Abstract 249P
Background
Approximately 30%-%0% of patients with HER2-positive breast cancer will develop central nervous system (CNS) metastasis. Trastuzumab deruxtecan (T-DXd) is known to have clinically relevant activity in HER2- positive metastatic breast cancer (MBC) patients who have progressed on prevsious lines of treatment. DESTINY-Breast01 and DESTINY-Breast03 highlighted the intracranial response and long-lasting clinical activity of T-DXd in HER2- positive MBC patients. In this study we aim to assess the response in the CNS in our Irish population on T-DXd.
Methods
We performed a restrospective chart review of patients with MBC receiving treatment with T-DXd in 5 cancer centres in Ireland between 2020 and 2023. A subgroup analysis of patients with CNS metastasis was performed to assess patient response within the CNS.
Results
A total of 64 patients were identified as receiving treatment with T-DXd for MBC in 5 cancer centres. Of these, 27 (41%) patients had CNS involvement, 26 had intracranial metastasis and 1 had leptomeningeal disease. The average age of this cohort was 54.5 years. All patients were HER2 positive with 24 (89%) positive by immunohistochemistry (3+ staining) and two patients positive by florescent in situ hybridization. Sixteen (59%) patients were hormone receptor positive. The average number of previous lines of treatment in the metastatic setting was 3.7(including trastuzumab, pertuzumab, docetaxel, capecitabine Neratinib, gemcitabine and lapatinib). A total of twelve (44%) patients had a response in the CNS (11 partial response and 1 complete response). Two patients (7%) had stable disease. Seven (26%) had progression of disease. Data was unavailable for 6 patients who are awaiting restaging.
Conclusions
In this cohort the response rate of 44% is comparable to that seen in the DESTINY Breast01 subgroup analysis which showed a response rate of 58%. T-DXd continues to show a significant response rate in this important population of patients.
Legal entity responsible for the study
The Authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.