Prognostic Impact of Bone Metastasis in Patients With Metastatic Urothelial Carcinoma Treated With Durvalumab With or Without Tremelimumab in the DANUBE Study.

INTRODUCTION: Bone metastases (BM) in metastatic urothelial carcinoma (mUC) may impact patient outcomes, but their independent effect with immune checkpoint inhibitors (ICIs) is uncertain. We aimed to assess the impact of BM and PD-L1 status on outcomes in mUC patients treated with ICIs. PATIENTS AND METHODS: This post hoc analysis of the DANUBE study included 1032 mUC patients treated with durvalumab (D), D + tremelimumab (T), or standard chemotherapy (SoC). Patients were categorized by BM status and assessed for median overall survival (mOS) and median progression-free survival (mPFS) stratified by PD-L1 expression and treatment arm.  RESULTS: Among all patients enrolled in the study, those with BM had a lower mOS than those with no BM (8.7 vs. 15.8 months; P < .0001). Patients with BM and high PD-L1 expression, treated with D or D + T, had numerically longer mOS than patients with BM and low PD-L1 expression. In contrast, in the chemotherapy arm, there was no difference in mOS for BM or no BM, based on PD-L1 expression. Patients with BM had shorter mPFS compared to no BM (2.6 vs. 5.4 months; P < .0001). The study is limited by its post hoc nature. CONCLUSION: Presence of BM was associated with worse outcomes across treatment arms. Patients with BM and high PD-L1 expression treated with D or D + T had longer mOS, suggesting potential benefits of ICIs in this subgroup. Consideration of BM and PD-L1 status in treatment decisions for mUC patients receiving ICIs may improve clinical outcomes.

Comparison of Industry-Sponsored Trials (IST) and Investigator-Initiated Trials (IIT) in Advanced Genitourinary Cancers in the United States, Canada, United Kingdom and France.

BACKGROUND: Clinical trials are categorized as industry sponsored trials (ISTs) or investigator-initiated trials (IITs) based on the source of funding and sponsor of the trial. ISTs are usually run by pharmaceutical companies, and are primarily aimed at developing new drugs that ultimately gain regulatory approval. IITs are developed by academic investigators or cooperative groups, often sparked by a clinical need. Both are vital in advancing the field of oncology. To date, little has been published about current trends in ISTs or IITs in genitourinary (GU) oncology. The aim of this study was to assess growth trends of GU oncology ISTs and IITs in 4 countries with similar healthcare infrastructures. METHODS: We searched ClinicalTrials.gov for bladder, kidney, and prostate cancer trials conducted in the United States (US), Canada, France, and United Kingdom (UK) from January 2007 to December 2021. Trials were determined to be ISTs or IITs based on their funding source and sponsor. Trials were characterized based on type, purpose, phase, participants, masking, assignment, and allocation. RESULTS: Overall, 5,834 GU trials were identified, with a balanced distribution of ISTs (n = 3064, n = 52.5%) and IITs (n = 2770, 47.4%). By country, the US conducted the most GU trials (n = 3814) followed by Canada (n = 709), France (n = 677), and the UK (n = 634). Most ISTs were phase 3 trials with over 500 participants while most IITs were open-label phase 2 studies with only 20-49 participants. From 2017 onwards, there was a shift towards more ISTs, most noticeably in Canada and the UK. The COVID-19 pandemic did not have a major impact on the growth of ISTs and IITs. CONCLUSION: The gap between ISTs and IITs continues to widen, likely driven by resource and funding challenges faced by investigators. Barriers to completing IITs need to be better understood to promote IIT development and maintain their academically driven intentions.

Split-Dose Cisplatin in Patients With Locally Advanced or Metastatic Urothelial Carcinoma: A Systematic Literature Review and Network Meta-Analysis.

