PET imaging of epidermal growth factor receptor expression in tumours using 89Zr-labelled ZEGFR:2377 affibody molecules

Abstract

Epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor, which is overexpressed in many types of cancer. The use of EGFR-targeting monoclonal antibodies and tyrosine-kinase inhibitors improves significantly survival of patients with colorectal, non-small cell lung cancer and head and neck squamous cell carcinoma. Detection of EGFR overexpression provides important prognostic and predictive information influencing management of the patients. The use of radionuclide molecular imaging would enable non-invasive repeatable determination of EGFR expression in disseminated cancer. Moreover, positron emission tomography (PET) would provide superior sensitivity and quantitation accuracy in EGFR expression imaging. Affibody molecules are a new type of imaging probes, providing high contrast in molecular imaging. In the present study, an EGFR-binding affibody molecule (ZEGFR:2377) was site-specifically conjugated with a deferoxamine (DFO) chelator and labelled under mild conditions (room temperature and neutral pH) with a positron-emitting radionuclide 89Zr. The 89Zr-DFO-ZEGFR:2377 tracer demonstrated specific high affinity (160±60 pM) binding to EGFR-expressing A431 epidermoid carcinoma cell line. In mice bearing A431 xenografts, 89Zr-DFO-ZEGFR:2377 demonstrated specific uptake in tumours and EGFR-expressing tissues. The tracer provided tumour uptake of 2.6±0.5% ID/g and tumour-to-blood ratio of 3.7±0.6 at 24 h after injection. 89Zr-DFO-ZEGFR:2377 provides higher tumour-to-organ ratios than anti-EGFR antibody 89Zr-DFO-cetuximab at 48 h after injection. EGFR-expressing tumours were clearly visualized by microPET using 89Zr-DFO-ZEGFR:2377 at both 3 and 24 h after injection. In conclusion, 89Zr-DFO-ZEGFR:2377 is a potential probe for PET imaging of EGFR-expression in vivo.

Feasibility of imaging of epidermal growth factor receptor expression with ZEGFR:2377 affibody molecule labeled with 99mTc using a peptide-based cysteine-containing chelator

“…2). Affinity of 99m Tc-ZEGFR:2377 was 274±16 pM, in the same picomolar range as affinity of 89 Zr-labeled DFO-ZEGFR:2377 (160±60 pM) (38). The internalization by two EGFR-expressing cell lines was relatively slow (Fig.…”

“…The internalization by two EGFR-expressing cell lines was relatively slow (Fig. 3), which is typical for EGFR-binding affibody molecules (35,38). Blocking of EGFR receptors in A431 xenografts with the antibody cetuximab reduced significantly (P<0.005) uptake of 99m Tc-ZEGFR:2377, which unambiguously demonstrated specificity of in vivo targeting (Fig.…”

“…This might be exemplified by comparison of the biodistribution of ZEGFR:2377 labeled with 99m Tc and with a long-lived (T 1/2 =78.4 h) positron emitting radionuclide 89 Zr. We have recently studied ZEGFR:2377 labeled with 89 Zr using deferoxamine (DFO) chelator (38). Both studies used the same experimental methods and the same animal models, which facilitates comparison.…”

“…Combination of small size (6–7 kDa) with high affinity makes affibody molecules attractive as imaging probes, which has been shown in preclinical (32) and clinical studies (33). Several anti-EGFR affibody molecules have been developed and labeled with 111 In (34,35) for SPECT and 18 F (36,37) or 89 Zr (38) for PET imaging. The present study was focused on the ZEGFR:2377 affibody molecule (35,39), which has equal affinity to human and murine EGFR.…”

Active targeting theranostic iron oxide nanoparticles for MRI and magnetic resonance-guided focused ultrasound ablation of lung cancer

“…Epidermal growth factor receptor (EGFR) is a tyrosine kinase cellular transmembrane receptor and is linked to aberrant survival and poor prognosis. It is overexpressed in various epithelial tumors, such as non-small cell lung, kidney, breast, and head-and-neck squamous cell carcinoma [21, 22]. In this study, the surface of these PEGylated SPIO nanoparticles was further decorated with high affinity anti-EGFR monoclonal antibody (Cetuximab) to form a nanocomposite (anti-EGFR-PEG-SPIO) for targeted delivery to EGFR overexpressing H460 lung cancer.…”