Quantification of CD44v6 and EGFR expression in head and neck squamous cell carcinomas using a single-dose radioimmunoassay.
ABSTRACT In the growing field of tumor targeting, there is an urgent need to profile suitable molecular targets. In this study, CD44v6 and EGFR expression was quantified in samples of patients with head and neck squamous cell carcinoma (HNSCC) using a single-dose (SD) radioimmunoassay.
The SD radioimmunoassay using 125I-chimeric monoclonal antibody (cMAb) U36 and 125I-cMAb cetuximab was first validated and then applied to quantify the expression of their target antigen molecules, CD44v6 and EGFR, in patient samples. Results were compared to immunohistochemical staining.
The SD assay provided sensitive quantitative values of the molecular targets studied, generally agreeing with the immunohistochemistry (IHC) results. The results indicated that expression of CD44v6 (0.2-20 nmol/mug membrane) was generally higher than that of EGFR (0.6-2.3 nmol/microg membrane) in the tumor samples analyzed, which corresponded to an average of 700,000 and 90,000 antigen molecules per cell, respectively.
The SD radioimmunoassay is simple, reliable, and can be performed on a small amount (50 mg) of tissue. This assay could be a useful tool in the growing field of personalized cancer therapy, and can be used as a complement to IHC. In the tumors studied, CD44v6 was generally expressed at a higher level than EGFR, which might suggest that it could be more readily targeted by MAbs.
SourceAvailable from: Jens Pietzsch[Show abstract] [Hide abstract]
ABSTRACT: The epidermal growth factor receptor (EGFR) has evolved over years into a main molecular target for the treatment of different cancer entities. In this regard, the anti-EGFR antibody cetuximab has been approved alone or in combination with: (a) chemotherapy for treatment of colorectal and head and neck squamous cell carcinoma and (b) with external radiotherapy for treatment of head and neck squamous cell carcinoma. The conjugation of radionuclides to cetuximab in combination with the specific targeting properties of this antibody might increase its therapeutic efficiency. This review article gives an overview of the preclinical studies that have been performed with radiolabeled cetuximab for imaging and/or treatment of different tumor models. A particularly promising approach seems to be the treatment with therapeutic radionuclide-labeled cetuximab in combination with external radiotherapy. Present data support an important impact of the tumor micromilieu on treatment response that needs to be further validated in patients. Another important challenge is the reduction of nonspecific uptake of the radioactive substance in metabolic organs like liver and radiosensitive organs like bone marrow and kidneys. Overall, the integration of diagnosis, treatment and monitoring as a theranostic approach appears to be a promising strategy for improvement of individualized cancer treatment.Pharmaceuticals 03/2014; 7(3):311-38. DOI:10.3390/ph7030311
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ABSTRACT: The purpose of this study was to assess the effects of the monoclonal antibody cetuximab in a panel of cultured squamous cell carcinoma cell lines. This antibody, targeting the epidermal growth factor receptor (EGFR), is emerging as a promising agent for treatment of several cancers. As this antibody comes into clinical use, the identification of predictive markers of therapeutic benefit remains a pressing issue. Cells were first characterized according to EGFR expression, cell doubling time, and BRAF and K-ras mutations. The effects of cetuximab on cell-cycle distribution, proliferation, as well as cell growth rate were then evaluated. Cetuximab decreased cell proliferation in three out of four cell lines in a time-dependent manner, and all cell lines were found to exhibit wild type K-ras and BRAF genes. A possible correlation between EGFR expression and cetuximab effect on growth inhibition rate was observed, whereas reduction of cell doubling time seemed to be more dependent on initial growth rate. In addition, other factors may further influence the long-term treatment response of cetuximab. Moreover, the time-dependent manner of cetuximab response demonstrates the importance of long-term measurements for this substance.Tumor Biology 04/2010; 31(2):141-7. DOI:10.1007/s13277-010-0018-8 · 2.84 Impact Factor
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ABSTRACT: Overexpression of epidermal growth factor receptor (EGFR) in several types of malignant tumors correlates with disease progression. EGFR could, therefore, be an excellent candidate for targeted radionuclide diagnostics. However, the high natural expression of EGFR in the liver may be problematic. The aim of this study was to improve the tumor-to-liver ratio of radiolabeled epidermal growth factor (EGF) by blocking its uptake by the liver with a nonradiolabeled EGFR-targeting molecule in tumor-bearing mice. Intraperitoneally injected nonradiolabeled EGF was first evaluated as a blocking agent, preadministered at various time intervals before intravenous injection of (125)I-labeled EGF. The anti-EGFR Affibody molecule (Z(EGFR:955))(2) was then assessed as a blocking agent of (111)In-labeled EGF in a dual isotope study (50, 100, and 200 microg, preadministered 30 or 60 min before (111)In-EGF). The 30-min preadministration of nonradiolabeled EGF significantly decreased (125)I-EGF uptake in the liver, whereas uptake in the tumor remained unchanged. Furthermore, preadministration of only 50 microg (Z(EGFR:955))(2) as a blocking agent 30 min before the (111)In-EGF decreased the uptake of (111)In-EGF by the liver and increased its uptake by the tumor, thereby increasing the tumor-to-liver ratio sixfold. We conclude that the Affibody molecule (Z(EGFR:955))(2) shows promise as a blocking agent that could enhance the outcome of radionuclide-based EGFR-expressing tumor diagnostics and imaging.Tumor Biology 04/2010; 31(2):79-87. DOI:10.1007/s13277-009-0011-2 · 2.84 Impact Factor