Most Prostate Specific Membrane Antigens (PSMAs) targeting small molecules accumulate in the salivary glands (SGs), raising concerns about SG toxicity, especially after repeated therapies or therapy with 225Ac-labeled ligands. SG toxicity is assessed clinically by the severity of patient-reported xerostomia, but this parameter can be challenging to objectively quantify. Therefore, we explored the feasibility of using SG volume as a biomarker for toxicity. In 21 patients with late-stage metastatic resistant prostate cancer (mCRPC), the PSMA volume and ligand uptake of SG were analyzed retrospectively before and after two cycles of 177Lu-PSMA (LuPSMA; cohort A) and before and after one cycle of 225Ac-PSMA-617 (AcPSMA, cohort B). Mean Volume-SG in cohort A was 59 ± 13 vs. 54 ± 16 mL (-10%, p = 0.4), and in cohort B, it was 50 ± 13 vs. 40 ± 11 mL (-20%, p = 0.007), respectively. A statistically significant decrease in the activity concentration in the SG was only observed in group B (SUVmean: 9.2 ± 2.8 vs. 5.3 ± 1.8, p < 0.0001; vs. A: SUVmean: 11.2 ± 3.3 vs. 11.1 ± 3.5, p = 0.8). SG volume and PSMA-ligand uptake are promising markers to monitor the SG toxicity after a PSMA RLT.
International journal of molecular sciences. 2023 Nov 28*** epublish ***
Benedikt Feuerecker, Andrei Gafita, Thomas Langbein, Robert Tauber, Christof Seidl, Frank Bruchertseifer, Jürgen E Gschwendt, Wolfgang A Weber, Calogero D'Alessandria, Alfred Morgenstern, Matthias Eiber
Department of Nuclear Medicine, School of Medicine, Technical University of Munich, 81675 München, Germany., Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA., Department of Urology, School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, 81675 München, Germany., European Commission, Joint Research Centre (JRC), 76344 Karlsruhe, Germany.