A Prospective Study on the Circulation and Central Nervous System after Primary Central Nervous System B Cell Lymphoma Treatment with Rituximab.

e13518 Background: The use of rituximab(RTX)for the treatment of primary central nervous system lymphoma(PCNSL) is controversial, and whether the RTX permeability of the blood-brain barrier can be improved by craniotomy is unknown. Methods: ImmunocompetentPCNSL patients newly diagnosed via craniotomy or stereotactic biopsy were enrolled and received RTX (375 mg/m2, Q3w) treatment. Systemicnon-Hodgkin's B cell lymphoma (systemic-B-NHL)patients without CNS involvement served as the control group. The trough concentrations of RTX (CRTX) and CD19 levels in cerebrospinal fluid (CSF) and plasma were analyzed by ELISA and flow cytometry methods during each treatment cycle.The efficacy and adverse effects were recorded. Results: From December 2016 to February 2018, 21 PCNSL and 32 systemic-B-NHL patientswere enrolled. The CSF CRTXin the craniotomy-PCNSL group (0.2198±0.1866μg/ml) was significantly higher than those in the stereotactic-PCNSLgroup (0.0613±0.0408 μg/ml, P = 0.031) and the systemic-B-NHLgroup (0.0799±0.0614μg/ml, P = 0.046). The BBB penetrabilityof RTX in the craniotomy-PCNSL group (1.52±1.05%) was nearly four times that in the stereotactic-PCNSL group (0.41±0.19%, P = 0.048) and nearly three timesthat in the systemic-B-NHL group (0.54±0.61%, P = 0.012). No significant differences in the CRTXor BBB penetrability of RTX were observedbetween the stereotactic-PCNSL and systemic-B-NHL groups. CD19 levels in plasma fell below 0.1% in all patients before the second cycle of chemotherapy, and the time required for CSF CD19cell clearance in craniotomy-PCNSL patients tended to be reduced compared with that required by stereotactic-PCNSL patients. The CR and ORR rates of craniotomy-PCNSL patientswere 30% higher than those of stereotactic-PCNSL patients. Conclusions: The BBB penetrability of RTXand the CSF CRTXare significantly improved in PCNSL patients diagnosed via craniotomy.Rituximab could be recommended for routine use in craniotomy PCNSL patients. Clinical trial information: ChiCTR-TRC-11001687.