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.