A method is useful for predicting a response of a malignant disease to an immunotherapy which inhibits the PD-1 immune checkpoint signaling pathway. The method is characterized in that at least a part of an immunoregulatory gene selected from CTLA4, CD86, CD28, CD80 and/or ICOS of cells of the malignant disease and/or of immune cells interacting with cells of the malignant disease is subjected to a DNA methylation analysis, and the result is used to predict the response of the malignant disease to the immunotherapy.
