Spiliopoulou A, et al. - In the current study, researchers ascertained if genetic effects on response to TNF inhibitors (TNFi) in rheumatoid arthritis (RA) could be localised by considering known genetic susceptibility loci for relevant traits and assessed the usefulness of these genetic loci for stratifying drug response. They used a sample of 2938 European ancestry individuals for whom full clinical and genome-wide association studies data were available. Findings revealed that it is difficult to interpret the association with the CD39 trait because TNFi is often prescribed to patients with RA after failing to respond to methotrexate. Investigators suggested that the pathways of CD39 and CD40 may be relevant for drug therapy targeting.