Cardiac and Intramuscular Metastases Following Nephroureterectomy for Metachronous Urothelial Carcinoma.

BACKGROUND We present a case of metachronous cardiac and intramuscular metastases in a patient with a known history of radical nephroureterectomy for upper-tract urothelial carcinoma (UTUC). CASE REPORT A 58-year-old man had a history of metachronous renal pelvis urothelial carcinoma with prior left radical nephroureterectomy. He was also diagnosed with malignancy-associated deep vein thrombosis (DVT) and was on rivaroxaban. He presented at an oncology follow-up consult with shortness of breath and right scapular lump. CT scan revealed a soft-tissue mass at the surgical bed suspicious for local recurrence, as well as intracardiac hypodensities and intramuscular nodules in the right latissimus dorsi and right adductor muscles. The intracardiac hypodensities were located in the left atrial appendage and inter-atrial septum. Given that the patient had a history of DVT and in a pro-thrombotic state, differentials for the intracardiac densities included intracardiac thrombi or metastases. The intramuscular hypodensities were rim-enhancing. Given that the patient was on rivaroxaban, differentials included hematomas or metastases. As there was no overlying bruising and the lesions remained unchanged in size clinically, they were treated as metastases. The patient was treated with clexane but re-presented with worsening of shortness of breath and palpitations. CT scan showed increased size of intracardiac lesions, suggesting no response to anticoagulation, and therefore were likely metastatic in nature. He completed a 2-year course of IV pembrolizumab and was in complete remission. CONCLUSIONS Our case highlights the importance of this clinically challenging scenario when patients with known malignancy and on anticoagulation present with cardiac or musculoskeletal symptoms. Though these patients are at risk of thrombus and haematoma, cardiac and intramuscular metastasis should be considered, as the prognosis is guarded.

Association Between Serum Magnesium Levels and Outcomes of Atezolizumab in Patients With Metastatic Urothelial Carcinoma.

BACKGROUND/AIM: Evidence suggests that serum magnesium levels are associated with outcomes of immune checkpoint inhibitors (ICIs). However, this association remains under-explored in patients with metastatic urothelial carcinoma (UC) treated with ICIs. PATIENTS AND METHODS: This prognostic study used individual participant-level data from 1,281 patients with locally advanced or metastatic UC treated with atezolizumab (N=855) or chemotherapy (N=426) who participated in the IMvigor210 and the IMvigor211 trials. Multivariable Cox proportional hazards regression and Fine-Gray subdistribution hazards regression models were used to examine the association of baseline serum magnesium levels with overall survival (OS), progression-free survival (PFS), and immune-related adverse events (irAEs). RESULTS: No evidence of an association was found between baseline serum magnesium levels and PFS or OS in patients treated with atezolizumab [PFS, hazard ratio (HR)=1.03, 95% confidence interval (CI)=0.78-1.35; OS, HR=1.13, 95%CI=0.84-1.51] or chemotherapy (PFS, HR=0.93, 95%CI=0.62-1.40; OS, HR=0.91, 95%CI=0.59-1.40). We also found no evidence of association with irAEs (subdistribution HR=1.29, 95%CI=0.81-2.07) in patients receiving atezolizumab. CONCLUSION: This study found no evidence of an association between baseline serum magnesium levels and treatment outcomes or irAEs in patients with metastatic UC receiving atezolizumab. Contrary to previous research suggesting a role for magnesium in cancer therapy, these results indicate that serum magnesium levels may not serve as a biomarker to predict outcomes in these patients.

Establishment and validation of a nomogram for predicting overall survival of upper-tract urothelial carcinoma with bone metastasis: a population-based study.

