Sustained intravesical interferon protein exposure is achieved using an adenoviral-mediated gene delivery system: a study in rats evaluating dosing regimens

The Evolution of Nadofaragene Firadenovec: A Review and the Path Forward

BACKGROUND

The intravesical gene therapy nadofaragene firadenovec (rAd-IFNα/Syn3) was FDA approved in 2022 for non-muscle invasive bladder cancer (NMIBC) unresponsive to frontline treatment with BCG, and the first gene therapy developed for bladder cancer. This non-replicating recombinant adenovirus vector delivers a copy of the human interferon alpha-2b gene into urothelial and tumor cells, causing them to express this pleotropic cytokine with potent antitumor effects.

OBJECTIVE

To provide a historical overview describing how several decades of preclinical and clinical studies investigating the role of interferon in the treatment of bladder cancer ultimately led to the development of gene therapy with nadofaragene for NMIBC.

METHODS

We conducted a review of the literature using PubMed, Google Scholar, and ClinicalTrials.gov to summarize our knowledge of the evolution of interferon-based therapy in NMIBC.

RESULTS

The FDA approval of this therapy represents an important landmark in urologic oncology and several decades of research dedicated to the study of interferon's direct and indirect antitumor properties in NMIBC. The data gathered from the phase 1, 2, and 3 clinical trials continue to provide additional insights into the precise mechanisms underlying both the efficacy of and resistance to nadofaragene.

CONCLUSIONS

Nadofaragene leverages the cytotoxic, anti-angiogenic, and immune-modulatory roles of interferon to effectively treat NMIBC that is resistant to BCG. Ongoing studies of resistance mechanisms and prognostic biomarkers have been promising; these will ultimately improve patient selection and allow for the modulation of factors in the tumor or immune microenvironment to further increase therapeutic response.

Multidisciplinary consensus document on the current treatment of bacille Calmette-Guérin-unresponsive non-muscle invasive bladder tumor

Radical cystectomy is the current treatment of choice for patients with BCG-unresponsive non-muscle invasive bladder tumor (NMIBC). However, the high comorbidity of this surgery and its effects on the quality of life of patients require the investigation and implementation of bladder-sparing treatment options. These must be evaluated individually by the uro-oncology committee based on the characteristics of the BCG failure, type of tumor, patient preferences and treatment options available in each center. Based on FDA-required oncologic outcomes (6-month complete response rate for CIS: 50%; duration of response in responders for CIS and papillary: 30% at 12 months and 25% at 18 months), there is not currently a strong preference for one treatment over another, although the intravesical route seems to offer less toxicity. This work summarizes the evidence on the management of BCG-unresponsive NMIBC based on current scientific evidence and provides consensus recommendations on the most appropriate treatment.

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.

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.

Novel immunotherapeutic options for BCG-unresponsive high-risk non-muscle-invasive bladder cancer

BACKGROUND

High-risk non-muscle-invasive bladder cancer (HR-NMIBC) presents a challenge to many physicians due to its ability to resist Bacillus Calmette-Guérin (BCG) intravesical therapy and the substantial rate of progression into muscle-invasive bladder cancer (MIBC). Patients who are BCG-unresponsive have worse prognosis and thus require further management including radical cystectomy (RC), which significantly impacts quality of life. Moreover, the ongoing worldwide shortage of BCG warrants the need for policies that prioritize drug use and utilize alternative treatment strategies. Hence, there is a significant unmet need for bladder preserving therapy in this subset of patients.

METHODS

To address this issue, we searched the relevant literature in PUBMED for articles published from 2019 through May of 2023 using appropriate keywords. All clinical trials of patients with HR-NMIBC treated with immune-related agents were retrieved from clinicaltrials.gov.

FINDINGS AND FUTURE PERSPECTIVES

Exploratory treatments for BCG-Unresponsive HR-NMIBC included immune checkpoint inhibitors (ICI), oncolytic viral therapy, cytokine agonists, and other immunomodulators targeting TLR, EpCaM, FGFR, MetAP2, and IDO1. Some combination therapies have been found to work synergistically and are preferred therapeutically over monotherapy. Three drugs-pembrolizumab, valrubicin, and most recently, nadofaragene firadenovec-vncg-have been FDA approved for the treatment of BCG-unresponsive NMIBC in patients who are ineligible for or decline RC. However, all explored treatment options tend to postpone RC rather than provide long-term disease control. Additional combination strategies need to be studied to enhance the effects of immunotherapy. Despite the challenges faced in finding effective therapies, many potential treatments are currently under investigation. Addressing the landscape of biomarkers, mechanisms of progression, BCG resistance, and trial design challenges in HR-NMIBC is essential for the discovery of new targets and the development of effective treatments.

