Very few patients with endocrine-resistant, hormone-receptor positive metastatic breast cancer respond to single agent immunotherapy. Responses to chemotherapy are usually of short duration. Combining immunotherapy with chemotherapy that has minimal immunosuppressive effect, it may be possible to achieve higher response rates while keeping the immune-associated pattern of long durations of response.
This will be a single-center phase 1b study to evaluate the tumor response and appropriate dose of a chemo-immunotherapy regime consisting of treatment with pegylated liposomal doxorubicin (PLD) and pembrolizumab-based in endocrine-resistant breast cancer (ERBC) patients.
Up to 15 female patients, ages 18 and above, with pathological diagnosis of breast cancer, estrogen receptor (ER) positive, human epidermal growth factor receptor 2 (HER2-) negative subtype, stage III non-operable, or stage IV disease, who have received at least two lines of hormonal therapy, one of which included aromatase inhibitors will be eligible for enrollment to this single arm study.
Have pathological diagnosis of breast cancer, ER positive (%ER+ cells≥1%, Allred score ≥3), Her2 negative subtype, locally advanced (stage III non-operable), or metastatic (stage IV) disease.
Have measurable disease on computed tomography (CT) or positron emission tomography-computed tomography (PET-CT) scan.
Has known hypersensitivity to the study drugs or to any of their excipients.
Has congestive heart failure (New York Heart Association [NYHA] Class IV) or left ventricular ejection fraction (LVEF) ≤40%.
Has chronic obstructive pulmonary disease (COPD) >Stage 3 (forced expiratory volume in 1 second [FEV1] <50%, forced expiratory volume 1/forced vital capacity [FEV1/FVC] <70%).
Has cirrhosis (Child-Pugh Class C score).