Abstract P6-17-22: Progression free survival (PFS) and overall survival (OS) of patients treated with trastuzumab emtansine (T-DM1) after previous treatment with pertuzumab in patients with advanced breast cancer (NCT02338167)
Authors: Schneeweiss A , Lux MP , Hartkopf AD , Volz B , Kolberg H-C , Hadji P , Tesch H , Haeberle L , Ettl J , Lüftner DI , Wallwiener M , Müller V , Beckmann MW , Belleville E , Wimberger P , Hielscher C , Geberth M , Lermann J , Abenhardt W , Kurbacher C , Wuerstlein R , Thomssen C , Untch M , Overkamp F , Huober J , Taran F-A , Janni W , Wallwiener D , Brucker SY , Fasching PA , Fehm TN 
Published: May 2019

Abstract
Background
Studies leading to the approval of trastuzumab emtansine (T-DM1) have been conducted without pertuzumab as previous therapy. Therefore data about patient characteristics and the efficacy of T-DM1 after a treatment with pertuzumab is scarce. Aim of this study was to analyze a real world patient cohort of advanced breast cancer (aBC) patients, who were treated with T-DM1 after a treatment containing pertuzumab in the metastatic setting with regard to patient characteristics and progression free survival (PFS).
Methods
The PRAEGNANT metastatic breast cancer registry (NCT02338167) is a prospective registry for metastatic breast cancer patients with focus on molecular biomarkers. Patients of all therapy lines with any kind of treatment are eligible for this registry. Collected data comprises all relevant patient and tumor characteristics, therapies, adverse events, quality of life, patient reported outcomes, response and survival (PFS/OS). Here we report on the patient characteristics and PFS data for HER2 positive patients treated with T-DM1 after a treatment with pertuzumab. Patients had to be included before or at the beginning of the T-DM1 therapy.
Results
A total of 58 patients could be identified, who were suitable for the analysis. Of those 34 were treated in the second line, 14 in the third line and 10 in the fourth line or higher. Most of the pertuzumab therapies before T-DM1 were conducted in first line (n=46; 79.3%). Median PFS for all patients was 4.8 months (95% CI: 3.0-7.8 months). Median PFS for patients treated in the 3rdline and 4thline or higher was 4.2 months(95%CI: 2.3 - NA) and 4.0 months (95%CI: 1.8-N.A.), respectively. In patients treated 2ndline with T-DM1 PFS was 7.7 months (95%CI: 2.8 – 12.2).
Conclusion
T-DM1 is effective as 2ndand further line therapy following pretreatment with pertuzumab. Overall PFS was about 5 months with 7.7 months as 2nd-line therapy. The PFS in higher therapy lines might be shorter. As the sample size of this real world cohort was rather low and analyses have to be considered exploratory, this data need to be confirmed in studies with a larger sample size.
Citation Format: Schneeweiss A, Lux MP, Hartkopf AD, Volz B, Kolberg H-C, Hadji P, Tesch H, Haeberle L, Ettl J, Lüftner DI, Wallwiener M, Müller V, Beckmann MW, Belleville E, Wimberger P, Hielscher C, Geberth M, Lermann J, Abenhardt W, Kurbacher C, Wuerstlein R, Thomssen C, Untch M, Overkamp F, Huober J, Taran F-A, Janni W, Wallwiener D, Brucker SY, Fasching PA, Fehm TN. Progression free survival (PFS) and overall survival (OS) of patients treated with trastuzumab emtansine (T-DM1) after previous treatment with pertuzumab in patients with advanced breast cancer (NCT02338167) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-22.