Interspecies Scaling of Transgene Products for Viral Vector Gene Therapies: Method Assessment Using Data from Eleven Viral Vectors

The prediction of transgene product expression in human is important to guide first-in-human (FIH) dose selection for viral vector-based gene replacement therapies. Recently, allometric scaling from preclinical data and interspecies normalization of dose-response (D-R) relationship have been used to predict human transgene product expression of adeno-associated virus (AAV) vectors. In this study, we assessed two interspecies allometric scaling methods and two dose-response methods in predicting human transgene product expression of nine intravenously administered AAV vectors, one intramuscularly administered AAV vector, and one intravesical administered adenoviral vector. Among the four methods, normalized D-R method generated the highest prediction accuracy, with geometric mean fold error (GMFE) of 2.9 folds and 75% predictions within fivefold deviations of observed human transgene product levels. The vg/kg-based D-R method worked well for locally delivered vectors but substantially overpredicted human transgene product levels of some hemophilia A and B vectors. For both intravenously and locally administered vectors, the prediction accuracy of allometric scaling using body weight^-0.25 (AS by W^-0.25) was superior to allometric scaling using log(body weight) (AS by logW). This study successfully extended the use of allometric scaling and interspecies D-R normalization methods for human transgene product prediction from intravenous viral vectors to locally delivered viral vectors.

New Intravesical Agents for BCG-Unresponsive High-Risk Non-Muscle Invasive Bladder Cancer

BACKGROUND

With the exception of the FDA-approved valrubicin and pembrolizumab, there are no standard second-line treaments for BCG-unresponsive high-risk non-muscle invasive bladder cancer (NMIBC).

OBJECTIVES

To provide a systematic review of the novel intravesically administered therapeutic agents for the salvage treatment of BCG-unresponsive NMIBC.

METHODS

Online search of the PubMed, EMBASE and Web of Science databases was performed. The endpoints of this review were to evaluate the efficacy of the agents in terms of complete response rates (CR) and durability of CR, overall survival, recurrence-free survival and cancer-specific survival and to report on their toxicity profile. A search on Clinicaltrials.gov was performed to identify ongoing clinical trials.

RESULTS

14 studies were included in this review. The critical clinical need for the development of an effective, safe and durable intravesical drug for the salvage treatment of high-risk NMIBC seems to be met mainly by intravesical gene therapy; in fact, data support the FDA-approved nadofaragene firadenovec as a potentially important therapeutic advancement in this context. Promising results are also being obtained by the combination of N-803/BCG and by innovative drug delivery systems.

CONCLUSIONS

Considering the plethora of novel intravesical treatments that have completed phase II evaluation, one can reasonably expect that clinicians will soon have at their disposal new agents and treatment options for BCG-unresponsive NMIBC. In the near future, it will be up to the urologist to identify, for each specific patient, the right agent to use, based on safety, results and cost-effectiveness.

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.

Nadofaragene Firadenovec: First Approval

Nadofaragene firadenovec (nadofaragene firadenovec-vncg; Adstiladrin^®) is a non-replicating adenoviral vector-based gene therapy developed by Ferring Pharmaceuticals for the treatment of high-risk Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle invasive bladder cancer (NMIBC). Nadofaragene firadenovec constitutes vector DNA that encodes for interferon (IFN)-α2b and is the first approved gene therapy in bladder cancer. The production of IFN-α2b by transfected urothelial cells is associated with anticancer activity, including immunostimulatory, antiangiogenic and apoptotic effects. In December 2022, nadofaragene firadenovec received its first global approval in the USA for the treatment of high-risk BCG-unresponsive NMIBC with carcinoma in situ (CIS) with or without papillary tumours in adults. This article summarizes the milestones in the development of nadofaragene firadenovec leading to this first approval for this indication.

