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.

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.