Date of Award

2023

Document Type

Thesis (Master's)

Department or Program

Engineering Sciences

First Advisor

Kimberley Samkoe

Second Advisor

Petr Bruza

Third Advisor

P. Jack Hoopes

Abstract

Head and neck cancers affect thousands of people across the world, and photodynamic therapy (PDT) has been shown to have great potential to treat said cancers in a noninvasive manner. However, imaging head and neck cancers has been difficult, and molecular changes caused by PDT are not well-understood. Therefore, we propose the use of paired-agent imaging (PAI) to track changes in these cancers after after PDT treatment. For these studies, we primarily used benzoporphyrin derivative monoacid (BPD) for our photosensitizer, which is activated by a 690 nm laser. We first looked at changes in EGFR expression in vitro, and attempted to do so with cell-staining protocols on a 96-well plate using ABY-029 – an anti-EGFR affibody molecule labeled with IRDye 800CW – as a reporter for EGFR expression. Due to cross-talk between the emission filters for the required live/dead dyes on the Odyssey M scanner, we switched to using flow cytometry-based studies. Using these studies, we were able to ascertain a trend in EGFR expression across increasing levels of fluence from the laser, and were able to analyze this trend in both the live and dead cell populations. We then looked at verifying these trends in vivo, where we again used ABY-029 and IRDye 680LT as our targeted and untargeted agents, respectively, for PAI. Using this technique, we were able to determine the same trends in EGFR expression that we had observed in vitro and confirmed this trend in our IHC staining. We also used PAI to look at the binding potential of EGFR across different light doses, and found that the binding potential determined from PAI correlated with the binding potential we had determined from the IHC. In conclusion, PAI using EGFR targeted imaging agents appears to be a promising technique to track early molecular changes in HNSCC in vivo, and that this technique has the potential for applications in patient care.

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