Background/Purpose: Ixekizumab (IXE) is an FDA-approved monoclonal antibody that targets interleukin-17A.

Methods: Psoriatic Arthritis Real-World Study in the US (PARTUS) was a prospective, multicenter, non-interventional cohort study in patients with active Psoriatic Arthritis (PsA) beginning treatment with either IXE or an interleukin-23 inhibitor (IL-23i). The study assessed the effectiveness of Ixekizumab or Interleukin-23 in disease domains and subgroups. Clinical Disease Activity Index for PsA (cDAPSA) endpoints for key subgroups and outcomes in PsA disease domains were assessed at baseline (BL), week (W) 4, and W12. Change from baseline (CFB) in cDAPSA was assessed in the following subgroups: prior biologic failure (failure due to lack of efficacy and/or intolerance), duration of disease, sex, body mass index (BMI) (normal: BMI < 25 kg/m2, patients with overweight BMI 25 to < 30 kg/m2, patients with obesity: BMI ≥30 kg/m2), patients with baseline presence of enthesitis, dactylitis, nail psoriasis, or Body Surface Area (BSA) of psoriasis skin involvement (BSA < 3%, BSA ≥ 3%) (Figure (Fig.) 1). To assess PsA domains, CFB in tender/swollen joint count (TJC)/ (SJC), Leeds enthesitis index, dactylitis count and nail psoriasis Visual Analogue Scale (VAS) score and proportion of patients achieving BSA < 3 were evaluated (Table 2). Descriptive statistics are presented for both IXE and IL-23i arms.

Results: BL characteristics of 121 patients from the IXE cohort and 116 patients from the IL-23i cohort (risankizumab) (n=67) and guselkumab (n=49)) are presented in Table 1.The mean (SD) CFB in the cDAPSA score at W4 was -13.8 (15.9) and -9.3 (15.4), and at W12 was -17.3 (19.6) and -14.0 (19.3) in the IXE and IL-23i cohort respectively. At W4, 10.6% in the IXE cohort and 3.0% in the IL-23i cohort achieved remission of disease activity. These proportions increased for both cohorts by W12 (Table 2).Improvements in disease activity, as measured by the mean (SD) CFB in cDAPSA are reported for the following subgroups in the IXE cohort: ≤2 Years duration of disease since diagnosis (W4:-12.1 (15.0), W12: -16.3 (16.4)), >2 Years duration of disease since diagnosis (W4:-14.4 (16.3), W12 -17.7 (20.8)), male patients (W4:-16.0 (16.2), W12:-19.1 (20.1)), female patients (W4:-11.8 (15.6), W12 -15.7 (19.2)), patients with prior failure to any biologic (W4:-16.8 (16.8), W12: -21.5 (19.9)), patients with no prior failure to any biologic (W4:-12.4 (15.4), W12:-15.4 (19.4)). The mean (SD) CFB in cDAPSA in the above subgroups in the IL-23i cohort is in Fig. 1.The mean (SD) CFB in cDAPSA by PsA domains is in Fig. 1.

Conclusion: The results from the PARTUS study showed that patients with active PsA treated with IXE achieved rapid and meaningful improvements at W4 in disease activity across different subgroups of patients including BMI, sex, disease duration, prior biologic experience and PsA domains in real-world settings reaching the target of disease activity control as recommended in treatment guidelines. Further improvements were observed at W12. Trends in improvement were also observed in the patients treated with IL-23i, although to a less numerical extent. These data may guide rheumatologists treatment decisions for their diverse patient populations.

Table 1. Demographic and Clinical Characteristics at Baseline in patients with active PsA treated with IXE or IL-23i (GUS and RZB)

Note: Data are mean (SD) unless otherwise stated. Abbreviations: BSA= body surface area; cDAPSA= clinical Disease Activity Index for Psoriatic arthritis; GUS=guselkumab; IL-23i=interleukin-23p19 inhibitor; IXE=ixekizumab; LEI=Leeds enthesitis index; N&#3fnumber of patients in each cohort; n=number of patients in the specified category; PsO=psoriasis; RZB=risankizumab; SD=standard deviation; VAS=visual analogue scale

Table 2. Efficacy results in patients with active PsA treated with IXE or IL-23i (GUS and RZB)

Note: Data are mean (SD) unless otherwise stated. Abbreviations: BL=Baseline; BMI=Body mass index; BSA= body surface area; cDAPSA= clinical Disease Activity Index for Psoriatic arthritis; GUS=guselkumab; IL-23i=interleukin-23p19 inhibitor; IXE=ixekizumab; N&#3fnumber of patients in each cohort; n=number of patients in the specified category; PsO=psoriasis; RZB=risankizumab; SD=standard deviation; VAS=visual analogue scale

Figure 1. Clinical outcomes at W4 and W12 in patients with PsA treated with IXE or IL-23i (GUS and RZB): A. Change from baseline in cDAPSA by disease duration since diagnosis; B. Change from baseline by sex; C. Change from baseline by prior failure to any biologic; D. Change from baseline by BMI (Section 1: number of patients treated with IXE and BMI < 25: 11, number of patients treated with IL-23i and BMI < 25: 19); E. Change from baseline by presence of enthesitis; F. Change from baseline by presence of dactylitis; G. Change from baseline by presence of nail psoriasis: H. Change from baseline by presence of PsO affecting BSA

Note: The study was not powered for comparative analysis, therefore only descriptive results are presented.

Abbreviations: BMI=Body mass index; cDAPSA=clinical Disease Activity Index for PsA; CFB=change from baseline; GUS=guselkumab; IL-23i=interleukin 23p19 inhibitor; IXE=ixekizumab; PsA=psoriatic arthritis: PsO=psoriasis.

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