Here a synthetic Fab (NabFab) has been used as a label for the small 15 kDa nanobody bound to a membrane protein, thus enhancing the molecular weight to facilitate the cryo-EM analysis31. In summary, our cryo-EM reconstruction of CODVIg:IL13:RefAbFab ternary complex in the full antibody context confirms that CODVIg is structurally competent for the simultaneous binding of the interleukins IL4 and IL13 and therefore remains a very promising platform for cancer immunotherapy. Here, IL13 is linked to cancer.