Ph II Study of Pembrolizumab & Eribulin in Patients With HR+/HER2- MBC Previously Treated With Anthracyclines & Taxanes

This a multicenter, open-label, phase II clinical trial to assess the efficacy of pembrolizumab in combination with eribulin in female patients older than 18 years old with hormone receptor-(HR)positive/HER2-negative metastatic breast cancer (MBC) previously treated with at least one, but not more than two, prior chemotherapeutic regimens for treatment of locally recurrent and/or metastatic disease. Prior therapy must have included an anthracycline and a taxane in any combination or order and either in the early or metastatic disease setting unless contraindicated for a given patient. Prior anti-hormonal therapy is mandatory. The number of patients to be included is 44 patients at 11 sites. The primary objective is to assess the efficacy -as determined by the clinical benefit rate (CBR) (total number of objective responses plus stable disease for at least 24 weeks) based on RECIST v.1.1- of MK3475 (pembrolizumab) in combination with eribulin. Primary endpoint is CBR based on RECIST v.1.1. All eligible patients will be treated with MK3475 (pembrolizumab) 200 mg on day 1 of each 21-day cycle and eribulin 1.23 mg/m2 (equivalent to eribulin mesylate at 1.4 mg/m2) on days 1 and 8 of every 21-day cycle. Treatment with MK3475 (pembrolizumab) and eribulin will continue based on physician criteria. No maximum duration of treatment is specified. Study follow-up will be performed 12 months after last study dose. Available tumor tissue for PD-L1 biomarker analysis from a newly obtained core or excisional biopsy since last progression of a metastatic tumor lesion not previously irradiated is requested for this study. Translational research of this protocol involves the collection, processing, temporary storage, and shipment of samples from consenting patients enrolled in centers selected for participation in the study. The study plan includes collection and initial processing of tumor tissues and blood samples to the central laboratory of Institut Hospital del Mar d"Investigacions Mèdiques (IMIM), that will be used to identify dynamic biomarkers that may be predictive of response to MK3475 (pembrolizumab) and eribulin treatment.