Deintensification of Treatment for Low-grade Bladder Tumors: A Collaborative Review by the International Bladder Cancer Group (IBCG).

BACKGROUND AND OBJECTIVE: Management of low-grade (LG) urothelium-confined (Ta stage) non-muscle-invasive bladder cancer (NMIBC) poses a distinct therapeutic challenge. Transurethral resection of bladder tumor (TURBT), the standard treatment, frequently has to be repeated because of high tumor recurrence rates. This places a considerable strain on both patients and health care infrastructure, underscoring the need for alternative management approaches. Herein, the IBCG (International Bladder Cancer Group), conducted a review to explore the efficacy and safety of deintensified treatment strategies for recurrent LG Ta NMIBC. METHODS: We conducted a collaborative review of relevant literature in the PubMed/MEDLINE and Cochrane CENTRAL databases. Our focus was on high-quality evidence, including randomized controlled trials, systematic reviews, and meta-analyses. We also reviewed guidelines published by prominent urological associations. KEY FINDINGS AND LIMITATIONS: Active surveillance, chemoablation, and office fulguration are valid treatment options for recurrent LG Ta NMIBC. These deintensified approaches offer several advantages over TURBT: lower complication rates, less morbidity, lower health care costs, and better quality of life for patients. Importantly, these benefits are achieved without compromising oncological safety. CONCLUSIONS AND CLINICAL IMPLICATIONS: Our review demonstrates that less intensive treatment strategies for recurrent LG Ta NMIBC are both feasible and valuable. The IBCG recommends use of these approaches for carefully selected patients to help lower health care costs and enhance patients' quality of life. PATIENT SUMMARY: We reviewed studies on less invasive management options for low-grade noninvasive bladder cancer, including active surveillance, chemical ablation, and heat treatment. Recent results confirm that these less intense treatment options can reduce the treatment burden and costs for patients and preserve their quality of life without negatively affecting cancer control outcomes.

Urachal and Nonurachal Adenocarcinomas of the Urinary Bladder: A Comprehensive Genomic Profiling Study.

PURPOSE: Although both urachal (U) and nonurachal (NU) bladder adenocarcinomas (adenoCas) share several histologic similarities, they differ in location and sometimes in therapeutic options. We analyzed the differences in genomic alterations (GAs) between these tumor entities, with the aim of identifying potential therapeutic targets for clinical trials. MATERIALS AND METHODS: Overall, 133 U and 328 NU adenoCas were analyzed. Hybrid capture-based comprehensive genomic profiling (CGP) was performed to evaluate all classes of GA. Germline status of GA was predicted using a validated somatic-germline computational method. CGP was performed using the FoundationOne and FoundationOne CDx assays (Foundation Medicine, Inc). RESULTS: The most frequent GA in both U and NU cohorts included TP53 (86.5% v 81.1%) and KRAS (34.6% v 27.7%). GAs characteristic of colorectal adenoCa, such as SMAD4 (P = .069) and GNAS (P = .071), were more common in U versus NU. Conversely, TERT (P < .01) and RB1 (P = .071) were more prevalent in NU adenoCa. Notably, both U and NU adenoCas exhibited possibly targetable GA in PIK3CA (7.5% v 7.9%) and ERBB2 (6.8% v 7.6%). Biomarkers associated with potential benefit from anti-PD-1/L1 were infrequent. Median tumor mutational burden was 2.6 and 3.5 mutations per megabase for U and NU, respectively, and PD-L1 expression >1% was rare. Genomic ancestry and genomic signature distribution were similar in both tumor types. GAs were most commonly of somatic nature. Limitations include lack of clinical data, tumor heterogeneity, and retrospective nature. CONCLUSION: U and NU adenoCAs revealed differences in GA, with PIK3CA and ERBB2 being identified as putative therapeutic targets. Biomarkers of response to anti-PD-(L)1 were uncommon. Results highlight the potential of CGP to personalize treatment options of bladder adenoCa and inform clinical trial designs.

