A Phase I, Open-label, Multi-center Exploratory Safety and Efficacy Study With PSMA, SSTR2 and GRPR Targeted Radioligand Therapy in Metastatic Neuroendocrine Prostate Cancer.
The purpose of this study is to evaluate the change in the expression of treatment targets on the surface of tumor cells (Prostate Specific Membrane Antigen (PSMA), Somatostatin Receptor 2 (SSTR2), and Gastrin Releasing Peptide Receptor (GRPR) between the start and after the completion of radioligand therapy (RLT). Study will use radioligand imaging (RLI) to determine predominantly expressed target on the surface of tumor cells. Based on predominant expression of target, corresponding RLT targeting PSMA, SSTR2, or GRPR RLT will be given for up to 6 cycles every 6 weeks as intravenous (i.v.) injection in participants with metastatic neuroendocrine prostate cancer (mNEPC).
• 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 scans
• 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