eligibility_summary
Inclusion: Adults with metastatic HR+ (ER>10%), HER2-, PIK3CA-mutant breast cancer, measurable disease or lytic bone lesion, planned alpelisib+fulvestrant or AI, ECOG 0-1, life >=6 mo, able to swallow, consent, adequate organ function, women postmenopausal. Exclusion: hypersensitivity, >2 endocrine lines, active infection incl HIV/HBV/HCV, recent anti-IL-5/biologic or investigational drugs, prednisone >=20 mg/d, recent helminth, pregnant/lactating, benralizumab anaphylaxis, unsuitable.
trial_source
clinical_trials.gov from Dec 2, 2025
annotation_status
ai
ai_summary
NCT05966584 (RETENTION) was an open-label, single-arm phase 2 trial (terminated for limited eligible participants) testing benralizumab to prevent alpelisib-induced rash in metastatic HR+ HER2– PIK3CA-mutant breast cancer starting standard alpelisib plus endocrine therapy (fulvestrant or aromatase inhibitor). Benralizumab: biologic monoclonal antibody against IL-5 receptor α (afucosylated IgG1) that depletes eosinophils via ADCC and blocks IL‑5 signaling, targets eosinophils/basophils and the Th2/IL‑5 inflammatory axis to reduce eosinophilic skin inflammation. Alpelisib: oral small‑molecule PI3K‑α inhibitor targeting the PIK3CA/PI3K‑AKT‑mTOR pathway in tumor cells. Fulvestrant: SERD that antagonizes/degrades estrogen receptor. Aromatase inhibitors: small‑molecule blockers of aromatase, lowering estrogen. Target cells/pathways: eosinophils and IL‑5 pathway in skin, tumor PI3K‑α pathway, estrogen receptor signaling.