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May Editorial: The Current Hot Topics in Functional Urology

BJUI-May-2015-cover_smallFor some time, the challenge represented by managing the overactive bladder (OAB) has been dominant in functional urology research. The introduction of new therapies has galvanised the area, with mirabegron showing strong promise for many patients as a monotherapy. In addition, the potential for combined therapy using mirabegron with established antimuscarinics has recently been reported for urgency urinary incontinence [1]. Now that the place of onabotulinum-A injections in refractory cases is firmly established, management options have clearly taken a step forward in recent years. However, there remain people for whom even the more comprehensive current options are inadequate or intolerable. The need for basic science research remains a priority, in the hope of translation into clinical options. In this month’s BJUI, Aizawa et al. [2] report responses in an animal model to an inhibitor of fatty acid amide hydrolase, showing how exploiting the endocannabinoid pathway might be a translational focus for entirely new approaches in OAB. They consider an issue that is very important in developing clinical options, which is that the systems regulating bladder function are also fundamental in other organs, such as the CNS. As the compound they studied does not cross the blood–brain barrier, the potential generation of CNS adverse effects is reduced, which would be important for its potential as a new therapy.

OAB is a symptom syndrome based on storage-type LUTS [3]. Increasingly the field of functional urology is recognising the large number of people who present with voiding and post-micturition LUTS yet do not have BOO. Currently, there are no satisfactory treatment options for affected people and the symptoms can have considerable impact. Frustratingly, current diagnostic methods rely on urodynamic testing to establish whether the presence of detrusor underactivity explains voiding LUTS in an individual patient. Recently, the profession has established a move towards using symptoms to categorise the clinical need in patients [4]. Accordingly, the International Continence Society has established a working group to generate terminology for underactive bladder (UAB), which will report this year, including a symptom-based definition. A symptomatic diagnosis would be very helpful to enable therapy development to proceed without the need for urodynamic testing. Also, in this month’s BJUI, Kajbafzadeh et al. [5] report a clinical trial in UAB using transcutaneous interferential electrical stimulation in children. The treatment was delivered in the context of the rather laborious process currently required for managing this difficult problem, namely diet and fluid manipulation, scheduled voiding, toilet training, and pelvic floor and abdominal muscles relaxation training. The electrical stimulation was demonstrably beneficial, and included responses for the highly troublesome symptom of nocturnal enuresis. The comparatively straightforward nature of this therapeutic approach potentially makes it a valuable tool for dealing with a notoriously difficult problem.

Marcus J. Drake, Senior Lecturer
School of Clinical Sciences, University of Bristol, Bristol, UK

 

References

 

 

Article of the Month: Safety and efficacy of mirabegron as add-on therapy in patients with solifenacin-treated OAB (MILAI study)

Every Month the Editor-in-Chief selects an Article of the Month from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video from Prof. Osamu Yamaguchi discussing his paper. 

If you only have time to read one article this week, it should be this one.

Safety and efficacy of mirabegron as add-on therapy in patients with overactive bladder treated with solifenacin: a postmarketing, open-label study in Japan (MILAI study)

Osamu Yamaguchi, Hidehiro Kakizaki*, Yukio Homma, Yasuhiko Igawa, Masayuki Takeda§, Osamu Nishizawa, Momokazu Gotoh**, Masaki Yoshida††, Osamu Yokoyama‡‡, Narihito Seki§§, Akira Okitsu¶¶, Takuya Hamada¶¶, Akiko Kobayashi¶¶ and Kentarou Kuroishi¶¶

 

Division of Bioengineering and LUTD Research, School of Engineering, Nihon University, Koriyama, *Department of Urology, Asahikawa Medical University, Asahikawa, Department of Urology, University of Tokyo Graduate School of Medicine, Tokyo, ‡Department of Continence Medicine, University of Tokyo Graduate School of Medicine, Tokyo, §Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, ¶Department of Urology, Shinshu University, Matsumoto, **Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, ††Department of Urology, National Centre for Geriatrics and Gerontology, Obu, ‡‡Department of Urology, University of Fukui Faculty of Medical Sciences, Fukui, §§Department of Urology, Kyushu
Central Hospital of the Mutual Aid Association of Public School Teachers, Fukuoka, and ¶¶Astellas Pharma Inc., Tokyo, Japan

 

OBJECTIVE

To examine the safety and efficacy of mirabegron as ‘add-on’ therapy to solifenacin in patients with overactive bladder (OAB).

