A Trial Comparing Combination Treatment (Solifenacin Plus Mirabegron) With One Treatment Alone (Solifenacin)

Inclusion Criteria

• Main Inclusion at Screening:
• Subject has symptoms of OAB (urinary frequency and urgency with urgency incontinence) for >= 3 months prior to the screening visit
• Subject is willing and able to complete the micturition diary and questionnaires correctly, including collection and measurement of urine output for 3 days prior to each visit;
• Subject has symptoms of "wet" OAB (urinary frequency and urgency with incontinence or mixed incontinence with predominant urgency incontinence), and reports an average of at least 2 incontinence episodes per day.
• Main Inclusion at Run-in (Visit 2):
• Subject experiences on average at least 1 episode of urgency (grade 3 or 4) with or without incontinence per 24-hour period during the 3-day micturition diary period.
• Subject experiences on average at least 2 incontinence episodes per 24-hour period during the 3-day micturition diary period.
• Subject experiences on average at least 8 micturitions (excluding incontinence episodes) per 24-hour period during the 3-day micturition diary period.
• Main Inclusion at Randomization (Visit 3):
• Subject experiences at least 1 incontinence episode during the 3-day micturition diary period and wishes to increase their treatment for OAB symptoms.

Exclusion Criteria

• Main Exclusion at Screening:
• Subject in the opinion of the investigator has clinically significant Bladder Outlet Obstruction (BOO).
• Subject has significant Post-void residual (PVR) volume (PVR > 150 ml).
• Subject has significant stress incontinence or mixed stress/urgency incontinence where stress is the predominant factor as determined by the investigator
• Subject has an indwelling catheter or practices intermittent self catheterization.
• Subject has evidence of a UTI.
• Subject has chronic inflammation such as interstitial cystitis, bladder stones, previous pelvic radiation therapy, or previous or current malignant disease of the pelvic organs
• Subject has moderate to severe hepatic impairment
• Subject has severe renal impairment or End Stage Renal disease
• Subject has a clinically significant abnormal Electrocardiogram (ECG)
• Subject has a concurrent malignancy or history of cancer (except noninvasive skin cancer) within the last 5 years prior to screening.
• Subject has a QTcF interval > 450 ms for males or > 470 ms for females or is at risk of QT prolongation (e.g., family history of long QT syndrome, hypokalaemia).
• Subject has received intravesical treatment in the past 12 months with e.g., botulinum toxin, resiniferatoxin, capsaicin.
• Subject has severe uncontrolled hypertension, which is defined as a sitting average systolic blood pressure ≥ 180 mmHg and/or average diastolic blood pressure ≥ 110 mmHg.
• Main Exclusion at Randomization (visit 3):
• Subject has achieved 100% continence from Visit 2 to Visit 3 (no incontinence episodes are recorded in the 3 day diary administered for 3 days prior to Visit 3).
• Subject does not desire an increase in study medication.
• Subject has an average total daily urine volume > 3000ml as recorded in the micturition diary.
• Subject has severe uncontrolled hypertension, which is defined as a sitting average systolic blood pressure ≥ 180 mmHg and/or average diastolic blood pressure ≥ 110 mmHg.
• Subject has a clinically significant abnormal ECG