The invention relates to, among others, a method for assessing a prognosis of a patient with a malignant disease and / or for predicting the response of a patient with a malignant disease to immunotherapy. For this purpose, a DNA methylation analysis is carried out on at least one immunoregulatory gene of cells of the malignant disease and / or T lymphocytes which interact with the cells of the malignant disease, said gene coding for an immune checkpoint selected from B7 proteins and the receptors thereof, MHC-peptide complex-binding co-receptors, the members of the tumor necrosis factor receptorsuperfamily TNFRSF9, CD40, TNFRSF4, TNFRSF18, and CD27, the members of the immunoglobulin superfamily TIGIT, BTLA, HAVCR2, BTNL2, and CD48, and the andenosine-binding adenosine 2A receptor.