Clinical comparision of intravesical hyaluronic acid and hyaluronic acid-chondroitin sulphate therapy for patients with bladder pain syndrome/interstitital cystitis

Glycosaminoglycan Replacement Therapy with Intravesical Instillations of Combined Hyaluronic Acid and Chondroitin Sulfate in Patients with Recurrent Cystitis, Post-radiation Cystitis and Bladder Pain Syndrome: A Narrative Review

Defects in the glycosaminoglycan layer (GAG) of the bladder mucosa have been identified as a significant contributor to the pathogenesis and clinical progression of chronic inflammatory diseases of the bladder, such as post-radiation cystitis, bladder pain syndrome and recurrent urinary tract infections. This narrative review aims to explore the contemporary evidence on the role of GAG reconstitution with intravesical installations of hyaluronic acid and chondroitin sulfate in the management of those patients, with a goal to provide valuable insights for clinical practice. The reviewed studies consistently demonstrate that GAG reconstitution can result in varying degrees of clinical improvement in patients with post-radiation cystitis, bladder pain syndrome and recurrent urinary tract infections, and is associated with a very favorable safety profile. While the available evidence is growing, its level is still limited, mainly by relatively low number of randomized controlled trials, with small sample sizes. Further research with larger, well-designed trials is needed to solidify the findings and optimize the clinical application of GAG reconstitution.

Comparison of the Clinical Efficacy and Adverse Events between Intravesical Injections of Platelet-Rich Plasma and Botulinum Toxin A for the Treatment of Interstitial Cystitis Refractory to Conventional Treatment

BACKGROUND

Intravesical injection of Botulinum toxin A (BoNT-A) and platelet-rich plasma (PRP) have been reported to alleviate bladder pain and decrease nocturia in patients with refractory interstitial cystitis/bladder pain syndrome (IC/BPS). Both treatments are novel and there has no comparison between them. This study compared the therapeutic effects and adverse events between IC/BPS patients receiving PRP or BoNT-A injections.

MATERIALS AND METHODS

This study retrospectively analyzed female patients with IC/BPS who were refractory to conventional treatment and received BoNT-A (n = 26) or PRP (n = 30) injections within the previous two years. Patients were arbitrarily treated with four monthly injections of PRP or a single injection of 100 U of BoNT-A. All injections were followed by cystoscopic hydrodistention. The primary endpoint was the global response assessment (GRA), and secondary endpoints were changes in the O'Leary-Sant IC symptom score, visual analog score (VAS) of bladder pain, voiding diary, and uroflow measures from baseline to six months after the first injection day.

RESULTS

The baseline demographics revealed no significant difference between groups. The GRA at one, three, and six months was similar between groups. A significant improvement in IC symptom scores was noted in both groups. Although VAS was significantly improved in overall patients, no significant difference was noted between the PRP and BoNT-A groups at 6 months. Only half of the study cohort had a GRA ≥2 at six months. An increase in the post-void residual was noted one month after the BoNT-A injection, but there was no difference between groups at three and six months. More patients reported dysuria (19.2% vs. 3.3%, p = 0.086) and urinary tract infection (UTI, 15.4% vs. 0%, p = 0.041) after BoNT-A injection than after the PRP injections. The time from the first injection to receiving alternative treatment was similar between groups.

CONCLUSION

Both intravesical PRP and BoNT-A injections have similar efficacy in IC symptom improvement. However, only half of the study cohort had a GRA of ≥2 at the six-month follow-up BoNT-A injection carries a potential risk of UTI after treatment.

