Abstract
Tumor-associated peptide–human leukocyte antigen complexes (pHLAs) represent the largest pool of cell surface–expressed cancer-specific epitopes, making them attractive targets for cancer therapies. Soluble bispecific molecules that incorporate an anti-CD3 effector function are being developed to redirect T cells against these targets using 2 different approaches. The first achieves pHLA recognition via affinity-enhanced versions of natural TCRs (e.g., immune-mobilizing monoclonal T cell receptors against cancer [ImmTAC] molecules), whereas the second harnesses an antibody-based format (TCR-mimic antibodies). For both classes of reagent, target specificity is vital, considering the vast universe of potential pHLA molecules that can be presented on healthy cells. Here, we made use of structural, biochemical, and computational approaches to investigate the molecular rules underpinning the reactivity patterns of pHLA-targeting bispecifics. We demonstrate that affinity-enhanced TCRs engage pHLA using a comparatively broad and balanced energetic footprint, with interactions distributed over several HLA and peptide side chains. As ImmTAC molecules, these TCRs also retained a greater degree of pHLA selectivity, with less off-target activity in cellular assays. Conversely, TCR-mimic antibodies tended to exhibit binding modes focused more toward hot spots on the HLA surface and exhibited a greater degree of crossreactivity. Our findings extend our understanding of the basic principles that underpin pHLA selectivity and exemplify a number of molecular approaches that can be used to probe the specificity of pHLA-targeting molecules, aiding the development of future reagents.
Original language | English |
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Pages (from-to) | 2673-2688 |
Number of pages | 16 |
Journal | Journal of Clinical Investigation |
Volume | 130 |
Issue number | 5 |
Early online date | 20 Apr 2020 |
DOIs | |
Publication status | Published - 1 May 2020 |
Funding
The authors would like to thank Diamond Light Source for beam time and the staff for assistance with crystal testing and data collection. The authors would also like to thank Kate Lowe, Ita O’Kelly, and Michelle McCully for critically reading the manuscript. RMC’s studentship is funded by the Engineering and Physical Sciences Research Council (EPSRC). MWVDK is a Biotechnology and Biological Sciences Research Council (BBSRC) David Phillips Fellow (BB/M026280/1). This research made use of the Balena High Performance Computing (HPC) Service at the University of Bath as well as the computational facilities of the Advanced Computing Research Centre of the University of Bristol.
ASJC Scopus subject areas
- General Medicine
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