Single Arm Phase I/II Study of Everolimus and Intravesical Gemcitabine in Patients with Primary or Secondary Carcinoma In Situ of the Bladder who failed Bacillus Calmette Guerin (NCT01259063)

Experimental and New Approaches for Bladder Preservation in Intermediate and High-Risk Non-Muscle-Invasive Bladder Cancer (NMIBC)

About 75% of bladder cancers are detected as non-muscle invasive. High-risk patients have high progression risk. Although the standard is transurethral resection of bladder tumor plus full dose intravesical BCG for one to 3 years, due to the high risk of progression, radical cystectomy may be considered in specific cases. Although radical cystectomy is still the best approach for high-grade NMIBC from an oncological perspective, its high morbidity and impact on quality of life motivate studies of new strategies that may reduce the need for cystectomy. We carried out a mini-review whose objectives were: 1 - to identify bladder-sparing alternatives that are being studied as possible treatment for patients with intermediate and high-risk NMIBC; 2 - understand the evidence that exists regarding success rate, follow-up, and side effects of different strategies. Several studies have sought alternatives for bladder preservation, including immunotherapy, intravesical chemotherapy, chemo-hyperthermia, antibody-drug conjugates, viral genetic therapy, and others with promising results. The selection of an optimal therapy for high-risk NMIBC that can reduce the need for cystectomy, with low toxicity and high efficacy, is of paramount importance and remains an issue, however, several known medications are being tested as bladder-preserving alternatives in this scenario and have shown promise in studies.

BCG-Unresponsive Non-Muscle-Invasive Bladder Cancer: Current Treatment Landscape and Novel Emerging Molecular Targets

Urothelial carcinoma (UC), the sixth most common cancer in Western countries, includes upper tract urothelial carcinoma (UTUC) and bladder carcinoma (BC) as the most common cancers among UCs (90-95%). BC is the most common cancer and can be a highly heterogeneous disease, including both non-muscle-invasive (NMIBC) and muscle-invasive (MIBC) forms with different oncologic outcomes. Approximately 80% of new BC diagnoses are classified as NMIBC after the initial transurethral resection of the bladder tumor (TURBt). In this setting, intravesical instillation of Bacillus Calmette-Guerin (BCG) is the current standard treatment for intermediate- and high-risk patients. Unfortunately, recurrence occurs in 30% to 40% of patients despite adequate BCG treatment. Radical cystectomy (RC) is currently considered the standard treatment for NMIBC that does not respond to BCG. However, RC is a complex surgical procedure with a recognized high perioperative morbidity that is dependent on the patient, disease behaviors, and surgical factors and is associated with a significant impact on quality of life. Therefore, there is an unmet clinical need for alternative bladder-preserving treatments for patients who desire a bladder-sparing approach or are too frail for major surgery. In this review, we aim to present the strategies in BCG-unresponsive NMIBC, focusing on novel molecular therapeutic targets.

Anti-tumor effect of AZD8055 against bladder cancer and bladder cancer-associated macrophages

The increased activity of the mTOR pathway in bladder cancer has been extensively studied, but no satisfactory mTOR inhibitor has been found in bladder cancer. The role of AZD8055, a second-generation mTOR inhibitor, has not been reported in bladder cancer. Herein, we investigated the effects of AZD8055 on bladder cells and their interaction with macrophages in vivo and in vitro. In four bladder cancer cell lines, the phosphorylation of mTOR, AKT and S6K1 was suppressed by AZD8055. AZD8055 inhibited proliferation and induced G1 cell-cycle arrest and apoptosis of bladder cancer cells in a concentration-dependent manner. AZD8055 also inhibits the migration and invasion of bladder cancer cells by blocking EMT and MMP9. In addition, AZD8055 inhibited chemotaxis and M2 phenotype of macrophage after co-culture with bladder cancer cells. These anti-tumor effects of AZD8055 were verified in vivo. Our findings collectively demonstrated that low-dose AZD8055 induces cytotoxicity and apoptosis, and inhibits the Akt/mTOR activation, invasion and migration of bladder cancer. These findings also demonstrate that AZD8055 partially blocked the interactions of bladder cancer cells and macrophages. In conclusion, AZD8055 is a promising mTOR inhibitor for bladder cancer.

