Background/Purpose: Bimekizumab (BKZ), a humanized monoclonal IgG1 antibody that selectively neutralizes interleukin (IL)-17A and IL-17F, has shown clinical improvements in joint and skin outcomes over 48 weeks (wks) in patients (pts) with active psoriatic arthritis.¹ The primary outcome of ACR50 response at Wk 12 of the dose-ranging BE ACTIVE study was achieved by 24–46% of pts across dosing arms.¹ Due to the chronic nature of PsA, maintaining a long-term treatment response at high levels of disease control is particularly important. We assess maintenance of response over approximately 2 years of BKZ treatment in pts who demonstrated a response to BKZ at Wk 12.

Methods: Pts who completed 48 wks of the BE ACTIVE study (NCT02969525; design described elsewhere)¹ without meeting withdrawal criteria, were eligible for BE ACTIVE 2 OLE entry (NCT03347110). BKZ was given at 160 mg every 4 wks (Q4W) regardless of previous dose. Analyses include pts randomized to the three highest BKZ doses at BE ACTIVE study baseline (BL): 160 mg, 160 mg with 320 mg loading dose (LD), and 320 mg. Maintenance of response is reported as the percentage (%) of BKZ-treated pts achieving a response at Wk 12, with maintained response over time. Outcomes include ACR20/50/70, minimal disease activity (MDA) and very low disease activity (VLDA), Disease Activity in PSoriatic Arthritis (DAPSA) remission, and body surface area (BSA) 0% (for those pts with BSA ≥3% at BL). Non-responder imputation (NRI) was used for missing data. Results are presented from Wk 12 (end of double-blind treatment) to Wk 108, or Wk 120 for outcomes not recorded at Wk 108. Rates of treatment-emergent adverse events (TEAEs) are reported for the Safety Set (pts who received ≥1 dose BKZ).

Results: At BL in the BE ACTIVE study, 123 pts were randomized to the three highest BKZ doses (160–320 mg). 109 pts entered the OLE, all receiving BKZ 160 mg Q4W. ACR20/50/70 were achieved by 76 (62%), 46 (37%), and 27 (22%) pts, respectively, at Wk 12 of the double-blind phase. MDA and VLDA criteria were met by 48 (39%) and 18 (15%) pts, respectively; likewise, the number of pts who achieved DAPSA remission and BSA 0% at Wk 12 were 25 (20%) and 32 (40% of the 80 pts with BSA ≥3% at BL), respectively. The majority of pts who achieved responses at Wk 12, across the different outcomes, maintained them to Wk 108 or Wk 120 (Figures 1 and 2). The % of pts achieving ACR20/50/70 at Wk 12 who maintained the response to Wk 108 was 80/78/81%, respectively. MDA and VLDA responses were maintained at Wk 120 by 81% and 72% of Wk 12 responders, respectively; likewise, for DAPSA remission at Wk 108, the response from Wk 12 was maintained by 76%; for BSA 0%: 72%. TEAEs occurred in 87.7% of pts (exposure-adjusted event rate: 181.1/100 patient-years [PY]) and serious TEAEs in 9.3% (4.1/100 PY).

Conclusion: This BKZ-treated population, who achieved high levels of disease control as early as 12 weeks (including ACR50, MDA, VLDA, BSA 0% and DAPSA remission), demonstrated a consistent maintenance of response rate around 80% across both joint and skin outcomes. These results suggest that BKZ provides a robust maintenance of response over at least 2 years of treatment in pts with PsA.

Reference: 1. Ritchlin C. Lancet 2020;395:427–440.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/bimekizumab-maintenance-of-response-in-patients-with-psoriatic-arthritis-2-year-results-from-a-phase-2b-dose-ranging-study-and-its-open-label-extension/