Examines the safety and effectiveness of niraparib with TTFields in individuals having recurrent GBM.Examines the safety as well as the effectiveness of niraparib in combination with RT within individuals having recurrent GBM.Measures effectiveness of niraparib in patients who have diagnosed with GBM recently and patients with IDH mutation and ATRX loss is being evaluated in this phase 0 studies with an expansion phase. This evidence concerns the gene IDH2 and glioblastoma.