This randomized, placebo-controlled, double-blind, Phase 1 study assessed the magnitude, onset, and duration of response with intravenous (i.v.) and subcutaneous (s.c.) adalimumab (Humira, Abbott Laboratories) combined with methotrexate (MTX) in patients with active rheumatoid arthritis (RA) despite previous MTX therapy.
Fifty-four patients were randomized to two injections of i.v. or s.c. adalimumab (1 mg/kg) or placebo while continuing on MTX (mean dose, 15.7 mg/week). Dosing intervals were determined by the European League Against Rheumatism (EULAR) response criteria, and were allowed to range from 1 to 3 months. Efficacy was mainly assessed using the EULAR response criteria and the American College of Rheumatology (ACR) response criteria.
Moderate EULAR response was achieved at least once within 29 days after the first injection in 83% and 61% of patients receiving i.v. and s.c. adalimumab respectively, compared with 44% for placebo [probability (p) < or = 0.05 for i.v. adalimumab versus placebo]. A 20% improvement in disease activity according to the ACR criteria (ACR20 response) was achieved by 72% and 67% of patients receiving i.v. and s.c. adalimumab respectively, compared with 28% for placebo (p < or = 0.01 and p < or = 0.05, respectively, versus placebo). By Day 15 after the first and second injections, statistically significant moderate EULAR and ACR20 response rates were achieved with either i.v. or s.c. adalimumab compared with placebo (p < or = 0.05). The mean times to second injection for i.v. adalimumab, s.c. adalimumab, and placebo were 42.2 days (range: 27-84 days), 38.3 days (range: 26-85 days), and 28.4 days (range: 26-32 days), respectively (minimum time allowed by the protocol between the first and second injections was 4 weeks). Adalimumab in combination with MTX was well tolerated, with no patients being withdrawn because of adverse events.
Either i.v. or s.c. adalimumab added to MTX significantly improved the signs and symptoms of RA compared with MTX alone. Subcutaneously administered adalimumab appeared to provide a response that was as great, as rapid, and as enduring as that with i.v. adalimumab.