BACKGROUND: Gemcitabine plus cisplatin (GC) is a highly active and commonly used regimen in locally advanced/metastatic urothelial carcinoma (la/mUC). With GC, cisplatin is dosed at 70 mg/m2 on day 1 of a 3-week cycle; however, for many patients, impaired renal or cardiac function, neuropathy, or poor performance status (PS) can preclude the use of cisplatin. A promising alternative is split-dose GC, in which the cisplatin dose is divided over 2 days. METHODS: We conducted a systematic literature review (SLR) and network meta-analysis (NMA) to better understand treatment patterns and comparative effectiveness and safety of split-dose GC vs gemcitabine plus carboplatin (GCa), GC, and methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC). RESULTS: Among 120 identified studies, 16 studies representing 1,767 patients included split-dose GC. Common reasons for choosing split-dose GC were impaired renal function, age > 70 years, comorbidities, and physician preference. Split-dose GC had objective response rates (ORRs) of 39%-80%, median progression-free survival (PFS) of 3.5-9.9 months, and median overall survival (OS) of 8.5-18.1 months. Discontinuation rates due to adverse events were 5%-38%. In the NMA, ORR with split-dose GC was significantly higher than with GCa. PFS and OS for split-dose GC were similar to that observed with the other regimens (GCa, GC, and MVAC). CONCLUSIONS: This is the first SLR and NMA of split-dose GC in la/mUC. Despite heterogeneity in the limited studies included, split-dose GC demonstrated comparable effectiveness and safety profile to those seen with other regimens. Split-dose GC thus has the potential to extend the la/mUC population eligible to receive cisplatin-based regimens and warrants further prospective study.

Reevaluating the role of platinum-based chemotherapy in the evolving treatment landscape for patients with advanced urothelial carcinoma.

Platinum-based chemotherapy has been the standard first-line (1L) treatment for advanced urothelial carcinoma (UC) for decades, based on the proven efficacy and established safety profiles of cisplatin- and carboplatin-based regimens. With the emergence of novel regimens, it is important to reevaluate and contextualize the role of 1L platinum-based chemotherapy. Platinum-based chemotherapy followed by avelumab 1L maintenance in patients without disease progression following platinum-based chemotherapy was established as a standard 1L regimen based on the JAVELIN Bladder 100 phase III trial. More recently, the EV-302 phase III trial showed the superiority of 1L enfortumab vedotin (EV) + pembrolizumab versus platinum-based chemotherapy, and the Checkmate 901 phase III trial showed the superiority of 1L nivolumab + cisplatin/gemcitabine versus cisplatin/gemcitabine alone. These 2 regimens have now been included as standard 1L options in treatment guidelines for advanced UC. EV + pembrolizumab is now the preferred 1L treatment, and in locations where EV + pembrolizumab is not available or individual patients are not considered suitable, recommended options are platinum-based chemotherapy followed by avelumab maintenance or nivolumab + cisplatin-based chemotherapy. In this review, we discuss current treatment options for advanced UC recommended in guidelines, practical considerations with platinum-based chemotherapy, the role of avelumab 1L maintenance, recent phase III trials of EV + pembrolizumab and nivolumab + cisplatin/gemcitabine, safety profiles of recommended 1L treatments, and second-line treatment options.

A Podcast on Platinum Eligibility and Treatment Sequencing in Platinum-Eligible Patients with Locally Advanced or Metastatic Urothelial Carcinoma.

The treatment landscape for patients with advanced urothelial carcinoma continues to evolve. Enfortumab vedotin plus pembrolizumab has received Food and Drug Administration approval based on recent phase 3 trial data showing superior efficacy compared with first-line platinum-based chemotherapy; however, its distinct toxicity profile may make it less suitable for some patients, and availability in some countries may be limited by cost considerations. Consequently, platinum-based chemotherapy is expected to remain an important first-line treatment option. Choice of platinum regimen (cisplatin- or carboplatin-based) is informed by assessment of clinical characteristics, including performance status, kidney function, and presence of peripheral neuropathy or heart failure. For patients without disease progression after completing platinum-based chemotherapy, avelumab first-line maintenance treatment is recommended by international guidelines. For patients who have disease progression, pembrolizumab is the preferred approach. Additionally, following results from a recent phase 3 trial, nivolumab plus cisplatin-based chemotherapy has also received Food and Drug Administration approval and is an additional first-line treatment option for cisplatin-eligible patients. Later-line options for patients with advanced urothelial carcinoma, depending on prior treatment, may include enfortumab vedotin, erdafitinib (for patients with FGFR2/3 mutations or fusions/rearrangements), sacituzumab govitecan, and platinum rechallenge. For the small proportion of patients ineligible for any platinum-based chemotherapy (i.e., unsuitable for cisplatin or carboplatin), immune checkpoint inhibitor monotherapy with pembrolizumab or atezolizumab is a first-line treatment option, although approved agents vary between countries. In summary, this podcast discusses recent developments in the treatment landscape for advanced urothelial carcinoma, eligibility for platinum-based chemotherapy, potential first-line treatment options, and treatment sequencing. Supplementary file1 (MP4 246907 KB).

Management of urothelial cancer in patients with chronic kidney disease receiving platinum-based chemotherapy.

