IL17A and psoriatic arthritis: The IL23/IL17 axis has been targeted as a pathogenic signalling pathway for psoriatic arthritis and SpA.38 Monoclonal antibodies targeting IL17A, such as secukinumab, ixekizumab and netakimab, have shown beneficial effects in clinical studies.16–18 39 40 From a basic standpoint, prophylactic IL17A blockade by monoclonal antibody effectively inhibits inflammation as well as bone destruction and formation in the axial and peripheral joints of HLA-B27 transgenic animals as experimental SpA models.