Phase 3 Study of Xaluritamig Plus Abiraterone vs Investigator's Choice in Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer

Prior treatment

• Prior radionuclide therapy (radium-223) within 2 months of first dose of study treatment
• Prior palliative radiotherapy within 2 weeks before first dose of study treatment. Participants must have recovered from all radiation-related toxicities
• Prior CD3-directed therapy
• Concurrent cytotoxic chemotherapy, ARPI, immunotherapy, RLT, poly adenosine diphosphate ribose polymerase (PARP) inhibitor, biological therapy, investigational therapy
• Treatment with live and live-attenuated vaccines within 4 weeks before the first dose of study treatment
• Unresolved toxicities from prior antitumor therapy not having resolved to CTCAE version 5.0 grade 1 or baseline, with the exception of alopecia or toxicities that are stable and well-controlled AND there is an agreement to allow inclusion by both the investigator and the sponsor
• Prior six transmembrane epithelial antigen of the prostate 1 (STEAP1)-targeted therapy
• Prior treatment with any chemotherapy regimen in the mCRPC setting and/or greater than 6 cycles of docetaxel treatment in the mHSPC setting
• Any anticancer therapy, immunotherapy, or investigational agent within 4 weeks before first dose of study treatment with the following exceptions:  Androgen receptor pathway inhibitors (ARPIs; enzalutamide, darolutamide, apalutamide): minimum washout of 2 weeks prior to the first dose of study treatment Androgen suppression therapy (eg, luteinizing hormone-releasing hormone/gonadotropin releasing hormone [LHRH/GnRH] analogue [agonist/antagonist]) is permitted.
• Prior radioligand therapy (RLT) within 8 weeks of first dose of study treatment

Other illness

• Participants with a history of central nervous system (CNS) metastases
• Prior disease progression on or intolerance to abiraterone

• Participant has provided informed consent before initiation of any study-specific activities/procedures
• Adequate organ function
• Age greater than or equal to 18 years (or greater than or equal to legal age within the country if it is older than 18 years) at the time of signing the informed consent
• Participant must have histological, pathological, and/or cytological confirmation of adenocarcinoma of the prostate
• mCRPC with greater than or equal to 1 metastatic lesion that is present on baseline computed tomography (CT), magnetic resonance imaging (MRI), or bone scan imaging obtained within 28 days before enrollment
• Evidence of progressive disease (PD), defined as 1 or more PCWG3-modified RECIST 1.1 criteria
• Participants must have had prior orchiectomy and/or ongoing androgren-deprivation therapy (ADT) and a castrate level of serum testosterone (less than 50 ng/dL or less than 1.7 nmol/L)
• Prior disease progression on 1, and only 1, androgen receptor pathway inhibitor (ARPI) (either enzalutamide, apalutamide, or darolutamide) is required
• Participants intended to receive cabazitaxel must have previously received less than or equal to 6 cycles of docetaxel in the mHSPC setting
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1