**5.1 Anti-interleukin 17**

IL-17 is a pro-inflammatory cytokine produced by Th17 T cells, one of the key players in the pathogenesis of psoriasis. Due to its role in psoriasis, IL-17 is a new emerging target for biological therapy.

AMG 827 is a fully human IgG2 anti IL-17 receptor monoclonal antibody investigated in phase II trials for psoriasis, rheumatoid arthritis and Crohn's disease (Amgen, 2011). Preliminary data from a small study showed that psoriatic patients treated with 700 mg AMG 827 IV had a significant improvement in terms of histopathological features and PASI score (Russell et al, 2010).

AIN457 is a recombinant fully human anti-IL-17 monoclonal antibody that selectively binds and neutralizes IL-17. The efficacy and safety of AIN457 has been evaluated in a phase II trial (Jancin, 2009) which enrolled 36 patients suffering from chronic plaque psoriasis. A PASI 75 response was observed in 44% of patients receiving 3 mg/kg AIN457 IV compared with 9% of placebo group. AIN457 is currently undergoing phase II studies for psoriasis, psoriatic arthritis and rheumatoid arthritis and a phase III study for uveitis (Novartis, 2010).

LY2439821 is a new humanized IgG4 anti-IL-17 monoclonal antibody in a phase II trial for psoriasis and rheumatoid arthritis (Eli Lilly and Company, 2011).
