^99mTc-Hydrazinonicotinamide Epidermal Growth Factor–Polyethylene Glycol–Quantum Dot Imaging Allows Quantification of Breast Cancer Epidermal Growth Factor Receptor Expression and Monitors Receptor Downregulation in Response to Cetuximab Therapy

Abstract

Therapy of cancer, including basallike breast tumors, that targets the epidermal growth factor receptor (EGFR) would greatly benefit from noninvasive methods that can quantitatively monitor receptor status and treatment response. Methods: Here, we investigated the potential of a novel technique based on streptavidin cadmium selenide/zinc sulfide quantum dots (Qdots) multiplexed with polyethylene glycol (PEG), epidermal growth factor (EGF), and 99m Tc-hydrazinonicotinamide. In vitro binding affinity and specificity were evaluated in cultured cells. Biodistribution studies and in vivo imaging were performed in murine breast tumor xenografts of basallike phenotype MDA-MB-468 cells and EGFR-negative cells. Results: 99m Tchydrazinonicotinamide EGF-PEG-Qdot showed specific and high-affinity EGFR targeting on confocal microscopy, immunoblotting, and binding assays. When intravenously injected, MDA-MB-468 tumors were visualized with high contrast by both optical and scintigraphic imaging. Scintigraphic image-based quantification correctly discriminated high-EGFR-expressing MDA-MB-468 tumors from other tumors, and image-based tumor uptake closely correlated to EGFR content. Importantly, serial imaging of MDA-MB-468 tumors responding to cetuximab therapy could detect a significant reduction of tumor uptake that was paralleled by downregulation of EGFR expression. Furthermore, high baseline uptake predicted good response to cetuximab therapy. Conclusion: 99m Tc-hydrazinonicotinamide EGF-PEGQdot provides EGFR-targeted imaging of breast tumors and may allow noninvasive monitoring of EGFR status in living subjects before and after targeted therapies.Key Words: molecular imaging; oncology; breast cancer; epidermal growth factor receptor; scintigraphy Epi dermal growth factor receptors (EGFRs) play a key role in tumor growth, invasion, and metastasis (1-3) and have become a promising therapeutic target in many cancers (4,5). Breast carcinoma is the most common cancer in women and a major cause of mortality, accounting for 7% of all cancer-related deaths. EGFR is overexpressed in up to 35% of breast cancers and is associated with poorer prognosis (6,7). Recent data suggest potential benefits of EGFRtargeted agents not only for treating breast tumors but also for lowering their progression rate (8). The efficacy of targeted therapy depends on the expression status of the molecule being aimed for, and lessons from clinical trials with EGFR antagonists have illuminated the critical importance of this factor in selecting patients most likely to respond (4,5).Molecular profiling work on breast tumors identifies a distinct and highly malignant subtype called basallike breast cancer, which is linked with higher tumor grade, more frequent metastasis, and poor clinical outcome (9,10). This subgroup, with its characteristic molecular signature of negative estrogen/progesterone/HER2 receptor expression and positive EGFR expression, represents breast tumors that could most likely benefit from EGFR-targeted therapy because they lack other re...

Multiplexed mAbs: a new strategy in preclinical time-domain imaging of acute myeloid leukemia

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Radionuclide therapy using 131I-labeled anti-epidermal growth factor receptor-targeted nanoparticles suppresses cancer cell growth caused by EGFR overexpression

“…The use of active targeting radionuclide nanoparticles in internal radiotherapy has been successfully employed to image and treat tumor models preclinically. These radionuclide nanoparticles include human atherosclerotic plaque-specific peptide-1-targeted 111 In-labeled liposomes (Yang et al 2012), monoclonal antinuclear autoantibody 2C5 (mAb 2C5) targeting 111 In-immunoliposome for lung carcinoma (Elbayoumi et al 2007), α v β 3 -integrintargeted 111 In perfluorocarbon nanoparticles for targeted tumor imaging (Hu et al 2007), rituximab targeting 111 In carbon nanotubes for targeted tumor imaging (McDevitt et al 2007), RGD-or VEGF-targeted 64 Cu quantum dots or iron oxide for PET/NIRF and PET/MRI imaging Lee et al 2008), EGFR-targeted 99m Tc-chelated quantum dots for breast cancer imaging and therapy (Jung et al 2011), RGD-targeted 125 I-labeled gold nanoparticles for tumor imaging (Kim et al 2011), HER2-targeted nanoparticles loaded with an 125 I-labeled DNA intercalator (Fondell et al 2011), anti-prostate-specific membrane antigen nanoparticles loaded with 225 Ac for potential targeted anti-vascular α-particle therapy (Bandekar et al 2014), 76 Br-labeled RGD-directed-dendritic nanoprobes for PET imaging (Almutairi et al 2009), and integrin antagonist or anti-Flk-1 antibody-coated 90 Y-labeled nanoparticles (Li et al 2004).…”

Quantum Dot-Based Nanoprobes for In Vivo Targeted Imaging

“…At 24 h after injection, tumor fluorescence of either QDs or EGF-QDs was minimal and not readily detectable. In another report, specific EGFR targeting with 99m Tc-labeled, EGF-conjugated QDs was reported in a breast cancer model, which allowed for monitoring of EGFR downregulation upon therapy [155]. …”