PATIENTS AND METHODS

This multicentre, open-label, phase IV study enrolled patients aged ≥20 years with OAB, as determined by an OAB symptom score (OABSS) total of ≥3 points and an OABSS Question 3 score of ≥2 points, who were being treated with solifenacin at a stable dose of 2.5 or 5 mg once daily for at least 4 weeks. Study duration was 18 weeks, comprising a 2-week screening period and a 16-week treatment period. Patients meeting eligibility criteria continued to receive solifenacin (2.5 or 5 mg once daily) and additional mirabegron (25 mg once daily) for 16 weeks. After 8 weeks of treatment, the mirabegron dose could be increased to 50 mg if the patient’s symptom improvement was not sufficient, if he/she was agreeable to the dose increase, and the investigator judged that there were no safety concerns. Safety assessments included adverse events (AEs), laboratory tests, vital signs, 12-lead electrocardiogram, QT corrected for heart rate using Fridericia’s correction (QTcF) interval and post-void residual (PVR) volume. Efficacy endpoints were changes from baseline in OABSS total score, OAB questionnaire short form (OAB-q SF) score (symptom bother and total health-related quality of life [HRQL] score), mean number of micturitions/24 h, mean number of urgency episodes/24 h, mean number of urinary incontinence (UI) episodes/24 h, mean number of urgency UI episodes/24 h, mean volume voided/micturition, and mean number of nocturia episodes/night. Patients were instructed to complete the OABSS sheets at weeks −2, 0, 8 and 16 (or at discontinuation), OAB-q SF sheets at weeks 0, 8 and 16 (or at discontinuation) and patient voiding diaries at weeks 0, 4, 8, 12 and 16 (or at discontinuation).

RESULTS

Overall incidence of drug-related treatment-emergent AEs (TEAEs) was 23.3%. Almost all TEAEs were mild or moderate. The most common TEAE was constipation, with similar incidence in the groups receiving a dose increase to that observed in the groups maintained on the original dose. Changes in PVR volume, QTcF interval, pulse rate and blood pressure were not considered to be clinically significant and there were no reports of urinary retention. Significant improvement was seen for changes in efficacy endpoints from baseline to end of treatment (EOT) in all groups (patients receiving solifenacin 2.5 or 5 mg + mirabegron 25 or 50 mg).

CONCLUSIONS

Add-on therapy with mirabegron 25 mg once daily for 16 weeks, with an optional dose increase to 50 mg at week 8, was well tolerated in patients with OAB treated with solifenacin 2.5 mg or 5 mg once daily. There were significant improvements from baseline to EOT in OAB symptoms with combination therapy with mirabegron and solifenacin. Add-on therapy with mirabegron and an antimuscarinic agent, such as solifenacin, may provide an attractive therapeutic option.

 

Editorial: Combining solifenacin and mirabegron for OAB management

Overactive bladder (OAB) is one of the most frequent LUTS in both sexes, and is associated with significant bother and impact on quality of life [1]. In many cases, no underlying cause is found and OAB is stated as being ‘idiopathic’. Until recently, the first-line management of idiopathic OAB has been based on the use of antimuscarinics, solifenacin being one of the most prescribed drugs; however, the long-term adherence to antimuscarinics has been shown to be rather low because of lack of efficacy, treatment switch or adverse events, or for mixed reasons [2].

