IL17A and histiocytic sarcoma: In addition, several lines of evidence have pinpointed IL-17 as a key player in the pathogenesis of HS, paving the way for a number of targeted therapies against IL-17 in the clinical setting, including human immunoglobulin (Ig) G1/κ monoclonal antibodies (secukinumab and CJM112), a humanised IgG1 antibody (bimekizumab), a human IgG2 monoclonal antibody (brodalumab), ligand trap using Affibody® molecules (Izokibep, a novel subcutaneous inhibitor with a small molecular size), and a novel trivalent nanobody (sonelokimab, neutralises IL-17A and IL17F) [11].