<p>(A) Overview of <i>in vivo</i> IgG4 half antibody exchange mainly driven by the potential to form either interchain or intrachain disulfide bonds in the hinge region. A S228P mutation increases the sterical distance of the two cysteines preventing intrachain disulfide bonds. (B) Generated nBT062 model antibodies: Wild type (WT) nBT062, stable nBT062, half nBT062 and bispecific nBT062-natalizumab. Respective mutations are indicated.</p