Sara M. Tolaney, MD, MPH, associate director, Clinical Research, Breast Oncology, Susan F. Smith Center for Women's Cancers, senior physician, instructor in Medicine, Harvard Medical School, discusses a phase Ib/II trial exploring eribulin mesylate (Halaven) in combination with pembrolizumab (Keytruda) in patients with metastatic triple-negative breast cancer (TNBC).