1612: Window of opportunity with tocilizumab therapy in giant cell arteritis. Multicenter study of 471 patients of clinical practice

Background/Purpose: Tocilizumab (TCZ) is the only biological drug currently approved for the treatment of giant cell arteritis (GCA), regardless of GCA duration. The “window of opportunity” is an increasingly widespread in different immune mediated inflammatory diseases, such as rheumatoid arthritis or psoriatic arthritis. Window of opportunity is usually defined as the chance of achieving remission depending on early treatment. Our aim was to assess the window of opportunity in a wide series of GCA patients treated with TCZ in clinical practice.

Methods: Multicenter observational study of GCA patients treated with TCZ. Accordingly, to definitions of clinical trials in GCA, two groups of GCA were considered, “newly diagnosed GCA” and “relapsing GCA” depending on GCA diagnosis was made ≤6 or >6 weeks before initiation of TCZ, respectively. Window of opportunity in GCA was defined as the chance of achieving GCA-EULAR remission criteria (clinical and analytical remission). In addition, a multivariable study of associative factors with window of opportunity at 24 months of initiation of TCZ was conducted (logistic regression analysis).

Results: 471 patients (n=342; 72.6% female); mean age: 73.5±9 years were included. “Newly GCA” were 91 (19.3%) patients and “relapsing GCA”, 380 (80.7%). In the newly diagnosed GCA, headache and visual impairment were statistically more frequent and median ESR and CRP were higher (Table 1).

After 52 weeks of treatment, EULAR remission was similar regardless of time to TCZ initiation (Figure 1A,B&C), and GCA phenotypes (Figure 1D). In the multivariable analysis there was a non-statistically higher trend to a EULAR remission when TCZ initiation was shorter from GCA diagnosis, OR 0.985 (0.970-1.000) (Table 2).

Conclusion: In contrast with the “window of opportunity” observed in other immune mediated inflammatory diseases, a delay in the initiation of TCZ therapy in GCA may not decrease its effectiveness (EULAR remission) in clinical practice.