Urinary Biomarkers in Interstitial Cystitis/Bladder Pain Syndrome and Its Impact on Therapeutic Outcome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is defined as a chronic bladder disorder with suprapubic pain (pelvic pain) and pressure and/or discomfort related to bladder filling accompanied by lower urinary tract symptoms, such as urinary frequency and urgency without urinary tract infection (UTI) lasting for at least 6 weeks. IC/BPS presents significant bladder pain and frequency urgency symptoms with unknown etiology, and it is without a widely accepted standard in diagnosis. Patients’ pathological features through cystoscopy and histologic features of bladder biopsy determine the presence or absence of Hunner lesions. IC/PBS is categorized into Hunner (ulcerative) type IC/BPS (HIC/BPS) or non-Hunner (nonulcerative) type IC/BPS (NHIC/BPS). The pathophysiology of IC/BPS is composed of multiple possible factors, such as chronic inflammation, autoimmune disorders, neurogenic hyperactivity, urothelial defects, abnormal angiogenesis, oxidative stress, and exogenous urine substances, which play a crucial role in the pathophysiology of IC/BPS. Abnormal expressions of several urine and serum specimens, including growth factor, methylhistamine, glycoprotein, chemokine and cytokines, might be useful as biomarkers for IC/BPS diagnosis. Further studies to identify the key molecules in IC/BPS will help to improve the efficacy of treatment and identify biomarkers of the disease. In this review, we discuss the potential medical therapy and assessment of therapeutic outcome with urinary biomarkers for IC/BPS.

Recent advances and prospects of hyaluronan as a multifunctional therapeutic system

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG), cell-surface-associated biopolymer and is the key component of tissue extracellular matrix (ECM). Along with remarkable physicochemical properties, HA also has multifaceted biological effects that include but not limited to ECM organization, immunomodulation, and various cellular processes. Environmental cues such as tissue injury, infection or cancer change downstream signaling functionalities of HA. Unlike native HA, the fragments of HA have diversified effects on inflammation, cancer, fibrosis, angiogenesis and autoimmune response. In this review, we aim to discuss HA as a therapeutic delivery system development process, source, biophysical-chemical properties, and associated biological pathways (especially via cell surface receptors) of native and fragmented HA. We also tried to address an overview of the potential role of HA (native HA vs fragments) in the modulation of inflammation, immune response and various cancer targeting delivery applications. This review will also highlight the HA based therapeutic systems, medical devices and future perspectives of various biomedical applications were discussed in detail.

Comparative safety review of current pharmacological treatments for interstitial cystitis/ bladder pain syndrome

Introduction: Interstitial cystitis (IC)/bladder pain syndrome (BPS) is a frustrating disease of chronic bladder pain associated with lower urinary tract symptoms. Although there are many proposed treatment algorithms, the uncertainty as to their etiology has a negative impact on the therapeutic outcome. Oftentimes combination therapy of drugs with different mechanisms of action will be utilized to relieve the symptoms. With the various treatment options available to patients and providers, there is an ever-growing need to implement drug efficacy as well as safety to promote best practice in use of the approved drug.Areas covered: This review will focus on guideline-based pharmacotherapies as described by the AUA and EAU, specifically oral, and intravesical therapies with the most up-to-date published literature. Pharmacotherapies targeting bladder, and/or systemic factors in the overall treatment of IC/BPS are discussed with a particular focus on efficacy and drug safety evaluation.Expert opinion: IC/BPS is a syndrome that requires bladder targeting agents to restore the urothelium barrier function and inhibit bladder hypersensitivity as well as various drugs with anti-inflammatory effects, and immune modulation effects. Current pharmacotherapies for IC/BPS have various therapeutic effects and adverse effects depending on the dose and individual response.

A comparison of two intravesical bladder instillations for interstitial cystitis/bladder pain syndrome

OBJECTIVE

Bladder pain syndrome (BPS) is a chronic pain condition associated with injury to the glycosoaminoglycan (GAG) layer. We aimed to prospectively evaluate iAluRil® with multi-centre tertiary urogynaecology collaboration. We hypothesised that iAluRil® (a GAG therapy) would demonstrate equivalent symptom, pain and QOL scores compared to DMSO controls.

STUDY DESIGN

iAluRil® was administered for 7 instillations over 3 months in 34 women over 6 sites. 18 historical DMSO controls were matched 2:1. At baseline and 3 months post treatment validated questionnaires were collected.

RESULTS

Both iAluRil® and DMSO were associated with statistically significant improvements in IC/BPS specific questionnaire scores. iAluRil® showed statistically significant improvements in pain, symptoms, and QOL. 45 % of iAluRil® recipients had a greater than 50 % reduction in pain score as represented by the VAS. DMSO was also effective in improving measures of IC/BPS with statistically significant decreases in ICSI and ICPI. There was no statistically significant difference in the size of the effect between DMSO and IAluRil®.

CONCLUSIONS

iAluRil® is well tolerated and associated with significant improvements in pain and symptom scores. Almost half of refractory BPS will have a 50 % decrease in pain score at three months post treatment. This effect size is similar to DMSO.