Despite recent advances in the management of urothelial cancer (UC), cisplatin-based combination chemotherapy regimens remain critical. However, their use can be complicated in patients with chronic kidney disease (CKD), which is not uncommon in UC patients. Based on the Galsky criteria for cisplatin ineligibility, most patients with CKD will be excluded from receiving cisplatin-based chemotherapy altogether. For patients with borderline kidney function, several strategies - such as the use of split-dose cisplatin, dose reductions, or extra hydration - may facilitate the use of cisplatin, but these need to be prospectively validated. This review highlights the critical need for a multidisciplinary team, including onco-nephrologists, to help manage renal complications and optimize delivery of cancer care in complex UC patients with CKD.

In patients with urothelial cancer, the presence of chronic kidney disease can significantly impact treatment options, eligibility for clinical trials, and overall patient outcomes. This review discusses key strategies and newer treatment options that can be used to optimize outcomes in patients who often can't receive standard treatments. Importantly, this article also highlights the critical importance and need for a multidisciplinary team of specialists, including kidney specialists with a focus on cancer patients, to help manage kidney function and deliver high-quality care to patients with urothelial cancer and chronic kidney disease.

Clinical variables associated with immune checkpoint inhibitor outcomes in patients with metastatic urothelial carcinoma: a multicentre retrospective cohort study.

OBJECTIVES: Immune checkpoint inhibitors (ICIs) are indicated for metastatic urothelial cancer (mUC), but predictive and prognostic factors are lacking. We investigated clinical variables associated with ICI outcomes. METHODS: We performed a multicentre retrospective cohort study of 135 patients who received ICI for mUC, 2016-2021, at three Canadian centres. Clinical characteristics, body mass index (BMI), metastatic sites, neutrophil-to-lymphocyte ratio (NLR), response and survival were abstracted from chart review. RESULTS: We identified 135 patients and 62% had received ICI as a second-line or later treatment for mUC. A BMI ≥25 was significantly correlated to a higher overall response rate (ORR) (45.4% vs 16.3%, p value=0.020). Patients with BMI ≥30 experienced longer median overall survival (OS) of 24.8 vs 14.4 for 25≤BMI<30 and 8.5 months for BMI <25 (p value=0.012). The ORR was lower in the presence of bone metastases (16% vs 41%, p value=0.006) and liver metastases (16% vs 39%, p value=0.013). Metastatic lymph nodes were correlated with higher ORR (40% vs 20%, p value=0.032). The median OS for bone metastases was 7.3 versus 18 months (p value <0.001). Patients with liver metastases had a median OS of 8.6 versus 15 months (p value=0.006). No difference for lymph nodes metastases (13.5 vs 12.7 months, p value=0.175) was found. NLR ≥4 had worse OS (8.2 vs 17.7 months, p value=0.0001). In multivariate analysis, BMI ≥30, bone metastases, NLR ≥4, performance status ≥2 and line of ICI ≥2 were independent factors for OS. CONCLUSIONS: Our data identified BMI and bone metastases as novel clinical biomarkers that were independently associated with ICI outcomes in mUC. External and prospective validation are warranted.

The Survival Outcomes of the Metastatic Nonclear Cell Renal Cell Carcinoma in the Immunotherapy Era: Princess Margaret Cancer Centre Experience.

Immunotherapy (IO) with or without targeted therapy (TT) is the standard treatment for patients with metastatic clear cell renal cell carcinoma (RCC). The evidence supporting their use in metastatic nonclear cell renal cell carcinoma (nccRCC) subtypes is based on small prospective trials and retrospective analyses. Here, we report survival outcomes for patients with metastatic nccRCC treated with IO and/or TT at the Princess Margaret Cancer Centre, Toronto, ON, Canada. Demographics, disease characteristics, and survival outcomes were collected retrospectively. Overall (OS), progression-free survival (PFS), and objective response rates (ORR) were calculated. We identified 69 patients with metastatic nccRCC treated with IO and/or TT as the first-line treatment, and 36 (52.1%) patients as the second-line treatment. Median OS of the first line IO recipients (n = 12) and non-IO recipients (n = 57) was not reached (NR) and 17.2 months (95% confidence interval (95% CI): 7.3-27.0; P = 0.23), respectively. Median PFS of first-line IO recipients and non-IO recipients was NR and 4.7 months (95% CI: 3.7-5.6; P = 0.019), respectively. The ORR of IO recipients versus non-IO recipients was 50% versus 12.3% (P = 0.007). Median OS of the second-line IO recipients (n = 8) and non-IO recipients (n = 28) was NR and 6.3 months (95% CI: 3.2-9.3; P = 0.003), respectively. Median PFS of second-line IO recipients and non-IO recipients was 4.8 months (95% CI: 2.7-6.8) and 2.8 months (95% CI: 1.8-3.7; P = 0.014), respectively. ORR of IO recipients and non-IO recipients was 37.5% and 3.5%, respectively; P = 0.028. While the number of patients included in our retrospective review was small, our analysis suggested that patients with nccRCC have improved survival outcomes with IO treatment. Validation of prospective dataset is required before widespread clinical utilization.

