Evaluating the clinical, environmental, genetic, and genomic profile of men with early-onset aggressive prostate cancer (PCa)

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Background: Although PCa incidence has stabilized/decreased in most age groups, the incidence of metastatic disease has increased among men 50-69 years-old. The incidence of fatal PCa has decreased for most age groups, it has remained unchanged in men under 55 years-old. Studies have described genetic abnormalities in aggressive localized or end-stage PCa, but early-onset cases are not included or are under-represented. The primary objective of this study is to characterize the clinical, environmental, genetic and genomic features of high-risk advanced PCa. Methods: Study cohort includes men with PCa ≤ 60 years old with N1 or M1 stage at diagnosis or who develop metastases in 5-years after local therapy. Clinical (race, family history (Hx), environmental exposure), laboratory,/pathology, cell-free DNA germline analysis were collected. Primary/metastatic tumor tissue tested via the Tempus-Xe platform (DNA sequencing, whole transcriptome expression profiling, copy number analysis, comprehensive fusion gene analysis and calculation of tumor mutational burden). We report interim analysis. Results: Study completed accrual with 30 pts. Median age 55 years (41-60), 87% are white, 13% are black, 77% had a family Hx of malignancy in 1-6 family members, including 40% with family hx of PCa. Only 33% had Hx of smoking. Median Gleason score 9. Only 27% had nodal disease, and 73% had metastatic disease at diagnosis. Molecular data are available in 25 pts. Most common germline mutations: BRCA2 (12%), ATM (12%), RB1 (8%), MSH3 (8%) and MYBPC3 (8%). Most common somatic mutations:TP53 (40%), TMPRSS2-ERG fusion (32%), MUC4 (16%), PTEN (12%), C2CD4D (12%), SPOP (12%), OBSCN (12%), MXRA5 (12%), and MYO15A (12%). Microsatellite stability status was available in 15 pts and all were stable. Tumor mutational burden was low in all pts, ranging between 0.7 to 2.7 mutations/megabase. Conclusions: Our preliminary data suggest high rates of germline mutations in early onset lethal PCa. This aggressive subset of disease requires further studying to better characterize the underlying clinical/genomic factors driving this disease.

Association of molecular subtypes with pathologic response in a phase II study of co-expression extrapolation (COXEN) with neoadjuvant chemotherapy (NAC) for localized, muscle-invasive bladder cancer (SWOG S1314; NCT02177695)

5028

Background: Cisplatin-based NAC is recommended for patients with MIBC prior to radical cystectomy (RC) but the majority will not have a pathologic response. To identify responders the COXEN gene expression model with chemotherapy-specific scores (for DD-MVAC and GC) was developed and in a prospective rPII clinical trial (SWOG S1314) the GC score was associated with path downstaging in the pooled arms. We investigated RNA based molecular subtypes as additional predictive biomarkers for response to NAC in patients treated in S1314. Methods: Eligibility required cT2-T4a N0 M0, predominant urothelial, > 5 mm tumor, cisplatin eligible, and plan for RC and PLND. 237 patients were randomized between 4 cycles of ddMVAC and GC. Based on Affymetrix transcriptomic data used to assign COXEN scores, we determined subtypes using 3 classifiers: TCGA (k=5), Consensus (k=6), and MD Anderson (MDA; k=3). Primary objective was to assess subtype association with pathologic response to NAC in the pooled arms and to determine any association with COXEN. TCGA and Consensus classifiers were collapsed into 3 groups for ROC analyses. We tested whether each classifier contributed additional predictive power when added to a model based on pre-defined stratification factors (PS 0 vs. 1; T2 vs. T3, T4a). Results: 161 patients had adequate tissue and gene expression results, received at least 3 of 4 cycles of NAC and had pT-N response based on RC. Covariates were 78% PS=0, 89% T2, 84% male, median age 65, 51% randomized to ddMVAC, 49% GC with 33% pT0 and 52% downstaging. Although the TCGA 3 group classifier (Basal-Squamous (BS)/Neuronal, Luminal, Luminal infiltrated) and GC Coxen score yielded the largest AUCs (0.607, 0.610) for pT0 response, neither reached statistical significance (p=0.20, p=0.22). For downstaging (<pT2), the 3 category Consensus classifier (BS/NE-like, Luminal, Stroma-rich) significantly increased the AUC from 0.568 (strat factors alone) to 0.620 (p=0.044). The MDA classifier AUC was 0.640 and the GC Coxen score AUC was 0.626, but neither were significant (p=0.076, p=0.14. The MVAC Coxen score did not improve the AUC beyond the stratification factors. Conclusions: The Consensus classifier, which is based in part on the TCGA and MDA classifiers, modestly improved prediction for pathologic downstaging when added to clinical stage and PS. With additional followup, we will assess the association of COXEN scores and subtypes with overall survival. Clinical trial information: NCT02177695 .

Genomic heterogeneity in bladder cancer: challenges and possible solutions to improve outcomes

Histological and molecular analyses of urothelial carcinoma often reveal intratumoural and intertumoural heterogeneity at the genomic, transcriptional and cellular levels. Despite the clonal initiation of the tumour, progression and metastasis often arise from subclones that can develop naturally or during therapy, resulting in molecular alterations with a heterogeneous distribution. Variant histologies in tumour tissues that have developed distinct morphological characteristics divergent from urothelial carcinoma are extreme examples of tumour heterogeneity. Ultimately, heterogeneity contributes to drug resistance and relapse after therapy, resulting in poor survival outcomes. Mutation profile differences between patients with muscle-invasive and metastatic urothelial cancer (interpatient heterogeneity) probably contribute to variability in response to chemotherapy and immunotherapy as first-line treatments. Heterogeneity can occur on multiple levels and averaging or normalizing these alterations is crucial for clinical trial and drug design to enable appropriate therapeutic targeting. Identification of the extent of heterogeneity might shape the choice of monotherapy or additional combination treatments to target different drivers and genetic events. Identification of the lethal tumour cell clones is required to improve survival of patients with urothelial carcinoma.

