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.
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.
Out of 1858 patients included in the GIM14/BIOMETA study, 70 were eligible for the present analysis. Median age was 54 years; 36 patients (51%) had hormone receptor-positive/HER2-positive disease, and 27 (39%) had visceral involvement. All patients received TPH in the first-line setting, and 35 (50%) received taxane and trastuzumab in the adjuvant setting. At the time of data cutoff (April 30, 2018; median duration of follow-up 17.8 months), 30 patients (43%) were still receiving TDM1. Disease progression was the reason for treatment discontinuation in the remaining cases. Median PFS was 8.5 months (95% confidence intervals [CI] 5.3-12 months), and CB rate was 73%. One-year survival rate was 91%.
Our findings suggest that TDM1 is effective in patients progressing after TPH. A better performance was observed as compared to data previously published on TDM1 effectiveness after first-line TPH.
L. Del Mastro: Honoraria: Ipsen, Roche, Pfizer, Novartis, Eli Lilly, Eisai. All other authors have declared no conflicts of interest.