Pembrolizumab in the Treatment of Breast Cancer

Treatment for triple-negative breast cancers has always been perceived as a "north face" (an allusion to the fact that the north face of a mountain in the northern hemisphere is usually the most formidable and challenging for mountain climbers), and numerous studies have failed to confirm that particular treatments confer a substantial benefit. In this issue of the Journal, Cortes et al.1 report that pembrolizumab — a breakthrough therapeutic treatment for patients with advanced triple-negative breast cancer — combined with chemotherapy prolonged overall survival among these patients. These results confirm the relationship between programmed death ligand 1 (PD-L1) expression and . . .