Importance: It is known that high-grade dysplasia has an increased risk of malignant transformation when compared to normal or low-grade dysplasia. However, low-grade and high-grade dysplasia are histological definitions and cannot be differentiated by physical exam. We have developed a systemically injected fluorescent contrast agent that can differentiate dysplastic and malignant tissue based on differences in EGFR expression.
Objective: To determine if differences in EGFR expression can help discriminate low-grade from high-grade dysplasia from normal tissue in patients with head and neck squamous cell carcinoma (HNSCC).
Methods: We analyzed tumor specimens obtained from patients with HNSCC who were enrolled in a clinical trial assessing the efficacy of fluorescently labeled anti-EGFR antibody (panitumumab-IRDye800CW) as a fluorescent contrast agent (NCT02415881). Fluorescence images were obtained at the time of and following surgery and then fluorescence intensity was correlated with pathology. H&E stained slides were reviewed by a board-certified pathologist to delineate regions of invasive squamous cell carcinoma, high-grade dysplasia, and low-grade dysplasia, which was subsequently correlated with the fluorescence imaging.
Results: A total of 24 patients were included in the study, of which 11 were selected for further analysis of invasive squamous cell carcinoma, high-grade dysplasia, and low-grade dysplasia. We analyzed separate tissue sections from these patient specimens which allowed analysis of 44 normal, 38 low-grade dysplasia, 42 high-grade dysplasia, and 32 invasive SCC separate sections. We found that the intensity of fluorescence (measured as mean fluorescence intensity (MFI)) increased with the grade of dysplasia; normal mucosa (1.7 MFI), low-grade dysplasia (3.4 MFI), high-grade dysplasia (4.0 MFI). Low-grade dysplasia and high-grade dysplasia had significantly greater signal-to-noise ratio when compared to normal (p<0.05), and high-grade was distinguishable from low-grade dysplasia (p<0.05). This corresponded to increasing EGFR expression with increasing degree of dysplasia on IHC staining of consecutive slides.
Conclusions: We identified a novel fluorescent agent in clinical trials (Panitumumab-IRDye800CW) that can successfully discriminate low-grade and high-grade dyplasia lesions from normal tissue intra-operatively.