Efficacy and safety of Mirabegron as adjuvant treatment in children with refractory neurogenic bladder dysfunction

The urological evaluation and management of neurogenic bladder in children and adolescents-what every pediatric nephrologist needs to know

Neurogenic bladder (NGB) is an encompassing term that includes multiple causes of bladder dysfunction linked to a congenital or acquired neurological condition that adversely impacts the innervation of the lower urinary tract. Multiple static or progressive conditions can be associated with NGB in pediatric and adolescent patients. Currently, spinal dysraphism (i.e., spina bifida) is one of the most common etiologies, which occurs in 3-4 per 10,000 live births in developed nations. Abnormal bladder dynamics can lead to kidney damage secondary to high pressures or recurrent infections, as well as urinary incontinence. The current management paradigm centers on a proactive approach to preserving kidney function and achieving continence through behavioral, pharmacological, and surgical means. This educational review highlights the key components of urological management to maximize collaboration with pediatric nephrologists.

Long-term beneficial effects of mirabegron in pediatric patients with therapy-refractory neurogenic lower urinary tract dysfunction

INTRODUCTION

Neurogenic lower urinary tract dysfunction (NLUTD) in children can cause renal failure and urinary incontinence if not treated sufficiently. Antimuscarinics (AM) and intradetrusor botulinum toxin injections (BoNT-A) with clean intermittent catheterization (CIC) are widely used treatment options for children with NLUTD. However, a considerable number will become refractory to these treatment options. This study aimed to evaluate the efficacy and long-term outcomes of mirabegron in children with NLUTD as an add-on and as a stand-alone treatment.

MATERIAL AND METHODS

Patients under 18 years of age with NLUTD who were refractory to AM and/or BoNT-A and were treated with mirabegron 50 mg were retrospectively studied. Mirabegron was either used as monotherapy or in addition to AM and/or BoNT-A. Video-urodynamic studies (VUDSs) were performed before and after treatment with mirabegron. Changes in video-urodynamic parameters, the need for other NLUTD therapy during follow-up, patient-reported side effects, and urinary incontinence were outcomes of interest.

RESULTS

A total of 34 patients with NLUTD were included. All patients were on CIC and the median age was 13.1 years (IQR 15.9-10.3). Median follow-up was 31.4 months (IQR 57.4-11.4). Bladder compliance improved by 89.9%, from 14.9 to 28.3 ml/cm H2O (p-value<0.001). Maximum cystometric capacity, end-filling detrusor pressure, volume at first detrusor overactivity, vesicoureteral reflux, and urinary incontinence significantly improved after mirabegron. The add-on therapy group showed more significant improvements in video-urodynamic outcomes compared to the monotherapy group. The median time of requiring other NLUTD therapy was 25.5 months (IQR 39.8-14.8). None of the included patients reported side effects.

CONCLUSIONS

Mirabegron is an effective treatment for children with therapy-refractory NLUTD with an average efficacy of 2 years after which additional therapy is required. Despite the retrospective character of this study, our results confirm the beneficial effect of mirabegron in children with therapy-refractory NLUTD, in particular when mirabegron is used as add-on therapy in those with low-compliance bladders.

Cost analysis for mirabegron use in the treatment of children with neurogenic bladder

INTRODUCTION

Mirabegron is a beta-3 adrenergic receptor agonist that received FDA approval in 2021 to treat neurogenic detrusor overactivity (NDO) in children ages three years and older. Despite its safety and efficacy, access to mirabegron frequently remains restricted by payor coverage policies.

OBJECTIVE

This cost minimization study sought to determine the cost implications from a payor perspective of mirabegron use at different points in the treatment pathway for pediatric NDO.

