Longitudinally quantitative 2-deoxy-2-[18F] fluoro-D-glucose micro positron emission tomography imaging for efficacy of new anticancer drugs:: A case study with bortezomib in prostate cancer murine model

Purpose: The aim of this study was to validate quantitative metabolic response of tumors to a treatment measured by longitudinal 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) micro positron emission tomography (microPET) as a robust tool for preclinical evaluation of new anticancer agents. Procedures: Severe combined immunodeficiency mice with CWR22 xenografts were intravenously treated with bortezomib (Velcade) at 0.8 mg/kg on days 0, 3, 7, 10, and 14 and imaged with FDG microPET before, during and after treatment. Quantitative indices of tumor FDG uptake were developed. Results: FDG microPET images successfully revealed the gradual reduction of tumor FDG uptake on day 4 onward despite no absolute tumor shrinkage. The standardized uptake values of FDG in tumors was reduced to 43% of the baseline values. Using the total tumor FDG uptake as the viable tumor burden, we found 86% tumor inhibition, compared to a 55% tumor growth inhibition in tumor volume measurement. Conclusion: FDG microPET imaging can provide an additional dimension of the efficacy of anticancer therapies that may otherwise be underestimated by tumor volume measurement.