Pegylated Liposomal Doxorubicin Plus Adebrelimab With or Without Mirabegron in Relapsed Ovarian Cancer

Inclusion Criteria: * Has provided documented informed consent for the study. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Has histologically confirmed epithelial ovarian, fallopian tube, or primary peritoneal carcinoma. * Has received a front line platinum-based regimen (administered via either intravenous or intraperitoneal route) per local standard of care or treatment guideline following the primary or interval debulking surgery with documented disease recurrence (note: Maintenance treatment following the front line treatment is permitted and counted together as part of the front line treatment). * Has a platinum-free interval (PFI) of \< 12 months if the last regimen received is a platinum-based, or a treatment-free interval (TFI) of \< 12 months if the last regimen received is a non-platinum-based. * Has measurable disease at baseline based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. * Has a life expectancy of ≥12 weeks. * Has provided a tumor tissue sample either collected from prior cytoreductive surgery or fresh newly obtained tumor tissue at screening. * Has adequate organ function. * Has not recovered from AEs to ≤ Grade 1 or prior treatment level due to a previously administered agent. Exclusion Criteria: * Has nonepithelial cancers, borderline tumors, mucinous, seromucinous that is predominantly mucinous, malignant Brenner's tumor and undifferentiated carcinoma. * Has received prior therapy with an anti-programmed cell death (PD)-1, anti-PD-L1, anti-PD-L2 agent or with an agent directed to another co-inhibitory T-cell receptor (e.g. cytotoxic T-lymphocyte-associated antigen-4 \[CTLA-4\], tumor necrosis factor receptors OX-40 or CD137) or has participated in prior adebrelimab studies. * Has received prior systemic anticancer therapy including radiation therapy or maintenance therapy within 4 weeks before randomization. * Has severe hypersensitivity (≥Grade 3) or uncontrolled hypertension to pegylated liposomal doxorubicin, adebrelimab, mirabegron and any of their excipients. * Has undergone major surgery within 3 weeks before randomization or has complications/sequelae that have not yet recovered. * Has a known additional malignancy that progressed or required active treatment within the last 5 years. * Is pregnant or breastfeeding. * Has a history of allogenic tissue/solid organ transplant. * Has a history of thrombotic disorders, hemorrhage, hemoptysis, or active gastrointestinal bleeding within 6 months before randomization. * Has a history of active autoimmune disease. * Has an active infection requiring systemic therapy. * Has a history of human immunodeficiency virus (HIV) infection. * Has a history of Hepatitis B or C virus infection. * Has a history or current evidence of any condition, therapy, laboratory abnormality, or other circumstance that might confound the results of the study. * Has a known psychiatric or substance abuse disorder that would interfere with the participant's ability to cooperate with the requirements of the study.