Characterization and modulation of anti-αβTCR antibodies and their respective binding sites at the βTCR chain to enrich engineered T cells

Guido J.J Kierkels,Eline Van Diest,Patricia Hernández-López,Wouter Scheper,Anja C.M De Bruin,Elselien Frijlink,Tineke Aarts-Riemens,Sanne F.J Van Dooremalen,Dennis X Beringer,Rimke Oostvogels,Lovro Kramer,Trudy Straetemans,Wolfgang Uckert,Zsolt Sebestyén,Jürgen Kuball

doi:10.1016/j.omtm.2021.06.011

Abstract

T cell engineering strategies offer cures to patients and have entered clinical practice with chimeric antibody-based receptors; αβT cell receptor (αβTCR)-based strategies are, however, lagging behind. To allow a more rapid and successful translation to successful concepts also using αβTCRs for engineering, incorporating a method for the purification of genetically modified T cells, as well as engineered T cell deletion after transfer into patients, could be beneficial. This would allow increased efficacy, reduced potential side effects, and improved safety of newly to-be-tested lead structures. By characterizing the antigen-binding interface of a good manufacturing process (GMP)-grade anti-αβTCR antibody, usually used for depletion of αβT cells from stem cell transplantation products, we developed a strategy that allows for the purification of untouched αβTCR-engineered immune cells by changing 2 amino acids only in the TCRβ chain constant domain of introduced TCR chains. Alternatively, we engineered an antibody that targets an extended mutated interface of 9 amino acids in the TCRβ chain constant domain and provides the opportunity to further develop depletion strategies of engineered immune cells.

Highlights

The US Food and Drug Administration (FDA) approval of the first engineered T cells expressing chimeric antigen receptors (CARs) has paved the way for new cellular interventions in the clinic.[1,2] A wave of cell therapy will come with T cell receptor (TCR)-engineered T cells specific for targets on both solid and hematological malignancies.[3]
The main finding of our study is that replacing only 2 aa within the constant domain of the TCRb chain allows for the purification of abTCR-engineered T cells with GMP-ready tools,[38] without the need for additional complex genetic engineering
These new insights provide the molecular basis for developing select-kill strategies for increasing purity and augmenting the safety of abTCR engineered T cells, with only minor engineering steps

Summary

Introduction

The US Food and Drug Administration (FDA) approval of the first engineered T cells expressing chimeric antigen receptors (CARs) has paved the way for new cellular interventions in the clinic.[1,2] A wave of cell therapy will come with T cell receptor (TCR)-engineered T cells specific for targets on both solid and hematological malignancies.[3]. Purification of engineered T cells before infusion can overcome these hurdles, resulting in enhanced in vivo activity. Current methods for purification of engineered T cells often depend on the expression of artificial molecules such as truncated CD3410 or truncated NGFR,[11] in addition to the tumor-specific receptor. Selection of engineered T cells and subsequent in vivo elimination achieved with a single marker, which has previously been described for CD20,18 would be favorable, due to the relatively small transgene cassette and

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Conclusion