Purpose: There are sparse data in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer with brain metastases from real-world settings, especially where access to newer targeted therapies is limited.
Methods: This was a single institution, retrospective cohort study of patients with HER2-positive breast cancer diagnosed between January 2013 and December 2017 to have brain metastases and treated with any HER2-targeted therapy. The main objectives were to estimate progression-free survival (PFS) and overall survival (OS) from the time of brain metastases.
Results: A total of 102 patients with a median age of 52 (interquartile range, 45-57) years were included, of whom 63 (61.8%) had received one line and 14 (13.7%) had received two lines of HER2-targeted therapies before brain metastasis, 98 (96.1%) were symptomatic at presentation, 22 (25.3%) had solitary brain lesion, 22 (25.3%) had 2-5 lesions, and 43 (49.4%) had ≥ 5 lesions. Local treatment included surgical resection in nine (8.9%) and radiotherapy in all (100%) patients. The first HER2-targeted therapy after brain metastasis was lapatinib in 71 (68.6%), trastuzumab in 19 (18.6%), lapatinib and trastuzumab in three (2.9%), trastuzumab emtansine in four (3.9%), and intrathecal trastuzumab in five (4.9%) patients. At a median follow-up of 13.9 months, the median PFS and OS were 8 (95% CI, 6.2 to 9.8) months and 14 (95% CI, 10.8 to 17.2) months, respectively, with a 2-year OS of 25% (95% CI, 16.7 to 34.4). The median PFS in patients who received lapatinib-capecitabine regimen (n = 62) was 9.0 (95% CI, 7.3 to 10.7) months.
Conclusion: There was a substantial clinical benefit of local and systemic therapy in patients with brain metastases and HER2-positive disease in a real-world setting with limited access to newer HER2-targeted drugs.