18F-FDG and 18F-FLT-PET Imaging for Monitoring Everolimus Effect on Tumor-Growth in Neuroendocrine Tumors: Studies in Human Tumor Xenografts in Mice

Everolimus is a licenced medication for treatment of pancreatic NETS. Everolimus is a mTOR inhibitor has shown promising results in some but not all NETs. It would be helpful to be able assess response to therapy. Therefore, this study investigated the in vivo and in vitro treatment effect of everolimus in NET cell lines.

The effect of everolimus on the human NET cell line H727 was examined using the MTT assay and then underwent a baseline FDG or F-FLT PET scan, followed by therapy with placebo or everolimus for 10 days, following with repeat PET scans at day 1,3 and 10.

Everolimus showed significant inhibition of H727 cell proliferation in vitro at concentrations above 1nM. In vivo tumour volumes relative to baseline were significantly lower in the everolimus group compared to the control group.

Uptake of F-FDG at day 3 correlated with tumour growth day 10, whilst F-FLT uptake at day 1 predicted tumour growth on day 7.

This study demonstrates in principle PET imaging may be used to tailor therapy for NET patients through early identification of responders and non-responders.

Source: PLoS One