Antibody targeting of B7-H4 enhances the immune response in urothelial carcinoma

Patients with locally advanced and metastatic urothelial carcinoma have a low survival rate (median 15.7 months, 13.1–17.8), with only a 23% response rate to monotherapy treatment with anti-PDL1 checkpoint immunotherapy. To identify new therapeutic targets, we profiled the immune regulatory signatures during murine cancer development using the BBN carcinogen and identified an increase in the expression of the T cell inhibitory protein B7-H4 (VTCN1, B7S1, B7X). B7-H4 expression temporally correlated with decreased lymphocyte infiltration. While the increase in B7-H4 expression within the bladder by CD11b⁺ monocytes is shared with human cancers, B7-H4 expression has not been previously identified in other murine cancer models. Higher expression of B7-H4 was associated with worse survival in muscle-invasive bladder cancer in humans, and increased B7-H4 expression was identified in luminal and luminal-papillary subtypes of bladder cancer. Evaluation of B7-H4 by single-cell RNA-Seq and immune mass cytometry of human bladder tumors found that B7-H4 is expressed in both the epithelium of urothelial carcinoma and CD68+ macrophages within the tumor. To investigate the function of B7-H4, treatment of human monocyte and T cell co-cultures with a B7-H4 blocking antibody resulted in enhanced IFN-γ secretion by CD4⁺ and CD8⁺ T cells. Additionally, anti-B7-H4 antibody treatment of BBN-carcinogen bladder cancers resulted in decreased tumor size, increased CD8⁺ T cell infiltration within the bladder, and a complimentary decrease in tumor-infiltrating T regulatory cells (Tregs). Furthermore, treatment with a combination of anti-PD-1 and anti-B7-H4 antibodies resulted in a significant reduction in tumor stage, a reduction in tumor size, and an increased level of tumor necrosis. These findings suggest that antibodies targeting B7-H4 may be a viable strategy for bladder cancers unresponsive to PD-1 checkpoint inhibitors.

Mutation signatures to Pan-Cancer Atlas: Investigation of the genomic landscape of muscle-invasive bladder cancer

The Cancer Genome Atlas (TCGA) for bladder cancer was published in 2014 with updated annotation of over 400 patients with muscle-invasive bladder cancer (MIBC) in 2017. This tremendous work established the foundation of the genomic landscape of MIBC. The next steps to utilize information from The Cancer Genome Atlas is to (1) identify the causes of mutation, (2) determine the significant differences and sources of heterogeneity, and (3) apply these tools toward patient care. In this review, we discuss the full spectrum of the genomic landscape of MIBC toward the goal of therapeutic application.

Contemporary Comparison of Open to Robotic Prostatectomy at a Veteran's Affairs Hospital

INTRODUCTION

Among veterans, prostate cancer is the most common malignancy and has a higher incidence compared to the rest of the nation. No study has compared the effectiveness of Robotic-assisted-laparoscopic radical prostatectomy (RALP) vs. open radical prostatectomy (ORP) in the Veteran's Affairs (VA) hospital setting during the adoption of RALP.

METHODS

Institutional Review Board approval was obtained. Retrospective review was completed on Veterans with prostate cancer who underwent ORP or RALP from March 2011 to January 2017 during the introduction of RALP at one VA hospital. Perioperative and functional outcomes between ORP and RALP were compared as well as between the initial 50 and final 53 RALPs.

RESULTS

Among 91 ORPs and 153 RALPs, RALP had significant reductions in blood transfusions [2(1.3%) vs. 44(40%), p < 0.001], length of stay [2 days(1-2) vs. 3 days(2-4), p < 0.001], Clavien grade >2 complications [1(0.7%) vs. 20 (22.0%), p < 0.001], urine leak [2(1.3%) vs. 11 (12.1%), p < 0.001], and ICU readmissions [0(0%) vs. 3(3.3%), p < 0.001]. There were no significant differences in positive margin status or functional outcomes. Compared to the first 50 cases, the last 53 RALPs demonstrated a shorter operative time (349 vs. 292 min, p < 0.001), lower EBL (300 vs. 150 mL, p < 0.001), more frequent 1-day length of stay (34% vs. 60%, p = 0.02), and fewer composite adverse events (82% vs. 51%, p = 0.004). Operative time for the final 53 RALPs (292 minutes) was shorter than that of ORP (325 minutes, p = 0.013).

CONCLUSIONS

During the introduction of RALP at one VA hospital, RALP was associated with several improved parameters compared to ORP and similar operative times were noted after the first 100 cases of RALPs. RALP is safe to introduce in a VA setting without compromising outcomes.

Development of a composite biomarker-based calculator to predict the probability of pathologic complete response (pT0) after neoadjuvant pembrolizumab (pembro) in muscle invasive bladder cancer (MIBC)

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Background: The PURE01 study (NCT02736266) evaluates the use of pembro before radical cystectomy (RC) in MIBC. We assessed selected individual and combined biomarkers for predicting pT0 response after pembro, and developed a tool that may be used as an aid for clinical decision-making. Methods: Patients (pts) enrolled in the PURE01 were clinical (c) stage T≤4aN0M0 MIBC. Analysis to date included a comprehensive genomic profiling (FoundationONE assay), programmed cell-death-ligand-1 (PD-L1) combined positive score assessment (CPS, Dako 22C3 antibody) and whole transcriptome (Decipher assay) and RNA-seq profiling of pre/post therapy samples. Multivariable logistic regression analyses (MVA) evaluated baseline cT-stage and biomarkers in association with pT0 response. Corresponding coefficients were used to develop a risk calculator based on the tumor mutational burden (TMB), CPS, Immune190 signature score, and cT-stage. Decision-curve analysis was performed. Results: Complete biomarker data was available for 84 pts. Increasing TMB, CPS, and Immune190 scores showed a linear positive correlation with the pT0 probability in logistic regression (p=0.02, p=0.004, p=0.02). The c-index of the risk calculator was 0.79. Decision-curve analysis found the net-benefit of the model was higher than the “treat-all” option within the clinically-meaningful threshold probabilities of achieving a pT0 of 40-60%. Within this range, adding the Immune190 score improved the model over TMB and CPS. A significant decrease in median TMB values was observed (p=0.005) in 24 matched RC, versus a non-significant change in median CPS in 38 matched RC. Molecular subtyping switching was observed in 20/31 matched cases (64.5%), most frequently to the luminal-infiltrated subtype (80%). Conclusions: The study presents the first composite biomarker-based pT0 probability calculator for optimal pt selection. Pending validation, the model may be used to recommend neoadjuvant pembro to very selected MIBC pts. The observed changes in biomarker features in post-therapy samples may have an impact on future adjuvant strategies. Clinical trial information: NCT02736266.