STUDY DESIGN

A Markov decision analytic model was constructed to assess the costs for eight treatment strategies over a 10-year period, using six-month cycles (Table). Five strategies involve mirabegron use as first-, second-, third-, or fourth-line therapy. Two strategies, including the "base case," entail use of anticholinergic medications followed by onabotulinum toxin type A (Botox) injection and augmentation cystoplasty. A strategy involving first-line Botox was also modeled. The effectiveness, adverse event rates, attrition rates, and costs associated with each treatment option were obtained from the clinical literature and adjusted to a six-month cycle. Costs were adjusted to 2021-dollar value. A discount rate of 3% was used. To quantify uncertainty, costs and treatment transition probabilities were modeled as gamma and PERT distributions, respectively. One-way sensitivity analyses were performed. Probabilistic sensitivity analysis (PSA) was conducted using a Monte Carlo simulation with 100,000 iterations. Analyses were performed using Treeage Pro (Healthcare Version).

RESULTS

The least costly strategy involved first-line mirabegron (expected cost $37,954). All strategies involving mirabegron were less costly than the base case ($56,417). On PSA, first-line mirabegron was the least costly strategy in 88.9% of cases (mean $37,604, 95% CI: $37,579-37,628); in 100% of cases, the least costly strategy involved mirabegron use. Cost savings associated with mirabegron use were attributable to decreased use of augmentation cystoplasty and Botox injections.

DISCUSSION

This is the first study to compare costs across multiple strategies involving mirabegron to treat pediatric NDO. Mirabegron use likely yields cost savings for the payor: the least costly strategy involved first-line mirabegron, and all pathways incorporating mirabegron were less costly than those without mirabegron use. These findings provide an updated cost analysis for the treatment of NDO by investigating mirabegron use alongside more established treatment options.

CONCLUSION

Use of mirabegron for the treatment of pediatric NDO is likely associated with cost savings as compared to treatment pathways without mirabegron. Expansion of payor coverage for mirabegron, as well as clinical studies to study first-line mirabegron use, should be considered.

An evaluation of onobotulinumtoxinA as a therapeutic option for pediatric neurogenic detrusor overactivity

INTRODUCTION

Neurogenic detrusor overactivity (NDO) results in involuntary detrusor contractions during bladder filling or storage risking transmission of pressure to the upper urinary tracts and/or significant incontinence. The goals of bladder management in children with NDO prioritize the preservation of renal function, prevention of UTIs, and optimizing quality of life. First-line measures include intermittent catheterization and anticholinergic medication. However, when conservative measures fail, surgical intervention may be indicated. Historically, the next step was major reconstructive surgery to create a low-pressure urinary reservoir. The introduction of intravesical botulinum neurotoxin A (BoNT/A) for use in children in 2002 offered a less invasive option for management. However, its exact role is still evolving.

AREAS COVERED

This article summarizes the mechanism of action of BoNT/A for management of NDO and evaluates the current literature defining common practice and clinical efficacy in children with NDO. The findings of the recently completed phase III trial for intravesical onabotulinumtoxinA in children are discussed in detail.

EXPERT OPINION

As the first BoNT/A approved for use in children with NDO, onabotulinumtoxinA appears to be a safe and less invasive alternative to major reconstructive surgery. However, data defining appropriate patient selection and its role as a long-term treatment option continue to develop.

[EFFECTS OF COMBINATION THERAPY WITH VIBEGRON FOR ANTICHOLINERGIC-RESISTANT PEDIATRIC NEUROGENIC BLADDER]

(Objective) We report the effectiveness of combination therapy with vibegron in pediatric patients with neurogenic bladder inadequately responding to anticholinergic agents. (Subjects and methods) This retrospective study involved 13 pediatric patients with neurogenic bladder treated with anticholinergics at our department from November 2019 to January 2021 who had an inadequate response and received combination therapy with vibegron. Changes in the volume of urinary incontinence before and after the use of vibegron reported during interviews from the 13 patients were compared. In addition, bladder capacity at the end of examination, bladder capacity at the end of examination/expected bladder capacity (EBC), and bladder compliance were compared using the Wilcoxon signed rank test in 9 patients for whom urodynamics (UDS) or video urodynamics (VUDS) was performed before and after introduction of vibegron. (Results) The 13 patients comprised 8 boys and 5 girls. The median age was 13 years (range, 5-18 years). Underlying diseases included 9 cases of spina bifida, 1 case of Hinman syndrome, 1 case of cervical vertebra injury, 1 case of idiopathic cervical epidural hematoma combined with spina bifida, and 1 case of spinal cord infarction. Eight of the 13 patients experienced decrease in urinary incontinence after the introduction of vibegron. All 9 patients who underwent UDS or VUDS before and after introduction of vibegron displayed significant differences in bladder capacity at the end of the examination, bladder capacity at the end of the examination/EBC, and bladder compliance, indicating improvement. (Conclusion) Combination therapy with vibegron is effective for pediatric patients with neurogenic bladder who have inadequately responded to anticholinergic agents.