Recurrence mechanisms of non-muscle-invasive bladder cancer - a clinical perspective

Non-muscle-invasive bladder cancer (NMIBC) is an early-stage cancer without invasion into the detrusor muscle layer. Transurethral resection of bladder tumour (TURBT) is a diagnostic and potentially curative procedure for NMIBC, but has some limitations, including difficulties in ascertaining complete tumour removal upon piecemeal resection and the possibility of tumour re-implantation after the procedure. The oncological control of NMIBC is far from satisfactory, with a 1-year recurrence rate of 15-61%, and a 5-year recurrence rate of 31-78%. Various recurrence mechanisms have been described for NMIBC, such as undetected tumours upon cystoscopy, incomplete resection during TURBT, tumour re-implantation after TURBT, drop metastasis from upper tract urothelial carcinoma and field change cancerization. Understanding the recurrence mechanisms from a clinical perspective has strong implications for the optimization of NMIBC oncological outcomes, as a cure for patients with NMIBC can only be achieved by tackling all possible recurrence mechanisms in a comprehensive manner.

From Interferon to Checkpoint Inhibition Therapy-A Systematic Review of New Immune-Modulating Agents in Bacillus Calmette-Guérin (BCG) Refractory Non-Muscle-Invasive Bladder Cancer (NMIBC)

BACKGROUND

In Bacillus Calmette-Guérin (BCG) refractory non-muscle-invasive bladder cancer (NMIBC), radical cystectomy is the gold standard. The advent of immune checkpoint inhibitors (CPIs) has permanently changed the therapy landscape of bladder cancer (BC). This article presents a systematic review of immune-modulating (IM) therapies (CPIs and others) in BCG-refractory NMIBC.

METHODS

In total, 406 articles were identified through data bank research in PubMed/Medline, with data cutoff in October 2021. Four full-text articles and four additional congress abstracts were included in the review.

RESULTS

Durvalumab plus Oportuzumab monatox, Pembrolizumab, and Nadofaragene firadenovec (NF) show complete response (CR) rates of 41.6%, 40.6%, and 59.6% after 3 months, with a long-lasting effect, especially for NF (12-month CR rate of 30.5%). Instillations with oncolytic viruses such as NF and CG0070 show good efficacy without triggering significant immune-mediated systemic adverse events. Recombinant BCG VPM1002BC could prove to be valid as an alternative to BCG in the future. The recombinant pox-viral vector vaccine PANVAC™ is not convincing in combination with BCG. Interleukin mediating therapies, such as ALT-803, are currently being studied.

CONCLUSION

CPIs and other IM agents now offer an increasing opportunity for bladder-preserving strategies. Studies on different substances are ongoing and will yield new findings.

New Perspectives in the Medical Treatment of Non-Muscle-Invasive Bladder Cancer: Immune Checkpoint Inhibitors and Beyond

Non-muscle-invasive bladder cancer (NMIBC) is characterized by a high rate of cure, but also by a non-negligible probability of recurrence and risk progression to muscle-invasive disease. NMIBC management requires a proper local resection and staging, followed by a risk-based treatment with intravesical agents. For many years, the current gold standard treatment for patients with intermediate or high-risk disease is transurethral resection of the bladder (TURB) followed by intravesical bacillus Calmette-Guérin (BCG) instillations. Unfortunately, in about half of high-risk patients, intravesical BCG treatment fails and NMIBC persists or recurs early. While radical cystectomy remains the gold standard for these patients, new therapeutic targets are being individuated and studied. Radical cystectomy in fact can provide an excellent long-term disease control, but can deeply interfere with quality of life. In particular, the enhanced immune checkpoints expression shown in BCG-unresponsive patients and the activity of immune checkpoints inhibitors (ICIs) in advanced bladder cancer provided the rationale for testing ICIs in NMIBC. Recently, pembrolizumab has shown promising activity in BCG-unresponsive NMIBC patients, obtaining FDA approval. Meanwhile multiple novel drugs with alternative mechanisms of action have proven to be safe and effective in NMIBC treatment and others are under investigation. The aim of this review is to analyse and describe the clinical activity of new emerging drugs in BCG-unresponsive NMIBC focusing on immunotherapy results.

