Preclinical Evaluation of a Near-Infrared Labelled Antibody Targeting the Tumour Associated Xenoantigen N-Glycolyl-Neuraminic Acid GM3 Ganglioside.

Purpose: Targeted and broadly applicable molecular targets are important for image guided surgery. Xenoantigens represent a particularly interesting class of targets. This study evaluates the xenoantigen N-glycolyl-neuraminic acid GM3 ganglioside (Neu5Gc-GM3) as a potential fluorescence-guided surgical tool.

Procedures: The antibody 14F7hT is conjugated to the near-infrared dye (IRDye800CW) and characterized under GLP conditions. The quality and stability of the 14F7hT-IRDye800CW probe was assessed. In vivo imaging using 14F7hT-IRDye800CW in mice with Neu5Gc GM3 positive and negative xenografts were compared to a control IgG-IRDye800CW probe targeting an epitope not present on the xenografts. Biodistribution, pharmacokinetics, and toxicity were evaluated.

Results: The 14F7hT-IRDye800CW probe was 98 ± 2% pure as determined by micro-capillary electrophoresis. The KDapp as determined by binding cell-lines expressing the target was unchanged after conjugation. We demonstrate a peak accumulation window of 12 - 48 h in murine xenografts with male and female CD-1 nude mice administered 0.5 nmoles of the probe (i.v.) and very low uptake in other tissues. Preclinical toxicity studies in male and female balb/c mice support a no observed adverse effect level (NOAEL) of 50 mg/kg in mice.

Conclusions: The 14F7hT-IRDye800CW probe was found to be safe and have low non-specific uptake in a model organism known to express the target. These data support future clinical development of the probe.