Preparation and in vitro evaluation of 111In-CHX-A"-DTPA-labeled anti-VEGF monoclonal antibody bevacizumab

Abstract

Bevacizumab is a humanized monoclonal antibody that binds to vascular endothelial growth factor (VEGF) and prevents tumor angiogenesis. Radionuclide imaging using radiolabeled bevacizumab might be useful for selection of patients for anti-VEGF therapy. This study describes preparation of a potential imaging agent, 111In-CHX-A"-DTPA-bevacizumab, and evaluation of specificity of its binding to three tumor cell lines, SKOV3, LS174T and DU 145. Bevacizumab was conjugated with CHX-A"-DTPA and radiolabeled with 111In with high yield and excellent stability. Specificity of cellular binding was examined by a saturation assay using 100-fold excess of non-radiolabeled antibody. SKOV3 and LS174T tumor cell lines showed significantly specific binding, while DU 145 cells did not showed any specific binding. The specific binding is dependent to type of cell lines, which it is important for selection of tumor model for scintigraphic imaging of the VEGF expression.

Radioimmunotherapy with 131I-Bevacizumab as a Specific Molecule for Cells with Overexpression of the Vascular Endothelial Growth Factor

“…24 In our previous study, three tumor cell lines, SKOV-3, DU145, and LS174T, were investigated for specific binding with 111 In-bevacizumab; SKOV-3 showed significant specific binding to 111 In-bevacizumab. 13 Tumor targeting with radiolabeled bevacizumab is a possible strategy for anticancer therapies if a beta-emitting radionuclide is used. In this study, 131 I-bevacizumab was significantly bound to SKOV-3, which was significantly removed by saturated unlabeled bevacizumab.…”

“…13 Ten petri dishes (3.5 cm diameter) containing a cell monolayer (1 · 10 6 cells/dish) were used. Cells in five dishes were presaturated with 300-fold excess unlabeled bevacizumab 5 minutes before labeled 131 I-bevacizumab (12 nM) was added.…”

“…Bevacizumab was labeled with 131 I using chloramine T. Briefly, 10 lL chloramine T (40 lg in phosphate-buffered saline) and [11][12][13][14][15][16][17][18][19][20][21][22] MBq of sodium 131 I were added to 25 lL of a fresh antibody solution containing PBS (100 lg). Iodination was carried out by vortexing the mixture for 2 minutes, and then adding 20 lL of sodium metabisulfite in phosphate buffer.…”

“…12 We recently showed that bevacizumab labeled with 111 In has good specific binding to the SKOV-3 ovarian cancer cell line, and is a promising radiotracer for tumor imaging. 13 Recently, bevacizumab was labeled with 64 Cu for use as a positron emission tomography tracer. The tumor accumulation of 64 Cu-bevacizumab was found to be correlated with VEGF expression, and it was clearly accumulated in mice bearing human colorectal cancer xenografts.…”

Radiopharmaceuticals for Breast Cancer and Neuroendocrine Tumors: Two Examples of How Tissue Characterization May Influence the Choice of Therapy

“…For example, it is possible to study angiogenesis in the tumor environment with the Bevacizumab, a MoAb directed against the vascular endothelial growth factor (VEGF), that blocks the creation of new vessels thus reducing blood supply to the tumor. This drug can be radiolabeled with 99m-technetium ( 99m Tc) or 111-indium ( 111 In) or other isotopes for SPECT studies [3][4][5]; however, it can also be used for PET imaging, coupled to the radionuclide 89-zirconium ( 89 Zr). This radiopharmaceutical could be used to both visualize angiogenesis and to monitor the effect of anti-angiogenetic treatments in different neoplasms [6][7][8][9][10].…”