[18F]FLT-PET as a Predictive Imaging Biomaker of Treatment Responses to Regorafenib

Regorafenib will be administered 160 mg/day given orally on day 1 to days 21 following 7 days break, which consists of 4 weeks as 1 cycle. Treatment will be repeated every 4 weeks and continued until disease progression, unacceptable toxicity or the patient's refusal.

\[18F\]FLT-PET scans before and on 21st day from the administration of regorafenib.

\[18F\]FDG-PET will be performed before treatment and at 21 days after treatment.