Challenging the EAU Guidelines on Non–Muscle-Invasive Bladder Cancer (NMIBC): Single Instillation of Chemotherapy After Transurethral Resection of NMIBC and Chemotherapy Versus Bacillus Calmette-Guérin in Treatment of Intermediate-Risk Tumours

Mitochondrial targeting improves the selectivity of singlet-oxygen cleavable prodrugs in NMIBC treatment

Mitochondria play an essential role in cancer treatment by providing apoptotic signals. Hexyl aminolevulinate, an FDA-approved diagnosis for non-muscle invasive bladder cancer, induces the production of protoporphyrin IX (PpIX) preferentially by mitochondria in cancer cells. Photosensitizer PpIX upon illumination can release active chemotherapy drugs from singlet oxygen-activatable prodrugs. Prodrugs placed close enough to PpIX formed in mitochondria can improve the antitumor efficiency of PpIX-PDT. The preferred uptake of prodrugs by cancer cells and tumors can further enhance the selective damage of cancer cells over non-cancer cells and surrounding normal tissues. Mitochondriotropic prodrugs of anticancer drugs, such as paclitaxel and SN-38, were synthesized using rhodamine, a mitochondrial-targeting moiety. In vitro, the mitochondrial targeting helped achieve preferential cellular uptake in cancer cells. In RT112 cells (human bladder cancer cells), intracellular prodrug concentrations were 2-3 times higher than the intracellular prodrug concentrations in BdEC cells (human bladder epithelial cells), after 2 h incubation. In an orthotopic rat bladder tumor model, mitochondria-targeted prodrugs achieved as much as 34 times higher prodrug diffusion in the tumor area compared to the nontumor bladder area. Overall, mitochondria targeting made prodrugs more effective in targeting cancer cells and tumors over non-tumor areas, thereby reducing nonspecific toxicity.

Preclinical evaluation of singlet oxygen-cleavable prodrugs in combination with protoporphyrin IX-photodynamic therapy in an orthotopic rat model of non-muscle-invasive bladder cancer†

Photodynamic therapy (PDT) initially employed red light, which caused some patients to experience permanent bladder contractions. PDT using the FDA-approved drug hexaminolevulinate (HAL), which produces protoporphyrin IX (PpIX) in the tumor, showed some promise but has low efficacy in treating non-muscle-invasive bladder cancer (NMIBC). We developed singlet oxygen-activatable prodrugs of two anticancer drugs, paclitaxel and mitomycin C, to enhance the antitumor effect of PpIX-PDT without producing systemic side effects, by promoting only local release of the active chemotherapeutic agent. Orthotopic NMIBC model was used to compare the efficacy of prodrugs only, PpIX-PDT, and prodrugs + PpIX-PDT. 532 nm laser with a total power of 50 mW for 20 min (60 J, single treatment) was used with HAL and prodrugs. Histology and microscopic methods with image analysis were used to evaluate the tumor staging, antitumor efficacy, and local toxicity. Prodrug + PpIX-PDT produced superior antitumor efficacy than PpIX-PDT alone with statistical significance. Both PpIX-PDT alone and combination therapy resulted in mild damage to the bladder epithelium in the normal bladder area with no apparent damage to the muscle layer. Overall, SO-cleavable prodrugs improved the antitumor efficacy of PpIX-PDT without causing severe and permanent damage to the bladder muscle layer.

Singlet Oxygen Activatable Prodrugs of Paclitaxel, SN-38, MMC, and CA4: Non-mitochondria Targeted Prodrugs

We established a light-activatable prodrug strategy that produces the combination effect of photodynamic therapy (PDT) and site-specific chemotherapy. Prodrugs are activated by singlet oxygen (SO), generated from PS and visible or near IR light, in either intra- or inter-molecular manner. The goal of this study is to evaluate cytotoxic effects of non-mitochondria targeted prodrugs of a number of anticancer drugs with different mechanisms of action. They were tested in both 2D and 3D in vitro conditions via inter-molecular activation of prodrugs by SO generated in mitochondria by protoporphyrin IX-PDT (PpIX-PDT). Prodrugs of anticancer drugs (paclitaxel, SN-38, combrestatin A4, and mitomycin C) were synthesized using facile and high yielding reactions. Non-mitochondria targeted prodrugs showed limited dark toxicity while all of them showed greatly enhanced phototoxicity compared to PpIX-PDT in the 2D culture model. Prodrugs generated up to about 95% cell killing at 2.5 μM when administered with hexyl-aminolevulinate (HAL) to produce Protoporphyrin IX in cancer cells in both 2D monolayer and 3D spheroids model. The data demonstrate that mitochondria-targeting of prodrugs is not fully essential for our inter-molecular activation prodrug strategy. The prodrug strategy also worked for anticancer drugs with diverse MOAs.

Defining and treating the spectrum of intermediate risk nonmuscle invasive bladder cancer

PURPOSE

Low, intermediate and high risk categories have been defined to help guide the treatment of patients with nonmuscle invasive bladder cancer (Ta, T1, CIS). However, while low and high risk disease has been well classified, the intermediate risk category has traditionally comprised a heterogeneous group that does not fit into either of these categories. As a result, many urologists remain uncertain about the categorization of patients as intermediate risk as well as the selection of the most appropriate therapeutic option for this patient population. We review the current literature and clinical practice guidelines on intermediate risk nonmuscle invasive bladder cancer and, based on our findings, provide urologists with a better understanding of this heterogeneous risk group as well as practical recommendations for the treatment of intermediate risk patients.

