Leflunomide versus methotrexate: a comparison of the European and American experience

Abstract

This paper compares and contrasts the results of two major Phase III clinical trials that compared the efficacy and safety of leflunomide, a new disease-modifying antirheumatic drug (DMARD), and methotrexate. In both the American trial (US301) and the multinational trial (MN302), patients with active rheumatoid arthritis (RA) were given either leflunomide (20 mg/day after a loading dose of 100 mg/day for 3 days) or methotrexate (7.5-15 mg/week) for 52 weeks. US301 was also placebo-controlled. Folate supplementation was mandatory in US301 but was given to < 10% of the patients in MN302. In US301, American College of Rheumatology (ACR) 20% response rates and improvement in tender and swollen joints were significantly better than placebo in both treatment groups, but were not significantly different from each other. Both treatments significantly retarded radiographically assessed progression of RA compared to placebo, but the degree of retardation was significantly greater with leflunomide. In MN302, the ACR response rate and improvement in tender and swollen joints with leflunomide were similar to those seen in US301. The ACR response rate and improvements in all efficacy variables with methotrexate were significantly greater than with leflunomide, however. Radiographically assessed disease progression was not statistically different with the two treatments. Use of methotrexate without folate in MN302 was associated with a higher incidence of clinically significant elevations of liver enzyme levels. These results indicate that both leflunomide and methotrexate are effective DMARDs. The symptomatic relief provided by both drugs is similar when they are given with folate supplementation.