A study of >110,000 adult patients with cancer at Vanderbilt and the Mayo Clinic over 15 years demonstrated that in the subset with type II diabetes, metformin was associated with improved cancer survival and a 22% lower overall mortality compared to other oral hypoglycemics or insulin.47 These data support previous studies suggesting that metformin could produce a beneficial effect in a range of cancers. Phenome scanning in follow-up to a very large GWAS of rheumatoid arthritis (RA) identified pleiotropic disease or biomarker associations for approximately two-thirds of 98 RA-associated genes.48 These data then suggest that drugs currently marketed for such “pleiotropic” disease associations might be also effective in rheumatoid arthritis or in subsets of patients with rheumatoid arthritis. Some of these drug targets (anti-TNF agents, rituximab) are already used in the disease while others have been developed for other conditions, notably malignancies and have not yet entered human trials for rheumatoid arthritis.43
