Serguei Bannykh

Evidence for antibody-mediated pathogenesis in anti-NMDAR encephalitis associated with ovarian teratoma

We report the immunopathological analysis of the brain and tumor of two patients who died of anti-NMDAR-associated encephalitis, and of the tumor of nine patients who recovered. Findings included prominent microgliosis and deposits of IgG with rare inflammatory infiltrates in the hippocampus, forebrain, basal ganglia, and spinal cord. Detection of cells expressing markers of cytotoxicity (TIA, granzyme B, perforin and Fas/Fas ligand) was extremely uncommon. All tumors showed NMDAR-expressing neurons and inflammatory infiltrates. All patients’ NMDAR antibodies were IgG1, IgG2, or IgG3. No complement deposits were observed in any of the central nervous system regions examined. Overall, these findings coupled with recently reported in vitro data showing that antibodies downregulate the levels of NMDA receptors suggest that the antibody immune-response is more relevant than cytotoxic T-cell mechanisms in the pathogenesis of anti-NMDAR-associated encephalitis.

A transgenic Alzheimer rat with plaques, tau pathology, behavioral impairment, oligomeric aβ, and frank neuronal loss.

Alzheimers disease (AD) is hallmarked by amyloid plaques, neurofibrillary tangles, and widespread cortical neuronal loss (Selkoe, 2001). The “amyloid cascade hypothesis” posits that cerebral amyloid sets neurotoxic events into motion that precipitate Alzheimer dementia (Hardy and Allsop, 1991). Yet, faithful recapitulation of all AD features in widely used transgenic (Tg) mice engineered to overproduce Aβ peptides has been elusive. We have developed a Tg rat model (line TgF344-AD) expressing mutant human amyloid precursor protein (APPsw) and presenilin 1 (PS1ΔE9) genes, each independent causes of early-onset familial AD. TgF344-AD rats manifest age-dependent cerebral amyloidosis that precedes tauopathy, gliosis, apoptotic loss of neurons in the cerebral cortex and hippocampus, and cognitive disturbance. These results demonstrate progressive neurodegeneration of the Alzheimer type in these animals. The TgF344-AD rat fills a critical need for a next-generation animal model to enable basic and translational AD research.

p21Cip1 restrains pituitary tumor growth

As commonly encountered, pituitary adenomas are invariably benign. We therefore studied protective pituitary proliferative mechanisms. Pituitary tumor transforming gene (Pttg) deletion results in pituitary p21 induction and abrogates tumor development in Rb+/−Pttg−/− mice. p21 disruption restores attenuated Rb+/−Pttg−/− pituitary proliferation rates and enables high penetrance of pituitary, but not thyroid, tumor growth in triple mutant animals (88% of Rb+/− and 72% of Rb+/−Pttg−/−p21−/− vs. 30% of Rb+/−Pttg−/− mice developed pituitary tumors, P < 0.001). p21 deletion also accelerated S-phase entry and enhanced transformation rates in triple mutant MEFs. Intranuclear p21 accumulates in Pttg-null aneuploid GH-secreting cells, and GH3 rat pituitary tumor cells overexpressing PTTG also exhibited increased levels of mRNA for both p21 (18-fold, P < 0.01) and ATM (9-fold, P < 0.01). PTTG is abundantly expressed in human pituitary tumors, and in 23 of 26 GH-producing pituitary adenomas with high PTTG levels, senescence was evidenced by increased p21 and SA-β-galactosidase. Thus, either deletion or overexpression of Pttg promotes pituitary cell aneuploidy and p53/p21-dependent senescence, particularly in GH-secreting cells. Aneuploid pituitary cell p21 may constrain pituitary tumor growth, thus accounting for the very low incidence of pituitary carcinomas.

