In vitro method for the prognosis of patients suffering from HER2-positive breast cancer

1 . A method of treating a patient suffering from HER2+ breast cancer comprising

(i) measuring the level of expression of the genes [MMP11, CDC6, CDH3, TMEM45B, EXO1, FGFR4, RRM2, MLPH, KRT5, KRT14, MYC, PHGDH and BAG1] in a biological sample obtained from the patient, wherein a higher expression level of the genes [MMP11, CDC6, CDH3, TMEM45B, EXO1, FGFR4 and RRM2]; and a lower expression level of the genes [MLPH, KRT5, KRT14, MYC, PHGDH and BAG1], with respect to a pre-established reference level of expression, is indicative that the patient is a responder patient to anti-HER2 therapies, or wherein a lower expression level of the genes [MMP11, CDC6, CDH3, TMEM45B, EXO1, FGFR4, and RRM2]; and a higher expression level of the genes [MLPH, KRT5, KRT14, MYC, PHGDH, and BAG1], with respect to a pre-established reference level of expression, is indicative that the patient is a non-responder patient to anti-HER2 therapies; and

(ii) administering anti-HER2 therapy, or a pharmaceutical composition comprising an anti-HER2 agent, optionally including pharmaceutically acceptable excipients or carriers, to the responder patient.

2 . The method according to claim 1 , wherein the anti-HER2 therapy is selected from: trastuzumab, pertuzumab, lapatinib, pyrotinib, poziotinib, tucatinib, neratinib, DS-8201a, SYD985 or ado-trastuzumab emtansine.