CEACAM5 and neoplasm: Conventional near-infrared (NIR) fluorophores often alter the pharmacokinetic properties of the parental molecule that result in aggregation, altered biodistribution, and impaired tumor targeting.<h4>Methods</h4>This present study evaluates two charge-balanced heptamethine cyanine dyes, FNIR-Tag-766 and FNIR-Tag-804, conjugated to a humanized anti-carcinoembryonic antigen antibody (M5A).