Combination of entinostat-exemestane for use in a method to (a) treat breast cancer in a patient, wherein the method comprises continuing treatment with entinostat-exemestane combination therapy if the level of acetylation of the protein lysines determined after approximately 15 days of entinostat-exemestane combination therapy is greater than the level of acetylation of protein lysines before entinostatexemestane combination therapy； (b) treating breast cancer in a patient, wherein the method comprises (i) administering entinostat-exemestane combination therapy, and (ii) determining the change in acetylation levels of protein lysines during the course of said therapy compared to the levels of acetylation of the protein lysines prior to therapy, wherein the level of acetylation of the protein lysines is determined in a tissue sample that is obtained approximately 15 days after starting therapy ； (c) treating breast cancer in a patient, wherein the method comprises (i) determining the level of acetylation of protein lysines before administration of entinostatexemestane combination therapy, (ii) administering combination therapy entinostat-exemestane, and (iii) determine the level of acetylation of protein lysines during the cycle of said therapy, where the level of acetylation of protein lysines in a tissue sample is obtained that is obtained approximately 15 days after starting therapy； or (d) treating breast cancer that shows resistance to previous therapy with aromatase inhibitor, the method comprises administering to a patient a combination comprising entinostat and exemestane, wherein the patient does not demonstrate a complete response, a partial response or stable disease for more than six months during previous treatment with an aromatase inhibitor, and wherein the method further comprises determining the level of acetylation of protein lysines in a tissue sample that is obtained approximately 15 days after administration of the combination.Combinación de ent
