IL-17 is a key driving molecule in psoriasis, and moderate to severe psoriasis strongly impacts the quality of patient lives.82 To create an IL-17 blocking molecule with a potency superior to the monoclonal antibodies ixekizumab83 and secukinumab,84 IL-17-specific Affibody molecules were formatted into a small 18 kDa dimeric construct with built in long plasma half-life using a previously reported format.47 By simultaneously binding and blocking both subunits of the dimeric IL-17 molecule, the affinity was increased ten-thousand fold to sub-picomolar KD affinity. Here, IL17A is linked to psoriasis.