PSMA and SSTR2 Dual-Targeting Theranostic Agents for Neuroendocrine-Differentiated Prostate Cancer (NEPC)

Radioactive
prostate-specific membrane antigen (PSMA)-targeting
agents are clinically useful for the diagnosis and treatment of patients
with PSMA-positive metastatic castration-resistant prostate cancer
(mCRPC). Neuroendocrine-differentiated prostate cancer (NEPC), a highly
aggressive subtype that is strongly associated with a poor clinical
prognosis, may present with reduced PSMA expression and evade detection
with PSMA-targeted agents. Several studies have shown elevated uptake
of somatostatin receptor 2 (SSTR2) ligands in PSMA-negative NEPC.
By combining a SSTR2-targeting peptide, JR11, with previously reported
PSMA-targeting ligands, P16-093 and P17-087, [68Ga]Ga-1 and [68Ga]Ga/[177Lu]Lu-2 were designed and synthesized. The cell uptake of [68Ga]Ga-1 was comparable to [68Ga]Ga-P16-093
in PSMA-positive cell lines, while [68Ga]Ga-1 and [68Ga]Ga-2 showed a positive but slightly
lower uptake than [68Ga]Ga-DOTA-TATE in SSTR2-positive
cell lines. In vivo studies in SSTR2+ or PSMA+ tumor-bearing mice
demonstrated that [68Ga]Ga-1 and [68Ga]Ga/[177Lu]Lu-2 showed positive uptake
for both SSTR2+ and PSMA+ tumors. These dual-targeting radiotracers
are potentially valuable for the diagnosis and radioligand therapy
of NEPC.