Background and Importance Trastuzumab emtansine (T-DM1) as a single agent is approved for patients with HER2-positive locally advanced or metastatic breast cancer (MBC) previously treated with a taxane and trastuzumab.
Aim and Objectives To estimate the Overall Survival (OS) and the Progression-Free Survival (PFS) in patients with HER2-positive MBC treated with T-DM1. The results will be compared with those obtained with the pivotal trials.
Material and Methods Retrospective study which included all patients receiving T-DM1 for the treatment of HER2-positive MBC between 2016 and 2022 in a tertiary hospital.
The variables studied were sex, age, ECOG stage, treatment duration, reason for discontinuation and percentage of dead patients at the end of the study.
Data were collected through the electronical clinical record and the onco-haematological prescription program. Statistical analysis was performed with SPSS v.22.0. The Kaplan-Meier method was used to calculate OS and PFS.
Results A total of 30 patients were analysed (100% women). The median age was 58 (range, 48 to 66) years. The 66,7% of patients (N=20) had ECOG 0–1 and the 33,3% (N=10) had ECOG 2.
The median number of cycles received were 8 (range, 3 to 16) and the median treatment duration was 6 (range, 3 to 12) months.
The reasons for the treatment discontinuation were: 53,3% progression (N=16), 6,7% toxicity (N=2) and 10% death (N=3).
At the end of the study, the 30% of patients (N=9) continued with the treatment and the 48,3% (N=14) had died.
The median OS obtained was 16,80 months (95% CI 7,64 to 25,96) and the median PFS was 10,27 months (95 CI% 5,34 to 15,35).
In the study TDM4450g/BO21976, the median of PFS and OS were 9,4 and 30,9 months, respectively. In the pivotal trial TDM4370g/BO21977, the median PFS was 14,2 months and the OS could not be estimated.
Conclusion and Relevance The median PFS in patients with HER2-positive MBC treated with T-DM1 reported in our study was similar than the pivotal trials. However, the median OS was substantially lower than the study TDM4450g. This difference could be mainly due to the sample size. Moreover, patients included in the previous study had a better functional status (100% ECOG 0–1) than our patients at the start of the treatment.
Conflict of Interest No conflict of interest
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