Drs. Bessette and Kinch reply.

We thank Dr. Tchetina for their interest in our article, and we appreciate the opportunity to respond to their Letter to the Editor. In the letter and their recent publication, Tchetina et al describe the utility of gene expression analyses using peripheral blood mononuclear cells (PBMCs) from patients with rheumatoid arthritis (RA) to predict clinical response to tofacitinib (TOF)..