TOward a comPrehensive supportive Care intervention for Older men with metastatic Prostate cancer (TOPCOP3): A pilot randomized controlled trial and process evaluation.

INTRODUCTION: Current management of metastatic prostate cancer (mPC) includes androgen receptor axis-targeted therapy (ARATs), which is associated with substantial toxicity in older adults. Geriatric assessment and management and remote symptom monitoring have been shown to reduce toxicity and improve quality of life in patients undergoing chemotherapy, but their efficacy in patients being treated with ARATs has not been explored. The purpose of this study is to examine whether these interventions, alone or in combination, can improve treatment tolerability and quality of life (QOL) for older adults with metastatic prostate cancer on ARATs. MATERIALS AND METHODS: TOPCOP3 is a multi-centre, factorial pilot clinical trial coupled with an embedded process evaluation. The study includes four treatment arms: geriatric assessment and management (GA + M); remote symptom monitoring (RSM); geriatric assessment and management plus remote symptom monitoring; and usual care and will be followed for six months. The aim is to recruit 168 patients between two cancer centres in Toronto, Canada. Eligible participants will be randomized equally via REDCap. Participants in all arms will complete a comprehensive baseline assessment upon enrollment following the Geriatric Core dataset, as well as follow-up assessments at 1.5, 3, 4.5, and 6 months. The co-primary outcomes will be grade 3-5 toxicity and QOL. Toxicities will be graded using the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. QOL will be measured by patient self-reporting using the EuroQol 5 dimensions of health questionnaire. Secondary outcomes include fatigue, insomnia, and depression. Finally, four process evaluation outcomes will also be observed, namely feasibility, fidelity, and acceptability, along with implementation barriers and facilitators. DISCUSSION: Data will be collected to observe the effects of GA + M and RSM on QOL and toxicities experienced by older adults receiving ARATs for metastatic prostate cancer. Data will also be collected to help the design and conduct of a definitive multicentre phase III randomized controlled trial. This study will extend supportive care interventions for older adults with cancer into new areas and inform the design of larger trials. TRIAL REGISTRATION: The trial is registered at clinicaltrials.gov (registration number: NCT05582772).

Health-related Quality of Life in Patients with Previously Treated Advanced Urothelial Carcinoma from EV-301: A Phase 3 Trial of Enfortumab Vedotin Versus Chemotherapy.

BACKGROUND AND OBJECTIVE: In comparison to chemotherapy, enfortumab vedotin (EV) prolonged overall survival in patients with previously treated advanced urothelial carcinoma in EV-301. The objective of the present study was to assess patient experiences of EV versus chemotherapy using patient-reported outcome (PRO) analysis of health-related quality of life (HRQoL). METHODS: For patients in the phase 3 EV-301 trial randomized to EV or chemotherapy we assessed responses to the validated European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (QLQ-C30) at baseline, weekly for the first 12 wk, and then every 12 wk until discontinuation. We analyzed the QLQ-C30 change from baseline to week 12, the confirmed improvement rate, and the time to improvement or deterioration. KEY FINDINGS AND LIMITATIONS: Baseline PRO compliance rates were 91% for the EV arm (n = 301) and 89% for the chemotherapy arm (n = 307); the corresponding average rates from baseline to week 12 were 70% and 67%. Patients receiving EV versus chemotherapy had reduced pain (difference in change from baseline to week 12: -5.7, 95% confidence interval [CI] -10.8 to -0.7; p = 0.027) and worsening appetite loss (7.3, 95% CI 0.90-13.69; p = 0.026). Larger proportions of patients in the EV arm reported HRQoL improvement from baseline than in the chemotherapy arm; the odds of a confirmed improvement across ten QLQ-C30 function/symptom scales were 1.67 to 2.76 times higher for EV than for chemotherapy. Patients in the EV arm had a shorter time to first confirmed improvement in global health status (GHS)/QoL, fatigue, pain, and physical, role, emotional, and social functioning (all p < 0.05). EV delayed the time to first confirmed deterioration in GHS/QoL (p = 0.027), but worsening appetite loss occurred earlier (p = 0.009) in comparison to chemotherapy. CONCLUSIONS AND CLINICAL IMPLICATIONS: HRQoL with EV was maintained, and deterioration in HRQoL was delayed with EV in comparison to chemotherapy. Better results with EV were reported for some scales, with the greatest difference observed for pain. These findings reinforce the EV safety and efficacy outcomes and benefits observed in EV-301. PATIENT SUMMARY: Patients with previously treated advanced cancer of the urinary tract receiving the drug enfortumab vedotin maintained their HRQoL in comparison to patients treated with chemotherapy. The EV-301 trial is registered on ClinicalTrials.gov as NCT03474107 and on EudraCT as 2017-003344-21.