A pilot study of tazemetostat and MK-3475 (pembrolizumab) in advanced urothelial carcinoma (ETCTN 10183)

TPS607

Background: Few patients with metastatic urothelial carcinoma (UC) achieve a durable response despite early stabilization with chemotherapy or immunotherapy. Mutations in the COMPASS-related proteins KMT2D, KMT2C, and KDM6A are found in 66% of patients with UC, suggesting disruption of histone regulation may be an acquired mechanism of tumor viability. Using a carcinogen-derived mouse model of UC in which 80% of animals have alterations in Kmt2d, Kmt2d or both, we found regression of tumors when treated an enzymatic inhibitor of EZH2 (Tazemetostat). In vivo administration of Tazemetostat enhanced the immune response with more necrosis when combined with an anti-PD1 antibody. Therefore, we hypothesized that treatment of UC with an Tazemetostat may further improve the activity of immunotherapy as only 21% of cisplatin refractory (KN45) and 24% of cisplatin ineligible (KN52) patients achieve an objective response. We hypothesized that restoration of the epigenetic imbalance, combined with immunotherapy may improve survival in patients with metastatic UC. Methods: ETCTN10183 (NCT03854474) is a Phase I/II trial evaluating the efficacy of Tazemetostat at 800 mg BID + Pembrolizumab 200 mg IV every 3 weeks in patients with either cisplatin-refractory (Cohort A) or cisplatin-ineligible (Cohort B) metastatic UC. The safety lead-in portion of the trial will follow a “3+3” design with one dose de-escalation level (800mg or 600mg BID Tazemetostat) and will enroll 6-12 patients to establish the recommended phase II dose (RP2D) of Tazemetostat. All DLTs will be reviewed and if tolerated, two dose expansion cohorts will be initiated and will include 24 patients with 12 in each cohort (cisplatin refractory and ineligible). The primary objectives are to identify the RP2D of Tazemetostat in combination with Pembrolizumab, and secondary objectives are to determine the objective disease response in patients with either cisplatin-refractory or unresponsive UC per RECIST criteria, safety, tolerability and progression-free survival. Translational objectives include evaluation of tumor mutations in COMPASS genes, total mutation burden, T cell infiltration, TCR clonality, tumor subtyping and PD-L1 expression. Clinical trial information: NCT03854474.

INTACT: Phase III randomized trial of concurrent chemoradiotherapy with or without atezolizumab in localized muscle invasive bladder cancer—SWOG/NRG1806

TPS586

Background: Chemoradiotherapy(CRT) is a SOC for patients with muscle invasive bladder cancer (MIBC) who refuse or are not fit for radical cystectomy. Radiotherapy and chemotherapy are known to increases the PD-L1 expression in bladder cancer. Based on these observations, we hypothesized that addition of atezolizumab to CRT will increase its efficacy. Methods: This is a randomized phase III trial testing CRT with and without atezolizumab for 6 months in 475 patients with MIBC. Pts will be stratified on performance status (0-1 vs. 2); clinical stage (T2 vs T3/T4a, chemotherapy(cisplatin vs 5FU+mitomycin vs gemcitabine); and radiation field (bladder only vs small pelvis). Patients will undergo biopsy 18 week from registration. If they have residual disease they will be taken off protocol treatment and can proceed with alternative SOC option including radical cystectomy. Patients will be followed for 5 years. The primary end point of the study is bladder intact event –free survival (BIEFS). The event is comprised of: recurrence or residual muscle-invasive bladder cancer at 18 weeks or later, clinical evidence of nodal or metastatic disease, radical cystectomy, or death due to any cause. This composite endpoint is reflective of the intent of bladder preservation strategy with radical cystectomy included as one of the outcomes. Secondary end points include overall survival, modified event free survival, pathologic response at 18 weeks, metastasis free survival, cancer specific survival, rate of salvage cystectomy, rate of adverse event and QOL & PRO end points. The expected 3 year BIEFS for the control arm is 52%. The study leadership concluded that a 12% improvement in this endpoint is meaningful for this patient population. With a sample size of 475 patients the study has 85% power to detect the improvement from 52% to 64% in the BIEFS at 3 years (hazard ratio=0.68). The study team will perform translational studies evaluating tumor tissue, whole blood and urine for molecular and immunologic markers of immune response and response to RT. Successful completion of this trial could lead to a new treatment paradigm for patients with muscle invasive bladder cancer. Clinical trial information: NCT03775265.

Genomic and Therapeutic Landscape of Non-muscle-invasive Bladder Cancer

Non-muscle-invasive bladder cancer (NMIBC) is heterogeneous, but current diagnostic and treatment strategies rely primarily on clinical parameters, lacking individualization to tumor and host genetics and biology. The heterogeneity of NMIBCs is derived from mutations, mutation signatures, chromosomal loss, and disruption of molecular pathways, which ultimately affects tumor progression, recurrence, and responsiveness to intravesical and systemic chemotherapy. Although research is still underway, advances in sequencing technology, insight into differential bacillus Calmette-Guérin responses, and new investigational treatment targets will soon offer clinicians new, precision-based tools to risk stratify and determine treatment regimens for future patients with bladder cancer.

Molecular footprints of muscle-invasive bladder cancer in smoking and nonsmoking patients

BACKGROUND

Bladder cancer is the fifth most common cancer in the United States and smoking is the largest known risk factor. Tobacco-derived carcinogens may induce the accumulation of somatic mutations in urothelial cells, and likely promote tumorigenesis. However, it is still unknown whether smoking-induced bladder carcinogenesis results in tumors with distinctive molecular features that can be therapeutically exploited.

METHODS

We investigated the genomic alterations of human bladder cancer and examined their association with patient smoking history. We performed bioinformatic analyses and looked at differences in gene expression, somatic mutations, and DNA mutational signatures comparing nonsmokers, reformed smokers, and current smokers.

RESULTS

We detected a limited set of gene expression and gene mutation differences between smokers and nonsmokers. We also identified a specific mutational signature that is enriched in tumors from smokers. This mutational signature was described before and has been linked to specific DNA repair defects in human bladder tumors, as well as to the direct effect of nitrosamine carcinogens in the BBN murine model of bladder cancer.

CONCLUSION

We showed associations between smoking status and selected mutational signatures, which could provide insights in the biology of bladder carcinogenesis and tumor progression.

