Pembrolizumab in Early Triple-Negative Breast Cancer

To the Editor: In the KEYNOTE-522 trial, Schmid et al.(1) reported that the addition of pembrolizumab to neoadjuvant chemotherapy for early triple-negative breast cancer resulted in an increased percentage of patients with a pathological complete response (no invasive cancer in the breast and negative nodes). In a recent analysis of this trial (Feb. 10 issue),(2) the authors found that the addition of pembrolizumab improved event-free survival among the patients. The improvement in this outcome was predominantly restricted to patients who had not had a pathological complete response; the 3-year event-free survival was 67.4% among such patients in the pembrolizumab group . . .