This combination Phase I/II trial will test the safety and efficacy of adding tetrathiomolybdate to the standard chemotherapy (capecitabine) for women diagnosed with triple negative breast cancer (TNBC). Phase I will focus on the safety of this innovative combination by determining dosage and tolerability. Phase II will examine two groups of patients: group 1 will receive TM and chemotherapy, while group 2 will only receive chemotherapy. This will establish if adding TM to the standard chemotherapy helps improve disease progression and ultimately survival. If successful, this trial could lead to a new, well-tolerated, and inexpensive standard of care for patients with TNBC.