Provided are methods and compositions for treating hematological malignancies in patients carrying an IDH1 mutation using a combination of an inhibitor of mutant IDH1 enzyme, (S)-N-((S)-1-(2-chlorophenyl)-2-((3,3-difluorocyclobutyl)amino)-2-oxoethyl)-1-(4-cyanopyridin-2-yl)-N-(5-fluoropyridin-3-yl)-5-oxopyrrolidine-2-carboxamide, or a pharmaceutically acceptable salt thereof (COMPOUND 2) and a DNA demethylating agent.