Revolutionizing Treatment: Breakthrough Approaches for BCG-Unresponsive Non-Muscle-Invasive Bladder Cancer

Bladder cancer is the 10th most popular cancer in the world, and non-muscle-invasive bladder cancer (NMIBC) is diagnosed in ~80% of all cases. Treatments for NMIBC include transurethral resection of the bladder tumor (TURBT) and intravesical instillations of Bacillus Calmette-Guérin (BCG). Treatment of BCG-unresponsive tumors is scarce and usually leads to Radical Cystectomy. In this paper, we review recent advancements in conservative treatment of BCG-unresponsive tumors. The main focus of the paper is FDA-approved medications: Pembrolizumab and Nadofaragene Firadenovec (Adstiladrin). Other, less researched therapeutic possibilities are also included, namely: N-803 immunotherapy, TAR-200 and TAR-210 intravesical delivery systems and combined Cabazitaxel, Gemcitabine and Cisplatin chemotherapy. Conservative treatment and delaying radical cystectomy would greatly benefit patients' quality of life; it is undoubtedly the future of BCG-unresponsive NMIBC.

Mechanism of action of nadofaragene firadenovec-vncg

Effective bladder-preserving therapeutic options are needed for patients with bacillus Calmette-Guérin unresponsive non-muscle-invasive bladder cancer. Nadofaragene firadenovec-vncg (Adstiladrin®) was approved by the US Food and Drug Administration as the first gene therapy in urology and the first intravesical gene therapy indicated for the treatment of adult patients with high-risk bacillus Calmette-Guérin-unresponsive non-muscle-invasive bladder cancer with carcinoma in situ with or without papillary tumors. The proposed mechanism of action underlying nadofaragene firadenovec efficacy is likely due to the pleiotropic nature of interferon-α and its direct and indirect antitumor activities. Direct activities include cell death and the mediation of an antiangiogenic effect, and indirect activities are those initiated through immunomodulation of the innate and adaptive immune responses. The sustained expression of interferon-α that results from this treatment modality contributes to a durable response. This review provides insight into potential mechanisms of action underlying nadofaragene firadenovec efficacy.

Efficacy of hyperthermic intravesical chemotherapy (HIVEC) in patients with non-muscle invasive bladder cancer after BCG failure

PURPOSE

To evaluate hyperthermic intravesical chemotherapy (HIVEC) efficacy regarding 1-year disease-free survival (RFS) rate and bladder preservation rate in patients with non-muscle invasive bladder cancer (NMIBC) who fail bacillus Calmette-Guérin (BCG) therapy.

METHODS

This is a multicenter retrospective series from a national database (7 expert centers). Between January 2016 and October 2021, patients treated with HIVEC for NMIBC who failed BCG have been included in our study. These patients had a theoretical indication for cystectomy but were ineligible for surgery or refused it.

RESULTS

A total of 116 patients treated with HIVEC and with a follow-up > 6 months were included in this study and retrospectively analyzed. The median follow-up was 20.6 months. The 12 month-RFS (recurrence-free survival) rate was 62.9%. The bladder preservation rate was 87.1%. Fifteen patients (12.9%) progressed to muscle infiltration, three of them having a metastatic disease at the time of progression. Predictive factors of progression were T1 stage, high grade and very high-risk tumors according to the EORTC classification.

CONCLUSION

Chemohyperthermia using HIVEC achieved an RFS rate of 62.9% at 1 year and enabled a bladder preservation rate of 87.1%. However, the risk of progression to muscle-invasive disease is not negligible, particularly for patients with very high-risk tumors. In these patients who fail BCG, cystectomy should remain the standard of care and HIVEC may be discussed cautiously for patients who are not eligible for surgery and well informed of the risk of progression.

