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IL-17 and Psoriasis

Aiming for PASI 100

Read time: 40 mins
What should be the goal of psoriasis treatment? This section of the Learning Zone describes the importance of aiming for complete skin clearance when treating psoriasis. Recent advances in biologic treatments are making this aim achievable. Choose one of the subsections below, or scroll down the page, to learn more.

Psoriasis severity scales

Psoriasis severity is determined using several scales; the main ones being:

  • Body Surface Area (BSA) – the percentage of BSA affected by psoriatic lesions where the patient’s palm is estimated to be 1% BSA. Moderate-to-severe psoriasis is classed as having a BSA score ≥10 (10%) (National Psoriasis Foundation, 2018)
  • Psoriasis Area Severity Index (PASI) – the percentage reduction in disease severity (compared with baseline) observed following treatment. Commonly used PASI scores include PASI 50, 75, 90 and 100 indicating reductions of 50%, 75%, 90% and 100%, respectively (Feldman & Krueger, 2005)
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The evolution of biologics for treating psoriasis

Biologics such as anti-tumour necrosis factor (TNF) and the anti-IL-12/23 treatment ustekinumab, show lower efficacy in clinical trials of moderate-to-severe psoriasis when compared (head-to-head or network meta-analysis) with more recently developed biologics, such as anti-IL-17 therapies and IL-23’s (Blauvelt et al., 2017b; Reich et al., 2017; Sawyer et al., 2018a). 

Between 27‒80% of patients on ‘older’ biologics reach PASI 75 by 12–16 weeks (Hartz et al., 2016; Zweegers et al., 2016) and in general less patients achieve higher PASI scores and sustained efficacy during maintenance treatment than with more recently developed biologics (Sawyer et al., 2018a).

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Why PASI 100 is so important

Achieving PASI 100 substantially reduces the physical burden of psoriasis and improves patient satisfaction, compared with having any residual disease (Lebwohl et al., 2015; Puig et al., 2017).

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Key clinical data

Modern biological therapies that specifically block the IL-17 pathway and achieve complete skin clearance, a Psoriasis Area Severity Index 100 score (PASI 100), with an acceptable safety profile, represent a paradigm shift in the treatment of moderate-to-severe psoriasis (Strober et al., 2016; Wasilewska et al., 2016).

However, the number of patients who achieve PASI 100, and the speed and duration of response differs for each available therapy.

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Beringer A, Nopack M, Miossec P. IL-17 in chronic inflammation: From discovery to targeting. Trends Mol Med. 2016;22:230–41.

Bissonnette R, Bourcier M, Gooderham M, Hong C-H, Landells I, Lynde C, et al. Management of moderate to severe plaque psoriasis: the emerging role of IL-17 inhibition. J Cut Med Sur. 2017;21:2S–40S.

Bissonnette R, Luger T, Thaçi D, Toth D, Lacombe A, Xia S, et al. Secukinumab demonstrates high sustained efficacy and a favourable safety profile through 5 years of treatment in moderate to severe psoriasis (SCULPTURE Extension Study). J Eur Acad Dermatol Venereol. 2018;32(9):1507‒14.

Blauvelt A, Prinz JC, Gottlieb AB, Kingo K, Sofen H, Ruer-Mulard M, et al. Secukinumab administration by pre-filled syringe: efficacy, safety and usability results from a randomised controlled trial in psoriasis (FEATURE). Br J Dermatol. 2015a;172(2)484‒93.

Blauvelt A. Ixekizumab: a new anti-IL-17A monoclonal antibody therapy for moderate-to severe plaque psoriasis. Expert Opin Biol Ther. 2015b;16(2):255‒63.

Blauvelt A, Gooderham M, Iversen L, Balls S, Aquda NO, Reich K. Efficacy and safety of ixekizumab for the treatment of moderate-to-severe plaque psoriasis: results through 108 weeks of a randomized, controlled phase 3 clinical trial (UNCOVER-3). J Am Acad Dermatol. 2017a;77(5):855‒62.

Blauvelt A, Papp KA, Lebwohl MG, Green LJ, Hsu S, Bhatt V, et al. Rapid onset of action in patients with moderate-to-severe psoriasis treated with brodalumab: A pooled analysis of data from two phase 3 randomized clinical trials (AMAGINE-2 and AMAGINE-3). J Am Acad Dermatol. 2017b;77(2):372–4.