A few years ago, β3-adrenergics were successfully introduced as an alternative to antimuscarinics for OAB management. The efficacy of β3-adrenergics has been shown and they are associated with a new safety profile that differs from that of antimuscarinics [3]. Mirabegron, the most widely used β3-adrenergic drug, has thus gained popularity in clinical practice. Given that β3-adrenergics and anticholinergics have a distinct mechanism of action, the combination of both drugs has been seen as a possible option and has been tested through a huge randomized controlled trial [4].

In the present issue of BJUI, Yamaguchi et al. [5] report the results of the MILAI study, an open-label phase IV trial assessing the effects of mirabegron as an add-on therapy in patients treated for OAB with solifenacin. They found that the addition of mirabegron to solifenacin generated only mild to moderate adverse events, and led to promising efficacy results; however, this study, which the authors call a preliminary study, raises a number of questions that remain completely unanswered.

First, even if seen as fluctuant, idiopathic OAB is considered to be a chronic disease. Long-term results must be seen as a critical issue in the field, and there is no guarantee that the short-term data presented in the MILAI study will stand the test of time in terms of efficacy and adherence.

Second, the study raises an important question about the optimum use of mirabegron in idiopathic OAB. Should it be a first-line option, a secondary option after antimuscarinics (available for treatment switch), or an add-on therapy, as it is presented in the present trial? There might be some room for each of these pathways depending on the patient history and characteristics, and the results obtained under antimuscarinics. From that point of view, the MILAI study is probably too weak to identify factors associated with failure of the combination therapy. Further studies should better detail patient inclusion criteria (because ‘failure’ of antimuscarinics is a heterogeneous concept), as well as characteristics of non-responders. In the present study, these two points are not detailed, and the study provides only a global statistically significant improvement, paving the way for additional research. A better understanding of the mechanism of action of the treatment combination would be of great value to move forward and enable better patient selection.

Finally, one of the upcoming challenges will be to integrate mirabegron as an add-on therapy in the world of male LUTS, including benign prostatic obstruction, where β3-adrenergics probably have an important role to play. As underlined by the authors, several studies are on the way, and their results (in a male population) are urgently awaited.

After having been successfully introduced in most countries in the western world, the new life of mirabegron has begun (including post-marketing studies, extensions of market authorizations, potentially new indications, combination therapy). The future will tell us whether this success story will continue.

Jean-Nicolas Cornu 
Department of Urology, Tenon Hospital, Hopitaux Universitaires Paris-EST, Assistance publique Hopitaux de Paris, Universite Pierre et Marie Curie Paris 6, Paris, France

 

References

 

Video: Safety and efficacy of mirabegron as ‘add-on’ therapy in patients with OAB treated with solifenacin

Safety and efficacy of mirabegron as add-on therapy in patients with overactive bladder treated with solifenacin: a postmarketing, open-label study in Japan (MILAI study)

Osamu Yamaguchi, Hidehiro Kakizaki*, Yukio Homma, Yasuhiko Igawa, Masayuki Takeda§, Osamu Nishizawa, Momokazu Gotoh**, Masaki Yoshida††, Osamu Yokoyama‡‡, Narihito Seki§§, Akira Okitsu¶¶, Takuya Hamada¶¶, Akiko Kobayashi¶¶ and Kentarou Kuroishi¶¶

 

Division of Bioengineering and LUTD Research, School of Engineering, Nihon University, Koriyama, *Department of Urology, Asahikawa Medical University, Asahikawa, Department of Urology, University of Tokyo Graduate School of Medicine, Tokyo, ‡Department of Continence Medicine, University of Tokyo Graduate School of Medicine, Tokyo, §Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, ¶Department of Urology, Shinshu University, Matsumoto, **Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, ††Department of Urology, National Centre for Geriatrics and Gerontology, Obu, ‡‡Department of Urology, University of Fukui Faculty of Medical Sciences, Fukui, §§Department of Urology, Kyushu
Central Hospital of the Mutual Aid Association of Public School Teachers, Fukuoka, and ¶¶Astellas Pharma Inc., Tokyo, Japan

 

OBJECTIVE

To examine the safety and efficacy of mirabegron as ‘add-on’ therapy to solifenacin in patients with overactive bladder (OAB).

