Background: Malignant brain tumors have a dismal prognosis, with residual after surgery necessitating adjuvant chemoradiotherapy. We previously demonstrated that targeted Natural Killer (NK-92) cells could be delivered to the brain using a combination of MRI-guided focused ultrasound and Definity microbubbles. Once in the CNS, they can track to malignant tissues without inflicting collateral damage. The HER2 receptor is expressed by epithelial tumours including both breast and glioblastoma; breast tumors with HER2-amplification have a higher risk of CNS metastasis, and poorer prognosis. Methods: We investigated whether multiple combined treatments of targeted NK-92 cells and focused ultrasound with microbubbles could slow tumour growth and improve survival in an orthotopic HER2-amplified rodent brain tumour model using a human breast cancer line as a prototype. Results: Early daily treatments with targeted NK-92 cells and ultrasound improved survival and decreased tumour volumes compared with bi-weekly treatments, or either treatment alone. The intensive treatment paradigm resulted in cure in 50% of subjects. Conclusions: Many tumour proteins could be exploited for targeted therapy with the NK-92 cell line, and combined with the mounting safety evidence for transcranial ultrasound, this may soon provide a non-invasive and highly targeted treatment option for patients with brain tumours.