Faculty Bibliography

BACKGROUND: Glioblastomas, the most common and malignant brain tumors of the central nervous system, exhibit high invasive capacity, which hinders effective therapy. Therefore, intense efforts aimed at improved therapeutics are ongoing to delineate the molecular mechanisms governing glioma cell migration and invasion. METHODS: In order to perform the studies, we employed optimal cell culture methods and hypoxic conditions, lentivirus-mediated knockdown of protein expression, Western Blot analysis, migration assays and immunoprecipitation. We determined statistical significance by unpaired t-test. RESULTS: In this report, we show that U87MG, LN229 and LN308 glioma cells express CXCR7 and that exposure to hypoxia upregulates CXCR7 protein expression in these cell lines. CXCR7-expressing U87MG, LN229 and LN308 glioma cells migrated towards stromal-derived factor (SDF)-1alpha/CXCL12 in hypoxic conditions in the Boyden chamber assays. While shRNA-mediated knockdown of CXCR7 expression did not affect the migration of any of the three cell lines in normoxic conditions, we observed a reduction in the migration of LN229 and LN308, but not U87MG, glioma cells towards SDF-1alpha in hypoxic conditions. In addition, knockdown of CXCR7 expression in LN229 and LN308 glioma cells decreased levels of SDF-1alpha-induced phosphorylation of ERK1/2 and Akt. Inhibiting CXCR4 in LN229 and LN308 glioma cells that were knocked down for CXCR7 did not further reduce migration towards SDF-1alpha in hypoxic conditions and did not affect the levels of phosphorylated ERK1/2 and Akt. Analysis of immunoprecipitated CXCR4 from LN229 and LN308 glioma cells revealed co-precipitated CXCR7. CONCLUSIONS: Taken together, our findings indicate that both CXCR4 and CXCR7 mediate glioma cell migration towards SDF-1alpha in hypoxic conditions and support the development of therapeutic agents targeting these receptors.

Histiocytic sarcoma is a rare, lymphohematopoietic malignant neoplasm composed of tumor cells showing morphologic and immunophenotypic features of mature tissue histiocytes. Involvement of the central nervous system (CNS) as either a part of a systemic disease or as a primary lesion has rarely been described so far. We present a case of primary CNS histiocytic sarcoma in an adult patient and review the literature on this rare entity.

Background: Invasion is a dominant escape mechanism following angiogenic blockade in glioblastomas (GBM). Lithium has shown anti-invasive activity in glioma cells by inhibiting Glycogen Synthetase Kinase -3. This phase II study evaluated the safety and efficacy of using lithium and bevacizumab (BEV) in newly diagnosed GBM. Methods: From 2010 through 2012, 20 GBM patients with residual disease after surgery were treated with involved-field radiation therapy to 5940 cGy and concomitant temozolomide (TMZ) (75 mg/m2 daily for 42 days) along with BEV (10 mg/kg every 2 weeks), starting 29 days after surgery. This was followed by six 28-day cycles of TMZ (150 mg/m2 on days 1-7, BEV (10 mg/kg) on days 8 and 22, and lithium 300 mg BID. Lithium was increased every 7 days up to 600 mg BID with a serum lithium goal level of 0.8 to 1.2 mEq/L. Results: The median follow-up was 9.9 months (range 1.9-24.5). Fourteen patients (70.0%) received at least one dose of lithium and three patients completed the entire course of therapy. The median number of BEV infusion was 9 (range 2-19). Five patients discontinued trial due to skin sensitivity (n = 2), pulmonary embolism (n = 1), infection (n = 1), and hematological toxicity (n=1). Two patients experienced dose limiting lithium toxicity which included drowsiness (n = 1) and tremor (n = 1). No patients experienced grade 3/4 intra-cranial hemorrhage. The median progression free survival (PFS) was 9.3 months. The 12-month PFS and OS were 31.9% and 59.3% respectively. For the 14 patients who received lithium, the 12-month PFS and OS were 42.9% and 69.2% respectively. Conclusions: The strategy of targeting angiogenesis and invasion simultaneously in newly diagnosed GBM is effective and feasible

