Phase 3 Study of Xaluritamig vs Cabazitaxel or Second Androgen Receptor-Directed Therapy in Participants With Progressive Metastatic Castration-Resistant Prostate Cancer (XALute)

Inclusion Criteria:

* Participant has provided informed consent prior to initiation of any study-specific activities/procedures.
* Age ≥ 18 years (or ≥ 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. Mixed histologies (eg, adenocarcinoma with neuroendocrine component) are not permitted.
* mCRPC with ≥ 1 metastatic lesion that is present on baseline computed tomography (CT), magnetic resonance imaging (MRI), or bone scan imaging obtained within 28 days prior to enrollment.
* Evidence of progressive disease, defined as 1 or more PCWG3 criteria:

  * Serum PSA progression defined as 2 consecutive increases in PSA over a previous reference value measured at least 1 week prior. The minimal start value is 2.0 ng/mL.
  * Soft-tissue progression defined as an increase ≥ 20% in the sum of the diameter (SOD) (short axis for nodal lesions and long axis for non-nodal lesions) of all target lesions based on the smallest SOD since treatment started or the appearance of one or more new lesions or unequivocal progression of existing non-target lesions.
  * Progression of bone disease: defined by the appearance of at least 2 new bone lesion(s) by bone scan (as per the 2+2 PCWG3 criteria).
* Participants must have had a prior orchiectomy and/or ongoing androgen-deprivation therapy and a castrate level of serum testosterone (\< 50 ng/dL or \< 1.7 nmol/L).
* Prior progression on at least one ARDT (enzalutamide, abiraterone, apalutamide, darolutamide).
* Prior treatment with only one taxane therapy in the mCRPC setting. Note: Prior treatment with docetaxel in the metastatic hormone-sensitive prostate cancer (mHSPC) setting is permitted; however, participants must have also received one, and only one, taxane therapy in the mCRPC setting.
* Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1.
* Adequate organ function.
* Life expectancy of ≥ 12 weeks per the treating physician's assessment.

Key Exclusion Criteria:

Prior \& Concomitant Therapy:

* Prior six transmembrane epithelial antigen of the prostate 1 (STEAP1)-targeted therapy.
* Any anticancer therapy, immunotherapy, or investigational agent within 4 weeks prior to the first dose of study treatment, not including androgen receptor pathway inhibitors (ARPIs) (abiraterone, enzalutamide, darolutamide, apalutamide): minimum washout of 2 weeks prior to the first dose of study treatment and androgen suppression therapy (eg, luteinizing hormone-releasing hormone/gonadotropin-releasing hormone \[LHRH/GnRH\] analogue \[agonist/antagonist\]).
* Prior Prostate-Specific Membrane Antigen (PSMA) radioligand therapy (RLT) within 3 months of the first dose of study treatment unless participants received \< 2 cycles of therapy.
* Prior palliative radiotherapy within 2 weeks of first dose of study treatment. Participants must have recovered from all radiation-related toxicities.
* Concurrent cytotoxic chemotherapy, ARDT, immunotherapy, radioligand therapy, PARP inhibitor, biological therapy, investigational therapy. Note: Prior treatment with a PARP inhibitor is permitted as long as not within 4 weeks before first dose of study treatment.
* Prior radionuclide therapy (Radium-223) within 2 months of first dose of study treatment.
* Treatment with live and live-attenuated vaccines within 4 weeks before the first dose of study treatment.

Disease Related:

* Participants with a history of central nervous system (CNS) metastasis. Note: Participants with treated, asymptomatic, and clinically stable dural metastases are eligible.
* Unresolved toxicities from prior anti-tumor therapy not having resolved to CTCAE version 5.0 events grade above 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.