A Study of ASP8302 in Participants With Underactive Bladder

Inclusion Criteria: At visit 1: * Subject is diagnosed with UAB, defined as a bothersome chronic incomplete bladder emptying: * clinical condition is present for ≥ 6 months before screening, and * subject has a PVR ≥ 75 mL (measured by ultrasound after uroflowmetry; V1-PVRUS1). * Subject on clean intermittent catheterization (CIC) should have been on CIC for at least 1 month and should be able to void spontaneously and not be completely dependent on CIC. * Female subject must either: * Be of non-childbearing potential; post-menopausal (defined as at least 1 year without any menses for which there is no other obvious pathological or physiological cause) prior to screening, or documented surgically sterile (e.g., hysterectomy, bilateral salpingectomy, bilateral oophorectomy). * Or, if of childbearing potential; agrees not to try to become pregnant during the study and for 28 days after the final study drug administration, agrees to have a serum pregnancy test on all visits, have a negative serum pregnancy test at the screening visit, and agrees to consistently use 1 form of highly effective birth control starting at screening and throughout the study period and for 28 days after the final study drug administration. * Female subject must agree not to breastfeed starting at screening and throughout the study period, and for 28 days after the final study drug administration. * Female subject must not donate ova starting at screening and throughout the study period, and…