Exendin-4 PET Scan Detected Insulinomas with 100% Sensitivity, Outperforming All Conventional Imaging
A novel PET scan using a radioactively labeled version of the GLP-1 peptide exendin-4 detected insulinomas in all 12 patients, outperforming CT, MRI, and other conventional imaging methods.
Quick Facts
What This Study Found
18F-exendin-4 PET/CT achieved 100% sensitivity for insulinoma detection in 12 patients, significantly outperforming CT (83%), MRI (63%), endoscopic ultrasonography (90%), and selective arterial calcium stimulation (89%). The peptide-based probe showed significantly higher uptake in tumor tissue than surrounding pancreatic tissue. All 12 lesions were surgically confirmed as insulinomas, and all patients achieved complete resolution of hypoglycemia after resection.
Key Numbers
n=12 · 100% sensitivity (18F-exendin-4 PET/CT) · CT: 83% · MRI: 63% · endoscopic ultrasound: 90% · selective arterial calcium stimulation: 89% · scans at 60 and 120 min post-injection · all lesions surgically confirmed
How They Did This
Prospective single-center phase 2 clinical trial. Twelve patients with biochemically confirmed hyperinsulinemic hypoglycemia underwent 18F-exendin-4 PET/CT with scans at 60 and 120 minutes post-injection. Results were compared to conventional imaging (CT, MRI, endoscopic ultrasound, selective arterial calcium stimulation) and verified by surgical pathology.
Why This Research Matters
Insulinomas can be life-threatening but curable with surgery — if they can be located. Current imaging misses up to 37% of cases (MRI) or requires invasive procedures. This GLP-1 peptide-based imaging probe offers a noninvasive, highly sensitive alternative that could become the gold standard for preoperative insulinoma localization.
The Bigger Picture
This represents a new diagnostic application for GLP-1 receptor-targeting peptides. Exendin-4, originally developed as a diabetes treatment (exenatide/Byetta), is repurposed here as a molecular imaging probe that exploits the overexpression of GLP-1 receptors on insulinoma cells. The success of peptide-based targeted imaging could extend to other GLP-1 receptor-expressing tumors.
What This Study Doesn't Tell Us
Very small sample of only 12 patients from a single center. As an interim report from an ongoing phase 2 trial, the final results may differ. The 100% sensitivity in such a small cohort may not hold in larger populations. Specificity data (false positive rate) was not explicitly reported.
Questions This Raises
- ?Will the 100% sensitivity hold in the full phase 2 trial with a larger patient cohort?
- ?Could 18F-exendin-4 PET/CT also detect other GLP-1 receptor-expressing neuroendocrine tumors beyond insulinomas?
- ?How does the cost and radiation exposure of this peptide PET scan compare to existing diagnostic approaches?
Trust & Context
- Key Stat:
- 100% detection rate 18F-exendin-4 PET/CT found insulinomas in all 12 patients, compared to 63–90% for conventional imaging methods
- Evidence Grade:
- Prospective phase 2 clinical trial with surgical pathology verification. While the design is strong, the very small sample size (n=12) and single-center setting limit the generalizability. This is an interim report from an ongoing trial.
- Study Age:
- Published in 2025, this is a cutting-edge phase 2 trial result using the latest generation of peptide-based PET imaging technology. The findings are highly current and clinically relevant.
- Original Title:
- Qualitative and Quantitative Analyses of Noninvasive Diagnosis of Insulinoma Using [18F]FB(ePEG12)12-Exendin-4 PET/CT.
- Published In:
- The Journal of clinical endocrinology and metabolism, 111(1), 209-217 (2025)
- Authors:
- Murakami, Takaaki(3), Yoshida, Hayao, Sakaki, Kentaro, Otani, Daisuke, Kawai Miyake, Kanae, Shimizu, Yoichi, Fujimoto, Hiroyuki, Yabe, Daisuke, Nakamoto, Yuji, Inagaki, Nobuya
- Database ID:
- RPEP-12675
Evidence Hierarchy
Frequently Asked Questions
What is exendin-4 and how is it used for imaging?
Exendin-4 is a peptide originally found in Gila monster venom that binds strongly to GLP-1 receptors. In this study, it was labeled with a radioactive fluorine atom (18F) and injected into patients. Because insulinoma tumor cells have many GLP-1 receptors, the peptide accumulates in the tumor and lights up on a PET scan.
Why is finding insulinomas so difficult with regular imaging?
Insulinomas are often very small (sometimes under 1 cm) and located deep within the pancreas. Standard CT and MRI detect them based on size and shape, which is unreliable for tiny tumors. The exendin-4 approach works differently — it targets a specific receptor on the tumor cells — making it effective regardless of tumor size.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-12675APA
Murakami, Takaaki; Yoshida, Hayao; Sakaki, Kentaro; Otani, Daisuke; Kawai Miyake, Kanae; Shimizu, Yoichi; Fujimoto, Hiroyuki; Yabe, Daisuke; Nakamoto, Yuji; Inagaki, Nobuya. (2025). Qualitative and Quantitative Analyses of Noninvasive Diagnosis of Insulinoma Using [18F]FB(ePEG12)12-Exendin-4 PET/CT.. The Journal of clinical endocrinology and metabolism, 111(1), 209-217. https://doi.org/10.1210/clinem/dgaf253
MLA
Murakami, Takaaki, et al. "Qualitative and Quantitative Analyses of Noninvasive Diagnosis of Insulinoma Using [18F]FB(ePEG12)12-Exendin-4 PET/CT.." The Journal of clinical endocrinology and metabolism, 2025. https://doi.org/10.1210/clinem/dgaf253
RethinkPeptides
RethinkPeptides Research Database. "Qualitative and Quantitative Analyses of Noninvasive Diagnos..." RPEP-12675. Retrieved from https://rethinkpeptides.com/research/murakami-2025-qualitative-and-quantitative-analyses
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.