Pertuzumab Retreatment for Human Epidermal Growth Factor Receptor 2–Positive Locally Advanced/Metastatic Breast Cancer (PRECIOUS Study): Final Overall Survival Analysis

In the primary analysis of the open-label phase III PRECIOUS study, pertuzumab retreatment combined with trastuzumab plus chemotherapy of physician's choice (PTC) significantly improved investigator-assessed progression-free survival (PFS) compared with trastuzumab plus physician's choice chemotherapy (TC) in patients with human epidermal growth factor receptor 2 (HER2)-positive locally advanced/metastatic breast cancer (LA/mBC). Here, we report final overall survival (OS) at the median follow-up of 25.8 months. Patients who have previously received pertuzumab-containing regimens as first-/second-line treatment for LA/mBC were randomly assigned 1:1 to two groups, PTC group (n = 110) and TC group (n = 109). Median OS was longer in the PTC group (median OS 36.2 v 26.5 months; hazard ratio [HR], 0.73 [one side 95% CI upper limit, 0.97]). Updated median investigator-assessed PFS (5.5 v 4.2 months; HR, 0.81 [one side 95% CI upper limit, 1.02]) were also better in the PTC group. Median PFS by independent review did not show the difference between the two groups (4.4 v 4.4 months; HR, 1.03 [one side 95% CI upper limit, 1.36]). These findings suggest that dual HER2 blockade with pertuzumab plus trastuzumab could contribute to improving OS in patients who have previously been treated with pertuzumab-containing regimens for HER2-positive LA/mBC.