A Study of Radiation Dosimetry, Safety, and Tolerability of Extended Lutetium (177Lu) Vipivotide Tetraxetan Treatment in Chemo-naïve Adults With Metastatic Castration-resistant Prostate Cancer: RADIOpharmaceutical DOSimetry Evaluation (RADIODOSE) Study

Key Inclusion Criteria: * Signed informed consent must be obtained prior to participation in the study. * Participants must be adults ≥ 18 years of age. * Participants must have an ECOG performance status ≤ 1. * Participants must have histological confirmation of adenocarcinoma of the prostate. * Participants must be PSMA-positive per 68Ga-PSMA PET/CT scans at baseline * Participants must have a castrate level of serum/plasma testosterone (\< 50 ng/dL or \< 1.7 nmol/L) either by pharmaceutical or surgical methods. * Participants must have progressed only once on prior second generation ARPIs * Documented progressive mCRPC * Participants must have ≥ 1 metastatic lesion by conventional imaging that is present on screening/baseline CT, MRI, or bone scan * Renal: eGFR ≥ 60 mL/min/1.73m2 using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. * Participants must have recovered to ≤ Grade 2 from all clinically significant toxicities related to prior therapies except alopecia. Key exclusion Criteria: * Previous treatment with any of the following within 6 months of study enrollment: Strontium 89, Samarium-153, Rhenium-186, Rhenium-188, Radium-223, hemi-body irradiation * Any previous radioligand therapy. * Prior treatment with cytotoxic chemotherapy for metastatic castration-resistant or metastatic hormone-sensitive prostate cancer (mHSPC) (e.g., taxanes, platinum, estramustine, vincristine, methotrexate, etc.), immunotherapy or biological therapy \[including monoclonal antibodies\]. \[Note: Taxane exposure (maximum 6 cycles) in the adjuvant or neoadjuvant setting is allowed if 12 months have elapsed since completion of this adjuvant or neoadjuvant therapy. Prior treatment with sipuleucel-T is allowed\]. * Concurrent therapies: cytotoxic chemotherapy, immunotherapy, radioligand therapy, PARP inhibitor, biological, or investigational therapy * History of myocardial infarction (MI), angina pectoris, or coronary artery bypass graft (CABG) within 6 months prior to ICF signature and/or clinically active significant cardiac disease * Concurrent serious acute or chronic nephropathy and/or moderate to severe renal impairment as determined by the principal investigator. * Diagnosed with other active malignancies that are expected to alter life expectancy or may interfere with disease assessment * Sexually active males unwilling to use a condom during intercourse while taking study treatment and for 14 weeks after stopping study treatment. * Concurrent urinary outflow obstruction or unmanageable urinary incontinence * History of somatic or psychiatric disease/condition that may interfere with the aims and assessments of the study. Other protocol-defined inclusion/exclusion criteria may apply.