We report a patient with a seronegative autoimmune panencephalitis, adding a subtype to the emerging spectrum of seronegative autoimmune encephalitis, and we review the sparse literature on isolated psychiatric presentations of autoimmune encephalitis. (A PubMed search for "seronegative autoimmune encephalitis," "nonvasculitic autoimmune inflammatory meningoencephalitis," and related terms revealed <25 cases.) A 15-year-old girl developed an acute-onset isolated psychosis with prominent negative symptoms and intermittent encephalopathy. Despite clinical worsening, her brain magnetic resonance imaging (MRI) scans remained normal for 7 years. Serology was negative for voltage-gated potassium channel (VGKC)-complex, N-methyl-D-aspartate receptor (NMDAR), and glutamic acid decarboxylase (GAD) autoantibodies. We excluded genetic, metabolic, paraneoplastic, degenerative, and infectious etiologies. The patient's symptoms remitted fully with immune therapy, but recurred in association with widespread bihemispheric brain lesions. Brain biopsy revealed mild nonvasculitic inflammation and prominent vascular hyalinization. Immune therapy with plasma exchanges cleared the MRI abnormalities but, 10 years after onset, the patient still suffers neuropsychiatric sequelae. We conclude that autoimmune panencephalitis seronegative for VGKC-complex, NMDAR, and GAD autoantibodies is a subtype of autoimmune encephalitis that can present with pure neuropsychiatric features and a normal brain MRI. Immunologic mechanisms may account for psychiatric symptoms in a subset of patients now diagnosed with classical psychotic disorders. Delay in starting immune therapy can lead to permanent neuropsychiatric sequelae. We propose a standardized classification system for the autoimmune encephalitides, integrating earlier pathology-oriented terms with more recently defined serologic and clinical phenotypes.

Pilocytic astrocytoma (PA) is a World Health Organization grade I glioma that occurs most commonly in children and young adults. Specific genetic alterations have been described in PA, but the pathogenesis remains poorly understood. We studied microRNA (miRNA) alterations in a large cohort of patients with PA. A total of 43 PA, including 35 sporadic grade I PA, 4 neurofibromatosis-1 (NF1)-associated PA, and 4 PA with pilomyxoid features, as well as 5 nonneoplastic brain controls were examined. BRAF fusion status was assessed in most cases. RNA was examined using the Agilent Human miRNA Microarray V3 platform. Expression of miRNA subsets was validated using quantitative real-time PCR (qRT-PCR) with Taqman probes. Validation of predicted protein targets was performed on tissue microarrays with the use of immunohistochemistry. We identified a subset of miRNAs that were differentially expressed in pediatric PAs versus normal brain tissue: 13 miRNAs were underexpressed, and 20 miRNAs were overexpressed in tumors. Differences were validated by qRT-PCR in a subset, with mean fold change in tumor versus brain of -17 (miR-124), -15 (miR-129), and 19.8 (miR-21). Searching for predicted protein targets in Targetscan, we identified a number of known and putative oncogenes that were predicted targets of miRNA sets relatively underexpressed in PA. Predicted targets with increased expression at the mRNA and/or protein level in PA included PBX3, METAP2, and NFIB. A unique miRNA profile exists in PA, compared with brain tissue. These miRNAs and their targets may play a role in the pathogenesis of PA.

Background: CNS tumors are the second most common cancer in children and the leading cause of mortality due to disease. New therapies are desperately needed. Specific Aims: The primary aim of this phase I study was to determine the safety and feasibility of administering HLA-A2 restricted, tumor associated antigenic peptides with Montanide ISA-51 VG to children with refractory CNS tumors. Secondary aims were to evaluate immune response to the vaccine and tumor response. Methods: Each vaccine consisted of HLA-A2 restricted peptides targeting epitopes on the tumor associated antigens Her2, Trp2, EphA2 and gp100 mixed with Montanide ISA-51 VG as the immune adjuvant. The neoantigen KLH was given with the first vaccine as a control. Patients received the vaccines divided into 2 subcutaneous injections on weeks 1, 4 and 7. Immune responses induced by the vaccine were evaluated by tetramer and intracellular cytokine staining. Results: 15 patients, females=8, median age 12 years (range 7- 20 y) were treated between August 2009 and May 2012. Diagnoses included pilocytic astrocytoma=1, low grade glioneuronal tumor=1, pilocytic/pilomyxoid tumor=2, anaplastic astrocytoma= 3, DIPG=2, radiation-induced glioblastoma=1, and ependymoma=3. Two patients had unbiopsied presumed low grade astrocytomas. One patient with an ependymoma was removed after only 2 immunizations because of progressive disease. 14 pts received all 3 vaccines. Several patients had grade 1 local skin reactions at the injection sites. No patients had grade 2 or higher adverse reactions related to the vaccine. Analysis of immune response shows induction of T cell responses to the tumor associated antigens. Impressively, most patients evaluated so far had detectable T cell responses to gp100 and Her-2 post vaccination. Furthermore, both antibody and T cell responses to the control antigen KLH were detected in most patients. Five of 6 patients with low grade astrocytomas have had stable disease for a median of 24 months (range 6-36 mo). Three patients with anaplastic astrocytomas have stable disease for 16, 24, and 24 months. Conclusions: Vaccine therapy using tumor associated antigenic peptides with Montanide ISA-51 VG was well tolerated. Despite being heavily pre-treated, these children were able to mount both humoral and adaptive immune response. Stable disease was seen in children with refractory low grade and high grade gliomas