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

PRIMARY OBJECTIVE: I. To determine the efficacy of stereotactic radiation and pembrolizumab for treatment of recurrent meningioma compared to historical control based on progression free survival at 12 months (PFS12). SECONDARY OBJECTIVE: I. To assess overall survival and further assess progression free survival of stereotactic radiation and pembrolizumab for treatment of recurrent meningioma. EXPLORATORY OBJECTIVES: I. To assess immune-related tumor effects pembrolizumab treatment in meningioma using magnetic resonance (MR) imaging in conjunction with assessment by Response Assessment in Neuro-Oncology Criteria (RANO) and Immunotherapy (i)RANO criteria. II. To assess neurocognitive function and quality of life with pembrolizumab and radiation using the Neurologic Assessment in Neuro-Oncology (NANO) Scale, and European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire brain tumour module (QLQ-BN20). III. To assess safety of the combined treatment modalities in meningioma, through evaluation of grade III adverse events (AEs) and dose-limiting toxicity (DLT). OUTLINE: Within -3 to 0 days from the start of stereotactic radiation therapy, patients receive pembrolizumab intravenously (IV) over 30 minutes on days 1 and 22. Cycles repeat every 6 weeks in the absence of disease progression or unacceptable toxicity. Patients undergo stereotactic radiosurgery on day 1 or days 1-5 of cycle 1 in the absence of disease progression or unacceptable toxicity. All participants who have completed the first course, or stopped for complete response, may be eligible for up to an additional 17 cycles of pembrolizumab if there is investigator-determined progressive disease by iRANO after initial treatment. After completion of study treatment, patients are followed up at 30 days, every 12 weeks for 2 years, and then every 6 months thereafter for up to 5 years.