A pilot study evaluating the safety and impact of pretreatment with metformin on colorectal cancer stem cells (CCSC) in patients undergoing resection.

e14581 Background: The cancer stem cell (CSC) hypothesis of tumorigenesis suggests that unlike most cancer cells within a tumor CSC resist chemotherapy and can regenerate various cell types in tumor thereby causing relapse. Hence drugs that selectively target CSC may offer great promise for cancer therapy especially when combined with chemotherapy. Current treatment options for CRC rely on combination of surgical resection, cytotoxic and targeted drugs. Recent findings showed that metformin, an antidiabetic drug was associated with a significantly lower risk of CRC (0.63 [0.47–0.84]; P = 0.002) in pts with type 2 diabetes. We therefore hypothesize that administration of metformin will reduce CSC in human CRC. Methods: CRC pts undergoing resection of primary tumor were enrolled. Metformin was administered at 500mg orally twice daily for 2 wks and terminated 24 hrs prior to planned surgery. Both tumor and normal tissue was procured. Adverse events (AEs) were graded according to NCI CTCAE Version 3.0. Metfor...