Bladder-sparing Therapy for Bacillus Calmette-Guérin-unresponsive Non-muscle-invasive Bladder Cancer: International Bladder Cancer Group Recommendations for Optimal Sequencing and Patient Selection.

BACKGROUND AND OBJECTIVE: There has been a recent surge in the development of agents for bacillus Calmette-Guérin-unresponsive (BCG-U) non-muscle-invasive bladder cancer (NMIBC). Critical assessment of these agents and practical recommendations for optimal selection of patients and therapies are urgently needed, especially in the absence of randomized trials on bladder-sparing treatment (BST) options. METHODS: A global committee of bladder cancer experts was assembled to develop recommendations on BST for BCG-U NMIBC. Working groups reviewed the literature and developed draft recommendations, which were then voted on by International Bladder Cancer Group (IBCG) members using a modified Delphi process. During a live meeting in August 2023, voting results and supporting evidence were presented, and recommendations were refined on the basis of meeting discussions. Final recommendations achieved >75% agreement during the meeting, and some were further refined via web conferences and e-mail discussions. KEY FINDINGS AND LIMITATIONS: There is currently no single optimal agent for patients with BCG-U disease who seek to avoid radical cystectomy (RC). BST selection should be personalized, taking into account individual patient characteristics and preferences, tumor attributes, and efficacy/toxicity data for the agents available. For patients with BCG-U carcinoma in situ (CIS), gemcitabine/docetaxel (GEM/DOCE), nadofaragene firadenovec (NFF), and nogapendekin alfa inbakicept-pmln (NAI) + BCG are recommended; because of its systemic toxicity, pembrolizumab should only be offered after other options are exhausted. For patients with BCG-U papillary-only tumors, GEM/DOCE, NFF, NAI + BCG, single-agent chemotherapy, hyperthermic mitomycin C, and pembrolizumab are recommended. Given the modest efficacy of available options, clinical trial participation is encouraged. For unapproved agents with reported data, IBCG recommendations await the final results of pivotal trials. CONCLUSIONS AND CLINICAL IMPLICATIONS: The IBCG consensus recommendations provide practical guidance on BST for BCG-U NMIBC.

Long-term outcomes of bladder-sparing therapy vs radical cystectomy in BCG-unresponsive non-muscle-invasive bladder cancer.

OBJECTIVE: To quantify the oncological risks of bladder-sparing therapy (BST) in patients with Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer (NMIBC) compared to upfront radical cystectomy (RC). PATIENTS AND METHODS: Pre-specified data elements were collected from retrospective cohorts of patients with BCG-unresponsive NMIBC from 10 international sites. After Institutional Review Board approval, patients were included if they had BCG-unresponsive NMIBC meeting United States Food and Drug Administration criteria. Oncological outcomes were collected following upfront RC or BST. BST regimens included re-resection or surveillance only, repeat BCG, intravesical chemotherapy, systemic immunotherapy, and clinical trials. RESULTS: Among 578 patients, 28% underwent upfront RC and 72% received BST. The median (interquartile range) follow-up was 50 (20-69) months. There were no statistically significant differences in metastasis-free survival, cancer-specific survival, or overall survival between treatment groups. In the BST group, high-grade recurrence rates were 37% and 52% at 12 and 24 months and progression to MIBC was observed in 7% and 13% at 12 and 24 months, respectively. RC was performed in 31.7% in the BST group and nodal disease was found in 13% compared with 4% in upfront RC (P = 0.030). CONCLUSION: In a selected cohort of patients, initial BST offers comparable survival outcomes to upfront RC in the intermediate term. Rates of recurrence and progression increase over time especially in patients treated with additional lines of BST.

A Pilot Study of the CD38 Antagonist Daratumumab in Patients with Metastatic Renal Cell Carcinoma or Muscle Invasive Bladder Cancer.

