Abstract P1-18-14: Use of pertuzumab in combination with taxanes for HER2+ metastatic breast cancer: Analysis of U.S. electronic health records

Background: Clinical practice guidelines recommend the combination of pertuzumab (PERJETA®), trastuzumab (Herceptin®) (PH) and a taxane for first-line treatment of human epidermal growth factor receptor 2-positive metastatic breast cancer (HER2+ mBC) patients [Giordano et al., J Oncol Pract, 2018]. Most clinical trials investigating the efficacy and safety of pertuzumab and trastuzumab used docetaxel as the taxane (PHD) [Tian et al., Int J Clin Pharmacol Ther, 2017]. Paclitaxel used with pertuzumab and trastuzumab (PHP) is highly active and well tolerated and may be an effective alternative to docetaxel-based combination therapy (Bachelot et al., Ann Oncol, 2019; Dang et al., J Clin Oncol, 2017). We evaluated the use of taxanes with PH and patient outcomes after receiving PHP or PHD as first-line treatment for HER2+ mBC in a real-world setting. Methods: We conducted a retrospective cohort study, using the nationwide Flatiron Health Electronic Health Record (EHR)-derived de-identified database. Patients who received a taxane with PH as initial systemic therapy after mBC diagnosis between June 1, 2012 and April 30, 2019 were included. The taxane initiation and any switch was evaluated. An intention-to-treat analysis was adopted and we used Cox-proportional hazard model in the statistical analysis. Time To Last Administration (TTLA) was used as a proxy for treatment duration for PH and chemotherapy. Real world progression free survival (rwPFS) was used to describe the effectiveness of first-line therapies. Results: A total of 1054 patients received PH plus a taxane as first-line therapy for HER2+ mBC: 29.3% of patients received PHP (26.9% paclitaxel and 2.4% nab-paclitaxel) while 70.7% of patients received PHD. Patients in the PHP group at index date were significantly older (median age was 62.0 in PHP vs 58.0 in PHD group, Citation Format: Letizia Polito, Jinjoo Shim, Yolande Du Toit, Thy Do, Adam Knott, Thibaut Sanglier. Use of pertuzumab in combination with taxanes for HER2+ metastatic breast cancer: Analysis of U.S. electronic health records [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-18-14.