Abstract CT178: Prevalence of PD-L1 expression in 1st-line (1L) locally advanced/unresectable or metastatic urothelial carcinoma (UC)

Background: Treatments for 1L advanced, unresectable, or metastatic UC include platinum-based chemotherapy, immune checkpoint blockade, or clinical trial enrollment. Not all patients benefit from, or are eligible for, specific therapies due to comorbidities and performance status. There is an urgent need for biomarker-directed strategies to enable patient selection and improve outcomes. Currently the only clinically used molecular biomarker is programmed cell death ligand-1 (PD-L1) protein expression in tumor tissue. Although variably defined with different assays, higher PD-L1 expression generally correlates with increased response rates to immune checkpoint blockade. Improved understanding of the prevalence and potential prognostic role of PD-L1 testing can further enhance its clinical utility and guide novel clinical trial designs.

Methods: This observational study will enroll 250 patients diagnosed with advanced UC either prior to or during 1L therapy, as initiated at the discretion of participating clinicians from 60 US community sites. The primary endpoint is prevalence (with exact [Clopper-Pearson] 95% CI) of PD-L1 high expression by VENTANA SP263 Assay on pretreatment tumor tissue (classified as PD-L1 high if ≥25% of tumor cells [TCs] exhibit staining; or if immune cells [IC] present &gt;1% and IC with staining ≥25%; or IC present =1% and IC with staining =100%). Secondary endpoints include the association of pretreatment PD-L1 expression with pretreatment tumor tissue mutational burden (tTMB), descriptions of treatment response and outcomes (objective response rate based on RECIST 1.1, progressive-free survival [PFS], and overall survival [OS]) and assessment of their correlations with PD-L1 expression. Exploratory endpoints include the association of pretreatment tumor tissue PD-L1 with pretreatment blood-based tumor mutational burden (bTMB), changes in circulating tumor DNA levels, the correlation between tTMB and bTMB values, and the association of those biomarkers with PFS and OS. Enrollment will take place over 24 months. Patients will be followed for up to 30 months after enrollment. With 250 patients, the 95% CI for 30%, 45%, and 60% observed prevalence of PD-L1 high expression are (24.4%, 36.1%), (38.9%, 51.2%), and (53.6%, 66.1%), respectively; the various secondary and exploratory analyses will be descriptive.

Citation Format: Petros Grivas, Alicia K. Morgans, Yair Lotan, Jeffrey Gregg, Daniel Geynisman, Terence Friedlander, Piyush K. Agarwal, Marija Tesic-Schnell, Andrew Bernstein, Doris Makari, Joshua J. Meeks. Prevalence of PD-L1 expression in 1st-line (1L) locally advanced/unresectable or metastatic urothelial carcinoma (UC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT178.

A phase III, randomized, open label, multicenter, global study of efficacy and safety of durvalumab in combination with gemcitabine+cisplatin (G+C) for neoadjuvant treatment followed by durvalumab alone for adjuvant treatment in muscle-invasive bladder cancer (MIBC) (NIAGARA)

TPS4592

Background: Management of MIBC includes both surgery and systemic therapy. Neoadjuvant, cisplatin-based combination chemotherapy has demonstrated improved pathologic complete response (pCR), event-free survival (EFS), and OS compared with radical cystectomy alone. Many patients still develop recurrence, including progression to metastasis. Novel strategies such as combining chemotherapy and immunotherapy in a neoadjuvant setting and consolidating response post cystectomy in the adjuvant setting may improve clinical outcomes. Durvalumab is a selective, high affinity, engineered human IgG1 mAb that blocks PD-L1 binding to PD-1 and CD80. PD-L1 inhibition with durvalumab, in combination with a standard neoadjuvant regimen (G+C), may improve immune-mediated antitumor response and increase the rates of pathologic responses and long-term survival. Methods: NIAGARA (NCT03732677) is a Phase 3, randomized, open-label, multicenter, global study that will enroll ~1050 patients randomized (1:1) to durvalumab and G+C combination (Arm 1) or G+C (Arm 2) as neoadjuvant chemotherapy prior to radical cystectomy. Following radical cystectomy and during adjuvant therapy, patients in Arm 1 will receive durvalumab monotherapy for 8 cycles (8 months); patients in Arm 2 will receive no adjuvant treatment. Patients with resectable MIBC (clinical stage T2N0M0-T4aN0M0) with transitional cell histology planning to undergo a radical cystectomy will be included. Primary endpoints are pCR rates at time of cystectomy following neoadjuvant treatment and EFS. Secondary and exploratory endpoints include proportion of patients who achieve pathologic response <P2 (stages Pa, P1, and carcinoma in situ) at time of cystectomy following neoadjuvant treatment, EFS at 24 months, metastasis-free survival, proportion of patients who undergo cystectomy, and OS at 5 years. Safety, patient-reported outcomes, pharmacokinetics, immunogenicity, and biomarkers will also be assessed. Enrollment opened in Dec 2018. Clinical trial information: NCT03732677.

National society-supplied patient materials on prostate cancer screening for the general public: A readability analysis

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Background: Recent data suggest that prostate cancer mortality may be increasing for the first time in 20 years, possibly related to a decrease in PSA screening. Most professional societies recommend men aged 55 to 69 make screening decisions using a shared-decision making (SDM) model. However the quality and time of SDM can vary significantly, often leaving patients uncertain about the implications of pursuing or foregoing screening. In this setting of individualized decisions, patients may seek supplemental information. However, little is known about the accuracy, breadth and readability of available education materials, which if designed optimally could improve SDM. Methods: For 11 predetermined professional societies (ACP, ACPM, ACS, AFP, AMA, ASCO, AUA, CDC, NCI, NIH, USPSTF), patient education materials designed for prostate cancer screening were queried. Materials were analyzed using seven well-validated readability metrics and evaluated for educational content. For content comparison, 10 materials from academic cancer centers and independent organizations were identified using top public search engine results. Results: We identified 12 professional society materials and 20 from popular non-society sources. Mean readability level for society materials ranged from 9.7 to 11.3 grade, well above AMA and NIH recommended 6th and 8th grade reading levels (P < 0.0001). In comparison to general materials, professional society materials more often discussed the role of risk factors in making screening decisions (70% vs 100%, P = 0.03). However, society materials did often omit important guideline-based content, including statements that decisions should involve patient values and preferences (42%) and can vary by patient age (35%). Conclusions: Widely available prostate cancer screening education materials are written at inappropriately high reading levels and often omit important content. Improvement of such materials would encourage SDM for patients considering screening.[Table: see text]