Clinical Utility of β3-Adrenoreceptor Agonists for the Treatment of Overactive Bladder: A Review of the Evidence and Current Recommendations

This nonsystematic review provides a summary of current evidence on the use of β₃-adrenoreceptor agonists (β₃-ARAs) for the treatment for lower urinary tract symptoms. Soon after their discovery in 1989, β₃-ARs were identified as a predominant adrenoreceptor subtype in the human urinary bladder. Although it is widely believed that β₃-ARAs cause detrusor relaxation, the effect on bladder afferent signaling likely plays an important role in their mechanism of action as well. In 2011 and 2012, mirabegron was approved for clinical use in overactive bladder (OAB) patients. Pooled analysis of data from prospective randomized studies on >60,000 OAB patients showed that when compared to placebo, mirabegron was superior with respect to reducing the frequency, number, and severity of urgency episodes, number of incontinence episodes and increasing dry rate, but not in reduction of nocturia episodes. The only side effect showing significantly higher incidence than placebo was nasopharyngitis. Mirabegron is approved for OAB treatment in all age-groups and in pediatric patients with neurogenic bladder. Vibegron is another β₃-ARA approved for OAB treatment in the US and Japan. Several large, multicenter, double-blind, randomized trials have documented statistically significant superiority of vibegron over placebo on all efficacy end points. Other β₃-ARAs are being developed; however, to date none has been introduced to clinical use. All β₃-ARAs provide efficacy similar to anticholinergics. They have a favorable safety profile and are well tolerated. Due to their different mechanisms of action, combination of β₃-ARAs with anticholinergic compounds allows for increased efficacy.

Safety and short-term efficacy of mirabegron in children with valve bladder: a pilot study

AIMS

This pilot study aims to assess the short-term efficacy and safety of mirabegron in valve bladder, an important cause of persistent hydronephrosis after successful treatment of posterior urethral valves (PUV).

METHODS

Twenty-two patients with early valve bladder (no residual PUV; persistent hydronephrosis, wetting and urodynamic evidence of detrusor overactivity) were included. Three subjective parameters: frequency, wetting episodes; patient perception of bladder condition score (PPBC) and four objective parameters: uroflow index (UI = Qave/Qmax), voided volume (VV = voided volume/ expected bladder capacity), maximum filling pressure (P det-max) and society of fetal urology (SFU) hydronephrosis grading were analysed pre- and post-3-month treatment with mirabegron (0.5-1 mg/kg/day). All patients were observed for heart rate, BP, ECG changes during therapy.

RESULTS

There was significant reduction (p = 0.001) in mean frequency (pre 15; post 10), wetting episodes (pre 5; post 2) and PPBC (pre 4; post 3). There was significant improvement (p = 0.01) in mean UI (pre 0.3; post 0.5), VV (pre 0.54; post 0.72), Pdet-max (pre 42; post 25) and hydronephrosis grade (pre 3.5; post 2.2). There were no significant side effects.

CONCLUSION

This pilot study establishes short-term efficacy and safety of mirabegron in valve bladder with overactivity. Further larger long-term studies are warranted.

Spinal cord injury and neurogenic lower urinary tract dysfunction: what do we know and where are we going?

