Study of Glembatumumab Vedotin (CDX-011) in Patients With Metastatic, gpNMB Over-Expressing, Triple Negative Breast Cancer

CDX-011 consists of an antibody attached to a drug, monomethyl auristatin E (MMAE), that can kill cancer cells. The antibody delivers the drug to cancer cells by attaching to a protein called glycoprotein NMB (gpNMB) that is expressed on the cancer cell. The MMAE is then released inside of the cell, where it interferes with cell growth and may lead to cell death. This study will examine the efficacy and safety of CDX-011 in patients with advanced TNBC that makes the gpNMB protein. The effect of CDX-011 will be compared to treatment with capecitabine. Eligible patients who enroll in the study will be randomly assigned (by chance) to receive treatment with CDX-011 or with capecitabine. For every three patients enrolled, two will receive CDX-011 and one will receive treatment with capecitabine. All patients enrolled in the study will be closely monitored to determine if their cancer is responding to treatment and for any side effects that may occur.