Residualization Rates of Near-Infrared Dyes for the Rational Design of Molecular Imaging Agents

Abstract

Purpose Near infrared (NIR) fluorescence imaging is widely used for tracking antibodies and biomolecules in vivo. Clinical and preclinical applications include intraoperative imaging, tracking therapeutics, and fluorescent labeling as a surrogate for subsequent radiolabeling. Despite their extensive use, one of the fundamental properties of NIR dyes, the residualization rate within cells following internalization, has not been systematically studied. This rate is required for the rational design of probes and proper interpretation of in vivo results. Procedures In this brief report, we measure the cellular residualization rate of eight commonly used dyes encompassing three core structures (cyanine, BODIPY, and oxazine/thiazine/carbopyronin). Results We identify residualizing (half-life > 24 hrs) and non-residualizing dyes (half-life < 24 hrs) in both the far red (~650-680 nm) and near infrared (~740-800 nm) regions. Conclusions This data will allow researchers to independently and rationally select the wavelength and residualizing nature of dyes for molecular imaging agent design.

Oral Administration and Detection of a Near-Infrared Molecular Imaging Agent in an Orthotopic Mouse Model for Breast Cancer Screening

“…The image intensity shows that the amount of agent in the tumor stays relatively constant over a period of 48 h owing to the residualizing nature of the NIR fluorophore. 31 To demonstrate specificity, we used a low-affinity stereoisomer of the IRDye800CW agent, since the two most common techniques, blocking specific uptake or using an antigen-negative tumor, were not feasible. Complete blocking of the targeting receptor over the course of several hours while the agent is absorbed orally would require an impractical amount of the rapidly cleared nonfluorescent ligand, and antigen-negative xenografts still express integrins on the neovasculature and macrophages.…”

“…However, the anionic charge on the internalizing agents in this study can aid in trapping the dye within cells for days. 31 Despite the long time period between oral administration and imaging, this would still be favorable from a patient compliance standpoint, since intravenous delivery of low-molecular-weight agents requires a minimum of hours to develop contrast. This would necessitate extended or multiple clinical visits—the first to receive an intravenous dose and monitoring for adverse reactions followed by an imaging visit several hours to days later.…”

Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging

“…The rapid plasma clearance allows imaging after the majority of probe is removed from the blood (< 0.5% in the case of the monomer, dimer, and trimer). However, due to the residualizing IRDye 800CW label[74], both specifically and non-specifically internalized IRDye 800CW label wash out of tissue extremely slowly, negating any benefit of later imaging times.…”

Multiscale Modeling of Antibody-Drug Conjugates: Connecting Tissue and Cellular Distribution to Whole Animal Pharmacokinetics and Potential Implications for Efficacy

“…Alexa Fluor 680 (AF680) was conjugated to T-DM1 following the manufacturer's instructions and as previously described(39). For reactions, a molar ratio of 0.7 was used that resulted in an overall degree of labeling of 0.3 to mitigate any potential physicochemical effects from the dye on the antibody.…”