A high molecular weight hyaluronic acid biphasic dispersion as potential therapeutics for interstitial cystitis

Interstitial cystitis (IC) is a progressive bladder disease characterized by increased urothelial permeability, inflammation of the bladder with abdominal pain. While there is no consensus on the etiology of the disease, it was believed that restoring the barrier between urinary solutes and (GAG) urothelium would interrupt the progression of this disease. Currently, several treatment options include intravesical delivery of hyaluronic acid (HA) and/or chondroitin sulfate solutions, through a catheter to restore the urothelial barrier, but have shown limited success in preclinical, clinical trials. Herein we report for the first time successful engineering and characterization of biphasic system developed by combining cross‐linked hyaluronic acid and naïve HA solution to decrease inflammation and permeability in an in vitro model of interstitial cystitis. The cross‐linking of HA was performed by 4‐arm‐polyethyeleneamine chemistry. The HA formulations were tested for their viscoelastic properties and the effects on cell metabolism, inflammatory markers, and permeability. Our study demonstrates the therapeutic effects of different ratios of the biphasic system and reports their ability to increase the barrier effect by decreasing the permeability and alteration of cell metabolism with respect to relative controls. Restoring the barrier by using biphasic system of HA therapy may be a promising approach to IC.

The role of bladder instillation in the treatment of bladder pain syndrome: Is intravesical treatment an effective option for patients with bladder pain as well as LUTS?

The aetiology of bladder pain syndrome/interstitial cystitis is still unknown. Numerous mechanisms have been proposed and treatments targeting various aspects of these are used. This review looks at the existing evidence on bladder instillations and whether they could be used in the treatment of lower urinary tract symptoms as well.

The role of glycosaminoglycans in the management of chronic pelvic pain: a systematic review

INTRODUCTION

Glycosaminoglycans (GAGs) are involved in the pathogenesis of several urologic chronic diseases. Thus, GAGs replenishment therapy is widely reported as a therapeutic tool for chronic pelvic pain (CPP) conditions such as interstitial cystitis/bladder pain syndrome (IC/BPS) and prostate pain syndrome/chronic prostatitis. In this article we reviewed the current status of evidence on the clinic applications of glycosaminoglycans (GAGs) in the CPP.

EVIDENCE ACQUISITION

A literature search from inception was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement to identify clinical trials, randomized controlled trials, meta-analyses, and guidelines.

EVIDENCE SYNTHESIS

A total of 29 papers were identified regarding the use of GAGs in CPP.

CONCLUSIONS

GAGs replenishment therapy results are encouraging in chronic forms of pelvic pain even though well-powered randomized clinical trials are needed to better comprehend the exact role of this treatment.

Assessment of long-term intravesical hyaluronic acid, chondroitin sulfate and combination therapy for patients with bladder pain syndrome

Introduction

The aim of this study was to evaluate the efficacy, safety and tolerability of intravesical hyaluronic acid (HA), chondroitin sulfate (CS) and combination therapies (HA+CS) for patients with bladder pain syndrome (BPS) - interstitial cystitis (IC) during a 24 months follow-up period.

Material and methods

The study was conducted with a prospective, randomized and double-blinded design. A total of 72 patients were divided into three groups as HA, CS and combination group. Outpatient visits were performed at the begining of the study and at every 3^rd month thereafter. Both objective parameters included in 3 day micturition diary such as number of micturitions per 24 hours, volume voided in each micturition and self-reported questionnaires such as Patient Perception of Bladder Condition Scale, Visual Analog Scale, Pain Urgency Frequency Questionnaire, Interstitial Cystitis Symptom and Problem Index, Health Related Quality of Life (HRQoL) were used to assess the efficacy of three different agents. Safety was defined as any adverse event beginning or worsening in the study and reported in each visit.

Results

All groups showed a significant improvement both in the parameters included in the 3 day micturition diary and self-reported questionnaires compared to the baseline values or scores recorded at the beginning of the study. Our primary end point was improvement in HRQoL score. The combination therapy was superior to both of the monotherapies in terms of improvement in HRQoL score and the difference was statistically significant (p = 0.02).

