Novel human monoclonal antibody against epidermal growth factor receptor as an imaging probe for hepatocellular carcinoma

Enhanced radiation effect on SMCC7721 cells through endoplasmic reticulum stress induced by C225-GNPs in vitro and in vivo

The high atomic number of gold nanoparticles (GNPs) enables them to offer potential as practical and efficient radiosensitizing agents for cancer radiotherapy applications. In the present study, it was demonstrated that GNPs can significantly modulate the irradiation response of hepatocellular carcinoma (HCC) cells in vitro and in vivo, of which the underlying mechanisms were investigated. Cetuximab (C225) is a targeting agent, which binds to the extracellular domain of epidermal growth factor receptor (EGFR). Hepatocyte-targeting, EGFR-specific C225 was synthesized onto GNP surfaces (C225-GNPs) to increase the GNP targeting specificity. C225-GNPs was synthesized successfully and characterized. The cytotoxicity was tested using a Cell Counting Kit-8 assay and 50% inhibition concentration of SMCC7721 cells was calculated. Cell uptake assay was detected using transmission electron microscopy. Radiosensitization was tested using a cell colony formation assay and cell cycle was detected using flow cytometry. The expression of a number of apoptotic proteins were tested by western blot analysis. Orthotropic SMCC7721 xenografts were used in order to verify its radiosensitizing effect. The results revealed that a higher number of C225-GNPs were effectively uptaken by SMCC7721 cells and markedly enhanced cancer cell death. The sensitization mechanism of C225-GNPs was associated with the apoptotic gene signalling process activated by endoplasmic reticulum stress and the unfolded protein response in cancer cells. In orthotopic SMCC7721 xenografts, the C225-GNPs significantly enhanced the radiation-induced suppression of tumour growth. The results of the present study provided evidence that C225-GNPs are potent radiosensitizers with radiotherapeutic value for HCC with the overexpression of EGFR.

Imaging of hepatocellular carcinoma patient-derived xenografts using ⁸⁹Zr-labeled anti-glypican-3 monoclonal antibody

Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention.

Molecular imaging of hepatocellular carcinoma xenografts with epidermal growth factor receptor targeted affibody probes

Hepatocellular carcinoma (HCC) is a highly aggressive and lethal cancer. It is typically asymptomatic at the early stage, with only 10%–20% of HCC patients being diagnosed early enough for appropriate surgical treatment. The delayed diagnosis of HCC is associated with limited treatment options and much lower survival rates. Therefore, the early and accurate detection of HCC is crucial to improve its currently dismal prognosis. The epidermal growth factor receptor (EGFR) has been reported to be involved in HCC tumorigenesis and to represent an attractive target for HCC imaging and therapy. In this study, an affibody molecule, Ac-Cys-Z_EGFR:1907, targeting the extracellular domain of EGFR, was used for the first time to assess its potential to detect HCC xenografts. By evaluating radio- or fluorescent-labeled Ac-Cys-Z_EGFR:1907 as a probe for positron emission tomography (PET) or optical imaging of HCC, subcutaneous EGFR-positive HCC xenografts were found to be successfully imaged by the PET probe. Thus, affibody-based PET imaging of EGFR provides a promising approach for detecting HCC in vivo.

Evaluation of (89)Zr-labeled human anti-CD147 monoclonal antibody as a positron emission tomography probe in a mouse model of pancreatic cancer

Introduction

Pancreatic cancer is an aggressive cancer and its prognosis remains poor. Therefore, additional effective therapy is required to augment and/or complement current therapy. CD147, high expression in pancreatic cancer, is involved in the metastatic process and is considered a good candidate for targeted therapy. CD147-specfic imaging could be useful for selection of appropriate patients. Therefore, we evaluated the potential of a fully human anti-CD147 monoclonal antibody 059-053 as a new positron emission tomography (PET) probe for pancreatic cancer.

Methods

CD147 expression was evaluated in four pancreatic cancer cell lines (MIA Paca-2, PANC-1, BxPC-3, and AsPC-1) and a mouse cell line A4 as a negative control. Cell binding, competitive inhibition and internalization assays were conducted with ¹²⁵I-, ⁶⁷Ga-, or ⁸⁹Zr-labeled 059-053. In vivo biodistribution of ¹²⁵I- or ⁸⁹Zr-labeled 059-053 was conducted in mice bearing MIA Paca-2 and A4 tumors. PET imaging with [⁸⁹Zr]059-053 was conducted in subcutaneous and orthotopic tumor mouse models.

Results

Among four pancreatic cancer cell lines, MIA Paca-2 cells showed the highest expression of CD147, while A4 cells had no expression. Immunohistochemical staining showed that MIA Paca-2 xenografts also highly expressed CD147 in vivo. Radiolabeled 059-053 specifically bound to MIA Paca-2 cells with high affinity, but not to A4. [⁸⁹Zr]059-053 uptake in MIA Paca-2 tumors increased with time from 11.0±1.3% injected dose per gram (ID/g) at day 1 to 16.9±3.2% ID/g at day 6, while [¹²⁵I]059-053 uptake was relatively low and decreased with time, suggesting that 059-053 was internalized into tumor cells in vivo and ¹²⁵I was released from the cells. PET with [⁸⁹Zr]059-053 clearly visualized subcutaneous and orthotopic tumors.

Conclusion

[⁸⁹Zr]059-053 is a promising PET probe for imaging CD147 expression in pancreatic cancer and has the potential to select appropriate patients with CD147-expressing tumors who could gain benefit from anti-CD147 therapy.