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Updated: Jun 11, 2025
Investigations on the GaIII Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue
Published on: August 17, 2016
[68Ga]Ga-DOTAGA-Glu(FAPi)2 Shows Enhanced Tumor Uptake and Theranostic Potential in Preclinical PET Imaging
Julie van Krimpen Mortensen1,2, Simona Mattiussi3, Lars Hvass1,2
1Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital-Rigshospitalet, 2100 Copenhagen, Denmark.
Abstract:
The use of fibroblast activation protein inhibitors (FAPis) for positron emission tomography (PET) imaging in cancer has garnered significant interest in recent years, yielding promising results in preclinical and clinical settings. FAP is predominantly expressed in pathological conditions such as fibrosis and cancer, making it a compelling target. An optimized approach involves using FAPi homodimers as PET tracers, which enhance tumor uptake and retention, making them more effective candidates for therapy. Here, a UAMC-1110 inhibitor-based homodimer, DOTAGA-Glu(FAPi)2, was synthesized and radiolabeled with gallium-68, and its efficacy was evaluated in vivo for PET imaging in an endogenously FAP-expressing xenografted mouse model, U87MG. Notably, 45 min post-injection, the mean uptake of [68Ga]Ga-DOTAGA-Glu(FAPi)2 was 4.7 ± 0.5% ID/g in the tumor with low off-target accumulation. The ex vivo analysis of the FAP expression in the tumors confirmed the in vivo results. These findings highlight and confirm the tracer's potential for diagnostic imaging of cancer and as a theranostic companion.
Insights
New fibroblast activation protein inhibitors (FAPis) homodimers show promise for cancer imaging. The novel [68Ga]Ga-DOTAGA-Glu(FAPi)2 tracer demonstrated effective tumor uptake and retention in preclinical models.
Area of Science:
- Oncology
- Radiochemistry
- Molecular Imaging
Background:
- Fibroblast activation protein (FAP) is a key target in cancer and fibrosis.
- Fibroblast activation protein inhibitors (FAPis) are emerging as valuable tools for diagnostic imaging.
- Optimized FAPi homodimers offer enhanced tumor uptake and retention as PET tracers.
Purpose of the Study:
- To synthesize and evaluate a novel FAPi homodimer, DOTAGA-Glu(FAPi)2, as a positron emission tomography (PET) tracer.
- To assess the in vivo efficacy of [68Ga]Ga-DOTAGA-Glu(FAPi)2 for PET imaging in a FAP-expressing xenograft mouse model.
- To confirm the tracer's diagnostic potential for cancer imaging.
Main Methods:
- Synthesis and radiolabeling of DOTAGA-Glu(FAPi)2 with Gallium-68.
- In vivo PET imaging studies in U87MG xenografted mice.
- Ex vivo analysis of FAP expression in tumor tissues.
Main Results:
- The novel homodimer [68Ga]Ga-DOTAGA-Glu(FAPi)2 was successfully synthesized and radiolabeled.
- High tumor uptake (4.7 ± 0.5% ID/g at 45 min post-injection) was observed in FAP-expressing tumors.
- Low off-target accumulation and confirmed FAP expression supported the in vivo findings.
Conclusions:
- DOTAGA-Glu(FAPi)2 is a promising PET tracer for imaging FAP-expressing cancers.
- The tracer demonstrates excellent tumor targeting and retention properties.
- This FAPi homodimer holds potential as a diagnostic imaging agent and theranostic companion.
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