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

Abstract

The epidermal growth factor receptor (EGFR) is overexpressed in a number of malignant tumors and is a molecular target for several specific anticancer antibodies and tyrosine kinase inhibitors. The overexpression of EGFR is a predictive biomarker for response to several therapy regimens. Radionuclide molecular imaging might enable detection of EGFR overexpression by a non-invasive procedure and could be used repeatedly. Affibody molecules are engineered scaffold proteins, which could be selected to have a high affinity and selectivity to predetermined targets. The anti-EGFR ZEGFR:2377 affibody molecule is a potential imaging probe for EGFR detection. The use of the generator-produced radionuclide 99mTc should facilitate clinical translation of an imaging probe due to its low price, availability and favorable dosimetry of the radionuclide. In the present study, we evaluated feasibility of ZEGFR:2377 labeling with 99mTc using a peptide-based cysteine-containing chelator expressed at the C-terminus of ZEGFR:2377. The label was stable in vitro under cysteine challenge. In addition, 99mTc-ZEGFR:2377 was capable of specific binding to EGFR-expressing cells with high affinity (274 pM). Studies in BALB/C nu/nu mice bearing A431 xenografts demonstrated that 99mTc-ZEGFR:2377 accumulates in tumors in an EGFR-specific manner. The tumor uptake values were 3.6±1 and 2.5±0.4% ID/g at 3 and 24 h after injection, respectively. The corresponding tumor-to-blood ratios were 1.8±0.4 and 8±3. The xenografts were clearly visualized at both time-points. This study demonstrated the potential of 99mTc-labeled ZEGFR:2377 for imaging of EGFR in vivo.

Novel EBV LMP-2-affibody and affitoxin in molecular imaging and targeted therapy of nasopharyngeal carcinoma

“…Because of their small size, affibody can be synthesized or recombinantly expressed. Since the first construct HER2-targeting affibody molecule Z HER2:342 was produced and confirmed to bind to HER2-positive cancer cell lines [24], several similar affibody molecules targeting EGFR [23,24], HER3 [27,28], IGF-1R [42], HIV-1-gp120 [43] and HPV16E7 [30,31] have been reported and also applied to image several tumour-associated molecular targets, such as HER2 [25,44], EGFR [45,46], HER3 [47]. The first clinical imaging study on patients with breast cancer was conducted using HER2-specific affibody, which Mice bearing C666-1tumor grafts were intravenously injected with 100 nmol/kg Z142X, Z142, or an equal amount of control agents or the same volume of PBS every two days for 15 times via tail vein.…”

“…To date, over 400 published studies show that affibody molecules have been selected for targeting more than 40 different proteins and served as affinity moieties in a variety of applications [22]. The affibody-targeted proteins include epidermal growth factor receptor (EGFR) [23,24], human epidermal growth factor receptor 2 (HER2) [25,26], human epidermal growth factor receptor 3 (HER3) [27,28], vascular endothelial growth factor (VEGF) [29], and human papillomavirus type 16 E7 (HPV16E7) [30,31]. In particularly, affibody molecules attached with a cytotoxin appear to be a straightforward and efficient way to direct the action of the toxin to desired cell targets [22].…”

Insights on animal models to investigate inhalation therapy: Relevance for biotherapeutics

“…Biotherapeutics can also be used as theranostic agents through the attachment of a radiolabel chelator to the biotherapeutic. For antibodies, the use of the short-lived 99m Tc improves physical imaging because of high proton flux, high resolution and low dosimetry (Andersson et al, 2016). It is also particularly relevant for Fab fragments which exhibit accelerated clearance resulting in better target-background ratio (Wahl et al, 1983).…”

Benefit of Later-Time-Point PET Imaging of HER3 Expression Using Optimized Radiocobalt-Labeled Affibody Molecules

“…However, it was previously observed that uptake of HER3 affibody molecules in normal organs decreases over time, while tumor-associated activity cleared more slowly [26,27]. Therefore, HER3 imaging contrast could potentially benefit from delayed imaging (up to 24 h pi), which was previously observed for indium-111-labeled anti-HER3 affibody molecules [26] and for radiolabeled anti-HER1 (EGFR) affibody molecules [28][29][30]. For PET imaging of HER3 expression, 18 F-and 68 Ga-labeled Z HER3 affibody molecules were able to visualize tumor uptake already 1 and 3 h pi in rodents.…”