PATIENTS AND METHODS

This multicentre, open-label, phase IV study enrolled patients aged ≥20 years with OAB, as determined by an OAB symptom score (OABSS) total of ≥3 points and an OABSS Question 3 score of ≥2 points, who were being treated with solifenacin at a stable dose of 2.5 or 5 mg once daily for at least 4 weeks. Study duration was 18 weeks, comprising a 2-week screening period and a 16-week treatment period. Patients meeting eligibility criteria continued to receive solifenacin (2.5 or 5 mg once daily) and additional mirabegron (25 mg once daily) for 16 weeks. After 8 weeks of treatment, the mirabegron dose could be increased to 50 mg if the patient’s symptom improvement was not sufficient, if he/she was agreeable to the dose increase, and the investigator judged that there were no safety concerns. Safety assessments included adverse events (AEs), laboratory tests, vital signs, 12-lead electrocardiogram, QT corrected for heart rate using Fridericia’s correction (QTcF) interval and post-void residual (PVR) volume. Efficacy endpoints were changes from baseline in OABSS total score, OAB questionnaire short form (OAB-q SF) score (symptom bother and total health-related quality of life [HRQL] score), mean number of micturitions/24 h, mean number of urgency episodes/24 h, mean number of urinary incontinence (UI) episodes/24 h, mean number of urgency UI episodes/24 h, mean volume voided/micturition, and mean number of nocturia episodes/night. Patients were instructed to complete the OABSS sheets at weeks −2, 0, 8 and 16 (or at discontinuation), OAB-q SF sheets at weeks 0, 8 and 16 (or at discontinuation) and patient voiding diaries at weeks 0, 4, 8, 12 and 16 (or at discontinuation).

RESULTS

Overall incidence of drug-related treatment-emergent AEs (TEAEs) was 23.3%. Almost all TEAEs were mild or moderate. The most common TEAE was constipation, with similar incidence in the groups receiving a dose increase to that observed in the groups maintained on the original dose. Changes in PVR volume, QTcF interval, pulse rate and blood pressure were not considered to be clinically significant and there were no reports of urinary retention. Significant improvement was seen for changes in efficacy endpoints from baseline to end of treatment (EOT) in all groups (patients receiving solifenacin 2.5 or 5 mg + mirabegron 25 or 50 mg).

CONCLUSIONS

Add-on therapy with mirabegron 25 mg once daily for 16 weeks, with an optional dose increase to 50 mg at week 8, was well tolerated in patients with OAB treated with solifenacin 2.5 mg or 5 mg once daily. There were significant improvements from baseline to EOT in OAB symptoms with combination therapy with mirabegron and solifenacin. Add-on therapy with mirabegron and an antimuscarinic agent, such as solifenacin, may provide an attractive therapeutic option.

Article of the week: Mirabegron is an effective treatment for OAB

Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

If you only have time to read one article this week, it should be this one.

Phase III, randomised, double-blind, placebo-controlled study of the β3-adrenoceptor agonist mirabegron, 50 mg once daily, in Japanese patients with overactive bladder

Osamu Yamaguchi, Eiji Marui*, Hidehiro Kakizaki, Yukio Homma, Yasuhiko Igawa§, Masayuki Takeda, Osamu Nishizawa**, Momokazu Gotoh††, Masaki Yoshida‡‡, Osamu Yokoyama§§, Narihito Seki¶¶, Yasushi Ikeda*** and Sumito Ohkawa***

