Stereotactic Radiosurgery and Immunotherapy (Pembrolizumab) for the Treatment of Recurrent Meningioma

200mg given intravenously (IV) on day 1 (to -1) of radiation and then every 3 weeks until progression or unacceptable toxicity

Given in (a) single session treatment with margin dose of 15-20 Gy to the target for a maximum target volume of 8 cc or (b) five consecutive business days treatment to total dose of 25-30 Gy to the target for a maximum target volume of 20 cc when the target volume exceeds 8 cc or the target is in proximity to critical structures