Magnetic Resonance Imaging Assessment of Carcinogen-induced Murine Bladder Tumors

Murine bladder tumor models are critical for the evaluation of new therapeutic options. Bladder tumors induced with the N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) carcinogen are advantageous over cell line-based models because they closely replicate the genomic profiles of human tumors, and, unlike cell models and xenografts, they provide a good opportunity for the study of immunotherapies. However, bladder tumor generation is heterogeneous; therefore, an accurate assessment of tumor burden is needed before randomization to experimental treatment. Described here is a BBN mouse model and protocol to evaluate bladder cancer tumor burden in vivo using a fast and reliable magnetic resonance (MR) sequence (true FISP). This method is simple and reliable because, unlike ultrasound, MR is operator-independent and allows for the straightforward post-acquisition image processing and review. Using axial images of the bladder, analysis of regions of interest along the bladder wall and tumor allow for the calculation of bladder wall and tumor area. This measurement correlates with ex vivo bladder weight (rs= 0.37, p = 0.009) and tumor stage (p = 0.0003). In conclusion, BBN generates heterogeneous tumors that are ideal for evaluation of immunotherapies, and MRI can quickly and reliably assess tumor burden prior to randomization to experimental treatment arms.

Prevalence of PD-L1 expression in first-line (1L) locally advanced/unresectable or metastatic urothelial carcinoma (UC)

TPS67

Background: Treatments for 1L advanced/metastatic UC include platinum-based chemotherapy, an immune checkpoint inhibitor (ICI) or clinical trial enrollment. Not all patients benefit from, or are eligible for, specific therapies due to comorbidities and performance status. There is an urgent need for biomarker-directed strategies to enable patient selection and improve outcomes. Currently the only clinically used molecular biomarker is PD-L1 protein expression in tumor tissue. Although inconsistent and variable among assays, higher PD-L1 expression generally correlates with increased ICI response rate. Improved understanding of the prevalence and potential prognostic and/or predictive role of PD-L1 can further enhance its clinical utility and guide novel clinical trial designs. Methods: This observational study will enroll 250 patients with advanced UC prior to starting or during 1L therapy, as initiated at the discretion of participating clinicians, from 60 US community sites. The primary endpoint is prevalence of PD-L1 expression by VENTANA SP263 Assay (exact [Clopper-Pearson] 95% CI) on pre-treatment tumor tissue. Secondary endpoints include the association of pre-treatment PD-L1 expression with pre-treatment tumor tissue mutational burden (tTMB), descriptions of treatment response and outcomes (ORR based on RECIST 1.1, PFS, OS) and assessment of their correlations with PD-L1 expression. Exploratory endpoints include the association of pre-treatment tumor tissue PD-L1 with pre-treatment blood-based tumor mutational burden (bTMB), changes in circulating tumor DNA (ctDNA) levels at various timepoints, the correlation between tTMB and bTMB values, and the association of those biomarkers for outcomes of PFS and OS. Enrollment will take place over 24 months with follow-up to 30 months from study enrollment. With 250 patients, the 95% CI for 30%, 45%, and 60% observed prevalence of PD-L1 high are (24.4%, 36.1%), (38.9%, 51.2%), and (53.6%, 66.1%), respectively; the various secondary and exploratory analyses will be descriptive.

Evaluating the clinical, environmental, genetic, and genomic profile of men with early-onset aggressive prostate cancer (PCa)

TPS333

Background: Although PCa incidence has stabilized or decreased in most age groups, the incidence of metastatic disease has increased among men 50-69 years old. The incidence of fatal PCa has decreased for most age groups, it has remained unchanged in men under 55 years old. These observations are supported by data from 3 randomized trials. In S9346 in newly diagnosed M1, 18% of men (all-comers N = 3040) were ≤ 60 years. A significant percentage of younger men enrolled in CHAARTED had de-novo metastases at diagnosis; among 575 patients without prior local therapy, the median age was 62 years, and among men < 60 years old (n = 274), 80.3% (n = 220) had de novo metastatic disease. Lastly, in S9921 (N = 983) 15% of men ≤ 60 years had pN1 disease at enrollment. A significant proportion of men with metastatic disease progress to castration -resistance within a short interval of initiating androgen-deprivation therapy (ADT) ± docetaxel or abiraterone for metastatic hormone sensitive PCa. Pivotal studies have described genetic abnormalities in aggressive localized or end stage prostate cancers, but early-onset cases and those with early progression on systemic therapy are not included or are under-represented in these studies. Methods: The primary objective of this multi-institutional trial is to characterize the clinical, environmental, genetic and genomic features of high-risk advanced PCa: Cohort 1: men ≤ 60 years old with N1 or M1 at diagnosis or who develop metastases shortly after local therapy; Cohort 2: men with early progression to castration-resistant PCa in ≤ 1 year on ADT ± docetaxel or ADT ± abiraterone. Clinical and environmental history, peripheral blood for cell free DNA and germline analysis will be collected. Primary/metastatic tumor tissue will be tested via the Tempus platform, which includes DNA sequencing, whole transcriptome expression profiling, copy number analysis, comprehensive fusion gene analysis and calculation of tumor mutational burden. We will also prospectively correlate clinical and molecular characteristics with outcomes. To date, 5 patients have been registered.

Automated Extraction of Grade, Stage, and Quality Information From Transurethral Resection of Bladder Tumor Pathology Reports Using Natural Language Processing

PURPOSE

Bladder cancer is initially diagnosed and staged with a transurethral resection of bladder tumor (TURBT). Patient survival is dependent on appropriate sampling of layers of the bladder, but pathology reports are dictated as free text, making large-scale data extraction for quality improvement challenging. We sought to automate extraction of stage, grade, and quality information from TURBT pathology reports using natural language processing (NLP).

METHODS

Patients undergoing TURBT were retrospectively identified using the Northwestern Enterprise Data Warehouse. An NLP algorithm was then created to extract information from free-text pathology reports and was iteratively improved using a training set of manually reviewed TURBTs. NLP accuracy was then validated using another set of manually reviewed TURBTs, and reliability was calculated using Cohen's κ.