Heterogeneity of BCG unresponsive bladder cancer clinical trials limits patients' access to novel therapeutics

INTRODUCTION

Effective therapies for patients with nonmuscle invasive bladder cancer that recurs or progresses after Bacille Calmette-Guérin (BCG) are lacking. This unmet need is the focus of many drug development efforts, reflected in many completed/ongoing/planned clinical trials for patients with BCG unresponsive bladder cancer. Though BCG unresponsive criteria are well defined, enrollment criteria are variable such that, even at centers with several open trials in this space, a given patient with BCG unresponsive bladder cancer might not qualify for any. To understand the scope of this dilemma, we systematically analyzed enrollment criteria for all BCG unresponsive protocols registered on ClinicalTrials.gov to quantify heterogeneity in enrollment criteria and to determine what proportion of trials were inclusive to patients meeting U.S. Food and Drug Administration (FDA) BCG unresponsive criteria.

METHODS

The ClinicalTrials.gov search tool was queried for relevant trials using the terms "bladder cancer" "nonmuscle invasive bladder cancer" and "BCG". Previously published review articles were cross-referenced to ensure that search results were comprehensive. Inclusion and exclusion criteria for the resulting 31 protocols pertaining to distinct categories such as performance status, laboratory parameters, co-morbidities, active medications, and prior therapies were recorded. Based on enrollment criteria, the trial was assessed as fully inclusive or not to patients considered to be BCG unresponsive by the 2018 FDA criteria.

RESULTS

Of 31 trials, 15 (48%) had inclusion/exclusion criteria that were fully consistent with (inclusive of patients that met) the BCG unresponsive bladder cancer definition. 18 (58%) of trials excluded patients with a history of prior pelvic radiation therapy. 14 (45%) of trials excluded patients with ECOG performance status >2 (or Karnofsky Performance Status equivalent). The most common disease specific exclusion for patients with BCG unresponsive bladder cancer was a requirement for stage Tis (carcinoma in situ, CIS), which pertained to 7 (23%) of trials.

CONCLUSIONS

Enrollment criteria for patients with BCG unresponsive bladder cancer are highly variable. Over half of trials evaluated do not meet stringent criteria for this disease state based upon treatment history and cancer staging requirements. For patients who desire to enroll in clinical trials, this restricts access to novel agents. For bladder cancer treating physicians and regulatory bodies, this also hinders comparisons across agents.

Novel Therapies for High-Risk Non-Muscle Invasive Bladder Cancer

PURPOSE OF REVIEW

The treatment options for high-risk non-muscle invasive bladder cancer (NMIBC), particularly following BCG, remain limited. We highlight recent, promising therapies for high-risk NMIBC.

RECENT FINDINGS

Several therapies utilizing different mechanisms of action have demonstrated favorable results in the BCG-naïve and BCG-unresponsive settings. These treatments include intravenous and intravesical immunotherapy, viral- and bacterial-based intravesical therapies, combination intravesical chemotherapy regimens, and novel intravesical chemotherapy administration. Overall, the efficacy and tolerability of emerging treatments for NMIBC appear promising and provide potential alternatives to radical cystectomy. As the landscape of managing BCG-unresponsive disease evolves, clinical trials will explore future options and determine effective alternatives.

A systematic review on the available treatment modalities for Bacillus Calmette-Guérin-unresponsive carcinoma in situ and tumors in patients who are ineligible for or decline radical cystectomy

Introduction

Globally, urothelial bladder carcinoma is a disease which carries a poor prognosis. There are various treatment modalities for urothelial bladder carcinoma with intravesical Bacillus Calmette-Guérin immunotherapy being the most efficacious intravesical therapy and the treatment of choice for patients with carcinoma in situ. A number of chemotherapeutic drugs are also available for the management of Ta/T1 tumors such as mitomycin C and epirubicin. However, relapse and progression is quite common. The optimal management of patients with Bacillus Calmette-Guérin-unresponsive disease remains to be a challenge. The purpose of this study was to conduct a systematic review on the treatment modalities available for the management of Bacillus Calmette-Guérin-unresponsive carcinoma in situ and urothelial bladder carcinoma in patients who are ineligible or decline radical cystectomy.

Methods

Two authors independently searched three databases on the treatment modalities available for the management of Bacillus Calmette-Guérin-unresponsive carcinoma in situ and Bacillus Calmette-Guérin-unresponsive urothelial bladder carcinoma.

