Abstract 191P
Background
Since 2020, trastuzumab deruxtecan (T-DXd) has been used in France for patients with previously treated HER2-positive or HER2-low metastatic breast cancer (mBC). We aimed to describe the real-world use of T-DXd in patients with HER2-positive and HER2-low mBC, and assess the incidence of selected adverse events leading to hospitalizations among patients treated with T-DX-d.
Methods
Using the French National Health Data System (SNDS), we identified patients having initiated T-DXd for mBC from September 30, 2020 to September 30, 2023. Patients were categorized in three groups according to BC subtype and line of treatment: HER2-positive mBC third-line (HER2+3L) and second-line (HER2+2L), and HER2-low second-line (HER2-low2L). The incidences of adverse events-related hospitalizations were estimated. The Kaplan-Meier method was used to estimate overall survival (OS).
Results
The cohort comprised 5890 patients including 2010 (34.1%) HER2+3L, 1260 (21.4%) in HER2+2L and 2620 (44.5%) in HER2-low2L. Overall, median age was 60 (interquartile range, [IQR] 51-69) years; 25.4% (n = 1498) had brain metastases and 13.8% (n = 811) had a current or history of cardiovascular disease. Median follow-up was 1.2 (IQR 0.7-1.8) years for HER2+3L, 0.7 (IQR 0.3-1.1) years for HER2+2L and 0.4 (IQR 0.2-0.6) years for HER2-low2L. Incidence of hospitalizations for respiratory, hepatic, hematologic and cardiac disorders were similar in HER2+ patients treated in 2L or 3L (respectively 45.3, 19.8, 56.8 and 46.1 / 1000 person years [PY]) while HER2-low patients had higher incidence rates for these events (respectively 87.4, 75.0, 139.7 and 75.0 / 1000 PY). Median OS was 28.9 months (95% confidence interval [CI]: 26.7-32.3) for HER2+3L patients, was not reached for HER2+2L patients, and was 13.8 months (95% CI: 12.1 – not reached) for HER2-low2L patients.
Conclusions
In this large French study evaluating the use of T-DXd in the real world, T-DXd users were older, more comorbid and had more brain metastases than patients included in registration trials. The rapid expansion of clinical indications of T-DXd, calls for proactive surveillance and timely management of potentially life-threatening T-DXd-related toxicities.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.