MATERIALS AND METHODS

The IBCG analyzed published clinical trials, meta-analyses and current clinical practice guidelines on intermediate risk nonmuscle invasive bladder cancer available as of September 2013. The definitions of intermediate risk, patient outcomes and guideline recommendations were considered, as were the limitations of the available literature and additional parameters that may be useful in guiding treatment decisions in intermediate risk patients.

RESULTS

Current definitions and management recommendations for intermediate risk nonmuscle invasive bladder cancer vary. The most simple and practical definition is that proposed by the IBCG and the AUA of multiple and/or recurrent low grade Ta tumors. The IBCG suggests that several factors should be considered in clinical decisions in intermediate risk disease, including number (greater than 1) and size (greater than 3 cm) of tumors, timing (recurrence within 1 year) and frequency (more than 1 per year) of recurrence, and previous treatment. In patients without these risk factors a single, immediate instillation of chemotherapy is advised. In those with 1 to 2 risk factors adjuvant intravesical therapy (intravesical chemotherapy or maintenance bacillus Calmette-Guérin) is recommended, and previous intravesical therapy should be considered when choosing between these adjuvant therapies. For those patients with 3 to 4 risk factors, maintenance bacillus Calmette-Guérin is recommended. It is also important that all intermediate risk patients are accurately risk stratified at initial diagnosis and during subsequent followup. This requires appropriate transurethral resection of the bladder tumor, vigilance to rule out carcinoma in situ or other potential high risk tumors, and review of histological material directly with the pathologist.

CONCLUSIONS

Intermediate risk disease is a heterogeneous category, and there is a paucity of independent studies comparing therapies and outcomes in subgroups of intermediate risk patients. The IBCG has proposed a management algorithm that considers tumor characteristics, timing and frequency of recurrence, and previous treatment. Subgroup analyses of intermediate risk subjects in pivotal EORTC trials and meta-analyses will be important to validate the proposed algorithm and support clear evidence-based recommendations for subgroups of intermediate risk patients.

Treatment of non muscle invasive bladder tumor related to the problem of bacillus Calmette-Guerin availability. Consensus of a Spanish expert's panel. Spanish Association of Urology

CONTEXT

Since June 2012, the has been a worldwide lack of available of the Connaught strain. In December 2012, a group of experts met in the Spanish Association of Urology to analyze this situation and propose alternatives.

OBJECTIVE

To present the work performed by said committee and the resulting recommendations.

ACQUISITION OF EVIDENCE

An update has been made of the principal existing evidence in the treatment of middle and high risk tumors. Special mention has been made regarding the those related with the use of BCG and their possible alternative due to the different availability of BCG.

EVIDENCE SYNTHESIS

In tumors with high risk of progression, immediate cystectomy should be considered when BCG is not available, with dose reduction or alternating with chemotherapy as methods to economize on the use of BCG when availability is reduced. In tumors having middle risk of progression, chemotherapy can be used, although when it is associated to a high risk of relapse, BCG would be indicated if available with the mentioned savings guidelines. BCG requires maintenance to maintain its effectiveness, it being necessary to optimize the application of endovesical chemotherapy and to use systems that increase its penetration into the bladder wall (EMDA) if they are available.

CONCLUSIONS

Due to the scarcity of BCG, it has been necessary to agree on a series of recommendations that have been published on the web page of the Spanish Association of Urology.

A review of current guidelines and best practice recommendations for the management of nonmuscle invasive bladder cancer by the International Bladder Cancer Group

PURPOSE

Although the European Association of Urology, First International Consultation on Bladder Tumors, National Comprehensive Cancer Network and American Urological Association guidelines all provide an excellent evidence-based framework for the management of nonmuscle invasive bladder cancer, these guidelines vary with respect to important issues such as risk level definitions and management strategies for these risk categories. Therefore, we built on the existing framework provided by current guidelines, and provide consensus on the definitions of low, intermediate and high risk nonmuscle invasive bladder cancer, as well as practical recommendations for the treatment of patients in each of these risk categories.

MATERIALS AND METHODS

An international committee of experts on bladder cancer management identified and analyzed the European Association of Urology, First International Consultation on Bladder Tumors, National Comprehensive Cancer Network and American Urological Association guidelines as well as the published English language literature related to the treatment and management of nonmuscle invasive bladder cancer available as of April 2010.

RESULTS

Based on review of the current guidelines and literature, the International Bladder Cancer Group developed practical recommendations for the management of nonmuscle invasive bladder cancer.

CONCLUSIONS

Complete transurethral bladder tumor resection is recommended for all patients with nonmuscle invasive bladder cancer. For low risk disease a single, immediate chemotherapeutic instillation after transurethral bladder tumor resection is recommended. For intermediate or high risk disease there is no significant benefit from an immediate, postoperative chemotherapeutic instillation. For intermediate risk disease intravesical bacillus Calmette-Guérin with maintenance or intravesical chemotherapy is recommended. For high risk disease bacillus Calmette-Guérin induction plus maintenance is recommended. The appropriate management of recurrence depends on the patient level of risk as well as previous treatment, while the management of treatment failure depends on the type of failure as well as the level of risk for recurrence and disease progression.