Blauvelt A, Reich K, Tsai TF, Tyring S, Vanaclocha F, Kingo K, et al. Secukinumab is superior to ustekinumab in clearing skin of subjects with moderate-to-severe plaque psoriasis up to 1 year: Results from the CLEAR study. J Am Acad Dermatol. 2017c;76(1):60–9.

Bonifati C, Berardesca E. Clinical outcome measures of psoriasis. Reumatismo. 2007;59 Suppl 1:64–7.

Bushnell DM, Martin ML, McCarrier K, Gordon K, Chiou CF, Huang X, et al. Validation of the Psoriasis Symptom Inventory (PSI), a patient-reported outcome measure to assess psoriasis symptom severity. J Dermatolog Treat. 2013;24(5):356–60.

Campa M, Mansouri B, Warren R, Menter A. A review of biologic therapies targeting IL-23 and IL-17 for use in moderate-to-severe plaque psoriasis. Dermatol Ther (Heidelb). 2016;6(1):1‒12. NCT01597245: A phase 3 study in participants with moderate to severe psoriasis (UNCOVER-2). Available at: (accessed September 2018).

Cosentyx® Summary of Product Characteristics. 2018. Available at:  (accessed February 2019).

Drug Development Technology. 2018. Available at (accessed September 2018).

European Medicines Agency (EMA). Cosentyx. 2015. Available at: (accessed September 2018).  

Farahnik B, Beroukhim K, Abrouk M, Nakamura M, Zhu TH, Singh R, et al. Brodalumab for the treatment of psoriasis: A review of phase III trials. Dermatol Ther (Heidelb). 2016;6(2):111–24.

FDA Drug Trials Snapshot: Cosentyx. Available at: (accessed September 2018).

Feldman SR, Bushnell DM, Klekotka PA, Scanlon M, Martin ML, Wade SW, et al. Differences in psoriasis signs and symptom severity between patients with clear and almost clear skin in clinical practice. J Dermatolog Treat. 2016;27(3):224–7.

Feldman SR, Krueger GG. Psoriasis assessment tools in clinical trials. Ann Rheum Dis. 2005;64 Suppl 2:ii65-8; discussion ii69–73.

Furue K, Ito T, Furue M. Differential efficacy of biologic treatments targeting the TNF-α/IL-23/IL-17 axis in psoriasis and psoriatic arthritis. Cytokine 2018;111:182–8.

Godse K. Secukinumab – first in class interleukin-17 inhibitor for the treatment of psoriasis. Indian J Dermatol. 2017;62(2):195‒9.

Gordon  KB, Blauvelt A, Papp KA, Langley RG, Luger T, Ohtsuki M, et al. Phase 3 trials of ixekizumab in moderate-to-severe plaque psoriasis. N Eng J Med. 2016;375(4):345–5.

Griffiths CE, Reich K, Lebwohl M, van de Kerkhof P, Paul C, Menter A, et al. Comparison of ixekizumab with etanercept or placebo in moderate-to-severe psoriasis (UNCOVER-2 and UNCOVER-3): results from two phase 3 randomised trials. Lancet. 2015;386:541‒51.

Hartz S, Dutronc Y, Kiri SH, Schacht A, Walzer S, Dakin H. Network meta-analysis to evaluate the efficacy of ixekizumab in the treatment of moderate-to-severe psoriasis Available at: (accessed September 2018).

Institute for Clinical and Economic Review (ICER). Targeted Immunomodulators for the treatment of moderate-to-severe plaque psoriasis: effectiveness and value. 2016. Available at: (accessed September 2018).

Kyntheum® Summary of Product Characteristics, 2017. Available at: (accessed September 2018).

Langley RG, Boni E, Elewski, BE, Lebwohl M, Reich K, Griffiths CEM, et al. Secukinumab in plaque psoriasis – results from two phase 3 studies. N Engl J Med. 2014;371(4):326‒38.

Lebwohl M, Strober B, Menter A, Gordon K, Weglowska J, Puig L, et al. Phase 3 studies comparing brodalumab with ustekinumab in psoriasis. N Engl J Med. 2015;373(14):1318–28.

Lebwohl M, Puig L, Langley RG, Rosen M, Hansen K, Bachelez H. Brodalumab provides robust and sustained levels of efficacy in moderate-to-sever psoriasis: 120 weeks of treatment in the AMAGINE-2 study. (2017a). Presented at the 26th European Academy of Dermatology and Venerology Congress, 13–17 September 2017. Geneva, Switzerland. P1790.

