ERBB2 and breast cancer: New antibodies are tested in breast cancer: glembatumumab vedotin - an antibody-drug conjugate used in patients with advanced triple-negative breast cancer with cells that produce a protein called glycoprotein NMB, margetuximab, an anti-HER2 antibody used in patients with relapsed or refractory advanced breast cancer with cells that express HER2 at the 2+ level and lack HER2 gene amplification by FISH.