Results

The systematic search resulted in 15 studies. We recommend the use of intravesical CG0070 adenovirus or hyperthermic intravesical chemotherapy mitomycin C in patients with carcinoma in situ only disease. In patients with carcinoma in situ ± Ta/T1 disease, we recommend the use of intravesical radiofrequency-induced chemohyperthermia or electromotive drug administration of mitomycin C. In patients who have Ta/T1 disease, we recommend the use of either hyperthermic intravesical chemotherapy epirubicin or electromotive drug administration mitomycin C followed by chemohyperthermia mitomycin C. If any of these second line therapies fail, an alternative regimen would be a combination of gemcitabine, cabazitaxel, and cisplatin.

Conclusion

This recommendation is subject to the available resources and clinical expertise available in different hospitals. More studies using study designs such as randomized controlled trials comparing multiple drugs with larger sample sizes and regular follow-up intervals should be performed to accurately assess the different medications and aid in designing guidelines to guide the management of Bacillus Calmette-Guérin-unresponsive non-muscle invasive intravesical bladder cancer.

A longitudinal single center analysis of T1HG bladder cancer: An 18 year experience

OBJECTIVES

To re-evaluate the treatment of T1HG bladder cancer by analyzing our experience over 18 years.

METHODS AND MATERIALS

An IRB-approved, single-institution retrospective review was performed of all patients with T1HG bladder cancer between August 1999 and July 2017. We assessed clinicopathologic characteristics, treatment history (including intravesical therapy, cystectomy, systemic chemotherapy, and radiation), and oncologic outcomes.

RESULTS

We identified 191 patients with T1HG. Five patients underwent cystectomy at diagnosis. The five-year recurrence-free survival (RFS) for the 186 patients who initially underwent bladder sparing treatments was 50% (95% CI: 41%-58%). There were 83 patients (45%) with disease recurrence; median time to recurrence was 6.7 months (IQR: 4.9-17.5). Disease characteristics at initial recurrence was T2 or greater in 8 patients (10%), T1HG in 19 (23%), CIS in 30 (36%), TaHG in 10 (12%), T1 low-grade (LG) in 1 (1%), and TaLG in 15 (18%). For patients with no prior recurrences, neither re-resection (P = 0.12), receipt of induction therapy (P = 0.81), prostatic urethra positivity (P = 0.51), or age (P = 0.34) were significantly associated with risk of recurrence. Similarly, patients with a single recurrence also fared well without identifiable risk factors. In fact, baseline hazard function analysis demonstrated no differences in RFS comparing patients stratified by 0, 1, and 2+ prior recurrences (P = 0.46). The five-year overall survival (OS) was 76% (95% CI: 68%-82%), and median OS was 127 months. The five-year cancer-specific survival was 86% (95% CI: 78%-91%) for the overall cohort. Five-year cystectomy-free survival for patients with BCG responsive disease and unresponsive disease was 95% (95% CI: 85%-98%) and 72% (95% CI: 52%-84%), respectively.

CONCLUSION

For patients who recurred after intravesical therapy, including those with recurrent T1 disease, additional induction courses of intravesical therapy did not negatively affect oncologic outcomes. Pathology of initial recurrence was not found to be a statistically significant risk factor for future recurrence. These findings suggest that BCG-unresponsive disease does not necessarily require immediate cystectomy. A multicenter, pragmatically designed evaluation in a contemporary cohort would more validly interrogate this important patient population.

Contemporary outcomes of bladder carcinoma in situ treated with an adequate bacille Calmette-Guérin immunotherapy

OBJECTIVE

To assess whether bacillus Calmette-Guérin (BCG) responsiveness after initiation of an adequate BCG treatment (at least five of six instillations of induction and at least two of three instillations of maintenance) impacts oncological outcomes in patients with carcinoma in situ (CIS) of the bladder treated with BCG immunotherapy.