Lebwohl M, Rosen M, Hansen J, Reich K. Patients with inadequate response to ustekinumab achieve high levels of clearance after switching to brodalumab. (2017b) Presented at the 26th European Academy of Dermatology and Venerology Congress, 13–17 September 2017. Geneva, Switzerland. P1800.

Manalo IF, Gilbert KE, Wu JJ. Time to raise the bar to Psoriasis Area Severity Index 90 and 100. J Drugs Dermatol. 2015;14:1086–8.

Menter A, Cather JC, Jarratt M, Meng X, Guana A, Nyirady J. Efficacy of secukinumab on moderate-to-severe plaque psoriasis affecting different body regions: a pooled analysis of four phase 3 studies. Dermatol Ther (Heidelb). 2016;6(4):639‒47.

Mrowietz U, Kragballe K, Reich K, Spuls P, Griffiths CE, Nast A, et al. Definition of treatment goals for moderate to severe psoriasis: A European consensus. Arch Dermatol Res. 2011;303:1–10.

Mrowietz U, Leonardi CL, Girolomoni G, Toth D, Morita A, Balki SA, et al. Secukinumab retreatment-as-needed versus fixed-interval maintenance regimen for moderate to severe plaque psoriasis: A randomized, double-blind, noninferiority trial (SCULPTURE). J Am Acad Dermatol. 2015;73(1):27‒36.

Narayanan S, Guyatt V, Franceschetti A, Hautamaki EL. Disease burden and patient reported outcomes among patients with moderate to severe psoriasis: an ethnography study. Psoriasis (Auckl). 2014;5:1–7.

Nast A, Gisondi P, Ormerod AD, Saiag P, Smith C, Spuls PI, et al. European S3-Guidelines on the systemic treatment of psoriasis vulgaris - Update 2015 - Short version - EDF in cooperation with EADV and IPC. J Eur Acad Dermatol Venereol. 2015;29:2277–94.

National Psoriasis Foundation, 2018. How severe is my psoriasis? Available from: (accessed July 2018).

National Institute for Health and Care Excellence (NICE). Single Technology Appraisal: Brodalumab for treating moderate to severe plaque psoriasis [ID878]. Committee Papers. 2018. Available at: (accessed September 2018).

National Institute for Health and Care Excellence. NICE Guidance: BNF – Brodalumab. Available at: (accessed October 2018).

Papp KA, Lebwohl MG, Krueger JG, Gottlieb AB, Rastogi S, Radhakrishnan P, Robert JI. Impact of previous biologic use and failure on efficacy of brodalumab and ustekinumab: a pooled analysis of data from two phase 3 randomized clinical trials in moderate-to-severe plaque psoriasis (AMAGINE-2 and AMAGINE-3) (P-4978). Poster presented at: Annual Meeting of the American Academy of Dermatology, Orlando, FL, March 3‒7, 2017.

Papp KA, Gordon KB, Langley RG, Lebwohl MG, Gottlieb AB, Rastogi S, et al. Impact of previous biologic use on the efficacy and safety of brodalumab and ustekinumab in patients with moderate-to-severe plaque psoriasis: integrated analysis of the randomized controlled trials AMAGINE-2 and AMAGINE-3. Br J Dermatol. 2018a;179(2):320–8

Papp K, et al. Long-term Safety of Brodalumab for the Treatment of Moderate-to-Severe Psoriasis: 2-Year Data From 3 Pivotal Phase 3 Clinical Trials. (2018c) Poster 6402 presented at: 76th American Academy of Dermatology; February 16-20, 2018b; San Diego, CA.

Papp KA, Leonardi CL, Blauvelt A, Korman NK, Ohtsuki M, Paul C, et al. Ixekizumab treatment for psoriasis: integrated analysis of three double-blinded, controlled studies (UNDERCOVER-1, UNDERCOVER-2, UNDERCOVER-3). Br J Dermatol. 2018c;178(3):674‒81.

Paul C, Lacour JP, Tedremets L, Kreutzer K, Jazayeri S, Adams S, et al. Efficacy, safety and usability of secukinumab administration by autoinjector/pen in psoriasis: a randomised, controlled trial (JUNCTURE). J Eur Acad Dermatol Venerol. 2015;29(6):1082‒90.

Paul C, Griffiths CEM, van de Kerkhof PCM, Puig L, Dutronc Y, Henneges C, et al. Ixekizumab provides superior efficacy compared to ustekinumab over 52-weeks of treatment: results from IXORA-A, a phase 3 study. J Am Acad Dermatol. 2018. [Epub ahead of print].