Avelumab First-line Maintenance for Advanced Urothelial Carcinoma: Analysis from JAVELIN Bladder 100 by Duration of First-line Chemotherapy and Interval Before Maintenance.

BACKGROUND: In the JAVELIN Bladder 100 phase 3 trial, avelumab first-line maintenance + best supportive care (BSC) prolonged overall survival (OS) and progression-free survival (PFS) versus BSC alone in patients with advanced urothelial carcinoma (advanced UC) without progression after first-line platinum-based chemotherapy. OBJECTIVE: To report post hoc analyses of subgroups defined by the duration of first-line chemotherapy and interval before maintenance. DESIGN, SETTING, AND PARTICIPANTS: Patients with advanced UC without progression after four to six cycles of platinum-based chemotherapy and a 4-10-wk interval after chemotherapy (n = 700) were randomized to receive avelumab + BSC or BSC alone. Subgroups were defined by duration (quartile [Q]) and estimated number of cycles of chemotherapy, and interval between chemotherapy and maintenance. The median follow-up was >19 mo in both arms. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: OS (primary endpoint), PFS, and safety were assessed. RESULTS AND LIMITATIONS: Hazard ratios (95% confidence interval) for OS with avelumab + BSC versus BSC alone were as follows: by chemotherapy duration-Q3: 0.63 (0.39-1.00); by number of cycles-four cycles: 0.69 (0.48-1.00), five cycles: 0.98 (0.57-1.71), and six cycles: 0.66 (0.47-0.92); and by interval-4-<6 wk: 0.75 (0.54-1.04), 6-<8 wk: 0.67 (0.43-1.06), and 8-10 wk: 0.69 (0.47-1.02). Results were similar for PFS. Safety was similar across subgroups. All analyses were exploratory. CONCLUSIONS: Post hoc analyses of OS and PFS in subgroups defined by first-line chemotherapy duration and interval before maintenance were generally consistent with the results in the overall population, with similar safety findings. Prospective trials are warranted to confirm these findings. PATIENT SUMMARY: Avelumab maintenance treatment helped patients with advanced urothelial cancer without disease progression after at least four cycles of prior chemotherapy, and who started maintenance treatment at least 4 wk after chemotherapy, to live longer.

The effect of cisplatin-based neoadjuvant chemotherapy on the renal function of patients undergoing radical cystectomy.

INTRODUCTION: Cisplatin-based neoadjuvant chemotherapy (NAC) is the standard of care for patients with muscle-invasive bladder cancer (MIBC) undergoing radical cystectomy (RC). Cisplatin, however, can induce renal toxicity. Furthermore, RC is an independent risk factor for renal injury, with decreases in estimated glomerular filtration rate (eGFR) of up to 6 mL/min/1.73 m2 reported at one year postoperatively. Our objective was to evaluate the effect of cisplatin-based NAC and RC on the renal function of patients undergoing both. METHODS: We analyzed a multicenter database of patients with MIBC, all of whom received cisplatin-based NAC prior to RC. eGFR values were collected at time points T1 (before NAC), T2 (after NAC but before RC), and T3 (one year post-RC). eGFR and proportion of patients with eGFR <60 ml/min/1.73m2 (chronic kidney disease [CKD] stage ≥3) were compared between these time points. As all patients in this dataset had received NAC, we identified a retrospective cohort of patients from one institution who had undergone RC during the same time period without NAC for context. RESULTS: We identified 234 patients with available renal function data. From T1 to T3, there was a mean decline in eGFR of 17% (13 mL/min/1.73 m2) in the NAC cohort and an increase in proportion of patients with stage ≥3 CKD from 27% to 50%. The parallel cohort of patients who did not receive NAC was comprised of 236 patients. The mean baseline eGFR in this cohort was lower than in the NAC cohort (66 vs. 75 mL/min/1.73 m2). The mean eGFR decline in this non-NAC cohort from T1 to T3 was 6% (4 mL/min/1.73 m2), and the proportion of those with stage ≥3 CKD increased from 37% to 51%. CONCLUSIONS: Administration of NAC prior to RC was associated with a 17% decline in eGFR and a nearly doubled incidence of stage ≥3 CKD at one year after RC. Patients who underwent RC without NAC had a higher rate of stage ≥3 CKD at baseline but appeared to have less renal function loss at one year.

