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.
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.
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.
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.
The Authors.
Has not received any funding.
All authors have declared no conflicts of interest.