BACKGROUND: Bone metastasis (BM) carries a poor prognosis for patients with upper-tract urothelial carcinoma (UTUC). This study aims to identify survival predictors and develop a prognostic nomogram for overall survival (OS) in UTUC patients with BM. METHODS: The Surveillance, Epidemiology, and End Results database was used to select patients with UTUC between 2010 and 2019. The chi-square test was used to assess the baseline differences between the groups. Kaplan-Meier analysis was employed to assess OS. Univariate and multivariate analyses were conducted to identify prognostic factors for nomogram establishment. An independent cohort was used for external validation of the nomogram. The discrimination and calibration of the nomogram were evaluated using concordance index (C-index), area under receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis (DCA). All statistical analyses were performed using SPSS 23.0 and R software 4.2.2. RESULTS: The mean OS for UTUC patients with BM was 10 months (95% CI: 8.17 to 11.84), with 6-month OS, 1-year OS, and 3-year OS rates of 41%, 21%, and 3%, respectively. Multi-organ metastases (HR = 2.21, 95% CI: 1.66 to 2.95, P < 0.001), surgery (HR = 0.72, 95% CI: 0.56 to 0.91, P = 0.007), and chemotherapy (HR = 0.37, 95% CI: 0.3 to 0.46, P < 0.001) were identified as independent prognostic factors. The C-index was 0.725 for the training cohort and 0.854 for the validation cohort, and all AUC values were > 0.679. The calibration curve and DCA curve showed the accuracy and practicality of the nomogram. CONCLUSIONS: The OS of UTUC patients with BM was poor. Multi-organ metastases was a risk factor for OS, while surgery and chemotherapy were protective factors. Our nomogram was developed and validated to assist clinicians in evaluating the OS of UTUC patients with BM.

Management of Oligometastatic and Locally Recurrent Urothelial Carcinoma.

PURPOSE OF REVIEW: To summarize and evaluate the literature on treatment approaches for oligometastatic and locally recurrent urothelial cancer. RECENT FINDINGS: There is no clear definition for oligometastatic urothelial cancers due to limited data. Studies focusing on oligometastatic and locally recurrent urothelial cancer have been primarily retrospective. Treatment options include local therapy with surgery or radiation, and generalized systemic therapy such as chemotherapy or immunotherapy. Oligometastatic and locally recurrent urothelial cancers remain challenging to manage, and treatment requires an interdisciplinary approach. Systemic therapy is nearly always a component of current care in the form of chemotherapy, but the role of immunotherapy has not been explored. Consideration of surgical and radiation options may improve outcomes, and no studies have compared directly between the two localized treatment options. The development of new prognostic and predictive biomarkers may also enhance the treatment landscape in the future.

Genomic Profiling and Molecular Characterisation of Metastatic Urothelial Carcinoma.

The clinical management of metastatic urothelial carcinoma (mUC) is undergoing a major paradigm shift; the integration of immune checkpoint inhibitors (ICIs) and antibody-drug conjugates (ADCs) into the mUC therapeutic strategy has succeeded in improving platinum-based chemotherapy outcomes. Given the expanding therapeutic armamentarium, it is crucial to identify efficacy-predictive biomarkers that can guide an individual patient's therapeutic strategy. We reviewed the literature data on mUC genomic alterations of clinical interest, discussing their prognostic and predictive role. In particular, we explored the role of the fibroblast growth factor receptor (FGFR) family, epidermal growth factor receptor 2 (HER2), mechanistic target of rapamycin (mTOR) axis, DNA repair genes, and microsatellite instability. Currently, based on the available clinical data, FGFR inhibitors and HER2-directed ADCs are effective therapeutic options for later lines of biomarker-driven mUC. However, emerging genomic data highlight the opportunity for earlier use and/or combination with other drugs of both FGFR inhibitors and HER2-directed ADCs and also reveal additional potential drug targets that could change mUC management.

Association between comorbidities and survival in patients with metastatic urothelial carcinoma treated with pembrolizumab.

BACKGROUND: This study aims to investigate the relationship between comorbidities and survival in patients with mUC treated with pembrolizumab as a second-line treatment. METHODS: From February 2018 to October 2021, we analyzed the data of 185 consecutive patients with metastatic UC who received pembrolizumab as second-line therapy at The Jikei University Hospital and five affiliated hospitals. We used the Charlson Comorbidity Index (CCI) to assess the comorbidities. The outcomes of interest were progression-free survival (PFS) and overall survival (OS). To compare the survival differences, inverse probability of treatment weighting (IPTW)-adjusted Kaplan-Meier curves and the IPTW-adjusted Cox regression hazards model were used. RESULTS: After IPTW adjustment, patient characteristics were well-balanced between patients with high CCI and those with low CCI. The IPTW-adjusted Kaplan-Meier curves of PFS and OS based on CCI revealed that the patients with high CCI (2 or more) had a shorter PFS (median, 1.6 vs. 2.8 months) and a shorter OS (median, 12.4 vs. 18.8 months) (0-1). Similarly, in the IPTW-adjusted Cox regression hazards model, patients with high CCI had significantly shorter PFS [HR, 1.84 (95% CI 1.26-2.68; p = 0.002)] and OS [HR, 1.98 (95% CI 1.20-3.27; p = 0.008)] than those with lower CCI. CONCLUSIONS: High CCI was associated with a higher risk of disease progression as well as overall mortality in mUC patients treated with second-line pembrolizumab.

