Rituximab, Acalabrutinib, and Durvalumab (RAD) in Primary CNS Lymphoma.

Dose level 1:Rituximab 375mg/m2 infusion once every 4 weeks for 8 cycles Acalabrutinib 100mg PO once every day Durvalumab 1500mg infusion once every 4 weeks Dose level 2:Rituximab 375mg/m2 infusion once every 4 weeks for 8 cycles Acalabrutinib 100mg PO twice every day Durvalumab 1500mg infusion once every 4 weeks Expansion:Determined by the result of the dose escalation phase