Molecular characterization of type I IFN-induced cytotoxicity in bladder cancer cells reveals biomarkers of resistance

Although anti-tumor activities of type I interferons (IFNs) have been recognized for decades, the molecular mechanisms contributing to clinical response remain poorly understood. The complex functions of these pleiotropic cytokines include stimulation of innate and adaptive immune responses against tumors as well as direct inhibition of tumor cells. In high-grade, Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer, nadofaragene firadenovec, a non-replicating adenovirus administered locally to express the IFNα2b transgene, embodies a novel approach to deploy the therapeutic activity of type I IFNs while minimizing systemic toxicities. Deciphering which functions of type I IFN are required for clinical activity will bolster efforts to maximize the efficacy of nadofaragene firadenovec and other type I IFN-based therapies, and inform strategies to address resistance. As such, we characterized the phenotypic and molecular response of human bladder cancer cell lines to IFNα delivered in multiple contexts, including adenoviral delivery. We found that constitutive activation of the type I IFN signaling pathway is a biomarker for resistance to both transcriptional response and direct cytotoxic effects of IFNα. We present several genes that discriminate between sensitive and resistant tumor cells, suggesting they should be explored for utility as biomarkers in future clinical trials of type I IFN-based anti-tumor therapies.

Immunotherapy of high risk non-muscle invasive bladder cancer

INTRODUCTION

Bladder cancer remains a prevalent and often lethal cancer. Fortunately, recent clinical trials using immunotherapeutics demonstrate promise to improve treatment outcomes. Several of these immunotherapies have already established their value in the metastatic space and likely will soon have indications in the non-metastatic space.

AREAS COVERED

This review will cover immunotherapies ranging for well-studied BCG administration to more novel medications such as PD-L1/PD-1 inhibitors, CTLA-4 inhibitors, IL-15 super agonists, and immune modulating gene therapies. Specifically, the article will address the mechanisms of actions, clinical evidence supporting their use, and the presence of any FDA regulatory approval for these medications in the treatment of high-risk non-muscle invasive bladder cancer.

EXPERT OPINION

With the publication of clinical data supporting the use of immunotherapies, these novel medications are likely to be adopted for treatment of high grade non-metastatic bladder cancer. While BCG is likely to remain a primary medication for high grade bladder cancer for the near future, BCG will likely be co-administered with immunomodulatory medications in some patients to enhance the medications effect in the future. Clinical trials are still ongoing and will demonstrate which of these multiple treatment options yield results worthy of a modification in our current treatment paradigm.

Intravesical nadofaragene firadenovec gene therapy for BCG-unresponsive non-muscle-invasive bladder cancer: a single-arm, open-label, repeat-dose clinical trial

BACKGROUND

BCG is the most effective therapy for high-risk non-muscle-invasive bladder cancer. Nadofaragene firadenovec (also known as rAd-IFNa/Syn3) is a replication-deficient recombinant adenovirus that delivers human interferon alfa-2b cDNA into the bladder epithelium, and a novel intravesical therapy for BCG-unresponsive non-muscle-invasive bladder cancer. We aimed to evaluate its efficacy in patients with BCG-unresponsive non-muscle-invasive bladder cancer.

METHODS

In this phase 3, multicentre, open-label, repeat-dose study done in 33 centres (hospitals and clinics) in the USA, we recruited patients aged 18 years or older, with BCG-unresponsive non-muscle-invasive bladder cancer and an Eastern Cooperative Oncology Group status of 2 or less. Patients were excluded if they had upper urinary tract disease, urothelial carcinoma within the prostatic urethra, lymphovascular invasion, micropapillary disease, or hydronephrosis. Eligible patients received a single intravesical 75 mL dose of nadofaragene firadenovec (3 × 1011 viral particles per mL). Repeat dosing at months 3, 6, and 9 was done in the absence of high-grade recurrence. The primary endpoint was complete response at any time in patients with carcinoma in situ (with or without a high-grade Ta or T1 tumour). The null hypothesis specified a complete response rate of less than 27% in this cohort. Efficacy analyses were done on the per-protocol population, to include only patients strictly meeting the BCG-unresponsive definition. Safety analyses were done in all patients who received at least one dose of treatment. The study is ongoing, with a planned 4-year treatment and monitoring phase. This study is registered with ClinicalTrials.gov, NCT02773849.

FINDINGS

Between Sept 19, 2016, and May 24, 2019, 198 patients were assessed for eligibility. 41 patients were excluded, and 157 were enrolled and received at least one dose of the study drug. Six patients did not meet the definition of BCG-unresponsive non-muscle-invasive bladder cancer and were therefore excluded from efficacy analyses; the remaining 151 patients were included in the per-protocol efficacy analyses. 55 (53·4%) of 103 patients with carcinoma in situ (with or without a high-grade Ta or T1 tumour) had a complete response within 3 months of the first dose and this response was maintained in 25 (45·5%) of 55 patients at 12 months. Micturition urgency was the most common grade 3-4 study drug-related adverse event (two [1%] of 157 patients, both grade 3), and there were no treatment-related deaths.