Background We performed a pilot study of daratumumab (monoclonal antibody directed against CD38) in muscle invasive bladder cancer (MIBC) and treatment refractory metastatic renal cell carcinoma (mRCC). Methods Patients with MIBC underwent baseline TURBT followed by 4 weekly doses of daratumumab prior to cystectomy. Patients with mRCC underwent a baseline and a sequential biopsy after 8 weekly doses. The primary endpoint was safety. The secondary endpoints: MIBC pathologic complete response rate (pCR), mRCC: objective response rate (ORR) and progression free survival (PFS). Exploratory analyses included immune monitoring. A Bayesian sequencing monitoring design for toxicity was used for excessive toxicity (TOX). Results: In both the MIBC (n=8) and mRCC (n= 8), no TOX events were encountered. In the MIBC cohort, 1 patient experienced pCR. In mRCC, no objective responses and the median PFS was 1.5 months (95%CI: 1.1, 1.8 months). Immune monitoring found significant reductions in NK cells in circulation in both cohorts' post treatment. In the tissue analysis, IHC found evidence of diminished CD38 presence in mRCC with treatment, while baseline levels in MIBC were low. Conclusions Treatment with daratumumab was safe. No signal of efficacy was detected in mRCC and conclusions on activity in MIBC were limited. Evidence of daratumumab targeting CD38 was detected in circulating immune cells and within the tumor microenvironment of mRCC and MIBC.

Clinical Validation of the Intermediate-risk Non-muscle-invasive Bladder Cancer Scoring System and Substratification Model Proposed by the International Bladder Cancer Group: A Multicenter Young Academic Urologists Urothelial Working Group Collaboration.

BACKGROUND AND OBJECTIVE: Intermediate-risk (IR) non-muscle-invasive bladder cancer (NMIBC) encompasses a broad spectrum of disease, with heterogeneous outcomes in terms of disease recurrence and progression. The International Bladder Cancer Group (IBCG) recently proposed an updated scoring model for IR substratification that is based on five key risk factors. Our aim was to provide a clinical validation of the IBCG scoring system and substratification model for IR NMIBC. METHODS: This was an international multicenter retrospective study. Patients diagnosed with IR NMIBC between 2012 and 2022 and treated with transurethral resection of the bladder and adjuvant intravesical chemotherapy were included. According to the presence or absence of risk factors, patients with IR NMIBC were further categorized in IR-low (no risk factors), IR-intermediate (1-2 risk factors), and IR-high (≥3 risk factors) groups. The 1-yr and 3-yr rates for recurrence-free survival (RFS) and progression-free survival (PFS) were evaluated for each subgroup. Cox regression analyses were used to compare oncological outcomes between the groups. KEY FINDINGS AND LIMITATIONS: Of the 677 patients with IR NMIBC included in the study, 231 (34%), 364 (54%), and 82 (12%) were categorized in the IR-low, IR-intermediate, and IR-high groups, respectively. There were significant differences in RFS and PFS rates between these groups. CONCLUSIONS AND CLINICAL IMPLICATIONS: We provide the first clinical validation of the IBCG scoring system and model for substratification of IR NMIBC. PATIENT SUMMARY: Our study demonstrates that patients with intermediate-risk non-muscle-invasive bladder cancer can be correctly classified into three distinct subgroups according to their risk of both disease recurrence and progression. Our results support use of this scoring system in clinical practice.

Current Status and Challenges in Rare Genitourinary Cancer Research and Future Directions.

PURPOSE OF REVIEW: In contemporary urological practice, managing rare genitourinary (GU) malignancies presents significant challenges, necessitating a comprehensive understanding of their unique characteristics and tailored treatment approaches. RECENT FINDINGS: Rare GU malignancies, whether per se, variants of common histologies, or common tumors in uncommon locations, often lack widely available clinical guidelines. Consequently, treatment decisions are frequently based on empirical evidence, risking suboptimal outcomes. However, recent advances in molecular profiling, targeted therapies, and immunotherapy offer promising avenues for improving management strategies and patient outcomes. This review provides a comprehensive overview of some rare GU malignancies encountered in clinical practice, including their distinct pathological features, current management approaches, and ongoing research directions. Understanding the complexities of these rare tumors and implementing multidisciplinary treatment strategies are essential for optimizing patient care and improving survival outcomes.