Puig L, Thom H, Mollon P, Tian H, Ramakrishna GS. Clear or almost clear skin improves the quality of life in patients with moderate-to-severe psoriasis: a systematic review and meta-analysis. J Eur Acad Dermatol Venereol. 2017;31:213–20.

Reich K, Griffiths C, Lebwohl M, Nikai E, Edson-Heredia E, Lin CY, et al. Complete resolution of psoriasis is associated with greater improvements in itch and health-related quality of life: an analysis from UNCOVER-1, a phase 3 clinical trial of ixekizumab. Presented at the European Academy of Dermatology and Venereology Congress. 7–11 October 2016. Copenhagen, Denmark. P1642.

Reich K, Armstrong AW, Foley P, Song M, Wasfi Y, Randazzo B, et al. Efficacy and safety of guselkumab, an anti-interleukin-23 monoclonal antibody, compared with adalimumab for the treatment of patients with moderate to severe psoriasis with randomized withdrawal and retreatment: Results from the phase III, double-blind, placebo- and active comparator-controlled VOYAGE 2 trial. J Am Acad Dermatol. 2017;76(3):418–31.

Riley RD, Jackson D, Salanti G, Buke DL, Price M, Kirkham J, et al. Multivariate and network meta-analysis of multiple outcomes and multiple treatments: rationale, concept, and examples. BMJ. 2017;358:j3932.

Russell CB, Rand H, Bigler J, Kerkof K, Timour M, Bautista E, et al. Gene expression profiles normalized in psoriatic skin by treatment with brodalumab, a human anti-IL-17 receptor monoclonal antibody. J Immunol. 2014;192:3828‒36.

Sawyer L, Fotheringham I, Gibbons C, Møller A. Brodalumab versus secukinumab in moderate-to-severe psoriasis: an indirect comparison of 52-week efficacy outcomes. Presented at the at the European Academy of Dermatology and Venerology Congress, 13–17 September 2017. Geneva, Switzerland. P1839.

Sawyer LM, Cornic L, Levin LA, Gibbons C, Møller A., Jemec BG. J Eur Acad Dermatol Venereol 2018a. Doi: 10.1111/jdv.15277.

Sawyer L, Fotheringham I, Wright E, Yasmeen N, Gibbons C, Møller A. The comparative efficacy of brodalumab in patients with moderate-to-severe psoriasis: a systemic literature review and network meta-analysis. J Dermatol Treat 2018b;29(6):577–68.

Sbidian E, Chaimani A, Garcia-Doval I, Do G, Hua C, Mazaud C, et al. Systemic pharmacological treatments for chronic plaque psoriasis: a network meta-analysis. Cochrane Database Syst Rev. 2017;12:Cd011535.

Strober B, Papp KA, Lebwohl M, Reich K, Paul C, Blauvelt A, et al. Clinical meaningfulness of complete skin clearance in psoriasis. J Am Acad Dermatol. 2016;75(1):77–82.

Taltz® Summary of Product Characteristics, 2018. Available at: (accessed February 2018).

Thaçi D, Blauvelt A, Reich K, Tsai TF, Vanaclocha F, Kingo K, et al. Secukinumab is superior to ustekinumab in clearing skin of subjects with moderate to severe plaque psoriasis: CLEAR, a randomised controlled trial. J Am Acad Dermatol. 2015;73(3):400‒9.

Torii H, Sato N, Yoshinari T, Nakagawa H; Japanese Infliximab Study Investigators. Dramatic impact of a Psoriasis Area and Severity Index 90 response on the quality of life in patients with psoriasis: an analysis of Japanese clinical trials of infliximab. J Dermatol. 2012;39:253–9.

US Food and Drug Administration, 2017. FDA approves new psoriasis drug brodalumab  [press release]. Available at: (accessed February 2019).

US Food and Drug Administration, 2015. FDA approves new psoriasis drug Cosentyx [press release]. Available at: (accessed September 2018).

Wasilewska A, Winiarska M, Olszewska M, Rudnicka L. Interleukin-17 inhibitors. A new era in treatment of psoriasis and other skin diseases. Adv Dermatol Allergol. 2016;34(4):247‒52.

Zweegers J, Otero ME, van den Reek JM, van Lümig PP, Driessen RJ, Kievit W, et al. Effectiveness of biologic and conventional systemic therapies in adults with chronic plaque psoriasis in daily practice: a systematic review. Acta Derm Venereol. 2016;96(4):453–8.

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