Preclinical evaluation of anti‐VEGFR2 monoclonal antibody ramucirumab labelled with zirconium‐89 for tumour imaging

Abstract

The key factors participating in angiogenesis include vascular endothelial growth factor (VEGF) and its receptors (VEGFRs), particularly VEGFR2. Angiogenesis suppression comprises the blocking of the VEGFR2 binding site by the monoclonal antibody ramucirumab (RAM). Our study focused on RAM radiolabelling with zirconium‐89 along with subsequent in vitro and in vivo biological evaluation. RAM was conjugated with the bifunctional chelator p‐SCN‐Bn‐deferoxamine (DFO) and subsequently radiolabelled with [89Zr]Zr‐oxalate. The binding affinity of [89Zr]Zr‐DFO‐RAM to VEGFR2 was tested in vitro on prostate (PC‐3) and ovary adenocarcinoma (SK‐OV‐3) cell lines. The positron emission tomography/computed tomography (PET/CT) imaging and ex vivo biodistribution experiments were performed in PC‐3 and SK‐OV‐3 xenografted mice. The in vitro experiments revealed the preserved binding affinity of [89Zr]Zr‐DFO‐RAM to VEGFR2. The obtained ex vivo biodistribution data showed the uptake in PC‐3 and SK‐OV‐3 tumours at about 8.7 ± 0.2 and 12.1 ± 1.6%ID/g, respectively. The tumour‐to‐muscle ratio for 1, 3 and 6 days post injection was 3.9, 5.5 and 5.12 for PC‐3 and 6.0, 8.0 and 8.82 for SK‐OV‐3 tumours, respectively. PET/CT images showed high radioactivity accumulation in the tumours starting already on the first day after tracer administration. The obtained results proved the potency of [89Zr]Zr‐DFO‐RAM to target and image VEGFR2‐positive tumours in vivo.

Synthesis, Biological Evaluation, and In Silico Modeling of N-Substituted Quinoxaline-2-Carboxamides

“…This is consistent with the HepG2 cytotoxicity observed in our in vitro experiments. Furthermore, HepG2 [ 20 ], PC-3, and SK-OV-3 [ 21 ] cell lines were proven to express VEGFR2, while cell lines U-87 MG [ 22 ] and A498 [ 23 ] expressed VEGFR1. This fact may explain the selective toxicity of compound 29 toward the HepG2, PC-3, and SK-OV-3 cell lines.…”

“…In compound 20, the extended linker (extra methylene group) caused the deviation in the position of the quinoxaline core, which led to the loss of interaction with Arg325. This unfavorable shift was observed for all docked poses of title compounds with the extended linker (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31).…”

“…Based on the observed whole-cell antimycobacterial activity (Table 1), we chose compound 2 as a representative of the N-phenyl subseries (1-14, excl. 6) and compound 20 as a representative of the N-benzyl series (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). These prototypic compounds were docked into mycobacterial DprE1 (pdb id: 4P8N).…”