Enfortumab Vedotin and Pembrolizumab in Untreated Advanced Urothelial Cancer.

BACKGROUND: No treatment has surpassed platinum-based chemotherapy in improving overall survival in patients with previously untreated locally advanced or metastatic urothelial carcinoma. METHODS: We conducted a phase 3, global, open-label, randomized trial to compare the efficacy and safety of enfortumab vedotin and pembrolizumab with the efficacy and safety of platinum-based chemotherapy in patients with previously untreated locally advanced or metastatic urothelial carcinoma. Patients were randomly assigned in a 1:1 ratio to receive 3-week cycles of enfortumab vedotin (at a dose of 1.25 mg per kilogram of body weight intravenously on days 1 and 8) and pembrolizumab (at a dose of 200 mg intravenously on day 1) (enfortumab vedotin-pembrolizumab group) or gemcitabine and either cisplatin or carboplatin (determined on the basis of eligibility to receive cisplatin) (chemotherapy group). The primary end points were progression-free survival as assessed by blinded independent central review and overall survival. RESULTS: A total of 886 patients underwent randomization: 442 to the enfortumab vedotin-pembrolizumab group and 444 to the chemotherapy group. As of August 8, 2023, the median duration of follow-up for survival was 17.2 months. Progression-free survival was longer in the enfortumab vedotin-pembrolizumab group than in the chemotherapy group (median, 12.5 months vs. 6.3 months; hazard ratio for disease progression or death, 0.45; 95% confidence interval [CI], 0.38 to 0.54; P<0.001), as was overall survival (median, 31.5 months vs. 16.1 months; hazard ratio for death, 0.47; 95% CI, 0.38 to 0.58; P<0.001). The median number of cycles was 12 (range, 1 to 46) in the enfortumab vedotin-pembrolizumab group and 6 (range, 1 to 6) in the chemotherapy group. Treatment-related adverse events of grade 3 or higher occurred in 55.9% of the patients in the enfortumab vedotin-pembrolizumab group and in 69.5% of those in the chemotherapy group. CONCLUSIONS: Treatment with enfortumab vedotin and pembrolizumab resulted in significantly better outcomes than chemotherapy in patients with untreated locally advanced or metastatic urothelial carcinoma, with a safety profile consistent with that in previous reports. (Funded by Astellas Pharma US and others; EV-302 ClinicalTrials.gov number, NCT04223856.).

Metastatic upper tract urothelial carcinoma with nest-like features presenting as malignant pleural effusion.

Metastatic urothelial carcinoma is a rare cause of pleural effusions. We report a case of urothelial carcinoma of the upper urinary tract in an oldest-old male patient, a smoker, with situs inversus totalis, that presented uniquely with malignant pleural effusion at presentation without evidence of a primary tumor on imaging. Cytological smears of the massive left pleural effusion revealed epithelioid neoplastic cells arranged in short cords, small-to-large clusters, and raspberry-like morules, mimicking mesothelioma; cell block preparations highlighted the presence of tubules and nest-like structures. The tumor cells showed a high nuclear-to-cytoplasmic ratio, nuclear grooves, and mitotic figures. Cytomorphologic features coupled with the immunophenotype of neoplastic cells (p63, GATA3, and uroplakin II positive) allowed the diagnosis of metastatic urothelial carcinoma and a possible nested subtype. These findings were supported by a total body computed tomography (CT) showing no evidence of a mass in the bladder or elsewhere in the urinary tract but a concentric parietal thickening of the proximal left ureter, suggesting malignancy. To our knowledge, a malignant effusion as a primary manifestation of urothelial carcinoma with nest-like features originating in the upper urinary tract has never been described previously. Our case focuses on the value of cell block in the working-up of neoplastic effusions by revealing the architectural pattern of an uncommon malignancy and the correlation between cytopathology and imaging gross findings to reach an accurate diagnosis.

First-line Management of Metastatic Urothelial Cancer: Current and Future Perspectives After the EV-302 and CheckMate-901 Studies.

