WE‐C‐BRC‐05: Use of FLT PET Imaging to Assess Tyrosine Kinase Inhibitor (TKI) Treatment Response

Background: Sunitinib (SU) is a tyrosine kinase inhibitor (TKI) with activity against VEGFR. During VEGFR TKI withdrawal, increased pain at sites of metastasis has been observed, which we hypothesize is due to the proliferative flare. [ 18 F ]‐fluoro‐3′‐deoxy‐3′‐L‐fluorothymidine (FLT) PET imaging was used as a marker of treatment response, to assess the proliferative flare and to investigate perfusion and vascular status of the tumor. Methods: 14 patients with advanced solid malignancies have been enrolled. SU was given at the standard dose of 50 mg for 4 weeks, followed by a 2 week break. 90‐minute dynamic FLT PET/CT scans were obtained at the baseline, week 4, and week 6. 8 patients with adequate follow‐up time were classified in two groups: with clinical benefit (CB; progressive disease (PD)>6 mo) or without clinical benefit (noCB; PD