Identification of characteristics predictive of long-term survival with durvalumab or durvalumab plus tremelimumab in metastatic urothelial carcinoma.

BACKGROUND: This retrospective analysis of data from clinical trials in metastatic urothelial carcinoma (mUC) was conducted to determine baseline patient characteristics associated with long-term survival (LTS) following treatment with immune checkpoint inhibitors. METHODS: Data for this analysis were from patients with platinum-refractory mUC who received durvalumab or durvalumab plus tremelimumab in phase 1/2 studies. The primary outcome measure was LTS. Patients were categorised as overall survival (OS) ≥ 2 years (from first dose) or OS < 2 years. A univariable analysis assessed independent associations with LTS and multivariable logistic regression was employed including each variable with P ≤ 0.05 as covariates. RESULTS: Among 360 patients, 88 (24.4%) had OS ≥ 2 years and 272 (75.6%) had OS < 2 years. In univariable analysis, several baseline characteristics and laboratory measurements were associated with LTS including sex, ECOG PS, PD-L1 expression, prior surgery, time from initial diagnosis, lymph node-only involvement, visceral disease, haemoglobin level, absolute neutrophil count, neutrophil-lymphocyte ratio and lactate dehydrogenase level. In multivariable analysis, LTS was significantly associated with ECOG PS, PD-L1 expression, haemoglobin level and absolute neutrophil count. CONCLUSIONS: Several baseline clinical characteristics and laboratory measurements were associated with LTS for patients with platinum-refractory mUC treated with durvalumab or durvalumab plus tremelimumab.

Clinical and dosimetric outcomes of image-guided, dose-painted radiotherapy in muscle invasive bladder cancer.

PURPOSE/OBJECTIVE: Definitive radiotherapy (RT) is an alternative to radical cystectomy for select patients with muscle invasive bladder cancer (MIBC); however, there is limited data on dose-painted RT approaches. We report the clinical and dosimetric outcomes of a cohort of MIBC patients treated with dose-painted RT. MATERIAL/METHODS: This was a single institution retrospective study of cT2-4N0M0 MIBC patients treated with external beam radiotherapy (EBRT) to the bladder, and sequential or concomitant boost to the tumor bed. The target delineation was guided by either intravesical injection of Lipiodol or through fusion of the pre-treatment imaging. The majority were treated with daily image-guidance. Kaplan-Meier was used to characterize overall survival (OS) and progression-free survival (PFS). Cumulative incidence function (CIF) was used to estimate local (intravesical) recurrence (LR), regional recurrence (RR) and distant metastasis (DM). Univariable and multivariable cause-specific hazard model was used to assess factors associated with LR and OS. RESULTS: 117 patients were analyzed. The median age was 73 years (range 43, 95). The median EQD2 to the boost volume was 66 Gy (range 52.1, 70). Lipiodol injection was used in 64 patients (55%), all treated with IMRT/VMAT. 95 (81%) received concurrent chemotherapy, of whom, 44 (38%) received neoadjuvant chemotherapy. The median follow-up was 37 months (IQR 16.2, 83.3). At 5-year, OS and PFS were 79% (95% CI 70.5-89.2) and 46% (95% CI 36.5-57.5). Forty-five patients had bladder relapse, of which 30 patients (67%) were at site of the tumor bed. Nine patients underwent salvage-cystectomy. Late high-grade (G3-G4) genitourinary and gastrointestinal toxicity were 3% and 1%. CONCLUSION: Partial boost RT in MIBC is associated with good local disease control and high rates of cystectomy free survival. We observed a pattern of predominantly LR in the tumor bed, supporting the use of a dose-painted approach/de-escalation strategy to the uninvolved bladder. Prospective trials are required to compare oncological and toxicity outcomes between dose-painted and homogeneous bladder RT techniques.