This is a Multicenter, Open-label, Phase II Clinical Trial to Evaluate the Efficacy and Safety of Niraparib plus Aromatase Inhibitors for Hormone Receptor (HR)-positive/Human Epidermal Growth Factor Receptor 2 (HER2)-negative Metastatic Breast Cancers with either Germline BRCA-mutated or Germinal BRCA-wild-type and Homologous Recombination Deficiency (HRD).~The main objetive is to assess the efficacy -as determined by the clinical benefit rate (CBR)- of niraparib in combination with AIs in unresectable locally advanced or metastatic HR-positive/HER2-negative breast cancer patients harboring either gBRCAms or gBRCAwt and HRD.~Upon meeting all selection criteria, patients enrolled in the study will receive the combination of niraparib either 300 mg or 200 mg orally (according to baseline criteria described in Table 4), once daily, flat- fixed, continuously in 28-day cycles and AI that must be identical to the last AI-containing regimen.~A total of 23 patients will be recruited as follows:~Stage I: N=6 patients in the cohort A;~Stage II: N=8 patients in the cohort A; N=9 patients in the exploratory cohort B~The total duration of the study period is 36 months follow until 5 years of follow up.
This study evalues the efficacy -as determined by the clinical benefit rate (CBR)- of niraparib in combination with AIs in unresectable locally advanced or metastatic HR-positive/HER2-negative breast cancer patients harboring either gBRCAms or gBRCAwt and HRD.~The planned number of patients is 23.~Investigational product is Niraparib 100 mg and the study dose will be 200mg or 300mg daily continuously in 28-day cycles plus aromatase Inhibitors.~Total study duration is 36 months and until 5 years of follow up.