Provided are compounds useful for treating cancer and methods of treating cancer comprising administering to a subject in need thereof a compound described herein. Disclosed herein are methods of treating advanced hematologic malignancies characterized by the presence of a mutant allele of IDH1. In one embodiment, the mutant IDHI has an R132X mutation. In one embodiment, the R132X mutation is selected from R132H, R132C, R132L, R132V, R132S and R132G. In some embodiments, the advanced hematologic malignancies harbor a comutation, e.g., a co-mutation selected from NPM1, FLT3, TET2, CEBPA, DNMT3A, and MLL. In one aspect, the present invention provides a method of evaluating a subject, the method comprising: acquiring a value for the level of a compound (S)-N-((S)-1-(2-chlorophenyl)-2-((3,3