Oncolytic adenoviral therapy plus pembrolizumab in BCG-unresponsive non-muscle-invasive bladder cancer: the phase 2 CORE-001 trial.

Cretostimogene grenadenorepvec is a serotype-5 oncolytic adenovirus designed to selectively replicate in cancer cells with retinoblastoma pathway alterations, previously tested as monotherapy in bacillus Calmette-Guérin (BCG)-experienced non-muscle-invasive bladder cancer. In this phase 2 study, we assessed the potential synergistic efficacy between intravesical cretostimogene and systemic pembrolizumab in patients with BCG-unresponsive non-muscle-invasive bladder cancer with carcinoma in situ (CIS). Thirty-five patients were treated with intravesical cretostimogene with systemic pembrolizumab. Induction cretostimogene was administered weekly for 6 weeks followed by three weekly maintenance infusions at months 3, 6, 9, 12 and 18 in patients maintaining complete response (CR). Patients with persistent CIS/high-grade Ta at the 3-month assessment were eligible for re-induction. Pembrolizumab was administered for up to 24 months. The primary endpoint was CR at 12 months as assessed by cystoscopy, urine cytology, cross-sectional imaging and mandatory bladder mapping biopsies. Secondary endpoints included CR at any time, duration of response, progression-free survival and safety. The CR rate in the intention-to-treat population at 12 months was 57.1% (20 out of 35, 95% confidence interval (CI) 40.7-73.5%), meeting the primary endpoint. A total of 29 out of 35 patients (82.9%, 95% CI 70.4-95.3%) derived a CR at 3 months. With a median follow-up of 26.5 months, the median duration of response has not been reached (95% CI 15.7 to not reached). The CR rate at 24 months was 51.4% (18 out of 35) (95% CI 34.9-68.0%). No patient progressed to muscle-invasive bladder cancer in this trial. Adverse events attributed to cretostimogene were low grade, self-limiting and predominantly limited to bladder-related symptoms. A total of 5 out of 35 patients (14.3%) developed grade 3 treatment-related adverse effects. There was no evidence of overlapping or synergistic toxicities. Combination intravesical cretostimogene and systemic pembrolizumab demonstrated enduring efficacy. With a toxicity profile similar to its monotherapy components, this combination may shift the benefit-to-risk ratio for patients with BCG-unresponsive CIS. ClinicalTrials.gov Identifier: NCT04387461 .

Novel Delivery Systems and Pharmacotherapeutic Approaches for the Treatment of Non-muscle-invasive Bladder Cancer.

BACKGROUND AND OBJECTIVE: Therapeutic options for patients with non-muscle-invasive bladder cancer (NMIBC) have traditionally been limited to intravesical immunotherapy or chemotherapy. A considerable number of new options have been investigated in recent years. Our aim was to review the efficacy and toxicity of novel therapeutic options (results already reported or currently under investigation) for patients with NMIBC. METHODS: We assessed the efficacy of various novel therapeutic options by examining key endpoints in diverse settings, including recurrence, progression, overall survival, disease-specific survival, and complete response. We identified the principal advantages and limitations for each option. Safety was predominantly evaluated as the incidence of grade ≥3 adverse events. Our investigation focused on evidence from scientific articles and congress abstracts published in English within the past 5 yr. KEY FINDINGS AND LIMITATIONS: To date, pembrolizumab, nadofaragene firadenovec, and the combination of BCG with N-803 have received US Food and Drug administration approval for the treatment of BCG-unresponsive carcinoma in situ of the bladder (with or without papillary tumours). Five phase 3 trials are recruiting BCG-naïve patients with high-risk NMIBC. There is increasing interest in an ablative rather than an adjuvant approach for patients with intermediate-risk NMIBC. CONCLUSIONS AND CLINICAL IMPLICATIONS: Novel drugs and device-assisted drug delivery systems are on the verge of changing the treatment of NMIBC. Novel intravesical options seem to have the same efficacy with fewer adverse events in comparison to systemic therapies. PATIENT SUMMARY: We reviewed new therapy options for non-muscle-invasive bladder cancer. Two agents (pembrolizumab and nadofaragene firadenovec) have been approved to date. Ongoing trials are assessing direct delivery of drugs in solution into the bladder. This route seems to have similar efficacy and fewer side effects than intravenous immunotherapy.

