Abstract
Psoriasis is a multifactorial chronic inflammatory skin disease of unknown etiology. Knowledge of the pathophysiology of psoriasis has evolved and identified IL-17 as a key pro-inflammatory mediator in psoriasis creating new medical avenues. Several agents targeting IL-17 or its receptor are in clinical trials for the treatment of moderate-to-severe psoriasis. This review focuses on the biological rationale and the results of clinical trials with ixekizumab, a humanized IgG4 monoclonal antibody. The currently available Phase I to III data indicate that ixekizumab is a well-tolerated promising drug, although long-term data of efficacy and safety are needed before ixekizumab and other IL-17 targeting therapeutics can find their place in clinical practice.
Papers of special note have been highlighted as: • of interest
References
- 1 . Global epidemiology of psoriasis: a systematic review of incidence and prevalence. J. Invest. Dermatol. 133(2), 377–385 (2013).Crossref, Medline, CAS, Google Scholar
- 2 . Th1 and Th2 cells: different patterns of lymphokine functional properties. Annu. Rev. Immunol. 7, 145–173 (1989).• The original publication on the Th1/Th2 dichotomy.Crossref, Medline, CAS, Google Scholar
- 3 . CTLA-8, cloned from an activated T cell, bearing AU-rich messenger RNA instability sequences, and homologous to a herpesvirus saimiri gene. J. Immunol. 150(12), 5445–5456 (1993).• Cloning of cDNA sequence termed CTLA-8 (IL-17).Medline, CAS, Google Scholar
- 4 . Recent advances in the IL-17 cytokine family. Curr. Opin. Immunol. 23(5), 613–619 (2011).Crossref, Medline, CAS, Google Scholar
- 5 Human IL-17: a novel cytokine derived from T cells. J. Immunol. 155, 5483–5486 (1995).Medline, CAS, Google Scholar
- 6 T cell interleukin-17 induces stromal cells to produce proinflammatory and hematopoietic cytokines. J. Exp. Med. 183(6), 2593–2603 (1996).• IL-17 influences the development of neutrophil granulocytes.Crossref, Medline, CAS, Google Scholar
- 7 Overrepresentation of IL-17A and IL-22 producing CD8 T cells in lesional skin suggests their involvement in the pathogenesis of psoriasis. PLoS ONE 5(11), e14108 (2010).Crossref, Medline, Google Scholar
- 8 Pivotal role of dermal IL-17-producing γδ T cells in skin inflammation. Immunity 35(4), 596–610 (2011).Crossref, Medline, CAS, Google Scholar
- 9 . Innate lymphoid cells in the skin. J. Invest. Dermatol. 135(3), 673–678 (2014).Crossref, Medline, Google Scholar
- 10 Cutting edge: interleukin 17 signals through a heteromeric receptor complex. J. Immunol. 177(1), 36–39 (2006).Crossref, Medline, CAS, Google Scholar
- 11 Molecular characterization of the human interleukin (IL)-17 receptor. Cytokine 9(11), 794–800 (1997).Crossref, Medline, CAS, Google Scholar
- 12 . Structural basis of receptor sharing by interleukin 17 cytokines. Nat. Immunol. 10(12), 1245–1251 (2009).Crossref, Medline, CAS, Google Scholar
- 13 . Expression of interleukin-17RC protein in normal human tissues. Int. Arch. Med. 1(1), 19 (2008).Crossref, Medline, Google Scholar
- 14 . Structure–function relationships in the IL-17 receptor: implications for signal transduction and therapy. Cytokine 41(2), 92–104 (2008).Crossref, Medline, CAS, Google Scholar
- 15 . Interleukin-17 in inflammatory skin disorders. Curr. Opin. Allergy Clin. Immunol. 7(5), 374–81 (2007).Crossref, Medline, CAS, Google Scholar
- 16 . Interleukin-17 and interferon-γ synergize in the enhancement of proinflammatory cytokine production by human keratinocytes. J. Invest. Dermatol. 111(4), 645–649 (1998).• Synergy between IL-17A and IFN-γ on keratinocytes and their production of pro-inflammatory cytokines.Crossref, Medline, CAS, Google Scholar
- 17 IL-17A enhances vitamin D3-induced expression of cathelicidin antimicrobial peptide in human keratinocytes. J. Immunol. 181(12), 8504–8512 (2008).Crossref, Medline, CAS, Google Scholar
- 18 Th17 cytokines interleukin (IL)-17 and IL-22 modulate distinct inflammatory and keratinocyte-response pathways. Br. J. Dermatol. 159(5), 1092–1102 (2008).• IL-17A and IL-22 mediate effects on keratinocytes that could be indicative of a role in psoriasis.Medline, CAS, Google Scholar
