Leucine-rich alpha-2-glycoprotein 1 (LRG1) as a novel ADC target.

Faiza Javaid,Calise Bahou,James R Baker,Vijay Chudasama,Camilla Pilotti,John Greenwood,Jack Blackburn,Stephen E Moss,David Kallenberg,Carlotta Camilli

doi:10.1039/d1cb00104c

Faiza Javaid, Calise Bahou + Show 8 more

Open Access

https://doi.org/10.1039/d1cb00104c

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Abstract

Leucine-rich alpha-2-glycoprotein 1 (LRG1) is present abundantly in the microenvironment of many tumours where it contributes to vascular dysfunction, which impedes the delivery of therapeutics. In this work we demonstrate that LRG1 is predominantly a non-internalising protein. We report the development of a novel antibody–drug conjugate (ADC) comprising the anti-LRG1 hinge-stabilised IgG4 monoclonal antibody Magacizumab coupled to the anti-mitotic payload monomethyl auristatin E (MMAE) via a cleavable dipeptide linker using the site-selective disulfide rebridging dibromopyridazinedione (diBrPD) scaffold. It is demonstrated that this ADC retains binding post-modification, is stable in serum and effective in in vitro cell studies. We show that the extracellular LRG1-targeting ADC provides an increase in survival in vivo when compared against antibody alone and similar anti-tumour activity when compared against standard chemotherapy, but without undesired side-effects. LRG1 targeting through this ADC presents a novel and effective proof-of-concept en route to improving the efficacy of cancer therapeutics.

Highlights

An antibody–drug conjugate (ADC) comprises an antibody that recognises tumour specific antigens to which a highly potent cytotoxic agent is conjugated via a chemical linkage.[1]
By applying the disulfide-rebridging PD scaffold to the hinge-stabilised human LRG1 (hLRG1)-targeting IgG4 antibody Magacizumab, we demonstrated that this ADC retains binding post-modification, displays excellent serum stability and is effective in in vitro cell viability assays
We demonstrate that Leucine-rich alpha-2 glycoprotein-1 (LRG1) and Magacizumab-LRG1 are predominantly noninternalising, and that a Magacizumab-fluorophore conjugate localises at the tumour site in an in vivo model

Summary

Introduction

An antibody–drug conjugate (ADC) comprises an antibody that recognises tumour specific antigens to which a highly potent cytotoxic agent is conjugated via a chemical linkage.[1] ADCs couple the targeting selectivity of an antibody moiety with the cell killing capacity of a cytotoxic payload. Leucine-rich alpha-2 glycoprotein-1 (LRG1) is a secreted glycoprotein which is commonly induced in pathological lesions where, amongst other properties, it promotes dysfunctional vessel growth.[19,20] LRG1 contributes to pathological angiogenesis by corrupting the homeostatic influence of TGFb signalling,[20] and promotes vessel dysfunction by interfering with vessel stabilisation and maturation.[21] Increasingly, LRG1 is seen as an important factor in determining vessel abnormality in a wide range of diseases, including cancer. Accumulating evidence suggests that LRG1 is involved in the growth and progression of a variety of cancer types as significantly elevated expression of LRG1 in serum and solid tumours has been found to be associated with a poor prognosis.[22,23,24,25,26,27]

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