The Chicken Chorioallantoic Membrane as a Low-Cost, High-Throughput Model for Cancer Imaging

Purpose Mouse models are invaluable tools for radiotracer development and validation. They are, however, expensive, low throughput, and are constrained by animal welfare considerations. Here, we assessed the chicken chorioallantoic membrane (CAM) as an alternative to mice for preclinical cancer imaging studies. Methods Growth of NCI-H460 Fluc tumors on the CAM was optimized using a range of physical and chemical supports. Tumor-bearing eggs were imaged by dynamic 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) or (4S)-4-(3-18F-fluoropropyl)-L-glutamate (18F-FSPG) PET/CT following intravenous injection, with mice bearing subcutaneous NCI-H460 Fluc xenografts imaged with 18F-FDG for comparison. The dependence of the transporter system xc- on in ovo 18F-FSPG tumor uptake was determined through treatment with imidazole ketone erastin. Additionally, 18F-FSPG PET/CT was used to monitor treatment response in ovo 24 h following external beam radiotherapy. Results NCI-H460 Fluc cells grown in Matrigel formed vascularized tumors of reproducible size without compromising embryo viability. By designing a simple method for cannulation it was possible to perform dynamic PET imaging in ovo, producing high tumor-to-background signal for both 18F-FDG and 18F-FSPG. 18F-FDG tumor uptake kinetics were similar in ovo and in vivo, with 18F-FSPG providing an early marker of both treatment response and target inhibition in CAM-grown tumors. Conclusions The CAM provides a low-cost alternative to tumor xenograft mouse models which may broaden access to PET and SPECT imaging. Rapid tumor growth and high-quality PET images that can be obtained with this model suggest its potential use for early radiotracer screening, pharmacological studies, and monitoring response to therapy.