Patient-reported outcomes (PROs) from TH3RESA, a phase 3 study of trastuzumab emtansine (T-DM1) versus treatment of physician’s choice (TPC) in patients with pretreated HER2-positive advanced breast cancer.

153 Background: Progression-free survival and objective response rate were significantly improved with T-DM1 vs TPC in TH3RESA. The impact of treatment on quality of life is a key aspect in determining treatment value. Here we present the PRO results from the TH3RESA study. Methods: Patients were randomized 2:1 to T-DM1 (3.6 mg/kg every 21 days) or TPC. Patients were asked to complete the EORTC QLQ-C30 (a 30-item questionnaire assessing symptom bother, functioning and health status) and the EORTC QLQ-BM22 (a 22-item survey evaluating pain from bone metastases) at the start of each cycle. Data from patients with a baseline and ≥1 post-baseline assessment were included; a clinically meaningful difference was defined as ≥10 points. Time to pain progression (TPP) was assessed using the Kaplan-Meier method and Cox proportional-hazards models. Results: A greater proportion of patients in the T-DM1 arm (n=297) vs. the TPC arm (n=117) experienced a clinically meaningful improvement in global health status (57.8% ...