Research Report 2010 - MDC

Structure of the GroupGroup LeaderProf. Dr. Wolfgang UckertScientistsDr. Haike Gelfort*Dr. Elisa KiebackDr. Lilian StärckWolfgang UckertMolecular Cell Biology andGene TherapyThe introduction of T cell receptor (TCR) genes into T cells has been developed over the past yearsas a strategy to induce defined antigen-specific T cell immunity. The potential value of TCR genetherapy was well established in mouse models and the feasibility of infusion of TCR gene-modifiedautologous T cells was shown in first clinical studies. The next steps will be the translation of TCRgene therapy from an experimental technique into a robust and safe clinical strategy.The focus of our group lies on the therapy of cancer and viral diseases using TCR gene therapy.We address questions related to: generation of T cells with new antigen specificity, modificationof TCR genes to generate T cells with high functional avidity, safety aspects of TCR genemodifiedT cells with respect to the recognition of self-antigens, adoptive transfer of TCR genemodifiedT cells in mice as preclinical models, and optimization of TCR transfer vectors.Redirection of T cell antigen specificity by TCRgene transferMatthias Leisegang, Daniel Sommermeyer, Lilian Stärck,Peter Meyerhuber, Haike Gelfort in collaboration withHelga Bernhard, Antonio Pezzutto, Dolores SchendelWe have molecularly cloned TCRα/β genes recognizingtumor-associated antigens (HER2, Mart-1, Melan-A, NY-ESO-1, RCC-26, RCC-53, Survivin, Tyrosinase), virus-specificantigens (CMV, EBV-EBNA3a, EBV-LMP2a), and modelantigens (LCMV-gp33, ovalbumin). Using retrovirus vectors,TCR genes were transferred into T cell lines and primaryT cells of mouse and human origin. TCR-α andβ-chains were expressed on the cell surface and functionalityof transgenic TCRs was demonstrated by antigenrecognition, cytokine secretion and lysis of tumor cells.Designer T cells by TCR optimizationDaniel SommermeyerTo increase the avidity of TCR-redirected T cells, weintroduced different modifications into the TCR genes(codon optimization, additional disulfide bond,murinization of constant regions of human TCR chains)and demonstrated exemplarily for the NY-ESO-1 TCRthat functional T cell avidity can be considerablyimproved (Figure).One of these modifications – “murinization” – whichreplaces the human TCR and TCR constant regions bytheir murine counterparts was analyzed in detail. Usinga series of mouse-human hybrid constructs, we identifiednine amino acids responsible for the improvedexpression of murinized TCRs. Five critical amino acidexchanges were identified in the TCR constant region,with exchange of an acidic glutamic acid (human) for abasic lysine (mouse) at position 18 of the constantregion, being most important. For the TCR constantregion, a domain of four amino acids was sufficient forimproved expression. The minimal murinized TCR variantsenhanced expression of human TCRs by supportingpreferential pairing of transferred TCR chains.Furthermore, usage of minimal murinized TCR chainsimproved the function of transduced primary human Tcells when compared to cells transduced with wild-typeTCRs. For TCR gene therapy, the utilization of minimal124 Cancer Research