The spectrum of cutaneous toxicities related to novel genitourinary cancer therapies.

CONTEXT: Genitourinary cancers (GUCs) encompass malignancies affecting the urinary and reproductive systems, including renal cell carcinoma (RCC), urothelial carcinoma (UC), and prostate cancer (PC). With the rapidly evolving therapeutic domain of these cancers, cutaneous adverse events (AEs) remain among the most observed toxicities. OBJECTIVE: To explore the dermatologic AEs linked to novel GUC treatments, their underlying pathophysiology, clinical presentations, and risk factors. EVIDENCE ACQUISITION: A narrative review of the literature from PubMed and Embase databases was conducted. The search strategy included dermatologic/cutaneous adverse events, risk factors, and pathophysiology in conjunction with the following classes of therapies; immune checkpoint inhibitors (ICIs), antiangiogenic therapies, enfortumab vedotin (EV), erdafitinib, and androgen receptor antagonists (ARAs). EVIDENCE SYNTHESIS: Maculopapular rash, pruritus, and alopecia are present among the five classes of therapies. ICIs demonstrate the highest incidence of severe drug AEs including Steven Johnson syndrome/toxic epidermal necrolysis. Unique cutaneous AEs present with specific therapies including hand-foot skin reaction and subungual splinter hemorrhage with antiangiogenic drugs, stomatitis/mucositis and onycholysis with erdafitinib. Incidence and type of cutaneous AE also differed within therapies in the same class as seen with apalutamide displaying the highest risk of cutaneous AEs within ARAs. Risk factors for development of cutaneous AEs can be general to therapies, or specific, and include age, immune status, BMI, and gender. CONCLUSIONS: Dermatologic AEs may impact patients' quality of life and increase the tendency to dose reduce, hold or discontinue life-saving therapies, underscoring the need for vigilant monitoring, early recognition, and collaborative management between medical oncologists, pharmacists, dermatologists and other specialists.

A phase II trial of apalutamide for intermediate-risk prostate cancer and molecular correlates.

OBJECTIVES: To determine whether 6 months of preoperative apalutamide for intermediate-risk prostate cancer (IRPCa) reduces the aggregate postoperative radiotherapy risk and to evaluate associations of molecular perturbations with clinical outcomes in this study cohort. PATIENTS AND METHODS: Between May 2018 and February 2020, eligible patients with IRPCa (Gleason 3 + 4 or 4 + 3 and clinical T2b-c or prostate-specific antigen level of 10-20 ng/mL) were treated with apalutamide 240 mg/day for 6 months followed by radical prostatectomy (RP) in this single-arm, phase II trial. The primary endpoint was presence of any adverse pathological feature at risk of pelvic radiation (pathological T stage after neoadjuvant therapy [yp]T3 or ypN1 or positive surgical margins). Translational studies, including germline and somatic DNA alterations and RNA and protein expression, were performed on post-apalutamide RP specimens, and assessed for associations with clinical outcomes. RESULTS: A total of 40 patients underwent a RP, and only one patient discontinued apalutamide prior to 6 months. In all, 40% had adverse pathological features at time of RP, and the 3-year biochemical recurrence (BCR) rate was 15%, with 27.5% being not evaluable. Genomic alterations frequently seen in metastatic PCas, such as androgen receptor (AR), tumour protein p53 (TP53), phosphatase and tensin homologue (PTEN), or BReast CAncer associated gene (BRCA1/2) were underrepresented in this localised cohort. Adverse pathological features and BCR at 3-years were associated with increased expression of select cell cycle (e.g., E2F targets: adjusted P value [Padj] < 0.001, normalised enrichment score [NES] 2.47) and oxidative phosphorylation (Padj < 0.001, NES 1.62) pathways. CONCLUSIONS: Preoperative apalutamide did not reduce the aggregate postoperative radiation risk to the pre-specified threshold in unselected men with IRPCa. However, transcriptomic analysis identified key dysregulated pathways in tumours associated with adverse pathological outcomes and BCR, which warrant future study. Further investigation of preoperative therapy is underway for men with high-risk PCa.