Fluorescence lifetime spectroscopy for guided therapy of brain tumors

This study evaluates the potential of time-resolved laser induced fluorescence spectroscopy (TR-LIFS) as intra-operative tool for the delineation of brain tumor from normal brain. Forty two patients undergoing glioma (WHO grade I-IV) surgery were enrolled in this study. A TR-LIFS prototype apparatus (gated detection, fast digitizer) was used to induce in-vivo fluorescence using a pulsed N2 laser (337 nm excitation, 0.7 ns pulse width) and to record the time-resolved spectrum (360-550 nm range, 10 nm interval). The sites of TR-LIFS measurement were validated by conventional histopathology (H&E staining). Parameters derived from the TR-LIFS data including intensity values and time-resolved intensity decay features (average fluorescence lifetime and Laguerre coefficients values) were used for tissue characterization and classification. 71 areas of tumor and normal brain were analyzed. Several parameters allowed for the differentiation of distinct tissue types. For example, normal cortex (N=35) and normal white matter (N=12) exhibit a longer-lasting fluorescence emission at 390 nm (τ390=2.12±0.10 ns) when compared with 460 nm (τ460=1.16±0.08 ns). High grade glioma (grades III and IV) samples (N=17) demonstrate emission peaks at 460 nm, with large variation at 390 nm while low grade glioma (I and II) samples (N=7) demonstrated a peak fluorescence emission at 460 nm. A linear discriminant algorithm allowed for the classification of low-grade gliomas with 100% sensitivity and 98% specificity. High-grade glioma demonstrated a high degree of heterogeneity thus reducing the discrimination accuracy of these tumors to 47% sensitivity and 94% specificity. Current findings demonstrate that TR-LIFS holds the potential to diagnose brain tumors intra-operatively and to provide a valuable tool for aiding the neurosurgeon-neuropathologist team in to rapidly distinguish between tumor and normal brain during surgery.

Mechanisms of Glioma Formation: Iterative Perivascular Glioma Growth and Invasion Leads to Tumor Progression, VEGF-Independent Vascularization, and Resistance to Antiangiogenic Therapy

As glioma cells infiltrate the brain they become associated with various microanatomic brain structures such as blood vessels, white matter tracts, and brain parenchyma. How these distinct invasion patterns coordinate tumor growth and influence clinical outcomes remain poorly understood. We have investigated how perivascular growth affects glioma growth patterning and response to antiangiogenic therapy within the highly vascularized brain. Orthotopically implanted rodent and human glioma cells are shown to commonly invade and proliferate within brain perivascular space. This form of brain tumor growth and invasion is also shown to characterize de novo generated endogenous mouse brain tumors, biopsies of primary human glioblastoma (GBM), and peripheral cancer metastasis to the human brain. Perivascularly invading brain tumors become vascularized by normal brain microvessels as individual glioma cells use perivascular space as a conduit for tumor invasion. Agent-based computational modeling recapitulated biological perivascular glioma growth without the need for neoangiogenesis. We tested the requirement for neoangiogenesis in perivascular glioma by treating animals with angiogenesis inhibitors bevacizumab and DC101. These inhibitors induced the expected vessel normalization, yet failed to reduce tumor growth or improve survival of mice bearing orthotopic or endogenous gliomas while exacerbating brain tumor invasion. Our results provide compelling experimental evidence in support of the recently described failure of clinically used antiangiogenics to extend the overall survival of human GBM patients.

Loss of PTEN is not associated with poor survival in newly diagnosed glioblastoma patients of the temozolomide era.

