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Updated: Apr 15, 2026
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Automated Preparation of [68Ga]Ga-3BP-3940 on a Synthesis Module for PET Imaging of the Tumor Microenvironment
Published on: April 25, 2025
PET imaging of insulin-like growth factor type 1 receptor expression with a 64Cu-labeled Affibody molecule
Xinhui Su1, Kai Cheng, Yang Liu
1Department of Nuclear Medicine, Zhongshan Hospital Xiamen University, Xiamen, China.
Abstract:
The insulin-like growth factor 1 receptor (IGF-1R) serves as an attractive target for cancer molecular imaging and therapy. Previous single photon emission computerized tomography (SPECT) studies showed that the IGF-1R-targeting Affibody molecules (99m)Tc-ZIGF1R:4551-GGGC, [(99m)Tc(CO)3](+)-(HE)3-ZIGF1R:4551 and (111)In-DOTA-ZIGF1R:4551 can discriminate between high and low IGF-1R-expression tumors and have the potential for patient selection for IGF-1R-targeted therapy. Compared with SPECT, positron emission tomography (PET) may improve imaging of IGF-1R-expression, because of its high sensitivity, high spatial resolution, strong quantification ability. The aim of the present study was to develop the (64)Cu-labeled NOTA-conjugated Affibody molecule ZIGF-1R:4:40 as a PET probe for imaging of IGF-1R-positive tumor. An Affibody analogue (Ac-Cys-ZIGF-1R:4:40) binding to IGF-1R was site-specifically conjugated with NOTA and labeled with (64)Cu. Binding affinity and specificity of (64)Cu-NOTA-ZIGF-1R:4:40 to IGF-1R were evaluated using human glioblastoma U87MG cells. Small-animal PET, biodistribution, and metabolic stability studies were conducted on mice bearing U87MG xenografts after the injection of (64)Cu-NOTA-ZIGF-1R:4:40 with or without co-injection of unlabeled Affibody proteins. The radiosynthesis of (64)Cu-NOTA-ZIGF-1R:4:40 was completed successfully within 60 min with a decay-corrected yield of 75 %. (64)Cu-NOTA-ZIGF-1R:4:40 bound to IGF-1R with low nanomolar affinity (K D = 28.55 ± 3.95 nM) in U87MG cells. (64)Cu-NOTA-ZIGF-1R:4:40 also displayed excellent in vitro and in vivo stability. In vivo biodistribution and PET studies demonstrated targeting of U87MG gliomas xenografts was IGF-1R specific. The tumor uptake was 5.08 ± 1.07 %ID/g, and the tumor to muscle ratio was 11.89 ± 2.16 at 24 h after injection. Small animal PET imaging studies revealed that (64)Cu-NOTA-ZIGF-1R:4:40 could clearly identify U87MG tumors with good contrast at 1-24 h after injection. This study demonstrates that (64)Cu-NOTA-ZIGF-1R:4:40 is a promising PET probe for imaging IGF-1R positive tumor.
Insights
This study developed a novel positron emission tomography (PET) probe, (64)Cu-NOTA-ZIGF-1R:4:40, for imaging the insulin-like growth factor 1 receptor (IGF-1R). The probe successfully visualized IGF-1R-positive tumors in preclinical models, showing potential for cancer diagnostics and therapy selection.
Area of Science:
- Molecular Imaging
- Radiochemistry
- Oncology
Background:
- Insulin-like growth factor 1 receptor (IGF-1R) is a key target for cancer therapy and molecular imaging.
- Previous SPECT imaging agents showed potential but PET offers superior sensitivity and quantification.
- Developing novel PET probes is crucial for advancing IGF-1R-targeted cancer diagnostics.
Purpose of the Study:
- To develop and evaluate a novel (64)Cu-labeled Affibody-based PET probe, (64)Cu-NOTA-ZIGF-1R:4:40, for imaging IGF-1R-positive tumors.
- To assess the binding affinity, specificity, stability, and in vivo performance of the developed PET probe.
Main Methods:
- Site-specific conjugation of an IGF-1R-targeting Affibody analogue (Ac-Cys-ZIGF-1R:4:40) with NOTA.
- Radiolabeling with Copper-64 ((64)Cu) and characterization of the resulting PET probe (64)Cu-NOTA-ZIGF-1R:4:40.
- In vitro binding assays using U87MG glioblastoma cells, and in vivo studies including small-animal PET, biodistribution, and metabolic stability in mice bearing U87MG xenografts.
Main Results:
- Successful radiosynthesis of (64)Cu-NOTA-ZIGF-1R:4:40 with high yield (75%) and rapid labeling (<60 min).
- The probe exhibited low nanomolar binding affinity (KD = 28.55 ± 3.95 nM) and high specificity for IGF-1R in vitro.
- In vivo studies demonstrated excellent stability, specific tumor targeting in U87MG xenografts (5.08 ± 1.07 %ID/g uptake at 24h), and clear tumor visualization with good contrast in PET imaging.
Conclusions:
- (64)Cu-NOTA-ZIGF-1R:4:40 is a highly stable and effective PET probe for imaging IGF-1R-positive tumors.
- The probe demonstrates specific tumor uptake and excellent imaging characteristics in preclinical models.
- This Affibody-based PET tracer holds significant promise for patient selection in IGF-1R-targeted cancer therapies.
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