Diagnostic performance of receptor-specific surgical specimen staining correlate with receptor expression level

Abstract

Identification of tumor margins in the operating room in real time is a critical challenge for surgical procedures that serve as cancer cure. Breast conserving surgery (BCS) is particularly affected by this problem, with current re-excision rates above 25%. Due to a lack of clinically available methodologies for detection of involved or close tumor margins, much effort is focused on developing intraoperative margin assessment modalities that can aid in addressing this unmet clinical need. BCS provides a unique opportunity to design contrast-based technologies that are able to assess tumor margins independent from the patient, providing a rapid pathway from bench to bedside at a much lower cost. Since resected tissue is removed from the patient's blood supply, non-specific contrast agent uptake becomes a challenge due to the lack of clearance. Therefore, a dual probe, ratiometric fluorescence imaging approach was taken in an effort to reduce nonspecific signal, and provide a modality that could demonstrate rapid, robust margin assessment on resected patient samples. Termed, dual-stain difference specimen imaging (DDSI), DDSI includes the use of spectrally unique, and fluorescently labeled target-specific, as well as non-specific biomarkers. In the present study, we have applied epidermal growth factor receptor (EGFR) targeted DDSI to tumor xenografts with variable EGFR expression levels using a previously optimized staining protocol, allowing for a quantitative assessment of the predictive power of the technique under biologically relevant conditions. Due to the presence of necrosis in the model tumors, ring analysis was employed to characterize diagnostic accuracy as measured by receiver operator characteristic (ROC) curve analysis. Our findings demonstrate the robust nature of the DDSI technique even in the presence of variable biomarker expression and spatial patterns. These results support the continued development of this technology as a robust diagnostic tool for tumor margin assessment in resected specimens during BCS.

In situ single-cell therapeutic response imaging facilitated by the TRIPODD fluorescence imaging platform

“…PAI was created for quantitative in vivo imaging, where non-specific accumulation of protein-based, radiolabeled affinity reagents dominated malignant tissue signals but could be corrected for by normalizing the targeted signal to the signal of a co-administered, control antibody labeled with an isotope of different energy [40]. In this reinvigorated technique, spectrally-distinct targeted and untargeted imaging probes are used to correct for non-specific uptake to quantify drug target availability (DTA; also termed "binding potential") [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. We have expanded the PAI technique to measure intracellular targets with the use of spectrally-distinct, fluorescently-labeled targeted and untargeted drug derivatives, such as TKIs [58].…”