Introduction Pre-temozolomide studies demonstrated that loss of the tumor suppressor gene PTEN held independent prognostic significance in GBM patients. We investigated whether loss of PTEN predicted shorter survival in the temozolomide era. The role of PTEN in the PI3K/Akt pathway is also reviewed. Methods Patients with histologically proven newly diagnosed GBM were identified from a retrospective database between 2007 and 2010. Cox proportional hazards analysis was used to calculate the independent effects of PTEN expression, age, extent of resection, Karnofsky performance scale (KPS), and treatment on overall survival. Results Sixty-five percent of patients were men with median age of 63 years, and 70% had KPS≥80. Most patients (81%) received standard treatment (temozolomide with concurrent radiation). A total of 72 (47%) patients had retained PTEN expression. Median overall survival (OS) was 19.1 months (95% CI: 15.0–22.5). Median survival of 20.0 months (95% CI: 15.0–25.5) and 18.2 months (95% CI: 13.0–25.7) was observed in PTEN retained and PTEN loss patients, respectively (p = .71). PTEN loss patients were also found to have amplifications of EGFR gene more frequently than patients with retained PTEN (70.8% vs. 47.8%, p = .01). Multivariate analysis showed that older age (HR 1.64, CI: 1.02–2.63, p = .04), low KPS (HR 3.57, CI: 2.20–5.79, p<.0001), and lack of standard treatment (HR 3.98, CI: 2.38–6.65, p<.0001) yielded worse survival. PTEN loss was not prognostic of overall survival (HR 1.31, CI: 0.85–2.03, p = .22). Conclusions Loss of expression of PTEN does not confer poor overall survival in the temozolomide era. These findings imply a complex and non-linear molecular relationship between PTEN, its regulators and effectors in the tumorigenesis of glioblastoma. Additionally, there is evidence that temozolomide may be more effective in eradicating GBM cancer cells with PTEN loss and hence, level the outcomes between the PTEN retained and loss groups.

Diffusion MRI in the early diagnosis of malignant glioma.

ObjectiveA subset of patients with malignant glioma comes to medical attention before their masses show rim enhancement and central necrosis. Tumors in those cases are frequently located in eloquent areas of the brain. Tissue diagnosis is limited to stereotactic biopsy providing limited material for accurate grading. We conducted this study to determine whether imaging characteristics of early stages of malignant gliomas could aid in timely definitive diagnosis.MethodsWe retrospectively analyzed patients with newly diagnosed malignant glioma seen at the Yale Brain Tumor Center between 2002 and 2005. Patients with typical radiographic presentation were excluded.ResultsOf 89 patients, eight meeting the inclusion criteria were identified. In five patients, patchy or small nodular enhancing lesions without central necrosis were present within the tumor mass. Diffusion-weighted imaging (DWI) showed areas of increased signal intensity in all cases. Apparent diffusion coefficient maps (ADC) revealed low-signal intensity in corresponding areas. At the time of imaging, biopsy was performed in seven patients but diagnosis of malignant glioma could only be established prior to further tumor growth in four cases.ConclusionsThe diagnosis in the early stages of malignant glioma can be challenging in a subset of cases. Information obtained through DWI should be incorporated in the clinical decision-making process. Mass lesions displaying decreased water diffusion indicating high cellularity, are suggestive of a high-grade glioma. Biopsies are recommended. However, even when biopsies are inconclusive, a strong suspicion of malignant glioma should be considered.

False negative PCR despite high levels of JC virus DNA in spinal fluid: Implications for diagnostic testing

Genome amplification methods such as polymerase chain reaction (PCR) have revolutionized our ability to detect viruses in spinal fluids of patients with neurologic diseases. It is not as well appreciated among clinicians that PCR protocols, quality assurance, and technical expertise vary significantly among laboratories. In a multi-laboratory blinded study of herpes simplex virus PCR, the most widely used and best validated CSF PCR assay, low-level positives were often missed and false positives were not uncommon [Schloss L, van Loon AM, Cinque P, Cleator G, Echevarria JM, Falk KI, et al. An international external quality assessment of nucleic acid amplification of herpes simplex virus. J Clin Virol 2003;28(2):175-85]. In addition, genome variability and mutations, which are increasingly recognized for a number of different viruses, can lead to falsely low or negative results. Both clinicians and laboratories must recognize the limitations of PCR, since misleading results may have serious consequences. We present here a case of a rapidly progressive, fatal neurologic illness in a young mother, whose CSF JCV DNA PCR at a reference laboratory was falsely negative. Ultimately, brain biopsy established the diagnosis of progressive multifocal leukoencephalopathy (PML). Repeat PCR testing of the same CSF targeting a different region of the genome yielded a high positive result.

