Patient‐reported outcomes from EMILIA, a randomized phase 3 study of trastuzumab emtansine (T‐DM1) versus capecitabine and lapatinib in human epidermal growth factor receptor 2–positive locally advanced or metastatic breast cancer

BACKGROUND: This report describes the results of an analysis of patient-reported outcomes from EMILIA (TDM4370g/BO21977), a randomized phase 3 study of the antibody-drug conjugate trastuzumab emtansine (T-DM1) versus capecitabine and lapatinib in human epidermal growth factor receptor 2 (HER2)-positive locally advanced or metastatic breast cancer. METHODS: A secondary endpoint of the EMILIA study was time to symptom worsening (time from randomization to the first documentation of a ≥ 5-point decrease from baseline) as measured by the Trial Outcome Index Physical/Functional/Breast (TOI-PFB) subset of the Functional Assessment of Cancer Therapy-Breast questionnaire. Predefined exploratory patient-reported outcome endpoints included proportion of patients with a clinically significant improvement in symptoms (per TOI-PFB) and proportion of patients with diarrhea symptoms (per Diarrhea Assessment Scale). RESULTS: In the T-DM1 arm, 450 of 495 patients had a baseline and ≥ 1 postbaseline TOI-PFB score versus 445 of 496 patients in the capecitabine-plus-lapatinib arm. Time to symptom worsening was delayed in the T-DM1 arm versus the capecitabine-plus-lapatinib arm (7.1 months versus 4.6 months, respectively; hazard ratio = 0.796; P = .0121). In the T-DM1 arm, 55.3% of patients developed clinically significant improvement in symptoms from baseline versus 49.4% in the capecitabine-plus-lapatinib arm (P = .0842). Although similar at baseline, the number of patients reporting diarrhea symptoms increased 1.5- to 2-fold during treatment with capecitabine and lapatinib but remained near baseline levels in the T-DM1 arm. CONCLUSIONS: Together with the EMILIA primary data, these results support the concept that T-DM1 has greater efficacy and tolerability than capecitabine plus lapatinib, which may translate into improvements in health-related quality of life.