medwireNews: Phase III trial results suggest that ABP 501 – the first US FDA-approved adalimumab biosimilar – has a similar efficacy, safety, and immunogenicity profile to its reference drug for the treatment of patients with moderate-to-severe rheumatoid arthritis (RA).
Stanley Cohen (University of Texas Southwestern Medical School, Dallas, USA) and study co-authors randomly assigned patients with a mean age of 55.9 years and duration of 9.39 years since diagnosis to receive treatment with ABP 501 at a dose of 40 mg every 2 weeks, or adalimumab at the same dose.
They found that 74.6% of 260 patients in the ABP 501 group achieved at least a 20% improvement in ACR criteria (ACR20) at week 24 compared with 72.4% of 261 patients in the adalimumab group, giving a risk ratio (RR) of 1.039.
The 90% confidence interval of the RR “was well within the predefined equivalence margin,” which demonstrated “clinical equivalence between ABP 501 and adalimumab,” report the researchers in the Annals of the Rheumatic Diseases.
The proportion of patients receiving at least a 50% or 70% improvement in ACR criteria at week 24 was also comparable in the ABP 501 and adalimumab groups, at 49.2% versus 52.0% and 26.0% versus 22.9%, respectively, and patients in both groups experienced a reduction from baseline in Disease Activity Score 28-joint count based on C-reactive protein (DAS28-CRP) of 2.32 points.
Half of patients receiving ABP 501 and 54.6% of those receiving adalimumab experienced at least one treatment-emergent adverse event. The most common adverse events reported by more than 3% of participants 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 were reported by 3.8% and 5.0% of patients, respectively.
These findings “indicate that ABP 501 and adalimumab have similar safety profiles,” say the study authors, noting that no new safety signals were identified in this study compared with other clinical trials of adalimumab in patients with RA.
The team also found that a similar percentage of patients in the ABP 501 and adalimumab groups tested positive for binding and neutralizing antibodies throughout the trial, at 38.3% versus 38.2% and 9.1% versus 11.1%, respectively, demonstrating similar immunogenicity of the two compounds.
“Since biosimilars are not identical molecules, the determination of immunogenicity by ADA formation is a major part of the registration programme for approval,” explain Cohen and colleagues.
And the researchers conclude that “[t]aken together, these data contribute to the totality-of-evidence-based requirements to demonstrate that ABP 501 is similar to adalimumab,” making the biosimilar a “valuable new therapeutic option for the treatment of moderate to severe RA.”
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