PATIENTS AND METHODS

Data were available for 193 patients with bladder CIS with or without associated cTa/cT1 disease who received an adequate BCG treatment between 2008 and 2015. Bladder biopsies were taken at 6 months and patients were then stratified as either BCG responsive (negative biopsies) or BCG unresponsive (positive biopsies). Inverse probability weighting (IPW)-adjusted Kaplan-Meier and IPW-adjusted Cox regression were performed to compare progression-free survival (PFS), radical cystectomy-free survival (RCFS), overall survival OS, and cancer-specific survival (CSS) in the two groups.

RESULTS AND LIMITATIONS

Comparing the BCG-responsive and BCG-unresponsive groups, IPW-adjusted Kaplan-Meier analysis revealed, respectively, a median (interquartile range) of PFS of 9 (5-15) vs 48.5 (28-77) months (P = 0.001), a RCFS of 11 (9-15) vs 49 (24-76) months (P < 0.001), and a CSS of 25 (13-60) vs 109 (78-307) months (P = 0.004). On IPW-adjusted Cox regression analysis, BCG-unresponsive patients had a worse PFS (hazard ratio [HR] 3.40, 95% confidence interval [CI] 1.59-7.27), RCFS (HR 3.52, 95% CI 1.77-7), and CSS (HR 4.42, 95% CI 1.95-10.01). We found no significant differences for OS.

CONCLUSION

Using an IPW method we found that lack of response after initiation of an adequate BCG treatment has prognostic implications beyond identification of complete response in patients with CIS. BCG-unresponsive patients, satisfying the novel definition of BCG unresponsive, showed a poor PFS, RCFS, and CSS. In this setting, the patients should be counselled regarding RC as a first option or enrolled in a clinical trial if they refuse RC or are unfit for surgery.

Time interval from transurethral resection of bladder tumour to bacille Calmette-Guérin induction does not impact therapeutic response

OBJECTIVES

To investigate bacille Calmette-Guérin (BCG) tolerability and response with respect to the timing of BCG administration after transurethral resection of bladder tumour (TURBT) in patients with non-muscle-invasive bladder cancer (NMIBC).

PATIENTS AND METHODS

A review of patients with NMIBC at our institution managed with at least 'adequate BCG' (defined by the United States Food and Drug Administration as at least five of six induction instillations, with two additional instillations comprising either maintenance or repeat induction) at our institution from 2000 to 2018 was performed. Time from TURBT to first instillation of induction BCG was stratified by quartile and analysed as a continuous variable. Kaplan-Meier and log-rank tests analysed differences in recurrence-free (RFS) and progression-free survival (PFS). Cox proportional hazards regression models identified associations between risk factors and survival outcomes.

RESULTS

A total of 518 patients received adequate BCG at a median (range) of 26 (6-188) days from TURBT. Overall, 45 patients (9%) developed BCG intolerance at a median (range) 12 (7-33) instillations. When time from TURBT to BCG was stratified into quartiles, there was no difference with respect BCG intolerance (P = 0.966), RFS (P = 0.632) or PFS (P = 0.789). On both uni- and multivariate regression analysis for RFS and PFS, time from TURBT to BCG was not a significant predictor when analysed by quartile or as a continuous variable (the hazard ratio for RFS was 1.00, 95% confidence interval [CI] 0.99-1.00, P = 0.449; and for PFS was 0.99, 95% CI 0.98-1.00, P = 0.074).

CONCLUSION

The rates of tolerability and response to adequate BCG are not predicated by the timing of induction BCG instillation after TURBT. Early administration in properly selected patients is safe and delays do not affect therapeutic response.

Intermediate- and high-risk nonmuscle invasive bladder cancer: Where do we stand?

INTRODUCTION

The standard of care for intermediate- and high-risk non-muscle invasive bladder cancer (NMIBC) patients is transurethral resection of bladder tumor followed by intravesical adjuvant immunotherapy with Bacillus Calmette-Guerin (BCG). However, a non-negligible portion of patients is doomed to fail BCG-therapy and, consequently, undergo radical cystectomy as only treatment option available. In this context, effective options to improve tumor response, thus delaying or even avoiding radical cystectomy, are urgently needed. A narrative review of the literature was performed to summarize the rationale and the clinical outcomes regarding the use of immunotherapy and novel therapeutic perspectives both for BCG-treated and BCG-naïve NMIBC patients.

