[^99mTc(CO)₃]-Radiolabeled Bevacizumab: In vitro and in vivo Evaluation in a Melanoma Model

Abstract

Introduction: Vascular endothelial growth factor (VEGF) is one of the classic factors to tumor-induced angiogenesis in several tumor types, including melanoma. Bevacizumab, a monoclonal antibody against VEGF, could be used as an imaging tool in preclinical studies. Objective: To radiolabel bevacizumab with [^99mTc(CO)₃(OH₂)₃]⁺ and evaluate it in vivo and in vitro for melanoma imaging properties. Methods: Bevacizumab was radiolabeled with [^99mTc(CO)₃(OH₂)₃]⁺ ion in saline. The radiochemical stability of the labeled antibody was assessed. The biodistribution and scintigraphy imaging of the radiolabeled antibody were evaluated in normal C57BL/6J mice and in C57BL/6J mice bearing murine B16F1 melanoma tumors. Immunoreactivity of bevacizumab to murine tumors was determined from direct immunofluorescence and immunoblotting assays. Results: We demonstrate that ^99mTc(CO)₃-bevacizumab was stable. In vivo biodistribution studies revealed that tumor uptake of ^99mTc(CO)₃-bevacizumab was 2.64 and 2.51 %ID/g at 4 and 24 h postinjection. Scintigraphy image studies showed tumor selective uptake of ^99mTc(CO)₃-bevacizumab in the tumor-bearing mice. This affinity was confirmed by immunoassays performed on B16F10 tumor samples. Conclusions:^99mTc(CO)₃-bevacizumab could be used as an approach for tumor nuclear imaging in preclinical studies. This should be useful to provide insights into the angiogenic stimulus before and after chemotherapy, which might help improve current antitumor therapy.

68Ga-TRAP-(RGD)3 Hybrid Imaging for the In Vivo Monitoring of αvß3-Integrin Expression as Biomarker of Anti-Angiogenic Therapy Effects in Experimental Breast Cancer

“…Inhibition of the VEGF pathway using the VEGF antibody bevacizumab as either single or combination therapy has become an established clinical anti-angiogenic treatment regimen applied in various tumor entities, including non-small-cell lung, colorectal, and breast cancer [13]. In vivo, intact murine VEGF is not recognized by bevacizumab, while cleaved murine VEGF can be recognized by this antibody in Western Blots [14]. …”

Anti-CD20 Immunoglobulin G Radiolabeling with a 99mTc-Tricarbonyl Core: In Vitro and In Vivo Evaluations

“…Indirect radiolabeling , via a bifunctional chelating agent (BFCA), has been promoted by development of new synthons such as MAG3 [ 4 ] and HYNIC [ 5 ]. Among the BFCAs, “tricarbonyl core” [Tc(CO) 3 (H 2 0) 3 ] + has many advantages, e.g., permitting 99m Tc to link with proteins under mild physiological conditions [ 6 , 7 ]. Moreover, tricarbonyl core is in a low oxidation state (+ I), with a high kinetic stability.…”

“…In this kit (IsoLink ® , Mallinckrodt), boranocarbonate sodium allows both the production of carbon monoxide and the reduction of technetium. Different antibody radiolabeling strategies using 99m Tc-tricarbonyl have been assessed, with direct antibody labeling [ 7 , 10 ] or using a spacer [ 11 ]. Investigations by Egli et al .…”

Anti‐bevacizumab idiotype antibody vaccination is effective in inducing vascular endothelial growth factor‐binding response, impairing tumor outgrowth

“…It is already known that even though bevacizumab seems to interact with degraded products of murine VEGF, it fails in inhibiting mVEGF‐induced activity and in displaying any effect on murine tumor growth . Despite this, sera from mice immunized with 10.D7 anti‐bevacizumab idiotype antibody recognize both murine and human VEGF, which makes it reasonable to assume that the in vivo data presented here might be, at least in part, the result of mVEGF immunoneutralization by VEGF‐binding antibody serum content.…”