Pertuzumab (P) as ≥ second-line therapy for HER2-positive metastatic breast cancer (mBC): Swiss clinical experience

Abstract

Background: P is approved in the EU and US as 1st-line therapy in combination with docetaxel and trastuzumab (H) for HER2-positive mBC based on phase III results (CLEOPATRA). Data in later lines are very limited. In Switzerland, national regulations allow physicians to use P in this setting. We identified P-naïve patients (pts) treated with ≥2nd-line P+H in Switzerland to gain insight on clinical outcomes with P beyond 1st line. Methods: Physicians from major Swiss oncology centres retrospectively completed a questionnaire for each pt providing data on treatment details, safety and survival. Results: The analysis included 35 pts with HER2-positive mBC. Most pts (95%) had invasive ductal carcinoma, 69% had oestrogen- and/or progesterone receptor-positive tumours, 49% were stage IV at 1st diagnosis and half had received prior H. Median age was 49 (range 35-87) years. The most common metastatic sites were bone (64%), liver (43%) and lymph nodes (43%). Analysis of the earliest line of P is shown below. Conclusions: In this small retrospective analysis, median overall survival was similar to that reported with 1st-line P in CLEOPATRA. Diarrhoea was generally unproblematic and low grade; cardiac safety was as expected. These data support P in later lines if not used in the 1st line. (Table Presented) .