Psoriasis is a common chronic, multisystem, inflammatory disease with predominantly skin and joint manifestations that affects approximately 2% of the world’s population.1 It occurs in a variety of clinical forms, from a few well-demarcated, erythematous plaques with a silvery scale to involvement of almost the entire body surface area. Beyond the debilitating physical ailments of the disease, psoriasis also may have psychosocial effects on quality of life.2 The pathogenesis of psoriasis is not fully understood but represents a complex multifactorial disease with both immune-mediated and genetic components. Characterized by hyperplasia of epidermal keratinocytes, psoriasis is shown to be mediated by infiltration of T-cell lymphocytes with an increase of various inflammatory cytokines, including tumor necrosis factor (TNF) α.3 More recently, interactions of helper T cells (TH17) via IL-17 and IL-23 have been supported to play a major role in the pathogenesis of psoriasis.4,5
With the growing understanding of the pathophysiology of psoriasis, focused biologics have been developed to target specific cytokines implicated in the disease process and have been increasingly utilized. Tumor necrosis factor α inhibitors, including adalimumab, infliximab, and etanercept, along with the IL-12/IL-23 inhibitor ustekinumab, have been revolutionary in psoriasis treatment by providing safe and effective long-term therapy; however, there is concern of life-threatening infections with biologics because of the immunosuppressive effects and mechanisms of action.6 Specifically, there have been reported cases of deep fungal infections associated with TNF-α inhibitor use.7
Recently, the advent of IL-17 and IL-23 inhibitors has garnered notable interest in these biologics as promising treatments for psoriasis. With IL-17 and IL-23 supported to have a major role in the pathogenesis of psoriasis, targeting the cytokine is not only logical but also has proven to be effacacious.8-10 Secukinumab, ixekizumab, and brodalumab are IL-17 inhibitors that have been approved by the US Food and Drug Administration (FDA) for the treatment of psoriasis. Secukinumab and ixekizumab are anti–IL-17A monoclonal antibodies, whereas brodalumab is an anti–IL-17 receptor antibody. Risankizumab, guselkumab, and tildrakizumab are IL-23 inhibitors that also have been approved by the FDA for the treatment of psoriasis. As with older biologics, there is concern over the safety of these inhibitors because of the central role of IL-17 and IL-23 in both innate and adaptive immune responses, particularly against fungi.11 Therefore, use of biologics targeting IL-17 and IL-23 may increase susceptibility to deep fungal infections.
Safety data and discussion of the risk for deep fungal infections from IL-17, IL-12/IL-23, and IL-23 inhibitor use for psoriasis treatment currently are lacking. Given the knowledge gap, we sought to synthesize and review the current evidence on risks for deep fungal infections during biologic therapy in patients with psoriasis, with a focus on IL-17 inhibitor therapies.
A PubMed search of articles indexed for MEDLINE from database inception to 2019 (1946-2019) was performed to find randomized controlled trials (RCTs), including extended trials and clinical trials, for IL-17, IL-12/IL-23, and IL-23 inhibitors approved by the FDA for psoriasis treatment. The following keywords were used: psoriasis or inflammatory disease and secukinumab, ixekizumab, brodalumab, ustekinumab, risankizumab, guselkumab, or tildrakizumab. Studies were restricted to the English-language literature, and those that did not provide adequate safety data on the specific types of infections that occurred were excluded.
Our search yielded RCTs, some including extension trials, and clinical trials of IL-17 inhibitors used for psoriatic disease and other nonpsoriatic conditions (Table).
Risk for Deep Fungal Infection With Secukinumab
The queried studies included 20 RCTs or clinical trials along with extension trials of 3746 patients with psoriasis or other inflammatory conditions, with follow-up ranging from 12 to 52 weeks. In a 3-year extension study of SCULPTURE, Bissonnette et al12 reported no new safety concerns for the 340 patients with moderate to severe psoriasis treated with secukinumab. Common adverse events (AEs) included nasopharyngitis, upper respiratory tract infections, and headache, but there were no reports of deep fungal infections.12 In a subsequent 5-year analysis of 168 patients that focused on the 300-mg fixed interval treatment with secukinumab, the safety profile remained favorable, with 0 reports of invasive fungal infections.13 A study (FEATURE) of 118 patients with psoriasis treated with a prefilled syringe of 300 or 150 mg of secukinumab also described an acceptable safety profile and reported no deep fungal infections.14 JUNCTURE, another study utilizing autoinjectors, also found that treatment with 300 or 150 mg of secukinumab was well tolerated in 121 patients, with no deep fungal infections.15 Common AEs for both studies included nasopharyngitis and headache.14,15 A 24-week phase 3 study for scalp psoriasis treated with secukinumab also reported 0 deep fungal infections in 51 patients.16 In an RCT comparing secukinumab and ustekinumab for moderate to severe plaque psoriasis, Blauvelt et al17 demonstrated that the incidence of serious AEs was comparable between the 2 groups, with no reports of invasive fungal infections in the 334 patients exposed to secukinumab. The CLEAR study, which compared secukinumab and ustekinumab, also found no reported deep fungal disease in the 335 patients exposed to secukinumab.18 Secukinumab exhibited a similar safety profile to ustekinumab in both studies, with common AEs being headache and nasopharyngitis.17,18 The GESTURE study investigated the efficacy of secukinumab in 137 patients with palmoplantar psoriasis and reported a favorable profile with no reports of deep fungal disease.19 In a subanalysis of the phase 3 study ERASURE, secukinumab was shown to have a robust and sustainable efficacy in 58 Japanese patients with moderate to severe plaque psoriasis, and there were no reports of invasive fungal infections.20 Another subanalysis of 36 Taiwanese patients from the ERASURE study also had similar findings, with no dose relationship observed for AEs.21 In a phase 2 study of 103 patients with psoriasis, Papp et al22 demonstrated AE rates that were similar across different doses of secukinumab—3×150 mg, 3×75 mg, 3×25 mg, and 1×25 mg—and described no incidences of invasive fungal disease. In a phase 2 regimen-finding study of 337 patients conducted by Rich et al,23 the most commonly reported AEs included nasopharyngitis, worsening psoriasis, and upper respiratory tract infections, but there were no reported deep fungal infections.