Durability of Response to Tocilizumab Therapy in Rheumatoid Arthritis: Data from the US-Based Corrona Rheumatoid Arthritis Registry

Introduction Understanding the durability of response to treatment and factors associated with failure to maintain response in a real-world setting can inform treatment decisions for patients with rheumatoid arthritis (RA). The aim of this study was to analyze durability of response to tocilizumab (TCZ) and factors associated with durability among US patients with RA in routine clinical practice. Methods TCZ initiators in the Corrona RA Registry were included. Durability of response was defined as maintaining continuous TCZ treatment and either an improvement of at least minimum clinically important difference (MCID) in Clinical Disease Activity Index (CDAI) score or low disease activity (LDA). Secondary analyses included patients treated with intravenous (IV) TCZ and excluded those who discontinued TCZ without reporting reasons for discontinuation. Durability was calculated with Kaplan–Meier survival analysis. Cox proportional hazards modeling identified factors associated with durability. Results Among 1789 TCZ initiators, 466, 272, and 162 were persistent (with or without durable response) with follow-up visits at 1, 2, and 3 years, respectively. Median MCID durability of response in CDAI was > 50% after 36 months overall, 26 months for TCZ-IV, and > 50% after 36 months for those with known reasons for discontinuation; longer durability was associated with increased duration of RA and higher baseline CDAI score and shorter durability with history of malignancy and history of diabetes. Median LDA durability of response was 13.0 months overall, for TCZ-IV, and for those with known reasons for discontinuation; shorter durability was associated with history of malignancy, history of diabetes, and higher baseline CDAI score. Conclusions Median durability of response to TCZ in RA was > 3 years when defined as maintenance of MCID in CDAI score and > 1 year with the more stringent criteria of maintenance of LDA. Trial Registration ClinicalTrials.gov identifier, NCT01402661