Objectives To investigate etanercept (ETN) serum levels and anti-etanercept antibodies (AEA) and evaluate whether ETN levels are associated with SDAI remission in rheumatoid arthritis patients in DAS28 remission treated with full-dose (25 mg twice weekly) and low-dose (25 mg once weekly) ETN.
Methods We selected 70 patients in stable (≥12 months) full-dose (35) or low-dose (35) ETN, in remission (DAS28<2.6 for ≥12 months) and with a treatment duration ≥5 years. AEA and basal ETN levels were tested by ELISA. A cut-off >142AU/ml was adopted for defining positive AEA. A concentration of ETN ≥3.1μg/mL was considered as a high ETN level . Multivariate regression analysis was used to investigate whether high ETN levels were associated with SDAI remission.
Results One blood sample in the low-dose group resulted inadequate. AEA were present in 1 patient in low-dose (1/34, 2.9% low-dose ETN vs 0/35, 0% full-dose ETN, p=0.507). Full-dose and a lower weight were associated with high ETN levels: 15/35, 42.9% vs 3/34, 8.8% p=0.001 and 55.0 kg (57.0;80.0) and 65.0 (51.0;69.8), p=0.014 for high and low ETN levels respectively. Lower ETN levels, low-dose and a longer low-dose duration were associated with SDAI remission but were not confirmed with multivariate regression (Table 1).
Conclusions AEA are almost absent in patients in stable remission, patient with full-dose ETN and lower weight have higher ETN levels. ETN levels are not predictive of SDAI remission.
Daïen CI, Daïen V, Parussini E, et al. Etanercept concentration in patients with rheumatoid arthritis and its potential influence on treatment decisions: a pilot study. J Rheumatol 2012.39(8):1533–8.
Disclosure of Interest None declared