Safety and efficacy data of ABP 501 have been confirmed in an open-label extension trial of the biosimilar. Data were published in Arthritis Research and Therapy.

Patients who completed a previous phase 3 study comparing ABP 501 with adalimumab in the treatment of moderate to severe rheumatoid arthritis (RA) (ClinicalTrials.gov identifier NCT01970475) were enrolled in an open-label extension study (Long-term Safety and Efficacy of ABP 501 in Subjects with Moderate to Severe Rheumatoid Arthritis; ClinicalTrials.gov identifier NCT02114931). Key safety and efficacy end points of this study included treatment-emergent (TEAEs) and serious adverse events, antidrug antibody incidences, and American College of Rheumatology (ACR)20 criteria and 28-item Disease Activity Score with C-reactive protein (DAS28-CRP) changes from baseline.

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The parent study included 494 patients treated with ABP 501 or adalimumab. Of those patients, 229 from the ABP 501 arm and 237 from the adalimumab arm participated in the current clinical trial. In total, 467 patients (81.2% women; 94.6% white) participated in the current study, with 88.2% of patients reaching completion. Nearly three-quarters (72.4%) of patients were treatment-naïve for prior biologic treatment for RA.

All participants received 40 mg of the ABP 501 biosimilar every other week for a period of 68 weeks. The rates of TEAEs and serious adverse events were 63.7% and 9.9%, respectively. Among TEAEs, 9% of events were grade ≥3. In addition, 17 patients who experienced these events discontinued their participation in the study.

In terms of key safety end points, 18.2% and 6.9% of patients developed binding or neutralized antidrug antibodies, respectively. The ACR20 response rate was 73.3% at baseline and 78.8% at week 70. Overall mean change in DAS28-CRP was −2.25 to −2.60 from baseline to week 70, with change noted at weeks 4 (−2.36), 24 (−2.41), and 48 (−2.55).

“This study provides further evidence of ABP 501 efficacy and safety in patients with RA,” the researchers wrote, noting that the efficacy was maintained throughout the course of the study. “ABP 501 was well tolerated during the extension study and displayed an extended safety profile consistent with that of adalimumab.”

They concluded, “This study, combined with the pivotal phase 3 study in patients with RA (the parent study), provides safety results for ABP 501 for a total period of 2 years and further confirms the similarity of ABP 501 to adalimumab.”

This study was sponsored by Amgen Inc. Cohen, Pablos, Pavelka, Müller, Matsumoto, Kivitz, Wang, and Krishnan report a variety of relationships with Amgen Inc. and other pharmaceutical companies. To view the complete disclosures, please see the reference.

Reference

Cohen S, Pablos JL, Pavelka K, et al. An open-label extension study to demonstrate long-term safety and efficacy of ABP 501 in patients with rheumatoid arthritis. Arthritis Res Ther. 2019;21(1):84.