Disclosed herein are pyridyo-pyrimidine-trione compounds represented by formula I where the substituents are as defined herein. Also disclosed are tautomers and pharmaceutically acceptable salts, combinations with suitable medicament and pharmaceutical compositions thereof. The compounds are inhibitors of MEK and are therefore intended for use in the treatment of diseases including cancer. Also disclosed are processes of preparation of the compounds. Specific examples of the compounds of formula I include 3-(3-(5-((2-fluoro-4-iodophenyl)amino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydropyrido[4,3-d]pyrimidin-1(2H)-yl)phenyl)propanamide and 1-(3-(1,1-dioxidothiomorpholine-4-carbonyl)phenyl)-5-((2-fluoro-4-iodophenyl)amino)-3,6,8-trimethylpyrido[4,3-d]pyrimidine-2,4,7(1H,3H,6H)trione.
