This real-world study described tildrakizumab initiators with prior experience of IL-17i and found that tildrakizumab survival exceeded 1 year. Improvements in clinician- and patient-reported outcomes at 1 year were evident, which is particularly notable because these patients had high prevalences of demographic and disease characteristics that have been associated with lower drug persistence and response to treatment in both clinical trials and observational studies [10,11,12].

This population is highly refractory to biologic therapy, as 73.6% initiated tildrakizumab as their third- or higher-line of advanced therapy. In a meta-analysis of eight observational studies, any prior biologic experience decreased the likelihood of achieving PASI90 by more than half at 6 months [11]. Additionally, 55.4% of the present study population had comorbid psoriatic arthritis at baseline, which has also been associated with lower achievement of PASI90 at both 16 and 36 months in patients who switched within IL-23i therapies [12].

Current findings are of particular interest in comparison to another study from the CorEvitas Psoriasis Registry that stratified tildrakizumab initiators by prior experience with any biologic therapy; patients with any biologic experience had a mean time to tildrakizumab discontinuation of 29.5 months, with accompanying improvements in many clinician- and patient-reported outcomes compared to biologic-naïve tildrakizumab initiators [13]. The current results for patients with IL-17i experience are comparable to those of the pooled cohort of patients with any biologic experience.

With an increase in available biologic therapies for psoriasis, switching medications has become more common. Switches may be influenced by many factors [1, 14, 15]; characteristics of IL-17i that may motivate a switch include lack of effectiveness, adverse events, access, cost, and inconvenience [2]. While IL-17i may confer increased risks of candidiasis and inflammatory bowel disease, increases in these adverse events have not been seen for IL-23i [5]. In addition, IL-23i, such as tildrakizumab, require fewer doses per year than IL-17i without ongoing monitoring requirements [2]. Because tildrakizumab is only approved for in-office use in the USA, it is covered through medical benefits rather than pharmacy benefits which cover many IL-17i; thus, switching to tildrakizumab may reduce or eliminate copays for many individuals [16]. Our results suggest that tildrakizumab may be a good option for patients who wish to switch biologic therapies after an IL-17i.

Observational studies have shown that patients who switched biologics within or across classes after not achieving treatment goals with their initial therapy experienced improved outcomes [8]. However, there are few studies specifically examining a switch from IL-17i to tildrakizumab or to IL-23i more broadly. In one analysis of data from Italy (n = 48), patients who switched from IL-17i to IL-23i (including tildrakizumab) had improvements in mean PASI at up to 1 year of follow-up, with 100% improvement in PASI (PASI100) in 61.9% of patients at 48 weeks [17]. Another study in Italy (N = 12) showed improvements in PASI and DLQI 6 months after switching from IL-17i to IL-23i [18], and a third (N = 23) demonstrated improvements in PASI at 28 weeks [19]. Although not a direct comparison, a fourth Italian study of 97 patients with “multi-failure” (who had failed on at least four biologic treatments) showed that those on IL-23i maintained improvement in PASI for up to 1 year [20]. The present analysis confirms these findings in a larger real-world population, many of whom could also be considered patients with “multi-failure.”

Strengths of the current study include evaluating patients from the CorEvitas Psoriasis Registry, a unique resource with a large sample size and longitudinal follow-up on real-world psoriasis treatments in the USA and Canada. The Registry facilitates evaluation of treatment persistence and effectiveness via an extensive set of both clinician- and patient-reported outcomes that are not available in all observational studies. Additional strengths of this study include nearly complete data and follow-up time that extended past 2 years for drug survival analysis.

Potential limitations of this study include those specific to the Registry and those common to observational cohorts. Patients in the Registry may not represent all adults with psoriasis in the USA and Canada, potentially introducing selection bias if certain subgroups (e.g., patients who are healthier or sicker) are consistently included or excluded. The history of biologic medication use before enrollment, including IL-17i, is based on patient and physician reports, which may lead to potential misclassification if patients cannot recall their entire medication histories. Changes in drug benefits, design, and formulary status could also affect drug utilization patterns and the number of patients switching medications. Furthermore, while the Registry captures physician-reported prescribing, it does not measure patient compliance. Since the analyses included all initiators with prior IL-17i use, and were unable to consider adherence, the effectiveness of tildrakizumab may be underestimated.