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Comparative evaluation of 111In-labeled NOTA‑conjugated affibody molecules for visualization of HER3 expression in
Ken G Andersson1, Maria Rosestedt2, Zohreh Varasteh2
1Division of Protein Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
Abstract:
Expression of human epidermal growth factor receptor type 3 (HER3) in malignant tumors has been associated with resistance to a variety of anticancer therapies. Several anti-HER3 monoclonal antibodies are currently under pre-clinical and clinical development aiming to overcome HER3-mediated resistance. Radionuclide molecular imaging of HER3 expression may improve treatment by allowing the selection of suitable patients for HER3-targeted therapy. Affibody molecules are a class of small (7 kDa) high-affinity targeting proteins with appreciable potential as molecular imaging probes. In a recent study, we selected affibody molecules with affinity to HER3 at a low picomolar range. The aim of the present study was to develop an anti-HER3 affibody molecule suitable for labeling with radiometals. The HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA HER3-specific affibody molecules were labeled with indium-111 (111In) and assessed in vitro and in vivo for imaging properties using single photon emission computed tomography (SPECT). Labeling of HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA with 111In provided stable conjugates. In vitro cell tests demonstrated specific binding of the two conjugates to HER3-expressing BT-474 breast carcinoma cells. In mice bearing BT-474 xenografts, the tumor uptake of the two conjugates was receptor-specific. Direct in vivo comparison of 111In-HEHEHE-Z08698-NOTA and 111In-HEHEHE-Z08699‑NOTA demonstrated that the two conjugates provided equal radioactivity uptake in tumors, although the tumor-to-blood ratio was improved for 111In-HEHEHE-Z08698-NOTA [12 ± 3 vs. 8 ± 1, 4 h post injection (p.i.)] due to more efficient blood clearance. 111In-HEHEHE-Z08698-NOTA is a promising candidate for imaging of HER3-expression in malignant tumors using SPECT. Results of the present study indicate that this conjugate could be used for patient stratification for anti-HER3 therapy.
Insights
Researchers developed radiolabeled affibody molecules for imaging human epidermal growth factor receptor type 3 (HER3) expression in tumors. Indium-111 labeled HEHEHE-Z08698-NOTA showed promising SPECT imaging properties for patient selection in HER3-targeted therapy.
Area of Science:
- Oncology
- Molecular Imaging
- Radiochemistry
Background:
- Human epidermal growth factor receptor type 3 (HER3) expression in tumors is linked to resistance against various cancer therapies.
- Targeting HER3 is a strategy to overcome this resistance, with several monoclonal antibodies in development.
- Molecular imaging of HER3 can aid in selecting patients for HER3-targeted treatments.
Purpose of the Study:
- To develop and evaluate anti-HER3 affibody molecules labeled with radiometals for molecular imaging.
- To assess the suitability of these affibody conjugates for single photon emission computed tomography (SPECT) imaging of HER3 expression.
Main Methods:
- Selected HER3-specific affibody molecules (HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA) were labeled with indium-111 (111In).
- In vitro studies assessed the binding affinity and specificity of the radiolabeled conjugates to HER3-expressing cells (BT-474).
- In vivo studies in mice with BT-474 xenografts evaluated tumor uptake, biodistribution, and imaging characteristics using SPECT.
Main Results:
- Stable 111In-labeled conjugates of HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA were successfully prepared.
- Both conjugates demonstrated specific binding to HER3-expressing cells in vitro.
- In vivo, the conjugates showed receptor-specific tumor uptake in mice.
- 111In-HEHEHE-Z08698-NOTA exhibited improved tumor-to-blood ratios due to faster blood clearance compared to 111In-HEHEHE-Z08699-NOTA.
Conclusions:
- 111In-HEHEHE-Z08698-NOTA is a promising SPECT imaging agent for detecting HER3 expression in malignant tumors.
- This affibody conjugate has the potential to facilitate patient stratification for anti-HER3 therapies.
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