by Benjamin Daniels, Belinda E. Kiely, Monica Tang, Nehmat
Houssami, Sarah J. Lord, Sallie-Anne Pearson
The Breast: Published:
May 07, 2021
Highlights
•Real-world T-DM1 recipients are older than trial
participants.
•Real-world T-DM1 recipients have more prior pertuzumab
exposure than trial participants.
•Median overall survival was 10 months shorter than that
reported from the trial.
Purpose
We aim to describe the treatment patterns and overall
survival (OS) outcomes in patients receiving trastuzumab emtansine (T-DM1) for
HER2-positive metastatic breast cancer (HER2+MBC) in routine clinical care.
Methods
Retrospective, whole-of-population cohort study of people
initiating T-DM1 for HER2+MBC between October 2015 and May 2019 in Australia.
We used dispensing claims to estimate time-to-T-DM1 initiation, duration of
treatment, and treatments administered prior to and following T-DM1 therapy. We
estimated OS from T-DM1 initiation and stratified results based on whether
patients received first- or second-line T-DM1 treatment. We benchmarked
outcomes to those reported in the pivotal, EMILIA trial.
Results
345 patients initiated T-DM1: 309 as second-line therapy for
HER2+MBC and 36 as first-line therapy. 51% of patients had received endocrine
therapy and 98% of second-line patients received pertuzumab prior to starting
T-DM1. The median age was 57 years (53 in EMILIA); median time-to-T-DM1
initiation from start of HER2-targeted therapy for HER2+MBC was 11.6 months
(IQR: 7.9–16.6); median duration of T-DM1 treatment was 6.5 months (3.1–13.5;
7.6 months in EMILIA), and median OS was 19.3 months (7.9–29.5; 29.9 months in
EMILIA).
Conclusions
Our findings highlight differences in patient
characteristics (older, more previous pertuzumab therapy) and outcomes (shorter
OS) from the T-DM1 pivotal trial and provide real-world estimates that can
inform patient, clinician and policy, decisions around the use of HER2-targeted
therapies in routine clinical care.
