Ixekizumab treatment response: Consistency over time and at each visit in psoriatic arthritis

Background: Ixekizumab (IXE), a high-affinity monoclonal antibody targeting IL-17A, has demonstrated superiority in achieving the combined endpoint of ACR50 and PASI100 at week (Wk) 24 compared to adalimumab (ADA) in the SPIRIT-H2H trial [1]. In this analysis, we looked at the efficacy responses at the individual patient (pt) level to assess consistency over time and at each visit. Objectives: To determine the American College of Rheumatology 50% (ACR50) response and Disease Activity in psoriatic arthritis (PsA) (DAPSA) response in pts treated with IXE and describe response consistency over time and at each visit from Wk 24 through Wk 52. Methods: This post-hoc analysis used data from SPIRIT-H2H (NCT03151551), a phase3b/4 randomised, open-label parallel-group study between IXE and ADA. Pts were randomised to receive either IXE 80 mg, every 4 Wks (IXE Q4W)) or ADA 40 mg, every 2 Wks (ADA Q2W)). The proportion (%) of pts in the intent-to-treat population who achieved each endpoint, either ACR50 or DAPSA≤14, at Wk 24 and at each post-baseline visit out to Wk 52 was assessed. Nine pts with active psoriasis and body surface area (BSA) ≥3% were assessed as PASI=0 at baseline, a medical inconsistency that was resolved using medical judgement. These pts were considered PASI100 responders if PASI=0 and BSA=0 at post baseline visits. Results: A total of 566 patients enrolled in the trial received either IXE (N=283) or ADA (N=283). Of the 143 pts treated with IXE who achieved ACR50 at Wk 24, 65% (N=93) maintained ACR50 at every visit. In total, 83% (N=118) of the ACR50 achievers at Wk 24 maintained ACR50 with some (18% (N=25)) fluctuations, between ACR50 and ACR20 (Figure 1). Of the 132 pts treated with ADA who achieved ACR50 at Wk 24, 55% (N=72) maintained ACR50 at every visit. In total, 80% (N=105) of ACR50 achievers maintained ACR50 with some (25% (N=33)) fluctuations between ACR50 and ACR20 (Table 1). Furthermore, of the174 pts treated with IXE who achieved low DA (DAPSA≤14) at Wk 24, 68% (N=119) maintained low DA at every visit. Of the low DA achievers at Wk 24, 82% (N=142) of pts maintained low DA with some (13% (N=23)) fluctuations between moderate and low DA (Figure 1B). Of the 171 pts treated with ADA who achieved low DA at Wk 24; 57% (N=97) maintained low DA at every visit. In total, 77% (N=131) of low DA achievers at Wk 24 maintained low DA with some (20% (N=34)) fluctuations between moderate and low DA (Table 1). Conclusion: This analysis demonstrates that a numerically higher proportion of pts treated with IXE versus ADA show consistency of response, as measured by ACR50 and DAPSA responses, over time and for each visit at the pt level.