The role of concomitant methotrexate in biologic therapy for rheumatoid arthritis.

From the first use of biologic therapy for the management of rheumatoid arthritis, methotrexate (MTX) has been commonly used as co-therapy. There are a number of mechanistic reasons why MTX may improve the efficacy of biologics, including reduced antigenicity as well as reduced clearance of the biologic agent. Clinical trial data for tumor necrosis factor inhibitors and for other biologic agents does suggest added efficacy when these agents are used in combination with MTX. One exception may be the interleukin-6 receptor antibody tocilizumab, for which there is some data to suggest that monotherapy may be as effective as combined therapy with MTX. Post-marketing registry data also supports the concomitant use of MTX with biologics, with evidence for greater efficacy and longer persistence on treatment when compared with monotherapy.