{"entity": "publication", "iuid": "862bcee89b994b9d9306b826716f7171", "timestamp": "2026-09-30T01:54:43.314Z", "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/publication/862bcee89b994b9d9306b826716f7171.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/publication/862bcee89b994b9d9306b826716f7171"}}, "title": "Phase I Clinical Study with the GRPR-Antagonist [99mTc]Tc-DB8 for SPECT Imaging of Prostate Cancer: Does the Injected Peptide Mass Make a Difference?", "authors": [{"family": "Orlova", "given": "Anna", "initials": "A", "orcid": "0000-0001-6120-2683", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/1c374f429702489494c05f84f298b4b7.json"}}, {"family": "Rybina", "given": "Anastasia", "initials": "A"}, {"family": "Medvedeva", "given": "Anna", "initials": "A"}, {"family": "Zelchan", "given": "Roman", "initials": "R"}, {"family": "Bragina", "given": "Olga", "initials": "O"}, {"family": "Tashireva", "given": "Liubov", "initials": "L", "orcid": "0000-0003-2061-8417", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/e462c38bfd8846588156097b5602341a.json"}}, {"family": "Larkina", "given": "Maria", "initials": "M", "orcid": "0000-0003-1176-2441", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/557c8a9c8b2142a7a88d6211335d24e4.json"}}, {"family": "Varvashenya", "given": "Ruslan", "initials": "R", "orcid": "0009-0002-4282-3198", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/6ac73921d11b4877802947d43c317215.json"}}, {"family": "Lushnikova", "given": "Nadejda", "initials": "N"}, {"family": "Kanellopoulos", "given": "Panagiotis", "initials": "P", "orcid": "0000-0002-0617-3936", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/85ce3df2ffae4754946f11bb2e98ef97.json"}}, {"family": "Maina", "given": "Theodosia", "initials": "T", "orcid": "0000-0002-1123-2486", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/b43f747494e64e9cacf77979cdbaf0a6.json"}}, {"family": "Nock", "given": "Berthold A", "initials": "BA", "orcid": "0000-0002-6028-9112", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/58c006b61c854f2f8e61b2ddb0d21096.json"}}, {"family": "Tolmachev", "given": "Vladimir", "initials": "V", "orcid": "0000-0002-6122-1734", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/896ae9fae8b74251afe11b4354c62794.json"}}, {"family": "Chernov", "given": "Vladimir", "initials": "V"}], "type": "journal article", "published": "2025-10-12", "journal": {"title": "Pharmaceutics", "issn": "1999-4923", "volume": "17", "issue": "10", "issn-l": null}, "abstract": "Background/Objectives: The gastrin-releasing peptide receptor (GRPR) shows high-density expression in prostate cancer (PCa), especially in the early stages of the disease. The introduction of a safe radiotracer for assessing GRPR-expression in PCa may serve as an alternative or complementary tracer to PSMA-directed probes for patients with insufficient PSMA expression. In the present study, the tolerability and safety, biodistribution, and dosimetry of the new GRPR-targeting radiopeptide [99mTc]Tc-DB8 were investigated for the first time in male PCa patients. A mass escalation study was performed, aiming to improve tumor-to-background contrast and, thereby, to enhance diagnostic accuracy. Methods: Sixteen male patients were enrolled in a single-center diagnostic open-label exploratory Phase I clinical trial. Patients were administered a single intravenous injection of 40, 80, or 120 \u00b5g of [99mTc]Tc-DB8 peptide (n = 5-6) and underwent whole-body planar imaging (anterior and posterior) 2, 4, 6, and 24 h post-injection (pi) and SPECT-CT acquisition 2, 4, and 6 h pi. Results: Administration of [99mTc]Tc-DB8 was well tolerated at all tested peptide masses. The effective dose did not differ significantly between the injected peptide mass and was 0.005 \u00b1 0.003 mSv/MBq. High activity uptake was observed in the pancreas and kidneys, which 3-fold decreased with an increasing injected peptide mass from 40 to 120 \u00b5g. The activity uptake in primary tumors did not differ significantly between cohorts injected with different peptide masses [SUVmax 1.65-9.96]. The tumor-to-muscle ratios increased with time and were the highest for the cohort injected with 120 \u00b5g of peptide, 7.2 \u00b1 3.1 (4.64-11-25) at 4 h pi. Conclusions: Single intravenous administration of [99mTc]Tc-DB8, for visualization of GRPR expression in PCa using SPECT imaging was well tolerated in a peptide mass range of 40-120 \u00b5g. An injected peptide mass of 80-120 \u00b5g/patient and SPECT acquisition 2-4 h pi were found to be optimal for further clinical studies due to the significantly lower activity accumulation in the pancreas and kidneys.", "doi": "10.3390/pharmaceutics17101323", "pmid": "41155959", "labels": [], "xrefs": [{"db": "pmc", "key": "PMC12567192"}, {"db": "pii", "key": "pharmaceutics17101323"}], "notes": [], "created": "2026-09-23T13:24:51.969Z", "modified": "2026-09-23T13:24:52.121Z"}