One of the well reported but difficult to manage symptoms of spinal cord injury (SCI) is neurogenic lower urinary tract dysfunction (NLUTD). The type of NLUTD is variable based on location and extent of injury. SCI affects more males and NLUTD is especially debilitating for men with incomplete injury. This review summarizes the anatomical basis of NLUTD in SCI and discusses current diagnostic and management strategies that are being utilized clinically. The last two sections address new innovations and emerging discoveries with the goal of increasing scientific interest in improving treatment options for people with SCI. Areas warranting further investigation are pinpointed to address current gaps in knowledge and/or appropriate technology.

Triboelectric Nanogenerators for Therapeutic Electrical Stimulation

Current solutions developed for the purpose of in and on body (IOB) electrical stimulation (ES) lack autonomous qualities necessary for comfortable, practical, and self-dependent use. Consequently, recent focus has been placed on developing self-powered IOB therapeutic devices capable of generating therapeutic ES for human use. With the recent invention of the triboelectric nanogenerator (TENG), harnessing passive human biomechanical energy to develop self-powered systems has allowed for the introduction of novel therapeutic ES solutions. TENGs are especially effective at providing ES for IOB therapeutic systems given their bioconformability, low cost, simple manufacturability, and self-powering capabilities. Due to the key role of naturally induced electrical signals in many physiological functions, TENG-induced ES holds promise to provide a novel paradigm in therapeutic interventions. The aim here is to detail research on IOB TENG devices applied for ES-based therapy in the fields of regenerative medicine, neurology, rehabilitation, and pharmaceutical engineering. Furthermore, considering TENG-produced ES can be measured for sensing applications, this technology is paving the way to provide a fully autonomous personalized healthcare system, capable of IOB energy generation, sensing, and therapeutic intervention. Considering these grounds, it seems highly relevant to review TENG-ES research and applications, as they could constitute the foundation and future of personalized healthcare.

Mirabegron: Pediatric First Approval

Mirabegron (MYRBETRIQ^®), a beta-3 adrenergic agonist developed by Astellas Pharma Inc., is well established as a treatment for overactive bladder in adults and is available as extended-release (ER) tablets administered once daily. More recently, mirabegron has been investigated in pediatric patients with neurogenic detrusor overactivity (NDO) and received its first approval in this indication in pediatric patients aged ≥ 3 years on 25 March 2021 in the USA. In addition to mirabegron ER tablets (which can be used in pediatric patients weighing ≥ 35 kg), mirabegron is available as an ER oral suspension (MYRBETRIQ^® Granules) for pediatric patients; in those weighing < 35 kg, only the ER oral suspension formulation should be used. The ER tablet and ER oral suspension formulations are not substitutable on a mg-by-mg basis. This article summarizes the milestones in the development of mirabegron for NDO leading to this pediatric first approval.

Management of neurogenic bladder dysfunction in children update and recommendations on medical treatment

INTRODUCTION

Defective closure of the neural tube affects different systems and generates sequelae, such as neurogenic bladder (NB). Myelomeningocele (MMC) represents the most frequent and most severe cause of NB in children. Damage of the renal parenchyma in children with NB acquired in postnatal stages is preventable given adequate evaluation, follow-up and proactive management. The aim of this document is to update issues on medical management of neurogenic bladder in children.

MATERIALS AND METHODS

Five Pediatric Urologists joined a group of experts and reviewed all important issues on "Spina Bifida, Neurogenic Bladder in Children" and elaborated a draft of the document. All the members of the group focused on the same system of classification of the levels of evidence (GRADE system) in order to assess the literature and the recommendations. During the year 2020 the panel of experts has met virtually to review, discuss and write a consensus document.

RESULTS AND DISCUSSION

The panel addressed recommendations on up to date choice of diagnosis evaluation and therapies. Clean intermittent catheterization (CIC) should be implemented during the first days of life, and antimuscarinic drugs should be indicated upon results of urodynamic studies. When the patient becomes refractory to first-line therapy, receptor-selective pharmacotherapy is available nowadays, which leads to a reduction in reconstructive procedures, such as augmentation cystoplasty.