Nature Communications (Aug 2023)

Complementarity-determining region clustering may cause CAR-T cell dysfunction

  • Tina Sarén,
  • Giulia Saronio,
  • Paula Marti Torrell,
  • Xu Zhu,
  • Josefin Thelander,
  • Yasmin Andersson,
  • Camilla Hofström,
  • Marika Nestor,
  • Anna Dimberg,
  • Helena Persson,
  • Mohanraj Ramachandran,
  • Di Yu,
  • Magnus Essand

DOI
https://doi.org/10.1038/s41467-023-40303-z
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 11

Abstract

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Abstract Chimeric antigen receptor (CAR)-T cell therapy is rapidly advancing as cancer treatment, however, designing an optimal CAR remains challenging. A single-chain variable fragment (scFv) is generally used as CAR targeting moiety, wherein the complementarity-determining regions (CDRs) define its specificity. We report here that the CDR loops can cause CAR clustering, leading to antigen-independent tonic signalling and subsequent CAR-T cell dysfunction. We show via CARs incorporating scFvs with identical framework and varying CDR sequences that CARs may cluster on the T cell surface, which leads to antigen-independent CAR-T cell activation, characterized by increased cell size and interferon (IFN)-γ secretion. This results in CAR-T cell exhaustion, activation-induced cell death and reduced responsiveness to target-antigen-expressing tumour cells. CDR mutagenesis confirms that the CAR-clustering is mediated by CDR-loops. In summary, antigen-independent tonic signalling can be induced by CDR-mediated CAR clustering, which could not be predicted from the scFv sequences, but could be tested for by evaluating the activity of unstimulated CAR-T cells.