Detecting Epidermal Growth Factor Receptor Tumor Activity In Vivo During Cetuximab Therapy of Murine Gliomas

Abstract

Rationale and Objectives Noninvasive molecular imaging of glioma tumor receptor activity was assessed with diagnostic in vivo fluorescence monitoring during targeted therapy. The study goals were to assess the range of use for treatment monitoring and stratification of tumor types using EGFR status with administration of fluorescently labeled epidermal growth factor (EGF), and determine its utility for tumor detection compared to magnetic resonance imaging (MRI). Materials and Methods Epidermal growth factor receptor positive and negative (EGFR+ and EGFR−) glioma tumor lines (U251-GFP and 9L-GFP, respectively) were used to assess these goals, having a 20-fold difference between their EGF uptakes. Results Treatment with cetuximab, in the EGFR+ tumor-bearing animals led to decreased EGF tumor uptake, whereas for the EGFR− tumors no change in fluorescence signal followed treatment. This diagnostic difference in EGFR expression could be used to stratify the tumor-bearing animals into groups of potential responders and non-responders, and receiver operator characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.92 in separating these tumors. The non-localized growth pattern of U251-GFP tumors resulted in detection difficulty via standard MRI, however high EGFR expression made them detectable through fluorescence imaging (ROC-AUC = 1.0). The EGFR+, U251-GFP tumor-bearing animals could be noninvasively stratified into treated and untreated groups based on fluorescence intensity difference (p = 0.035, ROC-AUC = 0.90). Conclusions EGFR expression was tracked in vivo with fluorescence, and determined to be of use for stratification of EGFR+ and EGFR− tumors, detection of EGFR+ tumors and monitoring of molecular therapy.

Dynamic dual-tracer MRI-guided fluorescence tomography to quantify receptor density in vivo

“…U251 tumor cells have been reported to have elevated expression of EGF receptor (EGFR) (35). This receptor is associated with a number of cellular processes that maintain cancer cell proliferation, is commonly overexpressed in clinical cancers (36)(37)(38)(39), and thus is a natural drug target (38,40).…”

Improved tumor contrast achieved by single time point dual-reporter fluorescence imaging

“…Twenty-six-week-old mice were inoculated with a human neuronal glioblastoma (U251; supplied from Dr. Mark Israel, Norris Cotton Cancer Center, DartmouthHitchcock Medical Center), a cancer cell line known to express moderate levels of EGFR; 28,29 another six mice were inoculated with a human epidermoid carcinoma (A431; ATCC, Manassas, VA), known to express a very large amount of EGFR; 30 and the final six mice were inoculated with a rat gliosarcoma (9L-GFP; supplied by Dr. Bogdanov, Dartmouth Medical School), a cell line known to express very little EGFR. 28 In all cases, the tumors were introduced by injecting 1 × 10 6 tumor cells in Matrigel® (BD Biosciences, San Jose, CA) into the subcutaneous space on the left thigh of the mice. The tumors were then allowed to grow to a size of approximately 150 mm 3 before imaging (roughly 2 weeks).…”

New Approaches to Photodynamic Therapy from Types I, II and III to Type IV Using One or More Photons

“…The non-invasive fluorescence monitoring of fluorescently labelled epidermal growth factor (EGF) in glioma cells has been suggested as a useful tool to differentiate between EGFR-positive and EGFR-negative tumours noninvasively prior to PDT [137]. PDD was recently evaluated in human malignant glioma biopsies (from 33 patients) that received 5-ALA PDT.…”