IL17A and psoriasis: In multiple phase 3 trials in psoriasis patients, Otezla (Apremilast), a phosphodiesterase 4 (PDE4) inhibitor, reduced the production of IL-17A, IL-17F, IL-22 and TNFα by 40–50% at Week 4 with concomitant Psoriasis Area and Severity Index (PASI) -75 response rates of approximately 30% at Week 16 [10].