Optimizing the Use of Next-Generation Sequencing Assays in Patients With Urothelial Carcinoma: Recommendations by the 2023 San Raffaele Retreat Panel.

BACKGROUND: The application of precision medicine in clinical practice implies a thorough evaluation of actionable genomic alterations to streamline therapeutic decision making. Comprehensive genomic profiling of tumor via next-generation sequencing (NGS) represents a great opportunity but also several challenges. During the 2023 San Raffaele Retreat, we aimed to provide expert recommendations for the optimal use of NGS in urothelial carcinoma (UC). MATERIALS AND METHODS: A modified Delphi method was utilized, involving a panel of 12 experts in UC from European and United States centers, including oncologists, urologists, pathologists, and translational scientists. An initial survey, conducted before the meeting, delivered 15 statements to the panel. A consensus was defined when ≥70% agreement was reached for each statement. Statements not meeting the consensus threshold were discussed during the meeting. RESULTS: Nine of the 15 statements covering patient selection, cancer characteristics, and type of NGS assay, achieved a consensus during the survey. The remaining six statements addressing the optimal timing of NGS use, the ideal source of tumor biospecimen for NGS testing, and the subsequent need to evaluate the germline nature of certain genomic findings were discussed during the meeting, leading to unanimous agreement at the end of the conference. CONCLUSION: This consensus-building effort addressed multiple unanswered questions regarding the use of NGS in UC. The opinion of experts was in favor of broader use of NGS. In a setting where recommendations/guidelines may be limited, these insights may aid clinicians to provide informed counselling and raise the bar of precision and personalized therapy.

Hematuria Cancer Risk Score with Ultrasound Informs Cystoscopy Use in Patients with Hematuria.

BACKGROUND: Hematuria is a cardinal symptom of urinary tract cancer and would require further investigations. OBJECTIVE: To determine the ability of renal bladder ultrasound (RBUS) with the Hematuria Cancer Risk Score (HCRS) to inform cystoscopy use in patients with hematuria. DESIGN, SETTING, AND PARTICIPANTS: The development cohort comprised 1984 patients with hematuria from 40 UK hospitals (DETECT 1; ClinicalTrials.gov: NCT02676180) who received RBUS. An independent validation cohort comprised 500 consecutive patients referred to secondary care for a suspicion of bladder cancer. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Sensitivity and true negative of the HCRS and RBUS were assessed. RESULTS AND LIMITATIONS: A total of 134 (7%) and 36 (8%) patients in the development and validation cohorts, respectively, had a diagnosis of urinary tract cancer. Validation of the HCRS achieves good discrimination with an area under the receiver operating characteristic curve of 0.727 (95% confidence interval 0.648-0.800) in the validation cohort with sensitivity of 95% for the identification of cancer. Utilizing the cutoff of 4.500 derived from the HCRS in combination with RBUS in the development cohort, 680 (34%) patients would have been spared cystoscopy at the cost of missing a G1 Ta bladder cancer and a urinary tract cancer patient, while 117 (25%) patients would have avoided cystoscopy at the cost of missing a single patient of G1 Ta bladder cancer with sensitivity for the identification of cancer of 97% in the validation cohort. CONCLUSIONS: The HCRS with RBUS offers good discriminatory ability in identifying patients who would benefit from cystoscopy, sparing selected patient cohorts from an invasive procedure. PATIENT SUMMARY: The hematuria cancer risk score with renal bladder ultrasound allows for the triage of patients with hematuria who would benefit from visual examination of the bladder (cystoscopy). This resulted in 25% of patients safely omitting cystoscopy, which is an invasive procedure, and would lead to health care cost savings.

