LAUSR

Overexpression of (mutated) receptor tyrosine kinases is a characteristic of many aggressive tumors, and induction of receptor uptake has long been recognized as a therapeutic modality. A conjugate of a synthetically produced cell‐penetrating peptide (CPP), corresponding to amino acids 38–59 of human lactoferrin, and the recombinant llama single‐domain antibody (VHH) 7D12, which binds the human epidermal growth factor receptor (EGFR), was generated by sortase A mediated transpeptidation. The conjugate blocks EGF‐mediated EGFR activation with higher efficacy than that of both modalities alone; a phenomenon that is caused by both effective receptor blockade and internalization. Thus, the VHH–CPP conjugate shows a combination of activities that implement a highly powerful new design principle to block receptor activation by its clearance from the cell surface.