The standard of care for the first-line management of metastatic urothelial carcinoma has been recently challenged, with the combination of pembrolizumab and enfortumab vedotin (P-EV) strongly arising as a practice-changing option from classical platinum-based chemotherapies. With this paradigm shift on the horizon new questions, including the most suitable second line of treatment for these patients, and the role that the molecular characterization of these tumours will have when selecting these therapies will inevitably arise. Furthermore, after the negative results of the Keynote 361 and IMvigor 130 trials, the combination of nivolumab with platinum-based chemotherapy followed by nivolumab maintenance (Nivo GC-Nivo) has also shown positive results when compared with chemotherapy alone. Translational studies at a molecular, cellular, and functional level will be key to better explain these discordant results. In this Current Perspective, we discuss the potential impact of these results in clinical practice and propose specific guidance for prospective translational research.

Aggressive prostatic adenocarcinoma with urothelial-like morphology, with frequent CK7/CK20/HMWK expression and occasional diffuse neuroendocrine features: A clinicopathologic study of 12 cases.

INTRODUCTION: Prostatic adenocarcinoma can occasionally display urothelial carcinoma morphology, which prompts immunohistochemistry (IHC) studies to determine its lineage. Typically, prostate cancer is characterized by the lack of cytokeratin (CK) 7, CK20 and high molecular weight keratin (HMWK) expression, as opposed to bladder cancer. METHODS: We report a series of 12 prostatic adenocarcinoma cases with unusual urothelial-like morphology, diagnosed at two academic institutions in Toronto between 2018 and 2023, and analyzed by immunohistochemistry for prostatic, urothelial, and neuroendocrine marker expression. We collected patient age, androgen deprivation therapy (ADT) status, tumour site, histomorphology, Grade group (GG) and results of genetic testing. RESULTS: The median age of the 12 patients included in this case series was 75.5 years (range 41-85). A history of prostatic cancer was noted in 7/12 (58%) patients. Five of nine (56%) patients had elevated serum PSA level at diagnosis. Six of eleven (55%) patients had prior ADT. Tumour sites were prostate (n = 6), bladder (n = 3), liver metastases (n = 2), and lung metastasis (n = 1). GGs of the primary tumours were GG3 (n = 1) and GG5 (n = 8). The observed urothelial-like morphology was diffuse in ten cases, and focal in two cases. CK7 was strong/diffuse in 8/11 tested cases, and focal weak in one case. CK20, HMWK, p63 and GATA3 were patchy/focal/weak/moderate in 3/6, 4/7, 4/8 and 2/9 cases, respectively. Ten (83%) cases were positive for at least one prostatic marker; eight (67%) cases had loss/weak staining of at least one prostatic marker. AR loss was seen in 2/7 (29%) cases. Seven of ten (70%) cases had diffuse/strong expression of at least one neuroendocrine marker. No trend was evident between prior ADT/AR status and any IHC result. Molecular analyses for DNA damage repair (DDR) genes (n = 6) demonstrated one ATM deletion (bladder). In addition, one TMPRSS2:ERG fusion (lung metastasis) was identified. CONCLUSION: This series comprises high-grade and/or metastatic prostatic adenocarcinoma cases with distinctive urothelial-like morphology and frequent aberrant CK7/CK20/HMWK expression. Their histomorphology, highly suggestive of an urothelial origin, represents a diagnostic pitfall that can lead to considerable management repercussions. The fact that a high proportion of the reported cases had loss/weak expression of at least one of the tested prostatic-specific markers, and occasionally a diffuse positivity for neuroendocrine markers highlights the importance of (1) clinical history and (2) utilization of broad IHC panels to correctly diagnose such unusual prostate cancer cases.

Antibody-Drug-Conjugates (ADC): A Novel Treatment Option in Urothelial Carcinoma.

Antibody drug conjugates (ADC) are a new class of agents that have been expanding the spectrum of treatment options in metastatic urothelial carcinoma only recently. Preliminary data suggest that these compounds may have the potential even to replace current standard treatments as platinum-based chemotherapies. To this end, current and future preclinical and translational evaluation of novel treatment strategies should consider these novel compounds in addition to current standard options as well. In this context, the following article will provide an overview of this new class of agents, starting with general information on molecular structure and mode of action, clinical use of ADCs in urothelial carcinoma, and ending with considerations for designing preclinical and translational experiments implementing ADCs.

The efficacy and timing of adjuvant chemotherapy in upper tract urothelial carcinoma.

