An open-label extension study to demonstrate long-term safety and efficacy of ABP 501 in patients with rheumatoid arthritis

Stanley Cohen, Jose L. Pablos, Karel Pavelka, Gerard Anton Müller, Alan Matsumoto, Alan Kivitz, Hui Wang, Eswar Krishnan

Research output: Contribution to journalArticlepeer-review


Background: ABP 501 was evaluated in a phase 3 single-arm, open-label extension (OLE) study to collect additional safety and efficacy data in patients with rheumatoid arthritis (RA). Methods: Subjects completing the final visit in the parent phase 3 randomized, double-blind, controlled equivalence study comparing the efficacy and safety of the biosimilar ABP 501 with adalimumab reference product (RP) were enrolled in this open-label extension (OLE) study. All subjects received 40 mg ABP 501 every other week for 68 weeks. Key safety endpoints included treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and anti-drug antibody (ADA) incidences. Efficacy endpoints included ACR20 (at least 20% improvement in American College of Rheumatology core set measurements from baseline) and Disease Activity Score 28-joint count C-reactive protein (DAS28-CRP) change from baseline. Results: Among 466/467 patients treated with ABP 501, 229 transitioned from the ABP 501 arm of the parent study (ABP 501/ABP 501) and 237 from the adalimumab RP arm (RP/ABP 501); 412/467 (88.2%) patients completed the study. The overall TEAE incidence was 63.7% (297/466); grade ≥ 3 TEAE incidence was 9.0% (42/466). The incidence of TEAEs leading to discontinuation of investigational product was 3.6% (17/466). The SAE incidence was 9.9% (46/466). Overall, 18.2% (85/466) of subjects developed binding ADAs and 6.9% (32/466) developed neutralizing ADAs in the OLE study. The ACR20 response rate was 73.3% (340/464 subjects) at OLE baseline, and 78.8% (327/415 subjects) at week 70 of the OLE study. The overall mean DAS28-CRP change from the parent study baseline was - 2.25 at the OLE study baseline (n = 440), - 2.36 at week 4 (n = 463), - 2.41 at week 24 (n = 450), - 2.55 at week 48 (n = 433), and - 2.60 at week 70 (n = 412). Efficacy was maintained throughout the study. Conclusions: Efficacy previously demonstrated in the parent study was maintained in this OLE study with no new safety findings. Long-term safety, immunogenicity, and efficacy were similar in the ABP 501/ABP 501 and RP/ABP 501 groups. The single switch from RP to ABP 501 did not impact immunogenicity.

Original languageEnglish (US)
Article number84
JournalArthritis Research and Therapy
Issue number1
StatePublished - Mar 29 2019
Externally publishedYes


  • ABP 501
  • Adalimumab
  • Biosimilar
  • Efficacy
  • Long-term safety
  • Rheumatoid arthritis

ASJC Scopus subject areas

  • Rheumatology
  • Immunology and Allergy
  • Immunology


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