ERBB2 and breast cancer: In subgroup analysis for patients with HR-positive/HER2-negative breast cancer, median PFS was prolonged in patients treated with IO plus chemotherapy compared to IO alone (5.6 months [95% CI, 2.6-8.1] vs. 2.2 months [95% CI, 2.0-2.4], p = 0.0096) (Figure 3).