BACKGROUND: A recovery period between surgery and initiation of adjuvant chemotherapy (AC) is common in patients with upper tract urothelial carcinoma (UTUC), which can progress after a relatively long time. Therefore, the efficacy of AC initiated within 90 days after radical nephroureterectomy (RNU) was evaluated in UTUC patients at stage ≥pT2 (N0-3M0), in addition to the effect of delayed AC initiation on survival outcomes. METHODS: Clinical data for 428 UTUC patients diagnosed with transitional cell carcinoma with postoperatively confirmed pathological stages, muscle-invasive or greater-stage (pT2-4) disease, any nodal status, and metastasis-free (M0) disease were retrospectively analyzed. All patients who received AC were treated within 90 days after RNU and underwent at least 4 cycles of the AC procedure. Then, patients receiving AC were divided into the "within 45 days" and "45 to 90 days" groups according to the time interval between RNU and AC initiation. Their clinicopathological characteristics were evaluated and the survival outcomes of the 2 groups were compared. Any adverse events that occurred during the AC process were also recorded. RESULTS: A total of 428 patients were analyzed in the study, including 132 individuals who underwent the AC procedure with platinum in combination with gemcitabine within 90 days after RNU and 296 patients who failed to initiate AC within 90 days. The median age of all patients was 68 years (mean 67, range 28-90 years), and the median follow-up was 25 months (mean 36, range 1-129 months). There were no significant differences in age, sex, lymph node metastasis, tumor location, hydronephrosis status, hematuria status, cancer grade, or multifocality between the 2 groups. Individuals undergoing AC initiated within 90 days of RNU showed a significantly decreased mortality relative to those patients who did not receive AC. Shorter intervals between RNU and AC initiation within 45 days vs. 45-90 days did not improve patient OS and cancer-specific survival (CSS) and may have increased the incidence of adverse events. CONCLUSION: The present study data supported the finding that a platinum-based combination with gemcitabine regimen initiated postoperatively significantly improved OS and CSS in patients with UTUC at stages ≥pT2 (N0-3M0). Furthermore, no survival benefit was evident in patients who started AC within 45 days after RNU compared to those who received AC within 45 to 90 days.

Immune Checkpoint Inhibitors and Long-term Survival of Patients With Metastatic Urothelial Cancer.

This cohort study uses published clinical trial data to assess long-term survival of patients with metastatic urothelial carcinoma who are treated with immune checkpoint inhibitors.

A Phase II Trial of Guadecitabine plus Atezolizumab in Metastatic Urothelial Carcinoma Progressing after Initial Immune Checkpoint Inhibitor Therapy.

PURPOSE: On the basis of preclinical evidence of epigenetic contribution to sensitivity and resistance to immune checkpoint inhibitors (ICI), we hypothesized that guadecitabine (hypomethylating agent) and atezolizumab [anti-programmed cell death ligand 1 (PD-L1)] together would potentiate a clinical response in patients with metastatic urothelial carcinoma (UC) unresponsive to initial immune checkpoint blockade therapy. PATIENTS AND METHODS: We designed a single arm phase II study (NCT03179943) with a safety run-in to identify the recommended phase II dose of the combination therapy of guadecitabine and atezolizumab. Patients with recurrent/advanced UC who had previously progressed on ICI therapy with programmed cell death protein 1 or PD-L1 targeting agents were eligible. Preplanned correlative analysis was performed to characterize peripheral immune dynamics and global DNA methylation, transcriptome, and immune infiltration dynamics of patient tumors. RESULTS: Safety run-in enrolled 6 patients and phase II enrolled 15 patients before the trial was closed for futility. No dose-limiting toxicity was observed. Four patients, with best response of stable disease (SD), exhibited extended tumor control (8-11 months) and survival (>14 months). Correlative analysis revealed lack of DNA demethylation in tumors after 2 cycles of treatment. Increased peripheral immune activation and immune infiltration in tumors after treatment correlated with progression-free survival and SD. Furthermore, high IL6 and IL8 levels in the patients' plasma was associated with short survival. CONCLUSIONS: No RECIST responses were observed after combination therapy in this trial. Although we could not detect the anticipated tumor-intrinsic effects of guadecitabine, the addition of hypomethylating agent to ICI therapy induced immune activation in a few patients, which associated with longer patient survival.

Patient-reported Outcomes from JAVELIN Bladder 100: Avelumab First-line Maintenance Plus Best Supportive Care Versus Best Supportive Care Alone for Advanced Urothelial Carcinoma.

