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Specific increase in T cell potency via structure-based design of a T cell receptor for adoptive immunotherapy
  1. Karolina Malecek1,
  2. Arsen Grigoryan1,
  3. Shi Zhong2,
  4. Wei Jun Gu3,
  5. Laura A Johnson4,
  6. Steven A Rosenberg5,
  7. Timothy Cardozo1 and
  8. Michelle Krogsgaard1
  1. Aff1 grid.137628.90000000121698901NYU School of Medicine New York NY United States
  2. Aff2 Xiangxue Pharmaceutical Co., Ltd GuangZhou Peoples Republic of China
  3. Aff3 grid.137628.90000000121698901NYU New York NY United States
  4. Aff4 grid.25879.310000000419368972Perelman School of Medicine University of Pennsylvania Philadelphia PA United States
  5. Aff5 grid.94365.3d0000000122975165US National Institutes of Health (NIH) Bethesda MD United States

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Meeting abstracts

Adoptive immunotherapy with antigen-specific T lymphocytes is a powerful strategy for cancer treatment. However, most tumor antigens are non-reactive "self" proteins, which presents an immunotherapy design challenge. Studies have shown that tumor-specific T cell receptors (TCRs) can be transduced into normal peripheral blood lymphocytes, which persist after transfer in about 30% of patients and effectively destroy tumor cells. Still, recent clinical trial with affinity-enhanced TCRs has resulted in severe effects due to cross reactivity to an unrelated peptide. Thus, the challenge for targeted T cell therapy remains to increase T cell potency in order to improve clinical responses and ensure on-target specificity by avoiding unwanted cross reactivity. We used structure-based design to predict point mutations of a TCR (DMF5) that enhance its binding affinity for an agonist tumor differentiation antigen-major histocompatibility complex (pMHC), Mart-1(27L)-HLA-A2, which elicits full T cell activation to trigger immune responses. Structural based approaches have been used to increase TCR affinity, however their potential cross-reactivity has not been reported. Here, we analyzed the effects of selected TCR point mutations alone and in combination on T cell activation potency. Further, we analyzed their specificity and cross-reactivity with related antigens presented by different melanoma cell lines and donor-derived antigen presenting cells. Our structure-based approach allowed us to rationally design sequence substitutions that improve binding in contact areas between the TCR and pMHC without increasing cross-reactivity with a wide variety of self-antigens. We identified and evaluated point mutations in critical TCR positions resulting in more potent T cell activation but maintaining overall specificity. When double and triple combination mutations were introduced, they exhibited an additive enhancement that further improved T cell activation while retaining a high degree of specificity.

Conclusions

Such affinity-optimized TCRs could potentially be used in adoptive immunotherapy to treat melanoma while minimizing adverse autoimmunity effects.