Engineering a Dual Specificity γδ T-Cell Receptor for Cancer Immunotherapy.

Simple Summary: A protein known as the γδ T-cell receptor is the distinguishing hallmark of a small white blood cell subset known as γδ T-cells. γδ T-cells survey the body for potentially dangerous cells, including cancer. The most common γδ T-cell receptor found in the bloodstream is called Vγ9Vδ2 and this detects attributes of cancer cells called phosphoantigens. To generate large numbers of cells that detect phosphoantigens, the Vγ9Vδ2 T-cell receptor gene can be introduced into a more plentiful white blood cell subset called αβ T-cells. In this study, we have inserted a small additional peptide fragment into the Vγ9Vδ2 T-cell receptor, enabling it to also recognise a second tumour target called αvβ6 integrin. When this modified receptor was expressed in αβ T-cells, they acquired the ability to kill tumour cells that produce either phosphoantigens or αvβ6 integrin. By this means, we have broadened the tumour recognition capacity of these engineered T-cells. γδ T-cells provide immune surveillance against cancer, straddling both innate and adaptive immunity. G115 is a clonal γδ T-cell receptor (TCR) of the Vγ9Vδ2 subtype which can confer responsiveness to phosphoantigens (PAgs) when genetically introduced into conventional αβ T-cells. Cancer immunotherapy using γδ TCR-engineered T-cells is currently under clinical evaluation. In this study, we sought to broaden the cancer specificity of the G115 γδ TCR by insertion of a tumour-binding peptide into the complementarity-determining region (CDR) three regions of the TCR δ2 chain. Peptides were selected from the foot and mouth disease virus A20 peptide which binds with high affinity and selectivity to αvβ6, an epithelial-selective integrin that is expressed by a range of solid tumours. Insertion of an A20-derived 12mer peptide achieved the best results, enabling the resulting G115 + A12 T-cells to kill both PAg and αvβ6-expressing tumour cells. Cytolytic activity of G115 + A12 T-cells against PAg-presenting K562 target cells was enhanced compared to G115 control cells, in keeping with the critical role of CDR3 δ2 length for optimal PAg recognition. Activation was accompanied by interferon (IFN)-γ release in the presence of either target antigen, providing a novel dual-specificity approach for cancer immunotherapy. [ABSTRACT FROM AUTHOR]