Evaluation of Xaluritamig in High-Risk, Biochemically Recurrent, Non-metastatic Castrate-sensitive Prostate Cancer

The main objective of this study is to evaluate the safety and tolerability of xaluritamig monotherapy in adult participants with high-risk biochemical recurrent (BCR) nonmetastatic castration-sensitive prostate cancer (nmCSPC).

Inclusion Criteria * Histologically or cytologically confirmed adenocarcinoma of the prostate at initial biopsy, without neuroendocrine differentiation, signet cell, or small cell features. * Prostate cancer initially treated by radical prostatectomy (RP) or radiotherapy (XRT) (including brachytherapy) or both (eg, salvage radiotherapy), with curative intent. * PSA doubling time ≤ 12 months. * Participants must have biochemically recurrent disease after definitive treatment to prostate by either RP or XRT. * Screening PSA by the local laboratory ≥ 0.2 ng/mL for participants who had RP (with or without XRT) as primary treatment for prostate cancer or at least 2 ng/mL above the nadir (local assessments) for participants who had XRT or brachytherapy only as primary treatment for prostate cancer. * Serum testosterone ≥ 150 ng/dL (5.2 nmol/L). * Participants must have undergone a prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scan during or within 3 months of screening. Exclusion Criteria * Present evidence of metastatic disease in conventional CT scan and/or bone scan * Participants that present PSMA-positive lesions in the PSMA PET scan may be enrolled if the conventional imaging does not show suspicion of metastatic disease. * Prior hormonal therapy, exceptions include: * Neoadjuvant/adjuvant therapy to treat prostate cancer ≤ 36 months in duration and ≥ 9 months before enrollment, or * A single dose or a short course (≤ 6 months) of hormonal therapy given for rising PSA ≥ 9 months before enrollment. * Prior cytotoxic chemotherapy, aminoglutethimide, ketoconazole, abiraterone acetate, enzalutamide, apalutamide, or darolutamide for prostate cancer. * Abiraterone acetate, enzalutamide, apalutamide, or darolutamide are allowed if administered in a neoadjuvant/adjuvant setting ≤ 36 months in duration and ≥ 9 months before enrollment. * Prior systemic biologic therapy, including immunotherapy, for prostate cancer. * If, in the investigator's opinion, salvage therapy is the preferred intervention. * Autoimmune disease requiring systemic immunosuppression within the past 2 years. * Participant with symptoms and/or clinical signs and/or radiographic signs that indicate an acute and/or uncontrolled active systemic infection within 7 days prior to the first dose of study treatment. * Requirement for chronic systemic corticosteroid therapy (prednisone dose \> 10 mg/day or equivalent) or any other immunosuppressive therapies (including anti tumor necrosis factor alpha \[TNFα\] therapies) unless stopped (with adequate tapering) within 7 days prior to dosing.