{"entity": "publication", "iuid": "2ae734722085462e9e986d95b1264937", "timestamp": "2026-09-30T23:44:09.167Z", "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/publication/2ae734722085462e9e986d95b1264937.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/publication/2ae734722085462e9e986d95b1264937"}}, "title": "Evaluation of maSSS/maSES-PEG2-RM26 for their potential therapeutic use after labeling with Re-188. Could their [99mTc]Tc-labeled counterparts be used to estimate dosimetry?", "authors": [{"family": "Kanellopoulos", "given": "Panagiotis", "initials": "P", "orcid": "0000-0002-0617-3936", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/85ce3df2ffae4754946f11bb2e98ef97.json"}}, {"family": "Yu", "given": "Quanyi", "initials": "Q"}, {"family": "Abouzayed", "given": "Abouzayed", "initials": "A"}, {"family": "Bezverkhniaia", "given": "Ekaterina", "initials": "E"}, {"family": "Tolmachev", "given": "Vladimir", "initials": "V"}, {"family": "Orlova", "given": "Anna", "initials": "A"}], "type": "journal article", "published": "2025-01-17", "journal": {"title": "EJNMMI Radiopharm Chem", "issn": "2365-421X", "volume": "10", "issue": "1", "pages": "3", "issn-l": null}, "abstract": "Gastrin releasing peptide receptor (GRPR)-directed radiopharmaceuticals for targeted radionuclide therapy may be a very promising addition in prostate and breast cancer patient management. Aiming to provide a GRPR-targeting theranostic pair, we have utilized the Tc-99m/Re-188 radiometal pair, in combination with two bombesin based antagonists, maSSS-PEG2-RM26 and maSES-PEG2-RM26. The two main aims of the current study were (i) to elucidate the influence of the radiometal-exchange on the biodistribution profile of the two peptides and (ii) to evaluate the feasibility of using the [99mTc]Tc labeled counterparts for the dosimetry estimation for the [188Re]Re-labeled conjugates.\n\nBoth peptides were successfully labeled with Re-188 and evaluated both in vitro and in vivo. In GRPR expressing PC-3 cells, both [188Re]Re-labeled peptides displayed high cellular uptake (8.5 \u00b1 0.1% and 5 \u00b1 0.3% of added activity, respectively), heavily GRPR-driven, while retaining the radioantagonistic profile with slow internalization rates. Both agents demonstrated high receptor affinity when loaded with natRe (7.5 nM and 8 nM, respectively). When tested in vivo in GRPR expressing PC-3 xenografts, both radioantagonists demonstrated high tumor accumulation (6.3 \u00b1 0.5%IA/g and 5 \u00b1 1%IA/g at 1 h pi, respectively), with good retention over time (4 \u00b1 2%IA/g and 3.1 \u00b1 0.1%IA/g at 4 h pi, respectively). In addition, their biodistribution profiles were closely mimicking their [99mTc]Tc-labeled counterparts. Statistically significant lower tumor uptake was found for both conjugates labeled with Tc-99m, which may result in underestimation of the dose delivered to the tumor.\n\nAll the results indicate that Tc-99 m could be used for dosimetry evaluation for the two [188Re]Re-labeled radioligands, with minimal alterations in their biodistribution pattern and tumor targeting capabilities.", "doi": "10.1186/s41181-024-00326-3", "pmid": "39825204", "labels": [], "xrefs": [{"db": "pmc", "key": "PMC11748620"}, {"db": "pii", "key": "10.1186/s41181-024-00326-3"}], "notes": [], "created": "2026-09-23T13:18:21.144Z", "modified": "2026-09-23T13:18:21.161Z"}