Downregulation of 18F-FDG Uptake in PET as an Early Pharmacodynamic Effect in Treatment of Non-Small Cell Lung Cancer with the mTOR Inhibitor Everolimus

Everolimus downregulates glucose metabolism-associated genes in preclinical models. Inhibition of glucose metabolism measured by F-18-FDG PET was postulated to serve as a pharmacodynamic marker in everolimus-treated non-small cell lung cancer (NSCLC) patients. Methods: In 8 NSCLC patients treated with everolimus, the percentage change in F-18-FDG PET uptake (days 8 and 28 relative to baseline) was determined using a variety of summed standardized uptake value (SUV) measures. Both maximum and mean SUVs were used, with normalizations to body surface area and body weight and with and without correcting for plasma glucose levels. Results: In 5 patients, a reduction of F-18-FDG PET uptake on day 8 was observed with all methods, ranging from -12.8% to -72.2%. Conclusion: These observations demonstrate that inhibition of glucose metabolism is an early effect of everolimus treatment in NSCLC patients and can be assessed using F-18-FDG PET.