An infliximab biosimilar, PF-0643179/GP1111, is as effective and safe as the infliximab reference product for treating patients with moderate to severe active rheumatoid arthritis (RA) receiving background methotrexate, according to results published in Arthritis Research & Therapy.

The study included biologic-naïve participants with moderate to severe active RA despite methotrexate therapy (n=650). Participants were randomly assigned 1:1 to receive PF-0643179/GaP1111 or the infliximab reference product (3 mg/kg intravenous at 0, 2, and 6 weeks, then every 8 weeks). In participants who had an inadequate response, dose escalation to 5 mg/kg was allowed starting at 14 weeks. The primary end point was American College of Rheumatology criteria for ≥20% clinical improvement (ACR20) response at 14 weeks. The researchers defined therapeutic equivalence as the 2-sided 95% CI for the treatment difference being within the symmetric equivalence margin of ±13.5%.

At 14 weeks, 62.7% of participants in the PF-0643179/GP1111 group achieved ACR20 compared with 64.1% in the infliximab reference product group. Using non-responder imputation,ACR20 response at 14 weeks was 61.1% in patients receiving PF-0643179/GP1111 and 63.5% in patients receiving the infliximab reference product. The 95% (−9.91%, 5.11%) and 90% (−8.75%, 4.02%) CI for the treatment difference of −2.39 was entirely contained within the equivalence margins.

The results indicated that the treatments had similar efficacy and immunogenicity in patients with and without dose escalation at 14 weeks.

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The researchers found that PF-0643179/GP1111 and the infliximab reference product had similar safety profiles with no observed clinically meaningful differences.

“The results of this study, combined with previous results of an analytical (structural and functional) evaluation, demonstrate similarity of PF-06438179/GP1111 to infliximab [reference product],” the researchers wrote.

This study was funded by Pfizer Inc.

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Reference

Cohen SB, Alten R, Kameda H, et al. A randomized controlled trial comparing PF-0643179/GP1111 (an infliximab biosimilar) and infliximab reference product for treatment of moderate to severe active rheumatoid arthritis despite methotrexate therapy [published online July 27, 2018]. Arthritis Res Ther. doi:10.1186/s13075-018-1646-4