{"entity": "publication", "iuid": "b2924654d0164ed6a49aaaff90815e57", "timestamp": "2026-09-01T08:24:50.029Z", "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/publication/b2924654d0164ed6a49aaaff90815e57.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/publication/b2924654d0164ed6a49aaaff90815e57"}}, "title": "Preclinical Evaluation of 99mTc-Labeled GRPR Antagonists maSSS/SES-PEG2-RM26 for Imaging of Prostate Cancer.", "authors": [{"family": "Abouzayed", "given": "Ayman", "initials": "A"}, {"family": "Rinne", "given": "Sara S", "initials": "SS"}, {"family": "Sabahnoo", "given": "Hamideh", "initials": "H"}, {"family": "S\u00f6rensen", "given": "Jens", "initials": "J"}, {"family": "Chernov", "given": "Vladimir", "initials": "V"}, {"family": "Tolmachev", "given": "Vladimir", "initials": "V", "orcid": "0000-0002-6122-1734", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/896ae9fae8b74251afe11b4354c62794.json"}}, {"family": "Orlova", "given": "Anna", "initials": "A", "orcid": "0000-0001-6120-2683", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/1c374f429702489494c05f84f298b4b7.json"}}], "type": "journal article", "published": "2021-01-30", "journal": {"title": "Pharmaceutics", "issn": "1999-4923", "volume": "13", "issue": "2", "issn-l": null}, "abstract": "Gastrin-releasing peptide receptor (GRPR) is an important target for imaging of prostate cancer. The wide availability of single-photon emission computed tomography/computed tomography (SPECT/CT) and the generator-produced 99mTc can be utilized to facilitate the use of GRPR-targeting radiotracers for diagnostics of prostate cancers.\n\nSynthetically produced mercaptoacetyl-Ser-Ser-Ser (maSSS)-PEG2-RM26 and mercaptoacetyl-Ser-Glu-Ser (maSES)-PEG2-RM26 (RM26 = d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) were radiolabeled with 99mTc and characterized in vitro using PC-3 cells and in vivo, using NMRI or PC-3 tumor bearing mice. SPECT/CT imaging and dosimetry calculations were performed for [99mTc]Tc-maSSS-PEG2-RM26.\n\nPeptides were radiolabeled with high yields (>98%), demonstrating GRPR specific binding and slow internalization in PC-3 cells. [99mTc]Tc-maSSS-PEG2-RM26 outperformed [99mTc]Tc-maSES-PEG2-RM26 in terms of GRPR affinity, with a lower dissociation constant (61 pM vs 849 pM) and demonstrating higher tumor uptake. [99mTc]Tc-maSSS-PEG2-RM26 had tumor-to-blood, tumor-to-muscle, and tumor-to-bone ratios of 97 \u00b1 56, 188 \u00b1 32, and 177 \u00b1 79, respectively. SPECT/CT images of [99mTc]Tc-maSSS-PEG2-RM26 clearly visualized the GRPR-overexpressing tumors. The dosimetry estimated for [99mTc]Tc-maSSS-PEG2-RM26 showed the highest absorbed dose in the small intestine (1.65 \u00d7 10-3 mGy/MBq), and the effective dose is 3.49 \u00d7 10-3 mSv/MBq.\n\nThe GRPR antagonist maSSS-PEG2-RM26 is a promising GRPR-targeting agent that can be radiolabeled through a single-step with the generator-produced 99mTc and used for imaging of GRPR-expressing prostate cancer.", "doi": "10.3390/pharmaceutics13020182", "pmid": "33573232", "labels": [], "xrefs": [{"db": "pmc", "key": "PMC7912279"}, {"db": "pii", "key": "pharmaceutics13020182"}], "notes": [], "created": "2026-08-21T13:04:47.179Z", "modified": "2026-08-21T13:04:47.201Z"}