Abstract
Overactive epidermal growth factor receptor (EGFR) signaling is often involved in driving different types of carcinomas. It is a well-studied target for targeted therapies, with both monoclonal antibodies and kinase inhibitors available for clinical use. Even though these drugs show a clinical benefit, most patients develop resistance over time. The development of new therapeutic modalities is therefore highly motivated. Herein, we describe a new type of drug candidate targeting EGFR, a so-called affibody-based drug conjugate. It consists of an EGFR-targeting affibody molecule, Z(EGFR), expressed as a fusion to an albumin-binding domain for half-life extension, and coupled with the potent cytotoxic drug DM1 via a maleimidocaproyl linker. The resulting drug conjugate Z(EGFR)-ABD-mcDM1, showed strong binding to recombinant EGFR and EGFR-expressing cells. It was found to be highly potent in killing EGFR-expressing A431 cells with an IC(50) of 3.4 nM. In vivo, it showed moderate uptake in A431-derived xenografts with high EGFR expression. Collectively, the results from this study, demonstrate a potent and EGFR-specific drug candidate that holds promise for further development.