Oncometabolites are specific metabolites that accumulate to abnormal levels in cancer cells and contribute to tumorigenesis. One well-known oncometabolite is 2-hydroxyglutarate (2-HG), which is produced by mutated isocitrate dehydrogenase (IDH) enzymes. 2-HG can inhibit various enzymes involved in DNA and histone modification, leading to epigenetic changes that promote cancer development.