Identification of New DR5 Agonistic Nanobodies and Generation of Multivalent Nanobody Constructs for Cancer Treatment.

Golnaz Sadeghnezhad,Ema Romão,Serge Muyldermans,Robert Bernedo-Navarro,Sam Massa,Sadegh Hassania,Khosro Khajeh

doi:10.3390/ijms20194818

Abstract

Current cancer therapeutics suffer from a lack of specificity in targeting tumor cells and cause severe side effects. Therefore, the design of highly specialized drugs comprising antibody derivatives inducing apoptosis in targeted cancer cells is considered to be a promising strategy. Drugs acting on death receptor 5 (DR5) such as DR5 agonist antibodies replacing “TNF-related apoptosis-inducing ligand” (TRAIL) offer feasible opportunities in this direction. Although such agonists provided good antitumor activity in preclinical studies, they were less effective in clinical studies, possibly due to a disturbed Fc interaction with Fc-γ receptors. Thus, multimerized antigen binding fragments without Fc have been proposed to increase their efficacy. We generated nanobodies (Nbs), recombinant variable domains of heavy chain-only antibodies of camelids, against the DR5 ectodomain. Nb24 and Nb28 had an affinity in the nM and sub-nM range, but only Nb28 competes with TRAIL for binding to DR5. Bivalent, trivalent, and tetravalent constructs were generated, as well as an innovative pentameric Nb complex, to provoke avidity effects. In our cellular assays, these trimeric, tetrameric, and pentameric Nbs have a higher apoptotic capacity than monomeric Nbs and seem to mimic the activity of the natural TRAIL ligand on various cancer cells.

Highlights

Cancer ranks second among the common primary causes of death worldwide, and it is anticipated to have accounted for 9.6 million deaths in 2018 [1]
The extrinsic pathway of apoptosis is triggered by signals that employ extracellular death receptors (DR), and the manipulation of these receptor activation mechanisms has been considered as a tempting therapeutic strategy to induce, exclusively, apoptosis in tumor cells [3]
Among DRs, death receptor 5 (DR5), known as Tumor Necrosis Factor (TNF)-related apoptosis-inducing ligand” (TRAIL)-R2 or KILLER receptor, is the most promising candidate to develop a targeted therapy against cancer, since its expression level is significantly higher in cancer cells compared to that of healthy cells

Summary

Introduction

Cancer ranks second among the common primary causes of death worldwide, and it is anticipated to have accounted for 9.6 million deaths in 2018 [1]. The design of potent targeted therapies involving monoclonal antibodies to target cancer cells constitute a promising strategy to treat tumors in cancer patients [2]. “Evading apoptosis” is an important hallmark of cancer progression and most apoptotic programs divide into the intrinsic or the extrinsic pathway. The extrinsic pathway of apoptosis is triggered by signals that employ extracellular death receptors (DR), and the manipulation of these receptor activation mechanisms has been considered as a tempting therapeutic strategy to induce, exclusively, apoptosis in tumor cells [3]. Among DRs, death receptor 5 (DR5), known as TRAIL-R2 or KILLER receptor, is the most promising candidate to develop a targeted therapy against cancer, since its expression level is significantly higher in cancer cells compared to that of healthy cells. Its triggering may potentially mediate selective activation of apoptosis in cancer cells and their killing [4]

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