RESULTS

Of 3,042 TURBTs identified from 2006 to 2016, 39% were classified as benign, 35% as Ta, 11% as T1, 4% as T2, and 10% as isolated carcinoma in situ. Of 500 randomly selected manually reviewed TURBTs, NLP correctly staged 88% of specimens (κ = 0.82; 95% CI, 0.78 to 0.86). Of 272 manually reviewed T1 tumors, NLP correctly categorized grade in 100% of tumors (κ = 1), correctly categorized if muscularis propria was reported by the pathologist in 98% of tumors (κ = 0.81; 95% CI, 0.62 to 0.99), and correctly categorized if muscularis propria was present or absent in the resection specimen in 82% of tumors (κ = 0.62; 95% CI, 0.55 to 0.73). Discrepancy analysis revealed pathologist notes and deeper resection specimens as frequent reasons for NLP misclassifications.

CONCLUSION

We developed an NLP algorithm that demonstrates a high degree of reliability in extracting stage, grade, and presence of muscularis propria from TURBT pathology reports. Future iterations can continue to improve performance, but automated extraction of oncologic information is promising in improving quality and assisting physicians in delivery of care.

Development of a translational medicine protocol for an NCTN genitourinary clinical trial: Critical steps, common pitfalls and a basic guide to translational clinical research

Translational medicine (TM) components of prospective clinical trials provide an invaluable opportunity to test hypotheses that contribute to our knowledge of human disease biology and/or the mechanism of action of a given therapeutic intervention. Our ability to sample tumors and their microenvironment, and the depth and breadth of biological information that can be extracted from them, has increased exponentially in recent years. This information is critical to guide the next steps clinical research if we are to accelerate the pace of progress in cancer treatment. Thus, TM studies should be considered key components of any clinical trial. However, TM studies are costly and biologic sampling can impose significant morbidity on our patients. Therefore, TM investigators should be engaged early in the design process (similar to a statistician) to ensure that the most imperative research questions are rigourosly defined, that the obtained specimens can be used to answer them and that the results will serve as the foundation for additional studies. In this review, we focus on TM studies in the context of the National Cancer Institute's National Clinical Trials Network trials and offer a description of the genesis of TM components, methods in sample acquisition and biomarker research, and a guide to funding mechanisms, in order to provide a blueprint for future TM research protocols. While TM studies can take many forms, the research discussed primarily focusses on basic and translational research involving molecular, cellular, and immunobiology.

Bladder Cancer, Version 5.2017, NCCN Clinical Practice Guidelines in Oncology

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Bladder Cancer focuses on systemic therapy for muscle-invasive urothelial bladder cancer, as substantial revisions were made in the 2017 updates, such as new recommendations for nivolumab, pembrolizumab, atezolizumab, durvalumab, and avelumab. The complete version of the NCCN Guidelines for Bladder Cancer addresses additional aspects of the management of bladder cancer, including non-muscle-invasive urothelial bladder cancer and nonurothelial histologies, as well as staging, evaluation, and follow-up.

Abstract B29: A carcinogen-induced mouse model recapitulates the molecular alterations of human muscle-invasive bladder cancer

Bladder cancer is the fourth most common cancer in men and fifth most common malignancy in the United States. Survival of patients with muscle-invasive or metastatic bladder cancer is poor, with only 35% survival at 5 years. Developing innovative anticancer drugs relies on the availability of model systems that closely recapitulate the corresponding human disease at both the histologic and molecular levels. One of the major limitations in the field of bladder cancer research is the limited availability of such models.

The N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) mouse model is an attractive model system of muscle-invasive bladder cancer (MIBC) since it recapitulates the complex histology of human tumors in a background with intact immune system. However, it was unknown whether this carcinogen-induced model also mimicked human MIBC at the molecular and mutational level.

In our study, we analyzed the mutational landscape of the BBN model by whole-exome sequencing followed by a bioinformatic comparison to human MIBC using genomic data from The Cancer Genome Atlas and other repositories. Similar to human MIBC, BBN tumors had a high mutation burden. Next, we extracted mouse-specific mutational signatures that correspond to different genetic instability processes operating in BBN tumors. Interestingly, one of these de novo extracted signatures aligned to a human mutational signature previously associated to DNA-repair deficiencies in human bladder cancers. We further analyzed the most commonly mutated genes and their intratumor mutation frequencies with the aim of identifying potential driver mutations. Our analyses converged on three genes that seem crucial in the process of tumorigenesis in both mouse and human bladder cancers: the tumor suppressor Trp53 as well as the genes Kmt2c and Kmt2d. These encode for methyltransferases involved in the methylation of histone H3K4 and play a key role in the epigenetic regulation of enhancer activity. Also, many of the putative driver mutations found in the BBN genomes corresponded to human cancer hotspot mutations, supporting their role as driver mutations.

Together, our study revealed several similarities between human MIBC and the BBN mouse model. Our results highlighted the contribution of aberrations to chromatin regulators and genetic instability in both human and BBN bladder tumors, thus providing a strong rationale for the use of this mouse model in molecular and drug discovery studies.

Citation Format: Damiano Fantini, Alexander P. Glaser, Rimar J. Kalen, Wang Yiduo, Yanni Yu, Joshua J. Meeks. A carcinogen-induced mouse model recapitulates the molecular alterations of human muscle-invasive bladder cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B29.

Transversus Abdominis Plane Blockade as Part of a Multimodal Postoperative Analgesia Plan in Patients Undergoing Radical Cystectomy

Background:

Radical cystectomy (RC) is a morbid procedure with frequent complications that may benefit from implementation of an enhanced recovery after surgery (ERAS) protocol.

Objective:

To examine the benefits of a multimodal analgesic plan that uses continuous transversus abdominis plane (TAP) blockade as part of an ERAS protocol after RC.

Methods:

A retrospective comparison of consecutive patients undergoing RC over a 4-year period was conducted. Patients were designated as having surgery either before or after implementation of an ERAS protocol. A major component of the ERAS protocol was a multi-modal analgesia plan with TAP blockade. Patient demographics, comorbidities, operative details, and outcomes, including days to flatus, bowel movement (BM), narcotic usage, and length of stay (LOS) were compared.

Results:

In total, 171 patients were included: 100 pre-ERAS and 71 ERAS. There were no differences in age, smoking status, operative approach, or diversion type. The patients in the ERAS cohort were less likely to be male, had a higher median BMI, and more likely to have received neoadjuvant chemotherapy. Total and early postoperative narcotic use were lower in the ERAS cohort: 89 vs. 336 mg (p < 0.001) and 62 vs 203 mg (p = 0.001), respectively. The ERAS cohort had fewer days to flatus (3 vs. 4, p < 0.001) and fewer days to bowel movement (4 vs. 5, p < 0.001). Median LOS was shorter in the ERAS cohort (7 vs. 8.5d, p = 0.001). There were no differences in complications or readmission rates between the two cohorts.

