Research Highlights

 

Immune therapies using chimeric antigen receptors (CAR)-T cells have a major defect in antigen sensitivity and this leads to cancer relapse.

  • We have discovered methods to improve the sensitivity of CAR-T cells.
  • We secured venture capital seed funding to spin-out a company to improve these therapies.
  • MatchBio Ltd has been operational as of January 2024.

 

Patel A, Andre V, Eguiguren SB, Barton MI, Denham EM, Pettmann J, Morch AM, Kutuzov MA, Siller-Farfan JA, Dustin ML, van der Merwe PA, Dushek O (2024) Using CombiCells, a platform enabling titration and combinatorial display of cell surface ligands, to study T cell antigen sensitivity by TCRs, CARs, and BiTEs. EMBO J

  • Our ability to study cell-cell recognition has been limited by our inability to independently control cell surface ligands.
  • Here, we expressed the protein SpyCatcher, which forms a covalent bond with SpyTag, on the cell surface.
  • By adding any combination and concentration of purified ligands fused to Spytag, we can produce cells with desired ligand combinations/concentrations within minutes.
  • This platform has many applications, including studying the basic mechanism of cell-cell recognition and evaluating the performance of immunotherapies, such as BiTEs and CARs.

Burton J, Siller-Farfan JA, Pettmann J, Salzer B, Kutuzov M, van der Merwe PA, Dushek O (2023) Inefficient exploitation of accessory receptors reduces the sensitivity of chimeric antigen receptors. PNAS

  • The TCR uses diverse mechanisms to achieve its remarkable single pMHC ligand sensitivity (Siller-Farfan & Dushek (2018) Immunological Reviews).

  • However, Chimeric Antigen Receptors (CARs) have a profound sensitivity defect requiring >100-fold more antigen to activate T cells and this is thought to contribute to cancer relapse in patients.

  • By systematically studying the impact of different co-stimulation receptors on TCR and CAR antigen sensitivity, we identified that CARs fail to efficiently exploit adhesion receptors to enhance their antigen sensitivity.

  • We show that the ability of a variety of synthetic antigen receptors to exploit the adhesion receptor CD2 and LFA-1 can predict their antigen sensitivity. 

Pettmann J, Awada L, Bartosz R, Huhn A, Faour S, Kutuzov M, Limozin L, Weikl TR, van der Merwe PA, Robert P, Dushek O (2023) Mechanical forces impair antigen discrimination by reducing differences in T cell receptor off-rates. EMBO Journal (see associated News & Views)

  • The T cell antigen receptor (TCR) needs to discriminate between lower-affinity self pMHCs and higher-affinity foreign pMHCs.
  • Previous work suggested that mechanical forces may impact the ability of T cells to discriminate pMHC antigens.
  • Here, we used a cell-free system to study how mechanical forces impact the TCR/pMHC off-rate and find that mechanical pulling forces decrease differences in off-rates impairing antigen discrimination.

*Pettmann J, *Huhn A, *Abu Shah E, Kutuzov MA, Wilson DB, Dustin ML, Davis SJ, van der Merwe PA, Dushek O (2021) The discriminatory power of the T cell receptor. eLife (see associated Press Release)

  • The large community of T cell immunologists, including ourselves, have focused on explaining the apparent near-perfect ability of T cells to discriminate antigen based on the TCR/pMHC binding affinity.

  • However, we discovered that the foundational data on antigen discrimination used by the community contained artefacts in their affinity measurements

  • In this work, we developed a method to accurately measure TCR/pMHC affinities and used it to precisely quantify antigen discrimination.

  • We show that the discriminatory power of the TCR, although enhanced compared to conventional surface receptors (e.g. GPCR, RTKs, etc), is imperfect allowing responses even from ultra-low affinity pMHCs.

  • This suggests that T cell mediated autoimmunity is not necessarily a T cell defect but rather a defect in target cells that cause them to abnormally express high levels of self-antigens.