Effectiveness of trastuzumab emtansine (TDM1) in patients with HER2-positive advanced breast cancer (ABC) progressing after taxane plus pertuzumab plus trastuzumab

Abstract

Background: In patients with HER2-positive ABC who were previously treated with taxane and trastuzumab without pertuzumab, TDM1 showed a progression free survival (PFS) of 9.6 months and an overall survival (OS) of 29.9 months. Paucity of data is available on the efficacy of TDM1 in patients progressing after the current standard first-line therapy in this setting, based on the association of a taxane plus trastuzumab and pertuzumab (i.e. the TPH regimen). The present study aims to evaluate the effectiveness of TDM1 after first-line TPH.Methods: The Gruppo Italiano Mammella (GIM) 14/BIOMETA is a retrospective/prospective multicenter study on treatment patterns and outcomes of patients with ABC. The present analysis was performed on patients who received second-line TDM1 after previous TPH between January 2012 and March 2017. Median PFS, 1-year OS (i.e. percentage of patients alive 1 year after the starting of TDM1) and clinical benefit rate (CB) were calculated. Descriptive statistics are reported with point estimated and 95% CIs. PFS was estimated with the Kaplan-Meier method.