PURPOSE OF REVIEW: Over the last several years, novel immunologic pathways 
pivotal in the development of the pathobiology of psoriasis and psoriatic 
arthritis (PsA) have been revealed. These discoveries catalyzed a search for new 
treatment targets resulting in many new therapies that are now available for 
patients with psoriatic disease.
RECENT FINDINGS: Helper T cells that secrete interleukin-17 (TH17) along with 
CD8+ cells, innate lymphocyte cells, and gamma delta T cells are important in 
the pathogenesis of psoriasis and PsA. Recently, agents that target 
interleukin-17, the interleukin-17 receptor, and interleukin-23 (antip19) have 
been approved or are in clinical trials. Apremilast, a new oral agent, was 
approved for the treatment of psoriasis and PsA.
SUMMARY: Secukinumab, an interleukin-17A antibody, has been approved for 
treatment of psoriasis and PsA in the United States. It is effective with a good 
safety profile. Ixekizumab, another anti-interleukin-17A antibody, is currently 
in clinical trials and brodalumab, an interleukin-17 receptor antagonist, was 
removed from clinical trials because of safety concerns despite demonstrated 
efficacy in psoriasis and PsA. Targeting interleukin-23 with antibodies to p19 
is another approach with encouraging results in psoriasis. Apremilast, an oral 
agent, approved to treat psoriasis and PsA demonstrates moderate efficacy with 
an excellent safety record. The role of tofacitinib in psoriatic disease remains 
to be determined pending a safety review in psoriasis and completion of PsA 
trials.