NEPC Study: An Exploratory Safety and Efficacy Study With PSMA, SSTR2 and GRPR Targeted Radioligand Therapy in Metastatic Neuroendocrine Prostate Cancer.

Prior treatment

• Previous treatment with any of the following within 6 months prior to Screening: Strontium-89, Samarium-153, Rhenium-186, Rhenium-188, Radium-223, hemi-body irradiation
• Previous PSMA, SSTR2, or GRPR targeted radioligand therapy
• Other concurrent cytotoxic chemotherapy, immunotherapy, radioligand therapy or investigational therapy
• History of CNS metastases that are neurologically unstable, symptomatic, or receiving corticosteroids for the purpose of maintaining neurologic integrity

Other

• Symptomatic cord compression, or clinical or radiologic findings indicative of impending cord compression
• History or current diagnosis of ECG abnormalities indicating significant risk of safety for study participants
  • Other protocol-defined inclusion/exclusion criteria may apply.

• Participants must have metastatic prostate cancer with neuroendocrine differentiation as determined by at least one of the following:
  • Histologically small cell or neuroendocrine cancer from a primary prostate or metastatic biopsy confirmed by local laboratory.
  • Expression of NEPC markers (e.g., chromogranin or synaptophysin) in tumor tissue by IHC confirmed by local laboratory
  • Progression of visceral metastases in the absence of PSA progression
  • Serum chromogranin A \> 5x normal limit, or neuron-specific enolase \> 2x normal limit with control for proton-pump inhibitors (PPI) drugs among concomitant treatment
  • Prostate adenocarcinoma with molecular features of neuroendocrine differentiated cancer (e.g., 2 of the following 3: PTEN, TP53, or RB loss)
• PSMA and/or SSTR2 and/or GRPR PET-positive participants, with at least one measurable lesion per RECIST 1.1 with moderate target expression in at least one of the 3 PET/CT scans per BICR assessment
• Castrate level of serum/plasma testosterone (\< 50 ng/dl, or \< 1.7 nmol/L) for participants with adenocarcinoma component or stable testosterone level for participants with pure neuroendocrine carcinoma
• Recovered to ≤ Grade 2 from all clinically significant toxicities related to prior therapy
• Participant has adequate bone marrow and organ function (as assessed by central laboratory for eligibility)
• ECOG status =\< 2