Bortezomib Followed by Pembrolizumab and Cisplatin in metTNBC

The hypothesis of this pilot trial is that administration of bortezomib will inhibit NHEJ in metastatic TNBC leading at the time of disease progression to metastases that are HR-deficient and sensitive to pembrolizumab and cisplatin therapy. The trial will include in depth analysis of the patients' TNBC genome and phosphoproteome to evaluate HR-proficiency and deficiency, and nuclear proteins that drive NHEJ, before and upon progression with bortezomib therapy.