CD22 and asthma: While the therapeutic monoclonal antibody market is dominated by the IgG1 subclass, a number of IgG4 antibodies, with wildtype or stabilized hinges, are currently in clinical trials, including anti-IL-5 reslizumab for the treatment of asthma (124), anti-IL-17 ixekizumab for the treatment of psoriasis (125), anti-IL-13 tralokinumab for the treatment of asthma (126), and anti-CD22 inotuzumab ozogamicin, an antibody-drug conjugate (127) for the treatment of acute lymphoblastic leukemia, which highlights the suitability of IgG4 for therapeutic purposes.