Ann Rheum Dis 2016 Jan 5 DOI: 10.1136/annrheumdis-2015-208426 [Epub ahead of printMTX is the primary drug in RA management because of its long-term effectiveness and safety profile; however, in patients who have insufficient response (IR) to MTX, treatment adjustments are needed – either to combine a bDMARD with MTX or to switch to a bDMARD from MTX. In the SURPRISE study, the efficacy and safety of adding TCZ to MTX (ADD-ON) or switching MTX to TCZ (SWITCH) was evaluated in 233 patients with moderate to highly active RA who were randomised 1:1. Both treatment groups were administered TCZ 8 mg/kg every 4 weeks, and in the ADD-ON group, baseline MTX dosage was maintained throughout the study. The primary efficacy endpoint was DAS28 at week 24 and ΔmTSS radiographic assessment from baseline to week 52. Physical signs, laboratory tests, and AEs were monitored throughout the study. At week 24, remission rates in the ADD-ON group (69.6%) were significantly higher than in the SWITCH group (55.0%); however, by week 52, remission rates were comparable (72.2% and 70.3% for ADD-ON and SWITCH, respectively). Radiographically, ADD-ON was superior to SWITCH. Although the clinically relevant radiographic progression (CRRP) was not significantly different between the two groups, ΔmTSS in CRRP patients was significantly larger in the SWITCH group than the ADD-ON group supporting ADD-ON as a better strategy for preventing radiological progression. The overall number of AEs was significantly higher in the ADD-ON vs. SWITCH group, but serious AEs were comparable. Although the clinical efficacy at week 52 was comparable between treatment groups, the ADD-ON group showed continued superiority to the SWITCH group in radiographic progression. The authors posit that the MTX might have provided some extent of inflammation downregulation even though the patients were MTX-IR. This is reflected in the differing disease activity in the first 24 weeks, which impacted radiological outcomes at week 52. Future studies could focus on additional strategies of stopping or decreasing MTX after TCZ has made a sufficient contribution.