Patients with metastatic breast cancer with at least 2 brain metastases, eligible to receive SRS. Patients will complete radiation therapy within 1 week and Pembrolizumab may be continued every 3 weeks until evidence of brain progression or serious adverse toxicity. Patients will be followed until death.~Pembrolizumab will be infused the day before SRS, at the standard dose of 200mg IV over 30 minutes and repeated every 3 weeks until disease progression or unacceptable toxicity.
Patients with metastatic breast cancer with at least 2 brain metastases will receive pembrolizumab every 3 weeks. Patients will undergo stereotactic radiosurgery (SRS) to one of the brain lesions. Pembrolizumab will be infused a day before SRS at the standard dose of 200mg IV over 30 minutes and repeated every 3 weeks until disease progression or unacceptable toxicity.