Interleukin 17 is involved in the inflammatory cascade in several immune-mediated and inflammatory diseases such as psoriasis, psoriatic arthritis, and ankylosing spondylitis. It is, therefore, not surprising th at intense development of several specific inhibitory drugs followed identification of the five members of the interleukin-17 family, among which interleukin 17A is so far the best characterised regarding its inflammatory effects. 1 In The Lancet, Christopher Griffiths and colleagues2 report results from two randomised phase 3 trials, UNCOVER-2 and UNCOVER-3, comparing the efficacy and safety of ixekizumab, a humanised monoclonal