Conclusions

Combination therapy provides better results than the monotherapies to obtain symptomatic relief in patients with BPS/IC. Meta-analysis of different well-designed studies are required for more definitive results.

Hyaluronic acid and chondroitin sulfate, alone or in combination, efficiently counteract induced bladder cell damage and inflammation

Interstitial cystitis and/or bladder pain syndrome (IC/BPS) are characterized by discomfort, abdominal pain, and pelvic pain, and they are often associated with chronic diseases. Pathological conditions related to IC/BPS can occur due to a defect in the integrity of the bladder lining. This defect has been ascribed to damage to the glycosaminoglycan (GAG) layer of the urinary epithelium. In addition, the incipient cascade of inflammation events might prompt extracellular matrix degradation. Several medical devices based on GAG instillation were proposed to re-establish epithelial integrity by GAGs binding to proteoglycans or interacting with structural urothelium. However, to date, only in vitro studies have investigated the GAG, hyaluronic acid (HA). In the present study, TNFα treatment was used to mimic IC/BPS-induced damage in bladder cells in an in vitro model. Highly purified fermentative HA and pharmaceutical grade bovine chondroitin sulfate (CSb), alone or in combination, were evaluated for the ability to counteract bladder cell damage. We evaluated NF-κB with western blots, and we analyzed interleukin 6 and 8 expression at the transcriptional and protein levels with quantitative RT-PCR, western blotting, and ELISA. We also evaluated the expression of an antibacterial peptide, human β-defensin-2. We confirmed our results in a 3D bladder epithelium model. Our results demonstrated that inflammatory status was reduced in the presence of HA, CSb, and the combination of both (HA/CSb 1.6%/2% w/v). This result suggested that these GAGs might be suitable for treating IC/BPS. All the assayed biomarkers showed that HA/CSb treatment modulated cells towards a more physiological status. Finally, we compared two commercial products suggested for the IC/BPS treatments and found that the product with more Ca++, showed enhanced anti-inflammatory activity and provided superior mucoadhesivity.

Impact of intravesical hyaluronic acid treatment on bladder inflammation in interstitial cystitis rat model

OBJECTIVE

To evaluate the effect of intravesical hyaluronic acid (HA) treatment on inflammatory cells and the severity of inflammation in an interstitial cystitis rat model created with hydrogen chloride (HCL) via immunohistochemical studies and myeloperoxidase activity for the first time in the literature.

MATERIALS AND METHODS

A total of 30 adult female white Rattus Norvegicus rats were divided into 3 groups as the HCL group, hyaluronic acid treatment (HCL-HA) group and control group. Chemical cystitis was created by administering HCL(400 microL,10 mM) except control group. A single dose of intravesical HA(0.5 mL,0.8 mg/mL) was administered to the treatment group. The bladder tissues of all subjects were immunohistochemically stained. The cell surface markers were used to evaluate inflammatory cell infiltration. Mast cell activation and IL-6 was evaluated to assess the inflammation and severity of inflammation, respectively. Myeloperoxidase activity was measured as it shows neutrophil density. Statistical significance was accepted as P<0.05.

RESULTS

It was observed that there was rich monocyte, T lymphocyte, B lymphocyte, and Natural Killer cells infiltration and high IL-6 levels in the bladder tissue after the intravesical hydrogen chloride instillation, especially in the stroma layer(p<0.005). In the HCL-HA group, severity of inflammation had statistically significantly regressed to the levels of the control group(p<0.005). An increase was observed in the bladder myeloperoxidase activity of the HCL group compared to the other two groups(p<0.05).

CONCLUSIONS

Single dose intravesical hyluronic acid instillation reduces inflammatory cell infiltration and the severity of bladder inflammation in the rat model of bladder pain syndrome/interstitial cystitis.

The role of TSG-6 and uroplakin III in bladder pain syndrome/ interstitial cystitis in rats and humans

Objectives

We investigated the relationship between the expression of tumor necrosis factor-inducible gene 6 (TSG-6) with inflammation and integrity of the bladder epithelium in the bladder tissues of patients with bladder pain syndrome/interstitial cystitis (BPS/IC) and the mechanism of action using a rat model of BPS/IC.