Division of Bioengineering and LUTD Research, School of Engineering, Nihon University, Koriyama, *Department of Human Arts Sciences, University and Graduate School of Human Arts Sciences, Saitama, Department of Urology, Asahikawa Medical University, Asahikawa, Department of Urology, The University of Tokyo Graduate School of Medicine, Tokyo, §Department of Continence Medicine, The University of Tokyo Graduate School of Medicine, Tokyo, Department of Urology, University of Yamanashi, Yamanashi, **Department of Urology, Shinshu University, Matsumoto, ††Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, ‡‡Department of Urology, National Center for Geriatrics and Gerontology, Obu, §§Department of Urology, University of Fukui Faculty of Medical Sciences, Fukui, ¶¶Department of Urology, Kyushu Central Hospital of the Mutual Aid Association of Public School Teachers, Fukuoka, and ***Astellas Pharma Inc., Tokyo, Japan

Registered at clinicaltrials.gov (NCT00966004)

OBJECTIVE

• To evaluate the efficacy and safety of the β3-adrenoceptor agonist mirabegron, in a Japanese population with overactive bladder (OAB).

PATIENTS AND METHODS

• This randomised, double-blind, placebo-controlled phase III study enrolled adult patients experiencing OAB symptoms for ≥24 weeks. Patients with ≥ 8 micturitions/24 h and ≥1 urgency episode/24 h or ≥1 urgency incontinence episode/24 h were randomised to once-daily placebo, mirabegron 50 mg or tolterodine 4 mg (as an active comparator, without testing for non-inferiority of efficacy and safety) for 12 weeks.

• The primary endpoint was the change in the mean number of micturitions/24 h from baseline to final assessment. Secondary endpoints included micturition variables related to urgency and/or incontinence and quality-of-life domain scores on the King’s Health Questionnaire.

• Safety assessments included adverse events (AEs), post-void residual urine volume, laboratory variables, vital signs and 12-lead electrocardiogram.

RESULTS

• A total of 1139 patients were randomised to receive placebo (n = 381), mirabegron 50 mg (n = 380) or tolterodine 4 mg (n = 378). Demographic and baseline characteristics were similar among the treatment groups.

• At final assessment, mirabegron was significantly superior to placebo in terms of mean [sd] change from baseline in number of micturitions/24 h (–1.67 [2.212] vs -0.86 [2.354]; P < 0.001) and mean [sd] change from baseline in number of urgency episodes/24 h (–1.85 [2.555] vs –1.37 [3.191]; P = 0.025), incontinence episodes/24 h (–1.12 [1.475] vs –0.66 [1.861]; P = 0.003), urgency incontinence episodes/24 h (–1.01 [1.338] vs –0.60 [1.745]; P = 0.008), and volume voided/micturition (24.300 [35.4767] vs 9.715 [29.0864] mL; P < 0.001).

• The incidence of AEs in the mirabegron group was similar to that in the placebo group. Most AEs were mild and none were severe.

CONCLUSIONS

• Mirabegron 50 mg once daily is an effective treatment for OAB symptoms, with a low occurrence of side effects in a Japanese population.

 

Editorial: Mirabegron the first β3-adrenoceptor agonist for OAB: a summary of the phase III studies

The study reported in this edition of BJUI details the results of a large phase III study conducted in Japan contrasting 50 mg mirabegron, the new β3-adrenoceptor agonist, to placebo with tolterodine as an active comparator [1]. This adds to the body of knowledge already provided by phase III evaluations reported from Europe [2], where tolterodine was also used as an active comparator and North America [3], where the efficacy of 25–100 mg was compared with placebo [4]. As the first in this new class of compounds with a mechanism of action that is distinct from that of the antimuscarinic agents, which are the mainstay of overactive bladder (OAB) therapy to date, there is clearly interest in the efficacy and in particular the safety of this new class of compound. This has been evaluated in a long-term safety study [5].