Novel intravesical therapeutics in the treatment of non-muscle invasive bladder cancer: Horizon scanning

Introduction

Non-muscle-invasive bladder cancer (NMIBC) is a common and heterogeneous disease; many patients develop recurrent or progress to muscle-invasive disease. Intravesical drug therapy is a pillar in the current management of NMIBC; notwithstanding, Mitomycin C (MMC) and Bacillus Calmette-Guérin (BCG) have numerous limitations including international supply issues, and local and systemic toxicity. Here we review novel intravesical therapeutic options and drug delivery devices with potential for clinical use in the treatment of NMIBC.

Methods

PubMed, ClinicalTrials.gov and Cochrane Library searches were undertaken. Systematic reviews, meta-analyses, randomised controlled trials, single-arm clinical trials and national/international conference proceedings were included.

Results

Novel intravesical drugs, including chemotherapeutic agents, immune checkpoint inhibitors, monoclonal antibodies and gene therapies, have demonstrated varying efficacy in the treatment of NMIBC. Current evidence for the majority of treatments is mostly limited to single-arm trials in patients with recurrent NMIBC. Various novel methods of drug delivery have also been investigated, with encouraging preliminary results supporting the intravesical delivery of hyperthermic MMC and MMC hydrogel formulations.

Conclusions

Novel therapeutic agents and drug delivery systems will be important in the future intravesical management of NMIBC. As our understanding of the molecular diversity of NMIBC develops, molecular subtyping will become fundamental in the personalisation of intravesical treatments. Further randomised studies are urgently required to investigate the efficacy of novel intravesical treatments and novel regimens, in comparison to current standards-of-care, particularly in the context of international BCG shortages.

Emerging Roles for Mammalian Target of Rapamycin (mTOR) Complexes in Bladder Cancer Progression and Therapy

The mammalian target of rapamycin (mTOR) pathway regulates important cellular functions. Aberrant activation of this pathway, either through upstream activation by growth factors, loss of inhibitory controls, or molecular alterations, can enhance cancer growth and progression. Bladder cancer shows high levels of mTOR activity in approximately 70% of urothelial carcinomas, suggesting a key role for this pathway in this cancer. mTOR signaling initiates through upstream activation of phosphatidylinositol 3 kinase (PI3K) and protein kinase B (AKT) and results in activation of either mTOR complex 1 (mTORC1) or mTOR complex 2 (mTORC2). While these complexes share several key protein components, unique differences in their complex composition dramatically alter the function and downstream cellular targets of mTOR activity. While significant work has gone into analysis of molecular alterations of the mTOR pathway in bladder cancer, this has not yielded significant benefit in mTOR-targeted therapy approaches in urothelial carcinoma to date. New discoveries regarding signaling convergence onto mTOR complexes in bladder cancer could yield unique insights the biology and targeting of this aggressive disease. In this review, we highlight the functional significance of mTOR signaling in urothelial carcinoma and its potential impact on future therapy implications.

Novel anticancer therapy in BCG unresponsive non-muscle-invasive bladder cancer

INTRODUCTION

Many patients with non-muscle-invasive bladder cancer (NMIBC) failed intravesical BCG therapy. Currently, radical cystectomy is the recommended standard of care for those patients. There is unfortunately no effective other second-line therapy recommended.

AREAS COVERED

In this review, we present the topics of BCG unresponsive NMIBC; definition, prognosis, and further treatment options: immunotherapy, intravesical chemotherapy, gene therapy, and targeted individualized therapy.

EXPERT OPINION

There are major challenges of the management of NMIBC who failed BCG therapy as many patients refuse or are unfit for radical cystectomy. Multiple new modalities currently under investigation in ongoing clinical trials to better treat this category of patients. Immunotherapy, especially PD-1/PD-L1 inhibitors, offers exciting and potentially effective strategies for the treatment of BCG unresponsive NMIBC. As the data expands, it is sure that soon there will be established new guidelines for NMIBC.