Conclusions:

TAP blockade as part of an ERAS multi-modal pain plan is associated with low narcotic usage, and significant improvement in time to flatus, BM, and LOS compared to traditional post-RC pain management.

Rates and Predictors of Conversion to Open Surgery During Minimally Invasive Radical Cystectomy

OBJECTIVE

To assess the frequency of minimally invasive radical cystectomy (MIRC) conversion to open surgery, what factors influence conversion, whether or not the benefits of MIRC vs open radical cystectomy (ORC) persist after conversion, and compare ORC and MIRC outcomes.

MATERIALS AND METHODS

We performed a retrospective cohort study from the National Cancer Data Base (2010 to 2013) analyzing patients who underwent completed MIRC (n = 5750), converted MIRC (n = 245), and ORC (n = 12,053) without prior radiotherapy. Multivariable logistic and linear regression analyses were used to assess the association between covariates, open conversion as well as surgical approach, and secondary outcomes such as positive surgical margins (PSMs), use of lymphadenectomy, lymph node yield, hospital length of stay (LOS), and 30-day readmission.

RESULTS

Rates of conversion were independent of patient factors such as race, sex, use of neoadjuvant chemotherapy, and clinical stage. Conversion occurred in 245 of 5750 MIRCs (4.3%) and declined over time (5.8% in 2010 vs 3.2% in 2013, odds ratio [OR] 0.50, 95% confidence interval [CI] 0.34-0.75, p = 0.001). MIRC was associated with fewer positive margins, higher lymph node yield, shorter LOS, and fewer readmissions compared with ORC, however, patients requiring open conversion had longer median hospital stays (8 days vs 7 days, p = 0.013), lower median lymph node yields (14 vs 17, p = 0.007), more PSMs (17% vs 11%, p = 0.006), and more 30-day readmissions (14% vs 9%, p = 0.008) compared to nonconverted. Converted MIRC had similar hospital LOS and 30-day readmission rates compared to ORC.

CONCLUSION

Open conversion during MIRC is uncommon and has decreased in recent years despite the rising use of MIRC. MIRC had better short-term outcomes compared with ORC. These benefits were negated with open conversion; however, outcomes were similar compared to planned ORC.

Genomic characterization of high-risk non-muscle invasive bladder cancer

The genetic mechanisms associated with progression of high-risk non-muscle-invasive bladder cancer (HR-NMIBC) have not been described. We conducted selective next-generation sequencing (NGS) of HR-NMIBC and compared the genomic profiles of cancers that responded to intravesical therapy and those that progressed to muscle-invasive or advanced disease. DNA was extracted from paraffin-embedded sections from 25 HR-NMIBCs (22 with T1HG; 3 with TaHG with or without carcinoma in situ). Ten patients with HR-NMIBC developed progression (pT2+ or N+) (“progressors”). Fifteen patients had no progression (“non-progressors”). Tissue from 11 patients with metastatic bladder cancer (BC) were analyzed for comparison. We found no difference in frequency of mutations of TP53, PIK3CA, or KMT2D between the primary tumors of progressors compared to non-progressors and metastatic tumors. An increased frequency of deletions of CDKN2A/B was identified in tumors at progression (37%) compared to non-progressors (6%) (p = 0.10). We found a significant decrease in total mutational burden (TMB) that has been associated with immunotherapy response comparing non-progressors, progressors and metastatic tumors at 15, 10.1 and 5.1 mutations/MB respectively (p = 0.02). This association suggests more advanced tumors have decreased neoantigen burden and may explain the mechanism of BCG response in non-progressors. We found no novel genetic drivers in progressors and HR-NMIBC had many genetic features similar to metastatic BC. Loss of CDKN2A/B may occur late during invasion of BC and may represent an important step in progression. Further research is necessary to evaluate TMB and loss of CDKN2A/B locus as a biomarker for progression of NMIBC.

Clinical Outcome of Retroperitoneal Lymph Node Dissection after Chemotherapy in Patients with Pure Embryonal Carcinoma in the Orchiectomy Specimen

OBJECTIVE

To determine the pathologic findings and clinical outcome of patients with pure embryonal carcinoma (EC) of the testis who were diagnosed with testis cancer from January 1989 to January 2013 who underwent an orchiectomy, cisplatin-based chemotherapy and a postchemotherapy retroperitoneal lymph node dissection (PC-RPLND).

METHODS

We compared those patients with 100% EC with those with mixed nonseminomatous germ cell tumor pathology who underwent a PC-RPLND.

RESULTS

Of 1105 patients who underwent a PC-RPLND, 145 had pure EC. Twenty-six percent of patients presented with metastatic disease outside the retroperitoneum. Patients with mixed histologies tended to have worse International Germ Cell Cancer Collaborative Group risk compared to those with EC at orchiectomy (P = .037). Histology at PC-RPLND revealed fibrosis or necrosis in 76%, mature teratoma in 19% and viable cancer in 4%. Over one-third of the patients had a residual mass of <1 cm prior to RPLND; of whom 15% harbored mature teratoma in PC-RPLND histology. The Kaplan-Meier estimated probability of recurrence at 5 years of follow-up was 3.1% (95% CI 1.2%, 8.0%) for EC histology, 7.3% lower than mixed histology. For cancer-specific mortality, the Kaplan-Meier estimated probability at 5 years was 4.6% (95% CI 3.3%, 6.3%) and 1.7% (95% CI 0.4%, 6.8%) for mixed and pure EC histologies, respectively.

CONCLUSION

Approximately 20% of patients with pure EC had teratoma at PC-RPLND. We have shown that those with a maximum node size of <1 cm should not be precluded from RPLND.

