Recent advances in our understanding of psoriatic immune pathways have led to new generations of targeted therapies developed over the last 5 years. Although the pathogenesis of psoriasis remains to be fully elucidated, the success of these targeted therapies has confirmed a critical role of the IL-23/helper T cell (TH17) axis in maintaining the psoriatic immune cascade, a positive feedback loop in which IL-17, IL-12, and IL-23 released from myeloid dendritic cells lead to activation of helperT cells. Activated helper T cells—namely TH1, TH17, and TH22—release IL-17, IL-22, and other proinflammatory cytokines, amplifying the immune response and leading to keratinocyte proliferation and immune cell migration to psoriatic lesions. Inhibition of IL-17 and IL-23 by several biologics disrupts this aberrant inflammatory cascade and has led to dramatic improvements in outcomes, particularly among patients with moderate to severe disease.
Numerous biologics targeting these pathways and several oral treatments have been approved by the US Food and Drug Administration (FDA) for the treatment of psoriasis; in addition, a number of promising therapies are on the horizon, and knowledge of these medications might help guide our treatment approach to the patient with psoriasis. This article provides an update on the most recent (as of 2019) approved therapies and medications in the pipeline for moderate to severe plaque psoriasis, with a focus on systemic agents in phase 3 clinical trials. (Medications targeting psoriatic arthritis, biosimilars, and existing medications approved by the FDA prior to 2019 will not be discussed.)
Risankizumab-rzaa (formerly BI 655066) is a humanized IgG1 monoclonal antibody that targets the p19 subunit of IL-23, selectively inhibiting the role of this critical cytokine in psoriatic inflammation.
Phase 1 Trial
In a phase 1 proof-of-concept study, 39 patients with moderate to severe plaque psoriasis received varying dosages of intravenous or subcutaneous risankizumab or placebo.1 At week 12, the percentage of risankizumab-treated patients achieving reduction in the psoriasis area and severity index (PASI) score by 75% (PASI 75), 90% (PASI 90), and 100% (PASI 100) was 87% (27/31; P<.001 vs placebo), 58% (18/31; P=.007 vs placebo), and 16% (5/31; P=.590 vs placebo), respectively. Improvements in PASI scores were observed as early as week 2. Adverse events (AEs) were reported by 65% of the risankizumab group and 88% of the placebo group. Serious AEs were reported in 4 patients receiving risankizumab, none of which were considered related to the study medication.1
Phase 2 Trial
A phase 2 comparator trial demonstrated noninferiority at higher dosages of risankizumab in comparison to the IL-12/IL-23 inhibitor ustekinumab.2 Among 166 participants with moderate to severe plaque psoriasis, PASI 90 at week 12 was met by 77% of participants receiving 90 or 180 mg of risankizumab compared to 40% receiving ustekinumab (P<.001). Onset of activity with risankizumab was faster and the duration of effect longer vs ustekinumab; by week 8, at least PASI 75 was achieved by approximately 80% of participants in the 90-mg and 180-mg risankizumab groups compared to 60% in the ustekinumab group; PASI score reductions generally were maintained for as long as 20 weeks after the final dose of risankizumab was administered.2
Phase 3 Trials
The 52-week UltIMMa-1 and UltIMMa-2 phase 3 trials compared subcutaneous risankizumab (150 mg) to ustekinumab (45 or 90 mg [weight-based dosing]) or placebo administered at weeks 0, 4, 16, 28, and 40 in approximately 1000 patients with moderate to severe plaque psoriasis.3 Patients initially assigned to placebo switched to risankizumab 150 mg at week 16. At week 16, PASI 90 was achieved by 75.3% of risankizumab-treated patients, 42.0% of ustekinumab-treated patients, and 4.9% of placebo-treated patients in UltIMMa-1, and by 74.8% of risankizumab-treated patients, 47.5% of ustekinumab-treated patients, and 2.0% of placebo-treated patients in UltIMMa-2 (P<.0001 vs placebo and ustekinumab for both studies). Achievement of a static physician’s global assessment (sPGA) score of 0 or 1 at week 16 similarly favored risankizumab, with 87.8%, 63.0%, and 7.8% of patients in UltIMMa-1 meeting an sPGA score of 0 or 1 in the risankizumab, ustekinumab, and placebo groups, respectively, and 83.7%, 61.6%, and 5.1% in UltIMMa-2 meeting an sPGA score of 0 or 1 in the risankizumab, ustekinumab, and placebo groups, respectively (P<.0001 vs placebo and ustekinumab for both studies). Among patients initially assigned to risankizumab, improvements in PASI and sPGA continued to increase until week 52, with 81.9% achieving PASI 90 at week 52 compared to 44.0% on ustekinumab in UltIMMa-1, and 80.6% achieving PASI 90 at week 52 compared to 50.5% on ustekinumab in UltIMMa-2 (P<.0001 vs ustekinumab for both studies). Treatment-emergent AE profiles were similar for risankizumab and ustekinumab in both studies, and there were no unexpected safety findings.3
Risankizumab received FDA approval for the treatment of moderate to severe plaque psoriasis in April 2019.