Here, we provide the first characterization of MSCs within the human PDA microenvironment and demonstrate that CA-MSCs promote tumorigenesis through the production of GM-CSF. These data identify a novel cytokine pathway that mediates mesenchymal-epithelial cross-talk and is amenable to therapeutic intervention. Cancer Discov; 6(8); 886-99. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 803.

Targeting PARP in Prostate Cancer: Novelty, Pitfalls, and Promise.

Metastatic prostate cancer remains a highly lethal disease with no curative therapeutic options. A significant subset of patients with prostate cancer harbor either germline or somatic mutations in DNA repair enzyme genes such as BRCA1, BRCA2, or ATM. Emerging data suggest that drugs that target poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) enzymes may represent a novel and effective means of treating tumors with these DNA repair defects, including prostate cancers. Here we will review the molecular mechanism of action of PARP inhibitors and discuss how they target tumor cells with faulty DNA repair functions and transcriptional controls. We will review emerging data for the utility of PARP inhibition in the management of metastatic prostate cancer. Finally, we will place PARP inhibitors within the framework of precision medicine-based care of patients with prostate cancer.

ATDC/TRIM29 Drives Invasive Bladder Cancer Formation through miRNA-Mediated and Epigenetic Mechanisms.

Bladder cancer is a common and deadly malignancy but its treatment has advanced little due to poor understanding of the factors and pathways that promote disease. ATDC/TRIM29 is a highly expressed gene in several lethal tumor types, including bladder tumors, but its role as a pathogenic driver has not been established. Here we show that overexpression of ATDC in vivo is sufficient to drive both noninvasive and invasive bladder carcinoma development in transgenic mice. ATDC-driven bladder tumors were indistinguishable from human bladder cancers, which displayed similar gene expression signatures. Clinically, ATDC was highly expressed in bladder tumors in a manner associated with invasive growth behaviors. Mechanistically, ATDC exerted its oncogenic effects by suppressing miR-29 and subsequent upregulation of DNMT3A, leading to DNA methylation and silencing of the tumor suppressor PTEN. Taken together, our findings established a role for ATDC as a robust pathogenic driver of bladder cancer development, identified downstream effector pathways, and implicated ATDC as a candidate biomarker and therapeutic target.