Interval prolongation of etanercept in rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis: a randomized controlled trial.

OBJECTIVE: The majority of patients with a rheumatic disease treated with etanercept may be overexposed. Data regarding etanercept tapering are scarce, particularly in psoriatic arthritis (PsA) and ankylosing spondylitis (AS). We compared extending the dose interval to continuation of the standard dose and studied the success rate of etanercept discontinuation. Etanercept concentrations were measured throughout the study. METHOD: 160 patients with rheumatoid arthritis (RA), PsA, or AS with sustained minimal disease activity (MDA) were enrolled in this 18-month, open-label, randomized controlled trial. The intervention group doubled the dosing interval at baseline and discontinued etanercept 6 months later. The control group continued the standard dose for 6 months and doubled the dosing-interval thereafter. The primary outcome was the proportion of patients maintaining MDA at 6 month follow-up. RESULTS: At 6 months, MDA status was maintained in 47 patients (63%) in the intervention group and 56 (74%) in the control group (p = 0.15), with comparable results in all rheumatic diseases. And median etanercept concentrations decreased from 1.50 µg/mL (interquartile range 1.06- 2.65) to 0.46 µg/mL (0.28-0.92). In total, 40% discontinued etanercept successfully with maintained MDA for at least 6 months. CONCLUSION: Etanercept tapering can be done without losing efficacy in RA, PsA, and AS patients in sustained MDA. A substantial proportion of patients could stop etanercept for at least 6 months. In many patients, low drug concentrations proved sufficient to control disease activity. However, the risk of minor and major flares is substantial, even in patients continuing standard dosing.

Serum drug concentrations to optimize switching from adalimumab to etanercept in rheumatoid arthritis.

Objectives: Inadequate response to adalimumab can be caused by insufficient blockade of the target tumour necrosis factor (TNF) at low serum concentrations. In such cases, patients may respond to another TNF inhibitor. We investigated whether the serum adalimumab concentration is related to the efficacy of a second TNF inhibitor, etanercept, in rheumatoid arthritis (RA). Methods: Patients with RA starting etanercept treatment were prospectively observed in the Reade Rheumatology Registry. In patients previously on adalimumab, serum concentrations were determined before treatment discontinuation. According to this concentration, three subgroups were formed: < 0.5 µg/mL, 0.5-5.0 µg/mL, and ≥ 5.0 µg/mL. The European League Against Rheumatism (EULAR) good/moderate response rate after 52 weeks of etanercept was compared between the switcher subgroups and biologic-naive patients. Results: In total, 449 consecutive patients were included, of whom 69 switched from adalimumab (15%) and 380 were biologic naive (85%). EULAR good or moderate response was achieved by 74% of the biologic-naive patients and by 72%, 50%, and 52% of switchers with adalimumab concentration < 0.5 µg/mL, 0.5-5.0 µg/mL, and ≥ 5.0 µg/mL, respectively (p = 0.15). Patients with an adalimumab concentration ≥ 0.5 µg/mL were significantly less likely to achieve EULAR good/moderate response on etanercept compared to biologic-naive patients, whereas patients with a concentration < 0.5 µg/mL did not significantly differ from patients starting etanercept without prior biologic treatment. Conclusion: RA patients with an inadequate response to adalimumab, in the presence of sufficient drug concentrations, benefit less from switching to another TNF inhibitor, etanercept.