“We believe that prescribing this combination in routine practice is viable when combined with shared decision-making and strict monitoring of side effects,” write Michelle L.M. Mulder, MD, of the department of rheumatology at Sint Maartenskliniek in Nijmegen, the Netherlands, and her coauthors. Their findings were published in The Lancet Rheumatology.
The latest treatment guidelines from the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis and the European Alliance of Associations for Rheumatology recommend conventional synthetic disease-modifying antirheumatic drugs for patients with active PsA, but Dr. Mulder and her colleagues note a distinct lack of information on their effectiveness, especially this particular combination.
To assess the efficacy and safety of methotrexate plus leflunomide, they launched a single-center, double-blind, randomized trial that included 78 Dutch patients with PsA. The majority of the participants in this trial – dubbed COMPLETE-PsA – were men (64%), and the median age of the patients was 55 years. All had active disease at baseline; the median swollen joint count (SJC) and tender joint count were 4.0 in both groups.
Participants were assigned to receive either methotrexate plus leflunomide (n = 39) or methotrexate plus placebo (n = 39). After 16 weeks, mean Psoriatic Arthritis Disease Activity Score (PASDAS) had improved for patients in the combination therapy group in comparison with the monotherapy group (3.1; standard deviation, 1.4 vs. 3.7; SD, 1.3; treatment difference, –0.6; 90% confidence interval, –1.0 to –0.1; P = .025). The combination therapy group also achieved PASDAS low disease activity at a higher rate (59%) than did the monotherapy group (34%; P = .019).
Other notable differences after 16 weeks included improvements in SJC for 66 joints (–3.0 in the combination therapy group vs. –2.0 in the monotherapy group) and significantly better skin and nail measures – such as active psoriasis and change in body surface area – in the methotrexate plus leflunomide group.
When asked who should be prescribed the combination therapy and who should be prescribed methotrexate going forward, Dr. Mulder told this news organization, “At the moment, we have insufficient knowledge on who will benefit most or who will develop clinically relevant side effects. It seems warranted to discuss with every patient which approach they would prefer. This could be a step-down or -up approach.
“We hope to be able to better predict treatment response and side effects in the future via post hoc analysis of our study and via extensive flow-cytometric phenotyping of immune blood cells taken at baseline,” she added.
Three patients in the combination therapy group experienced serious adverse events, two of which were deemed unrelated to leflunomide. The most frequently occurring adverse events were nausea or vomiting, tiredness, and elevated alanine aminotransferase. Mild adverse events were more common in the methotrexate plus leflunomide group. No participants died, and all patients with adverse events recovered completely.
“It appears good practice to do blood draws for laboratory tests on liver enzymes at least monthly for the first 4 months and every 4 months after that once stable dosing is achieved, as well as have a telephone consultation after 6-8 weeks to talk about possible side effects a patient might experience and change or add therapy if necessary,” Dr. Mulder added.