Materials and Methods

Expression of TSG-6 and uroplakin III was determined by immuno- histochemistry of bladder biopsy samples from control human subjects and patients with verified BPS/IC. Our rat model of BPS/IC was employed to measure the perfusion of bladders with hyaluronidase, and assessment of the effect of TSG-6 administration on disease progression. Treatment effects were assessed by measurement of metabolic characteristics, RT-PCR of TGR-6 and interleukin-6, bladder histomorphology, and immunohistochemistry of TGR-6 and uroplakin III.

Results

The bladders of patients with BPS/IC had lower expression of uroplakin III and higher expression of TSG-6 than controls. Rats treated with hyaluronidase for 1 week developed the typical signs and symptoms of BPS/IC, and rats treated with hyaluronidase for 4 weeks had more serious disease. Administration of TSG-6 reversed the effects of hyaluronidase and protected against disease progression.

Conclusion

Our results indicate that TSG-6 plays an important role in maintaining the integrity of the bladder epithelial barrier.

Clinical comparison of intravesical hyaluronic acid and chondroitin sulfate therapies in the treatment of bladder pain syndrome/interstitial cystitis

INTRODUCTION

Intravesical glucosaminoglycan (GAG) replacement therapies are commonly used in the treatment of bladder pain syndrome (BPS)/interstitial cystitis (IC). Different intravesical glucosaminoglycan products are currently available. In this prospective study, clinical efficacy of chondroitin sulfate and hyaluronic acid are compared in patients with BPS/IC.

METHODS

Patients were randomized to CS and HA groups. All patients were evaluated for visual analogue pain scale (VAS), interstitial cystitis symptom index (ICSI), interstitial cystitis problem index (ICPI), voiding diary for frequency/nocturia, and mean urine volume per void at the beginning of the therapy and after 6 months. All patients had a potassium sensitivity test (PST) initially. Wilcoxon and Mann-Whitney U tests were used for statistical analysis.

RESULTS

There were 21 patients in both groups. Mean age of patients in CS and HA groups were 47.10 and 48.90, respectively(P > 0.05). Before treatment, Parson's test was positive in 64.3% of patients (27/42) with no difference between groups. VAS of pain, ICSI, ICPI, frequency at 24 h and nocturia results have improved significantly at both treatment arms. Intravesical CS was also found superior to intravesical HA in terms of 24 h frequency, nocturia and ICPI (P < 0.05). No severe adverse effects were reported.

CONCLUSIONS

Data comparing clinical efficiencies of different GAG therapies are very limited. In this study, intravesical CS was found superior to intravesical HA in terms of 24 h frequency, nocturia and ICPI in patients with BPS/IC in short term follow-up. To provide a definitive conclusion on superiority of one GAG therapy to others, further evaluation with long term follow up is required.

Investigational drugs for bladder pain syndrome (BPS) / interstitial cystitis (IC)

INTRODUCTION

Bladder pain syndrome (BPS)/interstitial cystitis (IC) is associated with sensory lower urinary tract symptoms. Unfortunately, many of the existing oral treatments are ineffective in most patients of BPS/IC, which is the motivation for developing new drugs and therapeutic approaches. This review covers the latest drugs that have been investigated in BPS/IC patients. Intravesical treatments offer the opportunity to directly target the painful bladder with less systemic side effects.

AREAS COVERED

In this review, the authors analyze the existing literature supporting the treatment of BPS/IC with conventional drugs including heparin, hyaluronic acid, chondroitin sulfate, and dimethylsulfoxide (DMSO). Furthermore, investigational drugs such as tanezumab and adalimumab, capable of sequestering nerve growth factor (NGF), and Tumor necrosis factor-α (TNF- α) are discussed. Investigational treatments such as liposomes, botulinum toxin (BTX), liposomal BTX, PD-0299685 (a Ca(2+) channel ɑ2δ ligand), continuous intravesical lidocaine, and AQX-1125 (a novel SHIP1 activating compound) are also covered.

EXPERT OPINION

New investigational drugs offer promising improvements in clinical outcomes for BPS/IC patients; however, BPS/IC is a chronic pain disorder that is very vulnerable to a strong placebo effect. In addition, BPS/IC is a heterogeneous disorder that can be classified into several phenotypes. Since different phenotypes of BPS/IC respond differently to systemic and intravesical treatments, the authors believe that new drugs developed for BPS/IC are more likely to meet their predetermined clinical endpoints if the inclusion/exclusion criterion is tailored to specific phenotype of BPS/IC patients.