INTERPRETATION

Intravesical nadofaragene firadenovec was efficacious, with a favourable benefit:risk ratio, in patients with BCG-unresponsive non-muscle-invasive bladder cancer. This represents a novel treatment option in a therapeutically challenging disease state.

FUNDING

FKD Therapies Oy.

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.

The development of interferon-based gene therapy for BCG unresponsive bladder cancer: from bench to bedside

BACKGROUND AND PURPOSE

BCG unresponsive bladder cancer is an inherently resistant disease state for which the preferred treatment is radical cystectomy. To date, no effective intravesical therapies exist for patients who possess these resistant tumors. For this reason, many research groups are actively investigating/testing novel therapeutic agents to aid in bladder preservation for this patient population. This review article describes our 15-year experience developing and testing IFN-based gene therapy.

METHODS

A comprehensive review was performed of all studies pertaining to IFN-based gene therapy for non-muscle invasive bladder cancer from 2003 to 2018.

RESULTS AND CONCLUSIONS

Over the past two decades, gene therapy has evolved into a powerful tool in our fight against cancer. After overcoming the initial barriers associated with gene delivery to the bladder, we have made significant strides forward in developing this novel therapeutic strategy for the treatment of this inherently resistant disease state. Our results to date are very encouraging; however, much work lies ahead to better understand and optimize this novel approach for treating non-muscle invasive bladder.

Intravesical rAd-IFNα/Syn3 for Patients With High-Grade, Bacillus Calmette-Guerin-Refractory or Relapsed Non-Muscle-Invasive Bladder Cancer: A Phase II Randomized Study

Purpose Many patients with high-risk non-muscle-invasive bladder cancer (NMIBC) are either refractory to bacillus Calmette-Guerin (BCG) treatment or may experience disease relapse. We assessed the efficacy and safety of recombinant adenovirus interferon alfa with Syn3 (rAd-IFNα/Syn3), a replication-deficient recombinant adenovirus gene transfer vector, for patients with high-grade (HG) BCG-refractory or relapsed NMIBC. Methods In this open-label, multicenter (n = 13), parallel-arm, phase II study ( ClinicalTrials.gov identifier: NCT01687244), 43 patients with HG BCG-refractory or relapsed NMIBC received intravesical rAd-IFNα/Syn3 (randomly assigned 1:1 to 1 × 10¹¹ viral particles (vp)/mL or 3 × 10¹¹ vp/mL). Patients who responded at months 3, 6, and 9 were retreated at months 4, 7, and 10. The primary end point was 12-month HG recurrence-free survival (RFS). All patients who received at least one dose were included in efficacy and safety analyses. Results Forty patients received rAd-IFNα/Syn3 (1 × 10¹¹ vp/mL, n = 21; 3 × 10¹¹ vp/mL, n = 19) between November 5, 2012, and April 8, 2015. Fourteen patients (35.0%; 90% CI, 22.6% to 49.2%) remained free of HG recurrence 12 months after initial treatment. Comparable 12-month HG RFS was noted for both doses. Of these 14 patients, two experienced recurrence at 21 and 28 months, respectively, after treatment initiation, and one died as a result of an upper tract tumor at 17 months without a recurrence. rAd-IFNα/Syn3 was well tolerated; no grade four or five adverse events (AEs) occurred, and no patient discontinued treatment because of an adverse event. The most frequently reported drug-related AEs were micturition urgency (n = 16; 40%), dysuria (n = 16; 40%), fatigue (n = 13; 32.5%), pollakiuria (n = 11; 28%), and hematuria and nocturia (n = 10 each; 25%). Conclusion rAd-IFNα/Syn3 was well tolerated. It demonstrated promising efficacy for patients with HG NMIBC after BCG therapy who were unable or unwilling to undergo radical cystectomy.

Novel therapeutic approaches for recurrent nonmuscle invasive bladder cancer

This article summarizes strategies being investigated in patients with nonmuscle invasive bladder cancer. Progress has been made toward improving the delivery method of intravesical agents. Intravesical therapy is limited by the amount of time that the agent remains in contact with the bladder. Bladder cancer is considered to be responsive to immune therapy. Thus, many novel approaches are immune-based therapies and include cancer vaccines, use of Bacillus Calmette-Guérin (BCG) subcomponents, and checkpoint inhibitors. Finally, access to bladder mucosa via direct catheterization into the bladder via the urethra has enabled unique strategies for delivery of cancer therapy including viral- or plasmid-based gene therapy.