Pembrolizumab monotherapy for high-risk non-muscle-invasive bladder cancer without carcinoma in situ and unresponsive to BCG (KEYNOTE-057): a single-arm, multicentre, phase 2 trial.

BACKGROUND: The KEYNOTE-057 trial evaluated activity and safety of pembrolizumab in patients with BCG-unresponsive high-risk non-muscle-invasive bladder cancer who were ineligible for or declined radical cystectomy. In cohort A (patients with carcinoma in situ, with or without papillary tumours) of the KEYNOTE-057 study, pembrolizumab monotherapy led to a complete response rate of 41% at 3 months, and 46% of responders maintained a response lasting at least 12 months. Here, we evaluate pembrolizumab monotherapy in cohort B of patients with papillary tumours without carcinoma in situ. METHODS: KEYNOTE-057 is a single-arm, phase 2 study in 54 sites (hospitals and cancer centres) in 14 countries. Cohort B eligible patients were aged 18 years and older, had an Eastern Cooperative Oncology Group performance status of 0-2, and had BCG-unresponsive high-risk non-muscle-invasive bladder cancer with papillary tumours (high-grade Ta or any-grade T1) without carcinoma in situ. Transurethral resection of bladder tumour within 12 weeks of first pembrolizumab dose was required. Patients received pembrolizumab 200 mg intravenously every 3 weeks for a maximum of 35 cycles. Primary endpoint was 12-month disease-free survival of high-risk non-muscle-invasive bladder cancer or progressive disease as assessed by cystoscopy, cytology, and central pathology and radiology review. Activity was assessed in all patients who received at least one dose of the study drug and had a baseline evaluation. Safety was assessed in all patients who received at least one dose of the study drug. This trial is registered with ClinicalTrials.gov number, NCT02625961, and is ongoing. FINDINGS: Between April 12, 2016, and June 17, 2021, 132 patients (104 [79%] men and 28 [21%] women) who had received a median of ten (IQR 9-15) previous BCG instillations were enrolled into cohort B of the study. Patients received a median of 10 cycles (IQR 6-27) of pembrolizumab. At data cutoff date, Oct 20, 2022, median follow-up was 45·4 months (IQR 36·4-59·3) and five (4%) of 132 patients remained on treatment. The 12-month disease-free survival was 43·5% (95% CI 34·9-51·9). Treatment-related adverse events occurred in 97 (73%) of 132 patients; 19 (14%) had a grade 3 or 4 treatment-related adverse event; the most common grade 3 or 4 treatment-related adverse events were colitis (in three [2%] patients) and diarrhoea (in two [2%]). 17 (13%) of 132 patients experienced serious treatment-related adverse events, of which colitis (three patients [2%]) was most common. No treatment-related deaths occurred. INTERPRETATION: Pembrolizumab monotherapy showed antitumour activity and manageable toxicity in patients with BCG-unresponsive high-risk Ta or T1 bladder cancer without carcinoma in situ and could potentially be a suitable treatment option for patients who decline or are ineligible for radical cystectomy. Findings will need to be confirmed in a randomised controlled trial. FUNDING: Merck Sharp & Dohme.