A Study to Evaluate the Efficacy, Safety, and Tolerability of Mirabegron in Men With OAB Symptoms While Taking Tamsulosin Hydrochloride for Lower Urinary Tract Symptoms (LUTS) Due to Benign Prostatic Hyperplasia (BPH)

Inclusion Criteria assessed at Visit 1 (Screening):

• Men ≥40 years of age with history of overactive bladder (OAB) symptoms (frequency of ≥8 micturitions per day and urgency episodes of ≥2 per day) while taking tamsulosin hydrochloride for at least 2 months to treat LUTS due to BPH.
• Subject has symptoms of OAB (urinary frequency and urgency with or without incontinence) for ≥3 months prior to Screening.
• Subject has an International Prostate Symptom Score (IPSS) score ≥8.
• Subject has Prostate-Specific Antigen (PSA) 200 mL.
• Subject has maximum urinary flow (Qmax) 3 rbc/hpf that has not been fully evaluated.
• Subject has evidence of Urinary Tract Infection (UTI). Urine culture and sensitivity will be performed for positive leukocytes, nitrites, or turbidity and will be confirmed with a culture greater than 100,000 cfu/mL. If a subject has a UTI, at Screening (Visit 1) the subject may be rescreened after successful treatment of the UTI (confirmed by a laboratory result of negative urine culture).
• Subject has neurogenic bladder (spinal cord injury, multiple sclerosis, Parkinson's, etc.).
• Subject has diabetic neuropathy.
• Previous open, robotic or minimally invasive prostate surgery (including transurethral procedures). Planned (scheduled) pelvic or prostate surgery during the study period.
• Planned (scheduled) cataract surgery.
• Subject with significant stress incontinence
• Subject with clinically significant bladder outlet obstruction.
• Subject has an indwelling catheter or practices intermittent self-catheterization.
• Subject has experienced 3 or more episodes of recurrent urinary tract infection within the last 12 months.
• Subject has a symptomatic urinary tract infection, prostatitis, chronic inflammation such as interstitial cystitis, bladder stones, previous pelvic radiation therapy, or previous or current malignant disease of the pelvic organs (i.e., within the confines of the pelvis including the bladder, prostate and rectum; organs of the lower gastrointestinal tract are not necessarily considered pelvic organs such as the distal ascending colon, the full transverse colon and proximal portion of the descending colon are in the abdomen).
• Subject has received intravesical injection in the past 12 months with botulinum toxin, resiniferatoxin, or capsaicin.
• Subject has ever received electro-stimulation therapy for OAB (e.g. sacral nerve stimulation or Percutaneous Tibial Nerve Stimulation [PTNS]).
• Subject began or has changed a bladder training program or pelvic floor exercises less than 30 days prior to Screening.
• Subject has postural hypotension or syncope or postural orthostatic tachycardia.
• Subject has moderate or severe hepatic impairment defined as Child-Pugh Class B or C.
• Subject has severe renal impairment defined as estimated creatinine clearance less than 29 mL/min/1.73 m2 as determined by hospital laboratory calculation of eGFR. A subject with End Stage Renal Disease (ESRD) or undergoing dialysis is also not a candidate for the study.
• Subject has severe uncontrolled hypertension, which is defined as a sitting systolic blood pressure ≥180 mmHg and/or diastolic blood pressure ≥110 mmHg.
• Subject has baseline resting pulse rate 90 BPM.
• Subject has evidence of QT prolongation on Screening (Visit 1) or Baseline (Visit 2) electrocardiogram (ECG) defined as QTcF >450 msec.
• Subject has any clinically significant ECG abnormality.
• Subject has AST or ALT >2x upper limit of normal (ULN), or γ-GT >3x ULN and considered clinically significant.
• Subject has a hypersensitivity to any components of mirabegron, tamsulosin hydrochloride, or any of the inactive ingredients.
• Subject has a history of angioedema.
• Subject has any clinical significant condition which makes the subject unsuitable for study participation.
• Subject has been treated with an experimental device within 28 days or received an investigational agent within 28 days or 5 half-lives, whichever is longer, prior to Screeni