Translational Breast Cancer Research Consortium 022: Pre- and Post-operative Neratinib for HER2-positive Breast Cancer Brain Metastases

ABSTRACT: Background This pilot study was performed to test our ability to administer neratinib monotherapy prior to clinically-recommended craniotomy in patients with human epidermal growth factor receptor 2 (HER2)-positive, metastatic breast cancer to the central nervous system (CNS), to examine neratinib’s CNS penetration at craniotomy, and to examine post-operative neratinib maintenance. Patients and Methods Patients with HER2-positive brain metastases undergoing clinically-indicated cranial resection of a parenchymal tumor received neratinib 240 mg orally once daily for 7-21 days pre-operatively and resumed therapy post-operatively in 28-day cycles. Exploratory evaluations of time-to-progression, survival, as well as correlative tissue, cerebrospinal fluid (CSF), and blood-based analyses examining neratinib concentrations were planned. Results We enrolled five patients between 5/22/2013-10/18/2016. As of March 1, 2019, patients had remained on study for 1-75+ postoperative cycles. Two patients had grade 3 diarrhea. Evaluation of the CSF showed low concentrations of neratinib, nonetheless two patients remained on therapy without progression for at least 13 cycles, with one on study treatment for nearly 6 years. Neratinib distribution in surgical tissue was variable for one patient, while specimens from two others did not produce conclusive results due to limited available samples. Conclusions Neratinib resulted in expected rates of diarrhea in this small cohort, with 2 of 5 patients on study treatment for durable periods. Although logistically challenging, we were able to test a limited number of CSF- and parenchymal-based neratinib concentrations. Our findings from resected tumor tissue in one patient revealed heterogeneity in drug distribution and tumor histopathology.