In Vivo VEGF Imaging with Radiolabeled Bevacizumab in a Human Ovarian Tumor

Vascular endothelial growth factor (VEGF), released by tumor cells, is an important growth factor in tumor angiogenesis. The humanized monoclonal antibody bevacizumab blocks VEGF-induced tumor angiogenesis by binding, thereby neutralizing VEGF. Our aim was to develop radiolabeled bevacizumab for noninvasive in vivo VEGF visualization and quantification with the single g-emitting isotope 111In and the PET isotope 89Zr. Methods: Labeling, stability, and binding studies were per-formed. Nude mice with a human SKOV-3 ovarian tumor xeno-graft were injected with 89Zr-bevacizumab, 111In-bevacizumab, or human 89Zr-IgG. Human 89Zr-IgG served as an aspecific con-trol antibody. Small-animal PET and microCT studies were obtained at 24, 72, and 168 h after injection of 89Zr-bevacizumab and 89Zr-IgG (3.56 0.5 MBq, 1006 6 mg, 0.2 mL [mean6 SD]). Small-animal PET and microCT images were fused to calculat