- 19 . IL-17 and IL-22 enhance skin inflammation by stimulating the secretion of IL-1β by keratinocytes via the ROS-NLRP3-caspase-1 pathway. Int. Immunol. 24(3), 147–158 (2012).Crossref, Medline, CAS, Google Scholar
- 20 Dermal clusters of mature dendritic cells and T cells are associated with the CCL20/CCR6 chemokine system in chronic psoriasis. J. Invest. Dermatol. 134(5), 1462–1465 (2014).Crossref, Medline, CAS, Google Scholar
- 21 . Assessment of interleukin-17 and vitamin D serum levels in psoriatic patients. J. Am. Acad. Dermatol. 69(5), 840–842 (2013).Crossref, Medline, Google Scholar
- 22 Keratinocyte overexpression of IL-17C promotes psoriasiform skin inflammation. J. Immunol. 190(5), 2252–2262 (2013).Crossref, Medline, CAS, Google Scholar
- 23 Increased expression of interleukin 23 p19 and p40 in lesional skin of patients with psoriasis vulgaris. J. Exp. Med. 199(1), 125–130 (2004).Crossref, Medline, CAS, Google Scholar
- 24 An anti-IL-12p40 antibody down-regulates type 1 cytokines, chemokines, and IL-12/IL-23 in psoriasis. J. Immunol. 177(7), 4917–4926 (2006).Crossref, Medline, CAS, Google Scholar
- 25 Comparison of ustekinumab and etanercept for moderate-to-severe psoriasis. N. Engl. J. Med. 362(2), 118–128 (2010).Crossref, Medline, CAS, Google Scholar
- 26 . IL-17 and Th17 cells. Annu. Rev. Immunol. 27, 485–517 (2009).Crossref, Medline, CAS, Google Scholar
- 27 . Population exposure-response model to support dosing evaluation of ixekizumab in patients with chronic plaque psoriasis. J. Clin. Pharmacol. 54(10), 1117–1124 (2014).Crossref, Medline, CAS, Google Scholar
- 28 A Phase II randomized study of subcutaneous ixekizumab, an anti-interleukin-17 monoclonal antibody, in rheumatoid arthritis patients who were naive to biologic agents or had an inadequate response to tumor necrosis factor inhibitors. Arthritis Rheumatol. 66(7), 1693–1704 (2014).Crossref, Medline, CAS, Google Scholar
- 29 IL-17A is essential for cell activation and inflammatory gene circuits in subjects with psoriasis. J. Allergy Clin. Immunol. 130(1), 145–154; e9 (2012).Crossref, Medline, CAS, Google Scholar
- 30 Anti-interleukin-17 monoclonal antibody ixekizumab in chronic plaque psoriasis. N. Engl. J. Med. 366(13), 1190–1199 (2012).Crossref, Medline, CAS, Google Scholar
- 31 A 52-week, open-label study of the efficacy and safety of ixekizumab, an anti-interleukin-17A monoclonal antibody, in patients with chronic plaque psoriasis. J. Am. Acad. Dermatol. 71(6), 1176–1182 (2014).Crossref, Medline, CAS, Google Scholar
- 32 LY2439821, a humanized anti-interleukin-17 monoclonal antibody, in the treatment of patients with rheumatoid arthritis: a Phase I randomized, double-blind, placebo-controlled, proof-of-concept study. Arthritis Rheumatol. 62(4), 929–939 (2010).Crossref, Medline, CAS, Google Scholar
- 33 . Antidrug antibodies in psoriasis: a systematic review. Br. J. Dermatol. 170, 261–273 (2014).Crossref, Medline, CAS, Google Scholar
- 34 . The role of IgG4 in cutaneous pathology. Rom. J. Morphol. Embryol. 53(2), 221–231 (2012).Medline, CAS, Google Scholar
- 35 Secukinumab, a novel anti-IL-17A antibody, exhibits low immunogenicity in clinical trials and human in vitro Assays. Presented at: 73 Annual Meeting, American Association. CA, USA, 20–24 March (2015).Google Scholar
- 36 Secukinumab rapidly reduces markers of both keratinocyte proliferation and skin integrity in psoriasis. Presented at: 73 Annual Meeting, American Association. CA, USA, 20–24 March (2015).Google Scholar
- 37 Effective treatment of psoriasis with etanercept is linked to suppression of IL-17 signaling, not immediate response TNF genes. J. Allergy Clin. Immunol. 124(5), 1022–1030.e395 (2009).Crossref, Medline, CAS, Google Scholar
- 38 Improvement of scalp and nail lesions with ixekizumab in a Phase 2 trial in patients with chronic plaque psoriasis. J. Eur. Acad. Dermatol. Venereol.
