The study met the primary endpoint, which was achievement of ACR20 (20% or greater improvement in ACR assessment) at week 24. At week 24, 74.6% of patients in the ABP 501 group and 72.4% in the adalimumab group met the ACR20 response criteria. The risk ratio of ACR20 was 1.039 with the two-sided 90% CI of 0.954-1.133, which fell within the predefined equivalence margin.
"Demonstrating biosimilarity is scientifically complex, but Amgen's 35 years of proven biologic R&D experience is facilitating the advancement of exciting programs like ABP 501," said Sean E. Harper, executive vice president of R&D at Amgen. "Our long-term commitment to advancing care in inflammation is as strong as ever, with a portfolio of novel and biosimilar compounds that have the potential to benefit patients worldwide."
ABP 501 is being developed as a biosimilar candidate to adalimumab, an anti-TNF-a monoclonal antibody, which is approved in many countries for the treatment of inflammatory diseases, including moderate-to-severe rheumatoid arthritis, moderate-to-severe plaque psoriasis, moderate-to-severe polyarticular juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, moderate-to-severe Crohn's disease and moderate-to-severe ulcerative colitis.
Secondary endpoints included the achievement of ACR50 and ACR70 (a 50 or 70 percent improvement in ACR assessment) within the predefined equivalence margin. At week 24, patients treated with ABP 501 compared with those treated with adalimumab achieved ACR50 (49.2% vs. 52.0%) and ACR70 (26.0% vs. 22.9%), respectively. Additionally, the secondary endpoint of a difference in change from baseline of DAS28-CRP (Disease Activity Score examines 28 joints in the body as measured by C reactive protein in the blood) over the entire study was also achieved. The difference in mean change from baseline in DAS28-CRP between ABP 501 and adalimumab was -0.01 (90% CI, -0.18 to 0.17) at week 24.
The incidence of treatment-emergent adverse events (TEAEs) was 50% for ABP 501 and 55% for adalimumab. The most frequently reported TEAEs (for ABP 501 and adalimumab, respectively) were nasopharyngitis (6.4% vs. 7.3%), headache (4.5% vs. 4.2%), arthralgia (3.0% vs. 3.4%), cough (2.7% vs. 3.1%) and upper respiratory tract infection (1.5% vs. 3.8%). Serious adverse events (3.8% vs. 5.0%) and serious infections (0.8% vs. 1.1%) were reported in patients treated with ABP 501 and adalimumab, respectively. By the end of week 24, binding antibodies (38.3% vs. 38%) and neutralizing antibodies were identified (9.1% vs. 11.1%) in patients treated with ABP 501 and adalimumab, respectively.
