A total of 153 psoriasis patients treated with IXE between March 22, 2016 and February 28, 2018 and who met the study eligibility criteria were included in the study. Among patients seen at each individual study follow-up visit, nearly all patients had sPGA (98%), BSA (99%), and DLQI (96%) documented. The median age at IXE-initiation was 47.7 years (range: 19.7–74.5), 65.4% of the study population was male, and 93.5% of patients were Caucasian (Table 1). The median time since psoriasis diagnosis was 11.9 years (range: 0.1–41.1 ). A total of 106 patients received prior biologic therapy for psoriasis; adalimumab was the most commonly used biologic prior to IXE initiation (n = 40), followed by secukinumab (n = 35). Almost half of the study cohort received prior non-biologic systemic treatment (n = 69, 45.1%) with the majority receiving methotrexate (n = 66, 43.1%). 38.6% (n = 59) patients received topical treatment during the pre-index period while only two patients (1.3%) received phototherapy. Among patients who switched to IXE from other biologic therapies, the majority of the patients discontinued their prior biologics due to inadequate response to treatment (TNF-a inhibitor: 90.8%, IL-12/23 inhibitor: 100%, IL-17 inhibitor: 82.9%, Table 2)
Speed of treatment effect
Disease severity during follow-up was summarized (Fig. 1). At index, 7.2%, 20.9%, and 19.6% of patients had sPGA (0, 1), DLQI (0,1), and BSA ≤ 1%, respectively. By 1-month post-index (n = 136), 58.8% of patients achieved clear or almost clear skin (sPGA 0, 1), 29.4% clear skin (sPGA 0), 55.9% DLQI (0, 1) and 66.9% BSA ≤ 1%. The proportion of patients achieving sPGA (0, 1), DLQI (0, 1), and BSA ≤ 1% (NPF target) during follow-up are shown in Fig. 1. At 3-month post-index, nearly three-quarters (73.5%) of patients had sPGA (0, 1), while 68.4% had DLQI (0,1), and 86% had BSA ≤ 1%. The median change during 24 months post-index period was approximately 3% reduction for BSA, -3 points for sPGA, and − 2 points for DLQI scores for the overall study cohort.
Subgroup analysis was done on early responders (defined as achieving sPGA 0, 1 at 1 month) and non-early responders (not achieving sPGA (0, 1) at 1 month). Among 135 patients with 1-month post-index sPGA data available, 59.2% (n = 80) of patients were early responders, among which 70% (n = 56) achieved DLQI (0, 1), and 85% (n = 68) achieved BSA ≤ 1%. Over 85%, 75%, and 65% of patients met the targets for BSA, sPGA, and DLQI, respectively, at all the time points after 1-month post-index among early-responders (Fig. 2). Among non-early responders (n = 55), 46.8%, 55.3%, and 74.5% of them achieved the targets for sPGA, DLQI, and BSA at 3-month post-index, respectively. The proportions remained largely the same for 24-month post-index (Fig. 2).
Additional subgroup analyses were done among biologic naïve patients and biologic experience patients prior to index date (Fig. 2). Of the 109 patients who received biologic treatments for psoriasis at any time prior to IXE initiation, 6.5% had sPGA (0, 1), 25.7% had DLQI (0, 1), and 22% had BSA ≤ 1% at IXE initiation. 95 patients in the biologic experienced group had data available at 1-month post-index, and 58.9% had sPGA (0, 1) including 28.4% with sPGA 0; 55.8% of the patients achieved DLQI (0, 1); and 66.3% achieved BSA ≤ 1%. At 3-month, the proportions of patients achieving sPGA, DLQI and BSA targets increased to 72.6% (52.6% patients had sPGA 0), 68.4%, and 83.2%, respectively. Of 44 biologic naïve patients, 41 patients had data available at 1- and 3-months post-index. The proportions of patients achieving sPGA, DLQI, and BSA targets were 58.5% and 75.7%, 68.3% and 75.7%, 68.3% and 92.7%, respectively at 1- and 3-months.
Long-term treatment effect
Disease severity and quality of life outcomes at 24-month post-index were available for 49 patients from the overall study cohort. Among the 49 patients, 75.5%, 69.4%, and 83.7% had treatment outcomes of sPGA (0, 1), DLQI (0,1), and BSA ≤ 1%, at 24-month post index respectively. Among early responders, 87.9% of patients had sPGA (0, 1), including 66.7% with sPGA 0; 75.8% patients had DLQI (0, 1); and 93.9% BSA ≤ 1% at 24 month.
Logistics regression model results showed that at 24 months post-index, early sPGA responders at 1-month not only had greater odds of achieving sPGA (0, 1) (OR = 10.1; 95% CI: 2.1–47.9; p-value = 0.003), but also greater odds of achieving BSA ≤ 1% (OR = 13.3; 95% CI: 2.2–80.2; p-value = 0.005) than non-early responders. No association was found for DLQI (0,1) at 24 months. Also, early sPGA responders were more likely to achieve the sPGA (0,1) outcome at 12 months than non-early responders (OR = 4.4; 95%CI: 1.7–11.1; p-value = 0.002, data not shown).