BACKGROUND: In JAVELIN Bladder 100, avelumab first-line maintenance plus best supportive care (BSC) significantly prolonged overall survival (OS; primary endpoint) versus BSC alone in patients with advanced urothelial carcinoma (aUC) without disease progression with first-line platinum-containing chemotherapy. OBJECTIVE: To evaluate patient-reported outcomes (PROs) with avelumab plus BSC versus BSC alone. DESIGN, SETTING, AND PARTICIPANTS: A randomized phase 3 trial (NCT02603432) was conducted in 700 patients with locally advanced or metastatic urothelial carcinoma that had not progressed with first-line gemcitabine plus cisplatin or carboplatin. PROs were a secondary endpoint. INTERVENTION: Avelumab plus BSC (n = 350) or BSC alone (n = 350). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: National Comprehensive Cancer Network/Functional Assessment of Cancer Therapy Bladder Symptom Index-18 (FBlSI-18) and EuroQol five-level EQ-5D (EQ-5D-5L) assessments were analyzed using descriptive statistics and mixed-effect models. Time to deterioration (TTD; prespecified definition: a ≥3-point decrease from baseline in the FBlSI-18 disease-related symptoms-physical subscale for two consecutive assessments) was evaluated via Kaplan-Meier analyses. RESULTS AND LIMITATIONS: Completion rates for scheduled on-treatment PRO assessments were >90% (overall and average per assessment). Results from descriptive analyses and mixed-effect or repeated-measures models of FBlSI-18 and EQ-5D-5L were similar between arms. TTD was also similar, both in the prespecified analysis (hazard ratio 1.26 [95% confidence interval: 0.90, 1.77]) and in the post hoc analyses including off-treatment assessments and different event definitions. Limitations included the open-label design and limited numbers of evaluable patients at later time points. CONCLUSIONS: Addition of avelumab first-line maintenance to BSC in patients with aUC that had not progressed with first-line platinum-containing chemotherapy prolonged OS, with a relatively minimal effect on quality of life. PATIENT SUMMARY: In this trial of people with advanced urothelial carcinoma who had benefited from first-line chemotherapy (ie, had stable disease or reduced tumor size), treatment with avelumab maintenance plus best supportive care (BSC) versus BSC alone improved survival significantly, without compromising quality of life, as reported by the patients themselves.

Bempegaldesleukin plus Nivolumab in First-line Metastatic Urothelial Carcinoma: Results from PIVOT-02.

BACKGROUND: Despite recent changes in the treatment landscape, there remains an unmet need for effective, tolerable, chemotherapy-free treatments for patients with advanced/metastatic urothelial carcinoma (mUC), especially cisplatin-ineligible patients. OBJECTIVE: To evaluate the immunostimulatory interleukin-2 cytokine prodrug bempegaldesleukin (BEMPEG) plus nivolumab in patients with advanced/mUC from the phase 2 multicenter PIVOT-02 study. DESIGN, SETTING, AND PARTICIPANTS: This open-label, multicohort phase 1/2 study enrolled patients with previously untreated locally advanced/surgically unresectable or mUC (N = 41). INTERVENTION: Patients received BEMPEG 0.006 mg/kg plus nivolumab 360 mg intravenously every 3 wk. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary objectives were safety and the objective response rate (ORR) in patients with measurable disease at baseline and at least one postbaseline tumor response assessment (response-evaluable). Secondary objectives were overall survival (OS) and progression-free survival (PFS). Exploratory biomarker analyses via univariate logistic regression were performed to test the association between potential biomarkers (CD8+ tumor-infiltrating lymphocytes, tumor mutational burden, and IFN-γ gene expression profile) and response. RESULTS AND LIMITATIONS: The ORR was 35% (13/37 evaluable patients) and the complete response rate was 19% (7/37 patients); the median duration of response was not reached. Median PFS was 4.1 mo (95% confidence interval [CI] 2.1-8.7) and median OS was 23.7 mo (95% CI 15.8-not reached). Overall, 40/41 patients (98%) experienced at least one treatment-related adverse event (TRAE); grade 3/4 TRAEs occurred in 11 patients (27%), most commonly pyrexia (4.9%; 2 patients). Exploratory biomarker analyses showed no association between biomarkers and response. Limitations include the small sample size and single-arm design. CONCLUSIONS: BEMPEG plus nivolumab was well tolerated and showed antitumor activity as first-line treatment in patients with locally advanced/mUC. PATIENT SUMMARY: We investigated an immune-stimulating prodrug called bempegaldesleukin plus the antibody nivolumab as the first therapy for patients with advanced or metastatic cancer of the urinary tract. This combination had manageable treatment-related side effects and was effective in a subset of patients. This trial is registered at ClinicalTrials.gov as NCT02983045.