Trial to Evaluate Efficacy and Safety of Pembrolizumab and Gemcitabine in HER2-negative ABC

Pembrolizumab at a dose of 200mg as an intravenous (IV) 30 minutes infusion on day 1 of each 21-day cycle. Treatment will be repeated on day 1 of each 21-day cycle until objective disease progression, clinical progression (under investigator criteria), unacceptable toxicity, death or withdrawal of consent, whichever occurs first. Patients completing 24 months of uninterrupted treatment with pembrolizumab or 35 administrations of study medication will stop pembrolizumab treatment (though may continue with gemcitabine). Subjects who stop pembrolizumab after 24 months may be eligible for up to one year of additional pembrolizumab treatment if they progress after stopping it.

Gemcitabine at a dose of 1,250mg/m2 as an intravenous (IV) 60 minutes infusion on day 1 and 8 of each 21-day cycle. Treatment will be repeated on day 1 of each 21-day cycle until objective disease progression, clinical progression (under investigator criteria), unacceptable toxicity, death or withdrawal of consent, whichever occurs first.