Durable complete response to dual immune checkpoint blockade in an MMR-deficient, Lynch syndrome-associated CNS WHO grade 3 meningioma

Lay Summary High-grade meningiomas are rare brain tumors with limited treatment options when they return after surgery and radiotherapy. We describe a patient with a recurrent meningioma associated with Lynch syndrome and genetic changes affecting the tumor’s ability to repair its DNA. The patient received two immunotherapy drugs followed by treatment with one drug alone and achieved complete disappearance of the tumor, which persisted after treatment was stopped. We also analyzed the tumor tissue collected before immunotherapy and found many active immune cells, indicating an environment potentially favorable to an immune response. This case highlights the importance of studying both tumor genetics and its immune environment.