Abstract: The present invention relates to a method for preparing tumour-specific T cells, comprising the steps of: providing a tumour sample obtained from a patient, wherein the tumour sample comprises T cells that infiltrated the tumour; isolating T regulatory cells from the tumour sample, selecting at least one clonotype of the isolated T regulatory cells, determining the T cells receptor sequence of the selected clonotype, providing T cells other than T regulatory cells of patient, and transducing T cells other than T regulatory cells obtain from said patient with the determined TCR sequence of selected clonotype thereby yielding tumour specific T cells.