Protein biomarker identification in the CSF of patients with CNS lymphoma.

PURPOSE: Elucidation of the CSF proteome may yield insights into the pathogenesis of CNS disease. We tested the hypothesis that individual CSF proteins distinguish CNS lymphoma from benign focal brain lesions. METHODS: We used a liquid chromatography/mass spectrometry-based method to differentially quantify and identify several hundred CSF proteins in CNS lymphoma and control patients. We used enzyme-linked immunosorbent assay (ELISA) to confirm one of these markers in an additional validation set of 101 cases. RESULTS: Approximately 80 CSF proteins were identified and found to be present at significantly different concentrations, both higher and lower, in training and test studies, which were highly concordant. To further validate these observations, we defined in detail the expression of one of these candidate biomarkers, antithrombin III (ATIII). ATIII RNA transcripts were identified within CNS lymphomas, and ATIII protein was localized selectively to tumor neovasculature. Determination of ATIII concentration by ELISA was significantly more accurate (> 75% sensitivity; > 98% specificity) than cytology in the identification of cancer. Measurement of CSF ATIII levels was found to potentially enhance the ability to diagnose and predict outcome. CONCLUSION: Our findings demonstrate for the first time that proteomic analysis of CSF yields individual biomarkers with greater sensitivity in the identification of cancer than does CSF cytology. We propose that the discovery of CSF protein biomarkers will facilitate early and noninvasive diagnosis in patients with lesions not amenable to brain biopsy, as well as provide improved surrogates of prognosis and treatment response in CNS lymphoma and brain metastasis.

Phase I study of intraventricular administration of rituximab in patients with recurrent CNS and intraocular lymphoma.

PURPOSE: We previously determined that intravenous administration of rituximab results in limited penetration of this agent into the leptomeningeal space. Systemic rituximab does not reduce the risk of CNS relapse or dissemination in patients with large cell lymphoma. We therefore conducted a phase I dose-escalation study of intrathecal rituximab monotherapy in patients with recurrent CNS non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: The protocol planned nine injections of rituximab (10 mg, 25 mg, or 50 mg dose levels) through an Ommaya reservoir over 5 weeks. The safety profile of intraventricular rituximab was defined in 10 patients. RESULTS: The maximum tolerated dose was determined to be 25 mg and rapid craniospinal axis distribution was demonstrated. Cytologic responses were detected in six patients; four patients exhibited complete response. Two patients experienced improvement in intraocular NHL and one exhibited resolution of parenchymal NHL. High RNA levels of Pim-2 and FoxP1 in meningeal lymphoma cells were associated with disease refractory to rituximab monotherapy. CONCLUSION: These results suggest that intrathecal rituximab (10 to 25 mg) is feasible and effective in NHL involving the CNS.

Gene expression and angiotropism in primary CNS lymphoma.

Primary CNS lymphoma is an aggressive form of non-Hodgkin lymphoma whose growth is restricted to the central nervous system. We used cDNA microarray analysis to compare the gene expression signature of primary CNS lymphomas with nodal large B-cell lymphomas. Here, we show that while individual cases of primary CNS lymphomas may be classified as germinal center B-cell, activated B-cell, or type 3 large B-cell lymphoma, brain lymphomas are distinguished from nodal large B-cell lymphomas by high expression of regulators of the unfolded protein response (UPR) signaling pathway, by the oncogenes c-Myc and Pim-1, and by distinct regulators of apoptosis. We demonstrate that interleukin-4 (IL-4) is expressed by tumor vasculature as well as by tumor cells in CNS lymphomas. We also identify high expression in CNS lymphomas of several IL-4-induced genes, including X-box binding protein 1 (XBP-1), a regulator of the UPR. In addition, we demonstrate expression of the activated form of STAT6, a mediator of IL-4 signaling, by tumor cells and tumor endothelia in CNS lymphomas. High expression of activated STAT6 in tumors was associated with short survival in an independent set of patients with primary CNS lymphoma who were treated with high-dose intravenous methotrexate therapy.