This paper [1] confirms the findings evident in these other publications, which suggest a favourable short- and long-term tolerability profile for mirabegron in patients with OAB. In particular, excluding typical anticholinergic side-effects, such as dry mouth, which occurred with a similar incidence with mirabegron as placebo, but was reported in 13.3% of tolterodine patients, there was no evidence of any cardiotoxicity with mirabegron, which is consistent with a previous pooled analysis of the European and North American studies [6]. In this pooled analysis, mirabegron was associated with mean increases of 0.4–0.6 mmHg in blood pressure and ≈1 beat/min in heart rate, both reversible upon treatment discontinuation. In the long-term study, the changes in heart rate seen with mirabegron 50 mg were less than those seen with tolterodine. Changes in vital signs did not result in more cardiovascular-related adverse events in patients treated with mirabegron compared with those treated with placebo or tolterodine in both the pooled 12-week and the 1-year long-term studies. In addition, there was one case of urinary retention with mirabegron in the pooled 12-week studies; the incidence being less than placebo or tolterodine. Clearly from the evidence now available, mirabegron has an efficacy similar to that seen with tolterodine and significantly better than placebo for most of the symptoms of the OAB symptom complex. In conclusion, mirabegron is well-tolerated and as efficacious as anticholinergic therapy. Further analyses of the phase III data has shown that mirabegron is effective in both naïve patients and those that have failed to either tolerate or respond to a previous anticholinergic therapy [7].

Future work should include an adequately powered direct comparison to antimuscarinic therapy. Furthermore, data on the combination of mirabegron and an antimuscarinic have already shown potential benefit in a phase II study, and this should be explored further [8]. Other interesting areas to explore will be the use of this therapy in both male patients and patients with neurogenic bladder dysfunction.

Christopher Chapple
Department of Urology, The Royal Hallamshire Hospital, Sheffield Teaching Hospitals, Sheffield, UK

 

References

  1. Yamaguchi O, Marui E, Kakizaki H et al. Phase III, randmised, double-blind, placebo-controlled study of the β3 -adrenoceptor agonist mirabegron, 50 mg once daily, in Japanese patients with overactive bladder. BJU Int 2014; 113: 951–960.
  2. Khullar V, Amarenco G, Angulo JC et al. Efficacy and tolerability of mirabegron, a β(3)-adrenoceptor agonist, in patients with overactive bladder: results from a randomised European-Australian phase 3 trial. Eur Urol 2013; 63: 283–295
  3. Nitti VW, Auerbach S, Martin N, Calhoun A, Lee M, Herschorn S. Results of a randomized phase III trial of mirabegron in patients with overactive bladder. J Urol 2013; 189: 1388–1395
  4. Herschorn S, Barkin J, Castro-Diaz D et al. A phase III, randomized, double-blind, parallel-group, placebo-controlled, multicentre study to assess the efficacy and safety of the β3 adrenoceptor agonist, mirabegron, in patients with symptoms of overactive bladder. Urology 2013; 82: 313–320
  5. Chapple CR, Kaplan SA, Mitcheson D et al. Randomized double-blind, active-controlled phase 3 study to assess 12-month safety and efficacy of mirabegron, a β(3)-adrenoceptor agonist, in overactive bladder. Eur Urol 2013; 63: 296–305
  6. Nitti VW, Khullar V, van Kerrebroeck P et al. Mirabegron for the treatment of overactive bladder: a prespecified pooled efficacy analysis and pooled safety analysis of three randomised, double-blind, placebo-controlled, phase III studies. Int J Clin Pract 2013; 67: 619–632
  7. Khullar V, Cambronero J, Angulo JC et al. Efficacy of mirabegron in patients with and without prior antimuscarinic therapy for overactive bladder: a post hoc analysis of a randomized European-Australian Phase 3 trial. BMC Urol 2013; 13: 45
  8. Abrams P, Kelleher C, Staskin D et al. Combination treatment with mirabegron and solifenacin in patients with overactive bladder: efficacy and safety results from a randomised, double-blind, dose-ranging, phase 2 study (symphony). Eur Urol 2014. doi: 10.1016/j.eururo.2014.02.012

 

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