Phase I trial of intravesical recombinant adenovirus mediated interferon-α2b formulated in Syn3 for Bacillus Calmette-Guérin failures in nonmuscle invasive bladder cancer

PURPOSE

A phase I trial of intravesical recombinant adenovirus mediated interferon-α2b gene therapy (rAd-IFNα) formulated with the excipient SCH Syn3 was conducted in patients with nonmuscle invasive bladder cancer who had disease recurrence after treatment with bacillus Calmette-Guérin. The primary objective was to determine the safety of rAd-IFNα/Syn3. Secondary end points were demonstrated effective rAd-IFNα gene expression and preliminary evidence of clinical activity at 3 months.

MATERIALS AND METHODS

A total of 17 patients with recurrent nonmuscle invasive bladder cancer after bacillus Calmette-Guérin treatment were enrolled in the study. A single treatment of rAd-IFNα (3 × 10(9) to 3 × 10(11) particles per ml) formulated with the excipient Syn3 was administered. Patient safety was evaluated for 12 or more weeks. Efficacy of gene transfer was determined by urine IFNα protein concentrations. Preliminary drug efficacy was determined at 3 months.

RESULTS

Intravesical rAd-IFNα/Syn3 was well tolerated as no dose limiting toxicity was encountered. Urgency was the most common adverse event and all cases were grade 1 or 2. rAd-IFNα DNA was not detected in the blood. However, transient low serum IFNα and Syn3 levels were measured. High and prolonged dose related urine IFNα levels were achieved with the initial treatment. Of the 14 patients treated at doses of 10(10) or more particles per ml with detectable urine IFNα, 6 (43%) experienced a complete response at 3 months and 2 remained disease-free at 29.0 and 39.2 months, respectively.

CONCLUSIONS

Intravesical rAd-IFNα/Syn3 was well tolerated with no dose limiting toxicity encountered. Dose dependent urinary IFNα concentrations confirmed efficient gene transfer and expression. Intravesical rAd-IFNα/Syn3 demonstrated clinical activity in nonmuscle invasive bladder cancer recurring after bacillus Calmette-Guérin.

New therapies for non-muscle-invasive bladder cancer

The treatment of non-muscle-invasive bladder cancer (NMIBC) remains a challenge owing to its increased tendency to recur and the possibility of progression to potentially dangerous muscle-invasive disease. Treatment outcomes by current therapeutic modalities are still not optimal. In recent years, there have been a number of substantive advances in the therapeutic options for the management of NMIBC. New chemotherapeutic drugs have been introduced, along with efforts made to improve the efficacy of existing agents and enhance delivery of agents to the bladder. There is also a growing trend toward combination of agents and multimodal therapy. Also of considerable interest are the investigation of newer approaches such as gene therapy, chemoenhancement and newer forms of immunotherapy. Here, we review the recent pre-clinical and clinical developments in the treatment of NMIBC, described in the broad categories of immunotherapy, chemotherapeutic agents, improved or device-assisted agent delivery and gene therapy.

Intravesical treatments of bladder cancer: review

For bladder cancer, intravesical chemo/immunotherapy is widely used as adjuvant therapies after surgical transurethal resection, while systemic therapy is typically reserved for higher stage, muscle-invading, or metastatic diseases. The goal of intravesical therapy is to eradicate existing or residual tumors through direct cytoablation or immunostimulation. The unique properties of the urinary bladder render it a fertile ground for evaluating additional novel experimental approaches to regional therapy, including iontophoresis/electrophoresis, local hyperthermia, co-administration of permeation enhancers, bioadhesive carriers, magnetic-targeted particles and gene therapy. Furthermore, due to its unique anatomical properties, the drug concentration-time profiles in various layers of bladder tissues during and after intravesical therapy can be described by mathematical models comprised of drug disposition and transport kinetic parameters. The drug delivery data, in turn, can be combined with the effective drug exposure to infer treatment efficacy and thereby assists the selection of optimal regimens. To our knowledge, intravesical therapy of bladder cancer represents the first example where computational pharmacological approach was used to design, and successfully predicted the outcome of, a randomized phase III trial (using mitomycin C). This review summarizes the pharmacological principles and the current status of intravesical therapy, and the application of computation to optimize the drug delivery to target sites and the treatment efficacy.

