Influence of rheumatoid factor on serum drug levels of TNF inhibitors with different structures in rheumatoid arthritis.

OBJECTIVES: Certolizumab pegol (CZP), an Fc-free antibody fragment, has shown stable serum levels and steady efficacy in the treatment of RA patients, irrespective of RF levels at baseline. Here, we examine, in clinical practice, the effect of baseline RF and ACPA levels on serum drug levels of IFX, ADL and CZP an Fc-free antibody fragment. METHODS: This is a retrospective study performed in real-world patients. We assessed 170 patients with RA: 90 (53%) received IFX, 48 (28%) ADL and 32 (19%) CZP. Demographic and clinical variables, RF and ACPA levels were obtained at the baseline visit (T0), and patients were stratified based on negative, low, medium, or high levels. After 6 months (T6) serum drug levels and anti-drug antibodies (ADAb), were computed. RESULTS: While CZP serum levels did not differ across RF groups at T6, high baseline RF was linked to lower serum drug levels compared to RF negative status in treatment with complete monoclonal antibodies IFX and ADL. No differences in disease activity measured by DAS28 at baseline were observed across RF quartiles in patients treated with IFX or ADL. ADAb was observed in 26 patients with IFX, 3 with ADL and 1 with CZP, following 6 months of treatment. Patients with high baseline RF levels dropped out more frequently by secondary non-response in IFX or ADL than CZP (80% vs. 75% vs. 33%, p=0.002). CONCLUSIONS: In this real word data evaluation, CZP serum levels were independent of RF levels in patients however patients with high baseline RF levels who obtained IFX or ADL had lower serum drug levels at 6 months than baseline RF-negative patients. In addition, secondary non-response was more frequent in patients with high RF levels treated with IFX and ADL.

Are we treating women patients with real axial spondyloarthritis?

INTRODUCTION: During the last years, regulatory agencies raised some relevant concerns with regard to the possibility of administrating biological therapy (BT) to non-SpA patients. Especially, the possibility of treating women with fibromyalgia as non-radiographic axSpA (nr-axSpA) was mentioned. OBJECTIVES: To evaluate if the gender distribution and clinical pattern of patients with axSpA initiating biological therapy (BT) was modified in clinical practice after its approval for non radiographic-axSpA (nr-axSpA). METHODS: Baseline dataset from a prospective ongoing cohort including all patients with axSpA treated with BT at the Rheumatology Department of University Hospital La Paz, Madrid, Spain, was analysed. Patient's characteristics and disease activity parameters were collected. Based on the approval indication date of BT for nr-axSpA, patients were classified in two periods according to the starting date for the first BT: period 1 (before 2013) and period 2 (during or after 2013). Gender distribution and disease' characteristics were compared between both groups using Chi-square and Student-t tests. RESULTS: In total, 385 patients initiated BT: 266 (69%) in period 1 and 119 (31%) in period 2. No significant differences between both periods were observed regarding gender distribution (38% and 39% of women; p = 0.8). Out of those patients with nr-axSpA initiating BT in period 2, the majority (60%) were men. Women starting BT in period 2 had significantly higher systemic inflammation and mobility restriction compared with women in period 1 [median (interquartile range) CRP 10.2 mg/l (3.0-24.9) vs 3.2 mg/l (2.0-9.4); p = 0.02 and BASMI 2.7 (1.8-3.5) vs. 2.0 (1.2-2.6); p = 0.01, respectively]. In addition, they also presented significantly higher disease activity [BASDAI 6.5 (5.4-8.0) vs. 5.8 (4.6-6.8); p = 0.02; ASDAS, mean (SD) 3.6 ± 3.4 vs. 3.2 ± 1.0; p = 0.02, respectively] and more functional limitation [BASFI 5.7 (3.8-6.7) vs. 4.3 (2.0-6.1); p = 0.01, respectively] than men treated in period 2. CONCLUSIONS: In our clinical practice, the frequency of women who started BT did not increase since their approval for nr-axSpA. Women treated with BT after 2012 had more objective disease activity parameters than before their approval for nr-axSpA treatment.