Malignant rhabdoid tumor in a pregnant adult female: literature review of central nervous system rhabdoid tumors.

SummaryRhabdoid tumors of the central nervous system are uncommon, aggressive childhood malignancies. The 13 described adult cases comprise both primary CNS tumors and malignant transformation of previously existing gliomas, meningiomas, and astrocytomas. Central nervous system rhabdoid lesions of adults have been diagnosed as primary malignant rhabdoid tumors, atypical teratoid/rhabdoid tumors, and more recently, rhabdoid glioblastomas. We report a case of a 20-year-old woman in her 30th week of pregnancy who presented with headache, nausea and blurry vision. MRI revealed a large rim-enhancing mass of the right occipital lobe. Gross total resection was achieved via a right parietal-occipital craniotomy. Pathologic evaluation revealed histology, electron microscopy and immunohistochemistry consistent with the diagnosis of malignant rhabdoid tumor. FISH studies were negative for the INI-1 genetic mutations and chromosome 22q deletion associated with childhood atypical rhabdoid/rhabdoid tumor in 75% of cases. The patient delivered her infant via caesarian section prior to initiating further therapy. We briefly describe the characteristics and current understanding of rhabdoid tumors, and review the literature comparing the 12 other cases of central nervous system rhabdoid tumors in adults. Furthermore, we consider and discuss the implications of this case being the second presentation of MRT during pregnancy in only six adult female patients.

Prognosis of patients with multifocal glioblastoma: a case-control study

OBJECT The prognosis of patients with glioblastoma who present with multifocal disease is not well documented. The objective of this study was to determine whether multifocal disease on initial presentation is associated with worse survival. METHODS The authors retrospectively reviewed records of 368 patients with newly diagnosed glioblastoma and identified 47 patients with multifocal tumors. Each patient with a multifocal tumor was then matched with a patient with a solitary glioblastoma on the basis of age, Karnofsky Performance Scale (KPS) score, and extent of resection, using a propensity score matching methodology. Radiation and temozolomide treatments were also well matched between the 2 cohorts. Kaplan-Meier estimates and log-rank tests were used to compare patient survival. RESULTS The incidence of multifocal tumors was 12.8% (47/368). The median age of patients with multifocal tumors was 61 years, 76.6% had KPS scores ≥ 70, and 87.2% underwent either a biopsy or partial resection of their tumors. The 47 patients with multifocal tumors were almost perfectly matched on the basis of age (p = 0.97), extent of resection (p = 1.0), and KPS score (p = 0.80) compared with 47 patients with a solitary glioblastoma. Age (>65 years), partial resection or biopsy, and low KPS score (<70) were associated with worse median survival within the multifocal group. In the multifocal group, 19 patients experienced tumor progression on postradiation therapy MRI, compared with 11 patients (26.8%) with tumor progression in the unifocal group (p = 0.08). Patients with multifocal tumors experienced a significantly shorter median overall survival of 6 months (95% CI 4-10 months), compared with the 11-month median survival (95% CI 10-19 months) of the matched solitary glioblastoma group (p = 0.02, log-rank test). Two-year survival rates were 4.3% for patients with multifocal tumors and 29.0% for the unifocal cohort. Patients with newly diagnosed multifocal tumors were found to have an almost 2-fold increase in the hazard of death compared with patients with solitary glioblastoma (hazard ratio 1.8, 95% CI 1.1-3.1; p = 0.02). Tumor samples were analyzed for expression of phosphorylated mitogen-activated protein kinase, phosphatase and tensin homolog, O(6)-methylguanine-DNA methyltransferase, laminin β1 and β2, as well as epidermal growth factor receptor amplification, and no significant differences in expression profile between the multifocal and solitary glioblastoma groups was found. CONCLUSIONS Patients with newly diagnosed multifocal glioblastoma on presentation experience significantly worse survival than patients with solitary glioblastoma. Patients with multifocal tumors continue to pose a therapeutic challenge in the temozolomide era and magnify the challenges faced while treating patients with malignant gliomas.