A Randomized, 2x2 Factorial Design Biomarker Prevention Trial of Low-dose ASA and Metformin in Stage I-III Crc Patients

Epidemiological studies and cardiovascular prevention trials have shown that low-dose aspirin (ASA) can inhibit colorectal cancer (CRC) incidence and mortality, including inhibition of distant metastases. Metformin (MET) has also been associated with decreased CRC incidence and mortality in meta-analyses of epidemiological studies in diabetics and has been shown to decrease by 40% colorectal adenoma recurrence in a randomized trial. Recent studies have shown that ASA is an inhibitor of mTOR/S6K1 and an activator of AMPK, targeting regulators of intracellular energy homeostasis and metabolism, and that the combination of ASA and MET, another AMPK activator and S6K1 inhibitor, has a striking additive effect on AMPK activation and mTOR inhibition, with increased autophagy and decreased cell growth in CRC cell lines. While both drugs are being tested as single agents, their combination has not been tested in trials. This is a randomized, placebo-controlled, double blind, 2x2 biomarker trial of ASA and MET to test the activity of either agent alone and the potential synergism of their combination on a set of surrogate biomarkers of colorectal carcinogenesis. After surgery 160 patients with stage I-III colon cancer will randomly be assigned in a four-arm trial to either ASA, 100 mg day, MET 850 mg bid, their combination, or placebo for one year. The primary endpoint biomarker is the change, defined as the difference between pre- and post-treatment expression of nuclear factor kappa-B (NFκB), in the unaffected mucosa of proximal and distal colon obtained by multiple biopsies in two paired colonoscopies one year apart. Additional biomarkers will include: 1) the genomic profile of candidate genes, pathways, and overall genomic patterns in tissue biopsies by genome wide gene expression arrays; 2) the IHC expression of tissue pS6K, p53, beta-catenin, PI3K; 3) the associations of mutations and SNPs with treatment response by next generation sequencing of primary tumors; 4) the measurement of circulating IL-6, CRP and VEGF and 5) plasma and colonic MET concentrations and their correlation with biomarker profiles.