Interstitial cystitis/bladder pain syndrome and glycosaminoglycans replacement therapy

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disease characterized by discomfort or recurrent abdominal and pelvic pains in the absence of urinary tract infections. Its symptomatology includes discomfort, increased bladder pressure, sensitivity and intense pain in the bladder and pelvic areas, increased voiding frequency and urgency, or a combination of these symptoms. For these reasons, this pathology has a very negative impact on quality of life. The etiology of IC/BPS is still not well understood and different hypotheses have been formulated, including autoimmune processes, allergic reactions, chronic bacterial infections, exposure to toxins or dietary elements, and psychosomatic factors. The finding of an effective and specific therapy for IC/BPS remains a challenge for the scientific community because of the lack of a consensus regarding the causes and the inherent difficulties in the diagnosis. The last recent hypothesis is that IC/BPS could be pathophysiologically related to a disruption of the bladder mucosa surface layer with consequent loss of glycosaminoglycans (GAGs). This class of mucopolysaccharides has hydrorepellent properties and their alteration expose the urothelium to many urinary toxic agents. It has been hypothesized that when these substances penetrate the bladder wall a chain is triggered in the submucosa. In order to improve the integrity and function of the bladder lining, GAG layer replenishment therapy is widely accepted as therapy for patients with IC/BPS who have poor or inadequate response to conventional therapy. Currently, Chondroitin sulfate (CS), heparin, hyaluronic acid (HA), and pentosan polysulphate (PPS), and combinations of two GAGs (CS and HA) are the available substances with different effectiveness rates in patients with IC/BPS. There are four different commercially available products for GAG replenishment including CS, heparin, HA and PPS. Each product has different concentrations and dosage formulations. Recently, a combination of CS and HA is the latest commercially available product with promising results.

Ultrasound-guided pulsed radiofrequency treatment of the pudendal nerve in chronic pelvic pain

Chronic pelvic pain is a condition that can be caused by pudendal neuralgia, interstitial cystitis, piriformis syndrome and neuropathy of the ilioinguinal, iliohypogastric and genitofemoral nerves. Based on three case reports this article discusses the clinical effectiveness of pulsed high-frequency radiofrequency (PRF) treatment applied to the pudendal nerve under ultrasound guidance in medicinally treated patients with chronic pelvic pain.

Advances in intravesical therapy for urinary tract disorders

INTRODUCTION

Intravesical therapy is a valuable option in the clinical management of urinary tract disorders such as interstitial cystitis/ painful bladder syndrome (IC/PBS) and refractory overactive bladder. This review will cover the latest advances in this field using polymer and liposomes as delivery platform for drugs, protein and nucleic acids.

AREAS COVERED

This review summarizes the significance of intravesical therapy for lower urinary tract disorders. The recent advancement of liposomes as a drug delivery platform for botulinum toxin, tacrolimus and small interfering RNA is discussed. The importance of polymers forming indwelling devices and hydrogels are also discussed, where all preparations improved efficacy parameters in rodent models. Clinical experience of treating IC/PBS with indwelling devices and liposomes are summarized and preclinical evidence about the downregulation of target gene expression in rodent bladder with liposomes complexed with siRNA is also reviewed.

EXPERT OPINION

There have been several advances in the field of intravesical therapy for improving clinical outcomes. One of the most promising research avenues is the repurposing of drugs, given previously by other routes of administration, such as tacrolimus. Intravesical therapy also opens up novel therapeutic targets with improved efficacy and safety for underactive bladder.

From bladder to systemic syndrome: concept and treatment evolution of interstitial cystitis

Interstitial cystitis, presently known as bladder pain syndrome, has been recognized for over a century but is still far from being understood. Its etiology is unknown and the syndrome probably harbors different diseases. Autoimmune dysfunction, urothelial leakage, infection, central and peripheral nervous system dysfunction, genetic disease, childhood trauma/abuse, and subsequent stress response system dysregulation might be implicated. Management is slowly evolving from a solo act by the end-organ specialist to a team approach based on new typing and phenotyping of the disease. However, oral and invasive treatments are still largely aimed at the bladder and are based on currently proposed pathophysiologic mechanisms. Future research will better define the disease, permitting individualization of treatment.