Would you add tucatinib to systemic therapy for ER+ HER2+ metastatic breast cancer, where there is systemic control but new brain metastasis?  

The patient has progressive disease in the brain, which will require treatment -- the standard of care option would be local therapy in the form of radiation +/- surgery. Data from HER2Climb suggests that the combination of capecitabine + tucatinib + trastuzumab controlled disease in the CNS for 9+ ...