Phase 1 Trial for a New PSMA Radioligand 177Lu‑PSMA‑VG01

177Lu‑PSMA‑VG01 is a next‑generation, small‑molecule PSMA‑targeting radiopharmaceutical designed to refine what 177Lu‑PSMA‑617 (Pluvicto) has already achieved. It uses a high‑affinity ligand to deliver the beta‑emitter lutetium‑177 directly to PSMA‑expressing tumor cells, aiming for greater tumor dosing with less exposure of healthy tissue.

A new phase 1 trial is testing its dosimetry and side effects on patients with metastatic castration-resistant prostate cancer.

Mechanistically, 177Lu‑PSMA‑VG01 binds to PSMA, which is markedly overexpressed on prostate cancer cells, particularly in metastatic and castration‑resistant disease. Once ligand and receptor interact, the complex is internalized, trapping lutetium‑177 inside the cell and its immediate microenvironment. The beta particles emitted by the isotope induce DNA damage and ultimately cell death, while relatively low PSMA expression in most normal organs (apart from kidneys and salivary glands) provides a biological basis for selectivity.

Preclinical characterization suggests that 177Lu‑PSMA‑VG01 improves on some key performance parameters of earlier agents. In vitro, it has shown substantially higher binding affinity for PSMA and more efficient internalization into PSMA‑positive cells, roughly in the two‑ to three‑fold range compared with 177Lu‑PSMA‑617. In mouse xenograft models such as LNCaP and 22Rv1, the compound produces dose‑dependent tumor growth suppression with high and sustained tumor uptake and minimal detectable activity in bone marrow. Importantly, biodistribution data indicate both higher absolute tumor uptake and a more favorable tumor‑to‑kidney ratio than the reference compound, which is critical because kidneys are a major dose‑limiting organ in PSMA‑targeted radioligand therapy.

Clinically, development is at an early stage. A first‑in‑human phase I trial in PSMA‑positive mCRPC is underway, using an open‑label, dose‑escalation design typical for radiopharmaceuticals. The study focuses on biodistribution and dosimetry via serial imaging, organ‑specific radiation exposure, pharmacokinetics, safety, and preliminary antitumor activity. Patient eligibility criteria mirror those used for other PSMA‑targeted lutetium agents, ensuring that participants have PSMA‑expressing disease and are appropriate candidates for this mechanism of action.

Clinical trial.