RESULTS

Several clinical trials are currently investigating immune checkpoint inhibitors and novel targeted approaches, including cancer vaccines, for NMIBC patients with BCG-naïve and BCG-unresponsive disease. Despite the lack of long-term safety data, novel therapeutic options, both by systemic and intravesical delivery, demonstrated a good tolerability, antitumor efficacy, and low rates of recurrence and/or progression to muscle-invasive disease.

CONCLUSIONS

Although clinical data available are mostly limited to phase I/II trials, novel targeted therapies have raised as an effective and reliable approach for patients failing BCG and for those who are therapy naïve. Phase III trials will be crucial in order to change the current clinical practice, after many years in which BCG was the only therapy available for intermediate- and high-risk NMIBC patients.

Improving Anti-PD-1/PD-L1 Therapy for Localized Bladder Cancer

In high-risk non-muscle invasive bladder cancer (HR-NMIBC), patient outcome is negatively affected by lack of response to Bacillus-Calmette Guérin (BCG) treatment. Lack of response to cisplatin-based neoadjuvant chemotherapy and cisplatin ineligibility reduces successful treatment outcomes in muscle-invasive bladder cancer (MIBC) patients. The effectiveness of PD-1/PD-L1 immune checkpoint inhibitors (ICI) in metastatic disease has stimulated its evaluation as a treatment option in HR-NMIBC and MIBC patients. However, the observed responses, immune-related adverse events and high costs associated with ICI have provided impetus for the development of methods to improve patient stratification, enhance anti-tumorigenic effects and reduce toxicity. Here, we review the challenges and opportunities offered by PD-1/PD-L1 inhibition in HR-NMIBC and MIBC. We highlight the gaps in the field that need to be addressed to improve patient outcome including biomarkers for response stratification and potentially synergistic combination therapy regimens with PD-1/PD-L1 blockade.

Intravesical Gene Therapy

Non-muscle-invasive bladder cancer is a challenging disease to treat, with few effective salvage intravesical options available for patients who develop bacillus Calmette-Guerin-unresponsive disease. Although radical cystectomy with pelvic lymphadenectomy remains the gold standard treatment for these patients, there remains an unmet need for other options for those who are unable or unwilling to undergo surgery. To this end, intravesical gene therapy is emerging as a potential alternative with promising early data and ongoing efforts to better understand the mechanisms of action to optimize therapy.

Role of Indoleamine-2,3-Dioxygenase Inhibitors in Salvage Therapy for Non-Muscle Invasive Bladder Cancer

Due to significant risks of cancer recurrence and progression, and limited options after intravesical Bacillus Calmette Guerin (BCG) therapy, there is a critical unmet need to identify novel treatments for those patients with BCG-unresponsive bladder cancer. There is active investigation of immunotherapies which provide both biologic and clinical rationales for indoleamine-2,3- dioxygenase inhibitors in salvage therapy for non-muscle invasive bladder cancer.

Current advances in BCG-unresponsive non-muscle invasive bladder cancer

Introduction: The current first line therapy for high grade (HG) non-muscle invasive bladder cancer (NMIBC) is intravesical Bacillus Calmette-Guerin (BCG). Patients who recur or progress despite BCG are recommended to undergo radical cystectomy or participate in clinical trials. There is an urgent need for alternative therapies in the BCG-unresponsive NMIBC realm. Areas covered: We queried clinicaltrials.gov and pubmed.gov for current and recently completed early clinical trials pertaining to investigational agents used for the treatment of BCG-unresponsive NMIBC. These included intravesical chemotherapy, immunotherapy, vaccines, gene therapy, viruses, and agents used with novel drug delivery methods. In this article, we discuss the treatment guidelines for non-muscle invasive bladder cancer and therapeutic approaches under investigation in clinical trials. Expert opinion: The FDA is currently allowing single-arm studies as a pathway for approval in BCG-refractory patients with CIS. Although many agents are currently undergoing testing, none have been approved since Valrubicin. Hopefully, we will identify therapies sufficiently effective and durable to achieve FDA approval. Other considerations in this realm include the use of biomarkers in NMIBC to identify patients who will most likely respond to specific interventions. In addition, as systemic agents such as checkpoint inhibitors, are studied further, a multidisciplinary approach may be needed to treat this subset of patients.

