The investigational infliximab biosimilar drug SB2 provided efficacy and safety equivalent to the originator drug Remicade in patients with moderate to severe rheumatoid arthritis in a phase III study that studied the drugs in combination with methotrexate.
Treatment with SB2, which is under development by Samsung Bioepis, met the prespecified definition of equivalence to Remicade on the primary efficacy endpoint of American College of Rheumatology 20 response rate at 30 weeks by staying within a margin of −15% and +15% on the 95% confidence interval of the ACR20 rate difference (64.1% for SB2 vs. 66.0%; 95% CI, –10.26% to 6.51%). Other efficacy outcomes also showed similarity between SB2 and Remicade, including disease activity score based on 28 joints, simplified disease activity index, clinical disease activity index, and European League Against Rheumatism (EULAR) response, Dr. Jung-Yoon Choe of Daegu Catholic University Medical Center, South Korea, and colleagues reported.
Treatment-emergent adverse events occurred in 58% of patients in both groups, including 9% with at least one serious event in each group. Latent tuberculosis (TB) infections occurred in 6%-7% of patients, and none developed active TB after prophylaxis. Serious infection or active TB occurred in 3.1% of SB2 and 2.0% of Remicade patients. Only one patient in each group developed active TB, and neither had latent TB at screening.
The trial involved 584 patients who were randomized double blind to 3 mg/kg IV infusion of either drug at week 0, week 2, week 6, week 14, week 22, and week 30. The patients took 10-25 mg/week oral or parenteral methotrexate along with 5-10 mg/week folic acid. The investigators allowed nonsteroidal anti-inflammatory drugs and corticosteroids at doses equivalent to 10 mg or less prednisolone if they had been taken on a stable dose for 4 weeks before randomization. Each patient had to have had RA for at least 6 months with least six tender joints and six swollen joints, as well as an erythrocyte sedimentation rate of 28 mm/h or greater or a C-reactive protein level of 1.0 mg/dL or higher. Patients had to take methotrexate for at least 6 months with a stable dose for the 4 weeks before randomization.
Read the full study in Annals of the Rheumatic Diseases ( 2015 Aug. 28 doi: 10.1136/annrheumdis-2015-207764 ).