Enhancement of intravesical delivery with Syn3 potentiates interferon-alpha2b gene therapy for superficial bladder cancer

Intravesical administration of interferon alpha-2b protein (IFN) has been successfully used in the treatment of patients with superficial bladder tumors. Local dosing of IFN minimizes well-known systemic side effects of the drug, but exposure to bladder tumors is limited by the duration of instillation and transient concentrations achieved in the urothelium. Intravesical delivery of the gene encoding interferon results in an alternative strategy for IFN-based therapy of the disease, enabling sustained exposure of IFN protein that results from production by tumor and non-tumor cells in the urothelium. Efficient gene delivery and expression of IFN has been achieved using a recombinant adenovirus gene delivery system (rAd-IFN) in conjunction with the novel small molecule excipient Syn3. Studies with rAd-IFN/Syn3 in animal models result in urine concentrations of IFN that persisted for weeks and correlated with potent anti-tumor effects. The objective of this review is to communicate the rationale and preclinical findings that support ongoing clinical investigation of intravesical rAd-IFN/Syn3 in superficial bladder cancer.

Conditionally replicating adenovirus-mediated gene therapy in bladder cancer: an orthotopic in vivo model

INTRODUCTION

The effects of a conditionally replicating adenovirus on various bladder cancer lines were explored, a truncated bone sialoprotein (BSP) promoter controlling the E1a/b lytic-regulating sequence was used, since BSP protein is found in many osteotropic neoplasms, including bladder cancer.

METHODS

Reverse transcriptase polymerase chain reaction analysis was used to determine expression patterns of BSP and Coxsackie adenovirus receptor, a receptor known to interact with adenovirus, on multiple lines of bladder cancer (253J, 253J B-V, RT4, transitional cell carcinoma, T24, UMUC3, and WH). Ad-BSP-E1a was tested in vitro for lytic activity on 4 of these cell lines. The 253J B-V cell line was used and inoculated into female nude mice either subcutaneously in the flank or orthotopically into the bladder, and treated with control or Ad-BSP-E1a virus.

RESULTS

BSP is expressed in RT4, transitional cell carcinoma, and WH. Meanwhile, Coxsackie adenovirus receptor was expressed in all lines except T24. Ad-BSP-E1a had the most impact on 253J and 253J B-V cells; cell density declined significantly when compared to phosphate-buffered saline and Ad-BSP-TK "dummy" virus-treatment groups. The 253J B-V tumors treated with Ad-BSP-E1a revealed a decreased percent change of size in the subcutaneous model when compared to controls at week 3. The orthotopic murine model showed decreased end tumor mass in the Ad-BSP-E1a treated group over controls. Histologic examination of in vivo tumors showed evidence of fibrosis and apoptosis in the Ad-BSP-E1a treated groups using hematoxylin-eosin, trichrome, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining. Control groups only had viable tumor in in vivo models.

CONCLUSION

Adenovirus therapy of orthotopic murine bladder tumors is feasible. Ad-BSP-E1a is effective in treating very aggressive yet sensitive bladder tumor cells. Further study of this conditionally replicating adenovirus treatment (Ad-BSP-E1a) with chemotherapeutic combination is warranted, and future translation of such combination therapy into human beings is a possibility.

Recent advances in intravesical drug/gene delivery

Targeting of drugs administered systemically relies on the higher affinity of ligands for specific receptors to obtain selectivity in drug response. However, achieving the same goal inside the bladder is much easier with an intelligent pharmaceutical approach that restricts drug effects by exploiting the pelvic anatomical architecture of the human body. This regional therapy involves placement of drugs directly into the bladder through a urethral catheter. It is obvious that drug administration by this route holds advantage in chemotherapy of superficial bladder cancer, and it has now become the most widely used treatment modality for this ailment. In recent years, the intravesical route has also been exploited either as an adjunct to an oral regimen or as a second-line treatment for neurogenic bladder. (Lamm, D. L.; Griffith, J. G. Semin. Urol. 1992, 10, 39-44. Igawa, Y.; Satoh, T.; Mizusawa, H.; Seki, S.; Kato, H.; Ishizuka, O.; Nishizawa, O. BJU Int. 2003, 91, 637-641.) Instillation of DNA via this route using different vectors has been able to restrict the transgene expression in organs other than bladder. The present review article will discuss the shortcomings of the current options available for intravesical drug delivery (IDD) and lay a perspective for future developments in this field.