Targeted Therapies in Brain Metastases

Brain metastases are a major clinical problem in patients with advanced breast cancer, lung cancer, melanoma, and renal cell carcinoma. Initial treatment for patients with brain metastases typically includes radiotherapy, either whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), or both. Surgical resection is generally reserved for good prognosis patients with limited/controlled extracranial metastases and a single brain lesion. Once patients progress through upfront treatment, the treatment approach is quite variable and there is no clearly defined standard-of-care. Over the past decade, the role of systemic therapies and in particular, targeted therapies has been increasingly explored in patients with brain metastases from solid tumors. For example, lapatinib has been studied as monotherapy, and in combination with capecitabine, in patients with HER2-positive breast cancer, and activity has been observed in both the upfront and refractory settings. In patients with nonsmall cell lung cancer (NSCLC), central nervous system (CNS) activity has been reported with gefinitib and erlotinib. Finally, in melanoma, the B-raf inhibitors vemurafenib and dabrafenib, and the immunomodulator, ipilumimab, have reported CNS activity. Moving forward, the challenge will be to understand how to optimize the activity of targeted agents in the CNS and how to best incorporate them into the current treatment paradigms in order to improve outcomes for this patient population.