Full 52-week results of the study, which included a switch from the reference adalimumab to SB5, demonstrate that the biosimilar was well tolerated and that switching led to no change in treatment-emergent adverse events.
Previously reported results of a phase 3 trial of Samsung Bioepis’ SB5, a biosimilar adalimumab candidate referencing Humira, found that the biosimilar and the reference product had similar safety and efficacy at week 24 in patients with rheumatoid arthritis (RA).
Now, the full 52-week results of the study, which included a switch from the reference adalimumab to SB5, demonstrate that the biosimilar was well tolerated and that switching led to no change in treatment-emergent adverse events (TEAEs).
In the trial, conducted at 51 sites in 7 countries, patients with RA were initially randomized to receive either SB5 (n = 271) or the reference adalimumab (n = 273), at a dose of 40 mg per week, through week 24. Then, patients receiving the reference were randomized again to either continue their treatment (n = 129) or switch to SB5 (n = 125) up to week 52. Patients who received SB5 for the first 24 weeks continued to receive the biosimilar.
Efficacy was not affected after a transition to the biosimilar, say the study authors; at week 52, the percentage of patients achieving American College of Rheumatology (ACR) criteria for 20%, 50%, and 70% improvement in the group that received the reference continuously was 73.4%, 50.8%, and 28.2%, respectively. In the group that switched to the biosimilar, the rates were 78.8%, 54.2%, and 26.3%, respectively.
Safety was also similar among patients who switched versus those who did not; 37.6% of those who switched experienced at least 1 TEAE, as did 32.3% of those who remained on SB5 and 33.1% of those who remained on the reference adalimumab. Serious TEAEs were observed in 3.2% of those who switched, in 2.4% of those who remained on SB5, and 3.1% of those who remained on the reference adalimumab.
The emergence of antidrug antibodies (ADAs) was comparable among groups; emergent ADAs after week 24 were detected in 6.3% of patients in the switch group, 5.6% of patients in the biosimilar group, and 18.3% of patients in the reference group. Increases in titers of ADAs were also similar, with increases observed in 35.6% of the switch group, 33.0% of the biosimilar group, and 30.8% of the reference group.
The authors concluded that, at 1 year, SB5 was well tolerated, safe, and effective, and that switching from the reference Humira to SB5 did not increase TEAEs or immunogenicity, and did not result in a loss of efficacy.
Weinblatt ME, Baranauskaite A, Dokoupilova E, et al. Switching from reference adalimumab to SB5 (adalimumab biosimilar) in patients with rheumatoid arthritis. Arthritis Rheumatol. 2018;70(6): 832-840. doi: 10.1002/art.40444.