CHICAGO – Etanercept monotherapy showed greater efficacy, compared with methotrexate monotherapy for the treatment of psoriatic arthritis, and combining the two agents provided no benefit over etanercept alone for most outcomes in the randomized, controlled, international, phase 3 SEAM-PsA study.
A 20% improvement in American College of Rheumatology criteria at week 24 – the primary endpoint of the study – was significantly greater in 284 patients treated with etanercept monotherapy and in 283 patients treated with combination etanercept and methotrexate than in 284 patients treated with methotrexate monotherapy (60.9% and 65.0% vs. 50.7%, respectively),, of the Swedish Medical Center and the University of Washington, Seattle, and his colleagues reported in a late-breaking poster on the (Etanercept and Methotrexate in Subjects with Psoriatic Arthritis) study at the of the American College of Rheumatology.
The key secondary endpoint of minimal disease activity response at week 24 also was significantly greater in the etanercept monotherapy and combination groups than in the methotrexate monotherapy group (35.9% and 35.7% vs. 22.9%, respectively), the investigators noted.
Additionally, at week 48, the etanercept monotherapy group and combination group both showed less radiographic progression than did the methotrexate monotherapy arm (mean change in modified total Sharp score from baseline, –0.04 and –0.01 vs. 0.08).
Overall, the etanercept monotherapy group and combination therapy group had similar results, with some differences in skin outcomes. Treatment was well tolerated, and except for more nausea occurring with methotrexate, adverse event rates were similar in the three study arms. No new safety signals were observed.
“The most common serious adverse events were infections and infestations, which occurred in 1.1% of patients in the methotrexate monotherapy arm, 2.8% of patients in the etanercept monotherapy arm, and 2.5% of patients in the combination therapy arm,” they wrote.
Study participants were biologic-naive adults with active PsA and no prior methotrexate treatment for their disease. They had a mean age of 48.4 years, most were white, and median disease duration was 0.6 years.
They were randomized to receive either 50 mg subcutaneous injections of etanercept plus oral placebo weekly, 50 mg subcutaneous etanercept plus 20 mg oral methotrexate weekly, or 20 mg oral methotrexate plus placebo injections weekly; the groups were well balanced with respect to baseline characteristics, the investigators said.
Rescue therapy of etanercept plus methotrexate was given after 24 weeks in patients with less than 20% improvement in tender joint counts and swollen joint counts from baseline.
“Agents used to treat PsA include disease-modifying antirheumatic drugs such as methotrexate and tumor necrosis factor inhibitors, but how to optimally use these agents to treat PsA is unknown,” they wrote, explaining that while methotrexate is widely used in this setting, little clinical evidence exists to guide its use, and that while tumor necrosis factor inhibitors have shown efficacy in PsA, the benefit of adding methotrexate remains unclear.
The current findings, however, demonstrate that adding methotrexate does not appear to increase the efficacy of etanercept monotherapy for most outcomes.
An exception was with combination therapy for some skin-related outcomes, including percent improvement in psoriasis-affected body surface area and percentage of patients with “status clear or almost clear,” they said.
Further, methotrexate monotherapy in this study appeared to have some “meaningful efficacy for both articular and nonarticular PsA symptoms,” the investigators noted.
“These results provide information of practical value for clinical practice when considering treatment option for PsA,” they concluded.
The study was supported by Amgen. Dr. Mease reported receiving research grants, speaker fees, and/or consulting fees from AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Galapagos, Genentech, Janssen Pharmaceuticals, Eli Lilly, Novartis, Pfizer, Sun Pharmaceutical, and UCB.
SOURCE: Mease PJ et al. Arthritis Rheumatol. 2018;70(Suppl 10): .