Psoriasis and psoriatic arthritis are chronic inflammatory and autoimmune disease, which occurs when our immune system mistakes our own skin and joint tissue for a foreign invader, attacking it and causing inflammation.  When the inflammatory process advances, chemical mediators released from white blood cells damage skin, cartilage, bone, and ligaments causing joints to become deformed.

Over the years, studies have demonstrated that disease-modified anti-rheumatic drugs (DMARDs) such as methotrexate (MTX), leflunomide and sulfasalazine are effective in treating PsA.  In the past decade, due to breakthroughs in genetic engineering and a better understanding of chemical mediators in inflammation, tumor necrosis factor-alpha (TNF-alpha), Interleukin 17( IL-17), interleukin 12(IL-12), and interleukin 23 ( IL-23), have proven to be the key chemical mediators, which initiate, maintain and perpetuate inflammation and cause joint damage.  Therefore, blocking these key chemical mediators can impede and even prevent joint pain and damage.

Enbrel, Humira, Remicade, Cimza and Simponi are all anti-TNF biologics which block chemical action of TNF-alpha.  Stelara (ustekinumab), another kind of biologic, targets IL-12/ IL-23 cytokines and Cosentyx (secukinumab) and Taltz (Ixekizmab)  block IL-17.  As a result, these drugs impede the inflammatory response, improve psoriasis, ease joint pain and swelling, and effectively slow down bone and cartilage damage.  Otezla, a small molecule, inhibits an enzyme called phosphodiesterase 4 (PDE4), to suppress inflammation in people with psoriasis and PsA.  Although Otezla is less expense and safe relative to biologics, it is not as effective as biologics.

Due to the safety issues and cost, not all patients with PsA need to be treated with biologics.  Most patients with PsA can be treated effectively with conventional DMARDs.  Biologics should be used in a highly selective way for patients who would benefit from cutting edge treatment.