Abstract: The present invention refers to an in vitro method for the prognosis of patients suffering from HER2+ breast cancer and/or for the prediction of response to anti-HER2 therapies in patients suffering from HER2+ breast cancer.

Abstract: The present invention refers to an in vitro method for determining the efficacy of anti-HER2 therapy in the absence of chemotherapy in a patient with HER2+ breast cancer comprising the detection and/or quantification of the expression of HER2 in an isolated biological sample of the patient, either (1) before or (2) before and during the anti-HER2 therapy in the absence of chemotherapy treatment. The present invention also refers to the use of a gene expression product of HER2 as a as an in vitro marker for determining the efficacy of anti-HER2 therapy in the absence of chemotherapy in a patient with HER2+ breast cancer, or alternatively as an in vitro marker for deciding or recommending whether to initiate an alternative medical regime to anti-HER2 therapy without chemotherapy in a patient with HER2+ breast cancer.

Abstract: Embodiments of the disclosure include methods and compositions related to treating an individual for HER2+ positive cancer with an appropriate treatment based on outcome of a multiparameter classifier. The methods allow for identification of HER2+ individuals that are suitable to avoid chemotherapy, in specific embodiments. Methods of the disclosure also allow for identification of HER2+ individuals that should not avoid chemotherapy. In specific embodiments, the multiparameter classifier identifies whether there is (1) a ratio of HER2 amplification, relative to a control probe, of greater than or equal to 4.5; (2) a HER2 expression level score of 3+, as determined by immunohistochemistry, in at least 90% of breast cancer cells; (3) whether there is a HER2-enriched molecular subtype; and (4) whether the individual has a wildtype PIKC3A gene.

Abstract: This new method relates to the development of a chemoendocrine score (CES), based on the known analysis PAM50 for predicting whether a patient with breast cancer will respond to chemotherapy or to endocrine therapy, specifically in a patient with HR+/HER2? breast cancer beyond the risk of recurrence (ROR) and PAM50 intrinsic subtypes. Specifically, the clinical utility of this CES predictor is based on the intermediate PAM50 ROR group, the proportion of each CES group (sensitive to endocrine therapy, intermediate, and sensitive to chemotherapy) being greater than 25%.

Abstract: The present invention refers to an in vitro method for determining the efficacy of anti-HER2 therapy in the absence of chemotherapy in a patient with HER2+ breast cancer comprising the detection and/or quantification of the expression of HER2 in an isolated biological sample of the patient, either (1) before or (2) before and during the anti-HER2 therapy in the absence of chemotherapy treatment. The present invention also refers to the use of a gene expression product of HER2 as a as an in vitro marker for determining the efficacy of anti-HER2 therapy in the absence of chemotherapy in a patient with HER2+ breast cancer, or alternatively as an in vitro marker for deciding or recommending whether to initiate an alternative medical regime to anti-HER2 therapy without chemotherapy in a patient with HER2+ breast cancer.