Current Clinical Trials in Non-muscle Invasive Bladder Cancer

PURPOSE OF REVIEW

As our molecular understanding of bladder cancer continues to advance, more and more novel agents are entering clinical trials across the spectrum of bladder cancer stages. The clinical trial activity for non-muscle invasive bladder cancer (NMIBC) has been boosted further by the evolution of specific disease states that set more uniform inclusion criteria for clinical trial design. Here, we aimed to review the current clinical trials landscape in non-muscle invasive bladder cancer with respect to these disease states.

RECENT FINDINGS

Most active clinical trials focus on high-risk NMIBC in either the BCG-naïve or BCG-unresponsive setting. Strict criteria to define the disease state and a clear pathway to drug registration have encouraged trials for patients with BCG-unresponsive NMIBC. The most promising potential breakthroughs for BCG-naïve patients include alternative BCG strains, immune-priming with intradermal BCG vaccination, and systemic immune checkpoint blockade. The latter therapy is also being actively investigated in multiple trials in BCG-unresponsive NMIBC, along with novel viral agents such as INSTILADRIN (nadofaragene firadenovec) and targeted agents such as oportuzumab monatox. After many years of relative stagnation, multiple new therapies currently under investigation in well-designed clinical trials appear poised for routine clinical implementation in the near future. These therapies should dramatically improve the outcome of patients with NMIBC. We can look forward to the challenges of biomarker-driven drug selection, optimal drug sequencing, and rational combination therapies.

Efficacy of Mycobacterium Phlei Cell Wall-Nucleic Acid Complex (MCNA) in BCG-Unresponsive Patients

Background: We have previously reported the results of a prospective multi-institutional study on the efficacy of MCNA in patients who recurred after intravesical BCG treatment [1]. Since that publication, a new standardized definition for BCG-unresponsiveness has been established [2]. Objective: We re-analyzed the oncologic outcomes following intravesical MCNA in patients classified as BCG-unresponsive according to the new definition. Methods: For this analysis, we focused on the enrolled patients who satisfied the requirements for BCG Unresponsiveness: i.e. adequate BCG treatment (at least 5/6 induction and 2/3 maintenance instillations) and high grade tumor within 6 months of prior BCG. Treatment course included 6 weekly intravesical instillations of 8 mg MCNA followed by 3 weekly instillations at months 3, 6, 12, 18, and 24. Followup assessments included cystoscopy, urine cytology and biopsy. Patients absent of high grade disease confirmed by central review of biopsy were deemed disease-free. Results: Of the 129 patients enrolled, 94 (68 CIS with/without papillary tumors, 26 papillary only tumors) fit the criteria for the new BCG Unresponsive definition. Overall, disease free survival (DFS) for all BCG unresponsive patients was 48.9% (95% CI 38.0-59.0%) at 6 months, 34.8% (95% CI 24.7-45%) at 1 year and 28.3% (15.7-34.3%) at 2 years post induction. In the group with papillary tumors, DFS measured at months 6, 12, and 24 were: 61.2% (38.2-77.8%), 61.2(38.2-77.8%), and 50.1% (27.5-69%). In the CIS-containing group, the corresponding DFS were: 44.8% (32.3-56.4%), 26.5% (16.3-37.9%), and 16.6% (8.6-26.9%), respectively. Conclusions: For patients who are BCG Unresponsive, MCNA has the potential to render 26.5% of patients with CIS and 61.2% of patients with papillary tumors disease-free for at least 1 year with an intact bladder. The higher efficacy noted in the true BCG-unresponsive cohort than was previously reported with all-comers emphasizes the importance of having clearly defined criteria for clinical trials investigating new intravesical therapies after BCG failure.