APOBEC-mediated mutagenesis in urothelial carcinoma is associated with improved survival, mutations in DNA damage response genes, and immune response

APOBEC enzymes are responsible for a mutation signature (TCW>T/G) implicated in a wide variety of tumors. We explore the APOBEC mutational signature in bladder cancer and the relationship with specific mutations, molecular subtype, gene expression, and survival using sequencing data from The Cancer Genome Atlas (n = 395), Beijing Genomics Institute (n = 99), and Cancer Cell Line Encyclopedia. Tumors were split into “APOBEC-high” and “APOBEC-low” based on APOBEC enrichment. Patients with APOBEC-high tumors have better overall survival compared to those with APOBEC-low tumors (38.2 vs. 18.5 months, p = 0.005). APOBEC-high tumors are more likely to have mutations in DNA damage response genes (TP53, ATR, BRCA2) and chromatin regulatory genes (ARID1A, MLL, MLL3), while APOBEC-low tumors are more likely to have mutations in FGFR3 and KRAS. APOBEC3A and APOBEC3B expression correlates with mutation burden, regardless of bladder tumor molecular subtype. APOBEC mutagenesis is associated with increased expression of immune signatures, including interferon signaling, and expression of APOBEC3B is increased after stimulation of APOBEC-high bladder cancer cell lines with IFNγ. In summary, APOBEC-high tumors are more likely to have mutations in DNA damage response and chromatin regulatory genes, potentially providing more substrate for APOBEC enzymes, leading to a hypermutational phenotype and the subsequent enhanced immune response.

Molecular Landscape of Non-Muscle Invasive Bladder Cancer

In this issue of Cancer Cell, Hurst et al. report an integrated analysis of non-invasive (stage Ta) bladder cancer. Two genomic subtypes are distinguished by chromosome 9q loss, resulting in increased AKT/PI3K/mTOR signaling. Tumors from female patients have a higher frequency of KDM6A mutations.

NCCN Guidelines Insights: Bladder Cancer, Version 2.2016

These NCCN Guidelines Insights discuss the major recent updates to the NCCN Guidelines for Bladder Cancer based on the review of the evidence in conjunction with the expert opinion of the panel. Recent updates include (1) refining the recommendation of intravesical bacillus Calmette-Guérin, (2) strengthening the recommendations for perioperative systemic chemotherapy, and (3) incorporating immunotherapy into second-line therapy for locally advanced or metastatic disease. These NCCN Guidelines Insights further discuss factors that affect integration of these recommendations into clinical practice.

Treatment of Non-Metastatic Muscle-Invasive Bladder Cancer: AUA/ASCO/ASTRO/SUO Guideline

PURPOSE

This multidisciplinary, evidence-based guideline for clinically non-metastatic muscle-invasive bladder cancer focuses on the evaluation, treatment and surveillance of muscle-invasive bladder cancer guided toward curative intent.

MATERIALS AND METHODS

A systematic review utilizing research from the Agency for Healthcare Research and Quality as well as additional supplementation by the authors and consultant methodologists was used to develop the guideline. Evidence-based statements were based on body of evidence strengths Grade A, B or C and were designated as Strong, Moderate and Conditional Recommendations with additional statements presented in the form of Clinical Principles or Expert Opinions.

RESULTS

For the first time for any type of malignancy, the American Urological Association, American Society of Clinical Oncology, American Society for Radiation Oncology and Society of Urologic Oncology have formulated an evidence-based guideline based on a risk-stratified clinical framework for the management of muscle-invasive urothelial bladder cancer. This document is designed to be used in conjunction with the associated treatment algorithm.

CONCLUSIONS

The intensity and scope of care for muscle-invasive bladder cancer should focus on the patient, disease and treatment response characteristics. This guideline attempts to improve a clinician's ability to evaluate and treat each patient, but higher quality evidence in future trials will be essential to improve level of care for these patients.

Robot-assisted retroperitoneal lymph node dissection (RA-RPLND) in the adolescent population

BACKGROUND

Robot-assisted retroperitoneal lymph node dissection (RA-RPLND) has built on success and techniques of laparoscopic RPLND, with the added benefits of robotic technology. This paper demonstrates use of the da Vinci Xi^® system for RA-RPLND in two adolescent patients.

METHODS

Case #1: A 17-year-old male presented with a left testicular mass and elevated alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG). Pathology revealed a mixed non-seminomatous germ cell tumor (60% embryonal, 35% yolk sac, 5% choriocarcinoma, + lymphovascular invasion). Tumor marker normalized post-orchiectomy, and staging imaging was without evidence of metastatic disease. After discussion of options he opted to undergo RA-RPLND. Case #2: A 15-year-old male presented with a right para-testicular mass and negative tumor markers. He underwent inguinal exploration and excision of the paratesticular mass. Final pathology revealed an ectomesenchymoma with a spindle cell rhabdomyosarcoma component. Staging imaging was negative, and after discussion of options he underwent completion orchiectomy and RA-RPLND.

RESULTS

The patient in Case #1 underwent a left modified-template nerve-sparing RA-RPLND. Sixteen lymph nodes were negative for tumor. The patient in Case #2 underwent complete bilateral nerve-sparing RA-RPLND. Forty-two lymph nodes were negative for tumor. Estimated blood loss was <50 cc for both cases, and console time averaged 262 min.

CONCLUSION

This was a report of two cases of RA-RPLND in the adolescent population. RA-RPLND is technically feasible in this population, and further study of RA-RPLND is needed to determine long-term outcomes, as this technique is becoming more widely adopted.

The emerging role of homologous recombination repair and PARP inhibitors in genitourinary malignancies

As cells age and are exposed to genotoxic stress, preservation of the genomic code requires multiple DNA repair pathways to remove single-strand or double-strand breaks. Loss of function somatic genomic aberrations or germline deficiency in genes involved in DNA repair can result in acute cell death or, after a latency period, cellular transformation. Therapeutic exploitation of DNA repair by inhibition of poly (adenosine diphosphate [ADP]) ribose polymerases (PARP), a family of enzymes involved in the repair of single-strand and in some cases double-strand breaks, has become a novel cancer treatment. Although the application of PARP inhibitors (PARPis) initially focused on tumors with BRCA1 or BRCA2 deficiencies, synthetic susceptibilities to PARPis have been expanded due to the identification of tumors with mutations pathways involved in DNA damage repair, in particular those that repair double-strand breaks using homologous recombination (HR). There is an increasing appreciation that genitourinary (GU) malignancies, including bladder cancer and especially prostate cancer, contain subsets of patients with germline and somatic alterations in HR genes that may reflect an increased response to PARPis. In this review, the authors describe the mechanisms and rationale of the use of PARPis in patients with GU cancers, summarize previously reported preclinical and clinical trials, and identify ongoing trials to determine how PARPis and strategies targeted at HR repair can have widespread application in patients with GU cancers. Cancer 2017;123:1912-1924. © 2017 American Cancer Society.