Chronic Sulforaphane Administration Inhibits Resistance to the mTOR-Inhibitor Everolimus in Bladder Cancer Cells

Progressive bladder cancer growth is associated with abnormal activation of the mammalian target of the rapamycin (mTOR) pathway, but treatment with an mTOR inhibitor has not been as effective as expected. Rather, resistance develops under chronic drug use, prompting many patients to lower their relapse risk by turning to natural, plant-derived products. The present study was designed to evaluate whether the natural compound, sulforaphane (SFN), combined with the mTOR inhibitor everolimus, could block the growth and proliferation of bladder cancer cells in the short- and long-term. The bladder cancer cell lines RT112, UMUC3, and TCCSUP were exposed short- (24 h) or long-term (8 weeks) to everolimus (0.5 nM) or SFN (2.5 µM) alone or in combination. Cell growth, proliferation, apoptosis, cell cycle progression, and cell cycle regulating proteins were evaluated. siRNA blockade was used to investigate the functional impact of the proteins. Short-term application of SFN and/or everolimus resulted in significant tumor growth suppression, with additive inhibition on clonogenic tumor growth. Long-term everolimus treatment resulted in resistance development characterized by continued growth, and was associated with elevated Akt-mTOR signaling and cyclin-dependent kinase (CDK)1 phosphorylation and down-regulation of p19 and p27. In contrast, SFN alone or SFN+everolimus reduced cell growth and proliferation. Akt and Rictor signaling remained low, and p19 and p27 expressions were high under combined drug treatment. Long-term exposure to SFN+everolimus also induced acetylation of the H3 and H4 histones. Phosphorylation of CDK1 was diminished, whereby down-regulation of CDK1 and its binding partner, Cyclin B, inhibited tumor growth. In conclusion, the addition of SFN to the long-term everolimus application inhibits resistance development in bladder cancer cells in vitro. Therefore, sulforaphane may hold potential for treating bladder carcinoma in patients with resistance to an mTOR inhibitor.

Systematic Review of the Therapeutic Efficacy of Bladder-preserving Treatments for Non-muscle-invasive Bladder Cancer Following Intravesical Bacillus Calmette-Guérin

CONTEXT

There is a critical need for effective bladder-sparing therapies for bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer (NMIBC). Owing to the current lack of effective agents that can be used as a control, the US Food and Drug Administration began to accept single-arm trials for patients with carcinoma in situ (CIS), using complete response rate (CRR) and duration of response as the primary endpoints to support marketing applications. Despite the ensuing growth of clinical trials in this space, no consensus exists on a clinically relevant benchmark for CRR.

OBJECTIVE

To elucidate the CRR and recurrence-free rate (RFR) using bladder-sparing agents after BCG failure in order to provide a frame of reference for future clinical trial results.

EVIDENCE ACQUISITION

We performed a systematic review of clinical trials utilizing bladder-sparing therapeutics for NMIBC recurring after intravesical BCG (PROSPERO CRD42019130553). The search was performed in MEDLINE, EMBASE, and Cochrane Library. Relevant studies identified from bibliography search and conference abstracts were searched to complement the systematic review. A total of 42 studies utilizing 24 treatment options and consisting of 2254 patients were included for final analysis.

EVIDENCE SYNTHESIS

Median CRRs in the treatment of CIS-containing tumors were 26% at 6 mo, 17% at 12 mo, and 8% at 24 mo after treatment. In comparison, median RFRs in the papillary-only studies were 67% at 6 mo, 44% at 12 mo, and 10% at 24 mo. Specifically in the BCG-unresponsive population, 6- and 12-mo CRRs in CIS-containing patients treated with Mycobacterium phlei cell wall-nucleic acid complex were 45% and 27%, respectively, and the median 6-, 12-, and 24-mo disease-free rates in the other studies were 43%, 35%, and 18%, respectively. The median progression-free rate was 91%: 95% in the CIS-containing studies and 89% in studies restricted to papillary-only recurrences. Toxicities of intravesical agents were generally mild, with very few dose limiting toxicities.

CONCLUSIONS

We demonstrate that, to date, bladder-sparing therapies achieved modest efficacy in patients with NMIBC after BCG. Results from the current study will serve as a frame of reference for emerging trial results in the BCG-unresponsive space.

PATIENT SUMMARY

In this study, we found that bladder-sparing therapies achieved modest efficacy in patients with non-muscle-invasive bladder cancer after bacillus Calmette-Guérin (BCG). These results will serve to inform future clinical trial results for salvage agents used to treat BCG-unresponsive bladder cancer.