Patients ( n = 124 ) with refractory breast cancer that expressed gpNMB in 5 % of epithelial or stromal cells by central immunohistochemistry were stratified by gpNMB expression ( tumor , low stromal intensity , high stromal intensity ) and were randomly assigned 2:1 to glembatumumab vedotin ( n = 83 ) or investigator 's choice ( IC ) chemotherapy ( n = 41 ) .