A Phase IIa Trial of Metformin for Colorectal Cancer Risk Reduction among Individuals with History of Colorectal Adenomas and Elevated Body Mass Index: Clinical trial of metformin in obese adenoma patients
التفاصيل البيبلوغرافية
العنوان:
A Phase IIa Trial of Metformin for Colorectal Cancer Risk Reduction among Individuals with History of Colorectal Adenomas and Elevated Body Mass Index: Clinical trial of metformin in obese adenoma patients
Obesity is associated with risk of colorectal adenoma (CRA) and colorectal cancer (CRC). The signaling pathway activated by metformin (LKB1/AMPK/mTOR) is implicated in tumor suppression in Apc(Min/+) mice via metformin-induced reduction in polyp burden, increased ratio of pAMPK/AMPK, decreased pmTOR/mTOR ratio, and decreased pS6(Ser235)/S6(Ser235) ratio in polyps. We hypothesized that metformin would affect colorectal tissue S6(Ser235) among obese patients with recent history of CRA. A phase IIa clinical biomarker trial was conducted via the U.S. National Cancer Institute-Chemoprevention Consortium. Non-diabetic, obese subjects (BMI ≥30) age 35–80 with recent history of CRA, were included. Subjects received 12 weeks of oral metformin 1000mg twice daily. Rectal mucosa biopsies were obtained at baseline and end-of-treatment (EOT) endoscopy. Tissue S6(Ser235) and Ki-67 immunostaining were analyzed in a blinded fashion using Histo score (Hscore) analysis. Among 32 eligible subjects, the mean baseline BMI was 34.9. Comparing EOT to baseline tissue S6(Ser235) by IHC, no significant differences were observed. Mean (SD) Hscore at baseline was 1.1 (0.57) and 1.1 (0.51) at EOT; median Hscore change was 0.034 (p=0.77). Similarly, Ki-67 levels were unaffected by the intervention. The adverse events were consistent with metformin’s known side effect profile. Among obese CRA patients, 12 weeks of oral metformin does not reduce rectal mucosa pS6 or Ki-67 levels. Further research is needed to determine what effects metformin has on the target tissue of origin as metformin continues to be pursued as a CRC chemopreventive agent.
