Influence of Molecular Design on the Targeting Properties of ABD-Fused Mono- and Bi-Valent Anti-HER3 Affibody Therapeutic Constructs.

Mohamed Altai,Charles Leitao,John Löfblom,Stefan Ståhl,Christina Atterby,Anzhelika Vorobyeva,Anna Orlova,Vladimir Tolmachev,Sara Rinne

doi:10.3390/cells7100164

Mohamed Altai, Charles Leitao + Show 7 more

Open Access

https://doi.org/10.3390/cells7100164

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Abstract

Overexpression of human epidermal growth factor receptor type 3 (HER3) is associated with tumour cell resistance to HER-targeted therapies. Monoclonal antibodies (mAbs) targeting HER3 are currently being investigated for treatment of various types of cancers. Cumulative evidence suggests that affibody molecules may be appropriate alternatives to mAbs. We previously reported a fusion construct (3A3) containing two HER3-targeting affibody molecules flanking an engineered albumin-binding domain (ABD035) included for the extension of half-life in circulation. The 3A3 fusion protein (19.7 kDa) was shown to delay tumour growth in mice bearing HER3-expressing xenografts and was equipotent to the mAb seribantumab. Here, we have designed and explored a series of novel formats of anti-HER3 affibody molecules fused to the ABD in different orientations. All constructs inhibited heregulin-induced phosphorylation in HER3-expressing BxPC-3 and DU-145 cell lines. Biodistribution studies demonstrated extended the half-life of all ABD-fused constructs, although at different levels. The capacity of our ABD-fused proteins to accumulate in HER3-expressing tumours was demonstrated in nude mice bearing BxPC-3 xenografts. Formats where the ABD was located on the C-terminus of affibody binding domains (3A, 33A, and 3A3) provided the best tumour targeting properties in vivo. Further development of these promising candidates for treatment of HER3-overexpressing tumours is therefore justified.

Highlights

Extensive research over the last decades has led to a better understanding of tumour biology and specific mechanisms of cancer development [1]
human epidermal growth factor receptor type 3 (HER3) overexpression in malignant tumours has been associated with resistance to targeted therapy and poor overall survival
MAbs directed against HER3 have been investigated in the clinics in combination with different therapies for treatment of various types of cancers and demonstrated promising results [34]

Summary

Introduction

Extensive research over the last decades has led to a better understanding of tumour biology and specific mechanisms of cancer development [1]. It has been demonstrated that cancer hallmarks such as resistance to apoptosis, invasiveness, and high proliferative rate are regulated and controlled by a sophisticated intracellular system of signalling cascades. These signalling pathways are often triggered by aberrantly expressed surface receptors such as receptor tyrosine kinases (RTKs). Advancements in our understanding of the mechanisms underlying cancer hallmarks have led to the design and development of a new class of anti-cancer drugs that are more cancer-specific. They are based on targeting of particular elements in the ligand–receptor–signalling chain. MAbs can be utilized as vehicles to deliver toxic payloads to targeted cells [4]

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