doi:10.1111/jdv.12996 (2015) (Epub ahead of print).Crossref, Google Scholar - 39 Efficacy and safety of open-label ixekizumab treatment in Japanese patients with moderate-to-severe plaque psoriasis, erythrodermic psoriasis and generalized pustular psoriasis. J. Eur. Acad. Dermatol. Venereol. 29(6), 1148–1155 (2015).Crossref, Medline, CAS, Google Scholar
- 40 . Clinical efficacy and safety of anti-IL-17 agents for the treatment of patients with psoriasis. Immunotherapy 9, 1–15 (2015).Link, Google Scholar
- 41 Brodalumab, an anti-interleukin-17-receptor antibody for psoriasis. N. Engl. J. Med. 366(13), 1181–1189 (2012).Crossref, Medline, CAS, Google Scholar
- 42 Efficacy and safety of secukinumab in the treatment of moderate-to-severe plaque psoriasis: a randomized, double-blind, placebo-controlled Phase II dose-ranging study. Br. J. Dermatol. 168(2), 412–421 (2013).Crossref, Medline, CAS, Google Scholar
- 43 IL-22 mediates mucosal host defense against Gram-negative bacterial pneumonia. Nat. Med. 14(3), 275–281 (2008).Crossref, Medline, CAS, Google Scholar
- 44 Requirement of interleukin 17 receptor signaling for lung CXC chemokine and granulocyte colony-stimulating factor expression, neutrophil recruitment, and host defense. J. Exp. Med. 194(4), 519–528 (2001).Crossref, Medline, CAS, Google Scholar
- 45 Differential roles of interleukin-17A and -17F in host defense against mucoepithelial bacterial infection and allergic responses. Immunity 30(1), 108–119 (2009).Crossref, Medline, CAS, Google Scholar
- 46 Chronic mucocutaneous candidiasis in humans with inborn errors of interleukin-17 immunity. Science 332(6025), 65–68 (2011).Crossref, Medline, CAS, Google Scholar
- 47 An ACT1 mutation selectively abolishes interleukin-17 responses in humans with chronic mucocutaneous candidiasis. Immunity 39(4), 676–686 (2013).Crossref, Medline, CAS, Google Scholar
- 48 Safety and efficacy of brodalumab for psoriasis after 120 weeks of treatment. J. Am. Acad. Dermatol. 71(6), 1183–1190.e3 (2014).Crossref, Medline, CAS, Google Scholar
- 49 . Pain in the mouth: mucocutaneous findings associated with IL-17 inhibition. Presented at: 73 Annual Meeting, American Association. CA, USA, 20–24 March (2015).Google Scholar
- 50 . Secukinumab shows efficacy in subjects regardless of previous exposure to biologic therapy: a pooled subanalysis from four Phase 3 clinical trials in psoriasis. Presented at: 73 Annual Meeting, American Association. CA, USA, 20–24 March (2015).Google Scholar
- 51 . PASI90 response: the new standard in therapeutic efficacy for psoriasis. J. Eur. Acad. Dermatol. Venereol. 29(4), 645–648 (2015).Crossref, Medline, CAS, Google Scholar
- 52 . Brodalumab-an IL-17RA monoclonal antibody for psoriasis and psoriatic arthritis. Expert Opin. Biol. Ther. 15(6), 883–893 (2015).Crossref, Medline, CAS, Google Scholar
- 53 Secukinumab, a human anti-IL-17A monoclonal antibody, for moderate to severe Crohn's disease: unexpected results of a randomised, double-blind placebo-controlled trial. Gut 61(12), 1693–1700 (2012).Crossref, Medline, CAS, Google Scholar

