Olaparib+Trastuzumab in HER2[+],Breast Cancer Susceptibility Gene (BRCA) Mutated Advanced Breast Cancer

This open-label, multicenter, single arm, two cohorts, Simon's Two-Stage minimax design, phase II clinical trial will assess the efficacy of olaparib in combination with trastuzumab in patients with HER2-positive ABC with gene alterations in HRR DNA pathway. To be included in the cohort A of the study, patients must exhibit germinal deleterious mutations in BRCA1 or BRCA2 genes. Eligible patients will have histologically proven diagnosis of adenocarcinoma of the breast with evidence of advanced disease, and at least one measurable disease as per RECIST v.1.1. Patients will have a documented history of progression on HER2-directed therapy for the treatment of HER2-positive breast cancer with not limits on prior therapies of chemotherapy and/or trastuzumab-lapatinib in advanced scenario, and at least one regimen of chemotherapy including trastuzumab. The accrual goal will be a total of 20 patients