Engineering an anti-HER2 biparatopic antibody with a multimodal mechanism of action

Florian Kast,Annemarie Honegger,Svende Pfundstein,Frauke Seehusen,Andreas Plückthun,Thomas G Weber,Jakob C Stüber,Gabriela Nagy-Davidescu,Josep M Monné Rodríguez,Felix Kroener,Martin Schwill,Karen Patricia Hartmann,Jacob Piehler,Patrick Ernst,Christian P Richter

doi:10.1038/s41467-021-23948-6

Abstract

The receptor tyrosine kinase HER2 acts as oncogenic driver in numerous cancers. Usually, the gene is amplified, resulting in receptor overexpression, massively increased signaling and unchecked proliferation. However, tumors become frequently addicted to oncogenes and hence are druggable by targeted interventions. Here, we design an anti-HER2 biparatopic and tetravalent IgG fusion with a multimodal mechanism of action. The molecule first induces HER2 clustering into inactive complexes, evidenced by reduced mobility of surface HER2. However, in contrast to our earlier binders based on DARPins, clusters of HER2 are thereafter robustly internalized and quantitatively degraded. This multimodal mechanism of action is found only in few of the tetravalent constructs investigated, which must target specific epitopes on HER2 in a defined geometric arrangement. The inhibitory effect of our antibody as single agent surpasses the combination of trastuzumab and pertuzumab as well as its parental mAbs in vitro and it is effective in a xenograft model.

Highlights

The receptor tyrosine kinase HER2 acts as oncogenic driver in numerous cancers
The current TZB/PZB treatment only employs a single mechanism of action (MOA), that of blocking the interaction between HER2 and HER3, and is only transiently effective to block HER2 function, which does not lead to apoptosis[7]
We designed and engineered biparatopic antibodies recognizing two different epitopes in a particular geometry on the HER2 ECD that surpass the effectiveness of the standard of care for metastatic malignancies, which is a mixture of TZB and PZB

Summary

Introduction

The receptor tyrosine kinase HER2 acts as oncogenic driver in numerous cancers. Usually, the gene is amplified, resulting in receptor overexpression, massively increased signaling and unchecked proliferation. The hallmark of sustained proliferative signaling is often caused by dysregulated receptor tyrosine kinases (RTKs) acting as tumor drivers[2]. The current TZB/PZB treatment only employs a single mechanism of action (MOA), that of blocking the interaction between HER2 and HER3 (in liganded and unliganded form), and is only transiently effective to block HER2 function, which does not lead to apoptosis[7] This is one reason for resistance to arise, which was previously shown to develop following prolonged antibody treatment[8] due to a variety of mechanisms, and it remains a major clinical challenge today. Because of its nature as a druggable disease driver and the marked overexpression on the target tissue, HER2 remains an excellent candidate to develop and study antibodies that are more advanced and have multiple MOAs. Bispecific antibodies allow additional functionality in one single molecule in comparison to conventional mAbs[10]

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Conclusion