The disclosure relates to a combination for the treatment of cancer wherein the combination exhibits a synergistic effect. The combination comprises radiation and at least one cyclin dependent kinase (CDK) inhibitor selected from the compounds of formula (I) or a pharmaceutically acceptable salt or a solvate thereof. The present disclosure also relates to the use of said CDK inhibitor for the preparation of a medicament that enhances the efficacy of radiotherapy for the treatment of cancer selected from a group consisting of head and neck cancer, cervical cancer, breast cancer, small cell lung cancer, non-small cell lung cancer, lung adenocarcinoma, ovarian cancer, pancreatic cancer, gastric cancer, colorectal cancer, hepatocellular carcinoma, multiple myeloma, mantle cell lymphoma and malignant melanoma.
