Jonathan B. Lamano

Heat shock protein vaccines against glioblastoma: from bench to bedside

Current adjuvant treatment regimens available for the treatment of glioblastoma are widely ineffective and offer a dismal prognosis. Advancements in conventional treatment strategies have only yielded modest improvements in overall survival. Immunotherapy remains a promising adjuvant in the treatment of GBM through eliciting tumor specific immune responses capable of producing sustained antitumor response while minimizing systemic toxicity. Heat shock proteins (HSP) function as intracellular chaperones and have been implicated in the activation of both innate and adaptive immune systems. Vaccines formulated from HSP-peptide complexes, derived from autologous tumor, have been applied to the field of immunotherapy for glioblastoma. The results from the phase I and II clinical trials have been promising. Here we review the role of HSP in cellular function and immunity, and its application in the treatment of glioblastoma.

Immunomonitoring in glioma immunotherapy: Current status and future perspectives

Abstract Given the continued poor clinical outcomes and refractory nature of glioblastoma multiforme to traditional interventions, immunotherapy is gaining traction due to its potential for specific tumor-targeting and long-term antitumor protective surveillance. Currently, development of glioma immunotherapy relies on overall survival as an endpoint in clinical trials. However, the identification of surrogate immunologic biomarkers can accelerate the development of successful immunotherapeutic strategies. Immunomonitoring techniques possess the potential to elucidate immunological mechanisms of antitumor responses, monitor disease progression, evaluate therapeutic effect, identify candidates for immunotherapy, and serve as prognostic markers of clinical outcome. Current immunomonitoring assays assess delayed-type hypersensitivity, T cell proliferation, cytotoxic T-lymphocyte function, cytokine secretion profiles, antibody titers, and lymphocyte phenotypes. Yet, no single immunomonitoring technique can reliably predict outcomes, relegating immunological markers to exploratory endpoints. In response, the most recent immunomonitoring assays are incorporating emerging technologies and novel analysis techniques to approach the goal of identifying a competent immunological biomarker which predicts therapy responsiveness and clinical outcome. This review addresses the current status of immunomonitoring in glioma vaccine clinical trials with emphasis on correlations with clinical response.

Prognostic factors for recurrence and complications in the surgical management of primary chordoid gliomas: A systematic review of literature

OBJECTIVE Chordoid gliomas (CG) are rare neoplasms which frequently arise within the third ventricle. Surgery remains the mainstay treatment for CG. The present study comprehensively reviews all reported cases of CG within the literature in order to identify risk factors for surgical complications and tumor recurrence. METHODS A comprehensive search on MEDLINE (OVID and PubMed), Scopus, Embase, and Web of Science was conducted following PRISMA guidelines to identify all reported cases of CG. RESULTS A total of 81 patients met the study criteria which comprised of 33 males and 48 females. Median age at diagnosis was 48 years with a range from 5 to 72 years, and mean tumor size was 3.1cm. Biopsy, subtotal resection (STR), and gross total resection (GTR) were achieved in 8, 34, and 33 patients, respectively, with six cases not reporting extent of resection (EOR). Thirteen patients underwent adjuvant radiotherapy. Postoperative complications were noted in 30 cases (37%), with new onset diabetes insipidus being the most common. Postoperative morbidity was not associated with age, tumor size, or extent of resection. A trans-lamina terminalis approach demonstrated a strong trend towards decreased overall rates of postoperative morbidity compared to other approaches (p=0.051). GTR was associated with improved progression-free survival (PFS; p=0.028), while adjuvant radiotherapy, age, tumor size and proliferative index were not predictive of patient outcomes. CONCLUSION GTR should be the primary goal for the management of CG, as it is associated with improved rates of tumor control without an increased rate of postoperative complications. Surgical approach was a stronger predictor of complication rates than extent of resection. Morbidity remains high, and future studies to further elaborate on factors predictive of postoperative complications are critical.

Clinical attributes and surgical outcomes of angiocentric gliomas

Angiocentric gliomas (AG) are exceedingly rare low-grade neoplasms which often present in the form of intractable epilepsy within younger patients. The current study extensively reviews all reported cases which were pathologically verified as AG in the literature to analyze clinical attributes and surgical outcomes of this neoplasm. There were 88 patients with AG reported in the literature consisting mostly of pediatric cases. The sex distribution consisted of 45 males and 36 females with the remaining seven cases not documenting sex. The average age of initial diagnosis was 16years with almost half of all diagnosed patients being within the first decade of life. In cases where extent of resection was reported, gross total resection (GTR) was achieved in 54 patients, subtotal resection (STR) in 16, and biopsy only in three. Post-operative complications were transient and only occurred in three patients with no reports of death following surgery. Only five cases reported tumor recurrence on follow-up. Eight patients had seizure recurrence post-operatively and GTR offered improved rates of seizure control when compared to STR (p=0.0005). Nearly half of the cases of AG are diagnosed within the first decade of life and they usually manifest with intractable seizures. GTR appears to offer better seizure control in the post-operative period. Surgical resection is the mainstay therapy for AG as post-operative complications and tumor recurrence remain uncommon. Since the number of reported cases is limited, future studies with longer follow-up periods will help elaborate more long-term outcomes.

Safety and outcomes of preoperative embolization of intracranial hemangioblastomas: A systematic review

INTRODUCTION While preoperative embolization is often reserved for large and highly vascular tumors in order to minimize blood loss, its safety and efficacy in the treatment of hemangioblastomas (HB) is unclear. We present the largest systematic review focusing on the safety and outcome of preoperative embolization of intracranial HB. MATERIALS AND METHODS To identify all cases of preoperative embolization for HB, a literature search was conducted via Medline (OVID and PubMed), Scopus, Embase, and Web of Science. Studies that were in English, included intracranial hemangioblastomas treated with preoperative embolization and provided sufficient disaggregated clinical data for each patient were included. Historical control patients with non-embolized intracranial HB undergoing resection were similarly identified. RESULTS A total of 111 patients that underwent preoperative embolization of HB prior to planned resection were identified. Patient age ranged from 12 to 72 years, with a cohort of 63% males and 36% females. Nine studies comprising 392 non-embolized patients were included as controls. Gross total resection was achieved in 83.7% of embolized and 95.6% of non-embolized patients. Intraoperative blood transfusion was required in 15.3% of embolized and 0.51% of non-embolized controls, while rates of post-operative hemorrhage were 8.4% and 1.6%, respectively. Complication rates from embolization were 11.7% and following consequent surgery were 20.7%. DISCUSSION Embolization did not increase rates of gross total resection, decrease estimated blood loss, or decrease incidence of complications. Not only does embolization fail to mitigate surgical risks, the embolization procedure itself carries significant risk for complications. Embolization should not be standard of care for intracranial HB.

Comparison of dendritic calcium transients in juvenile wild type and SOD1G93A mouse lumbar motoneurons

Previous studies of spinal motoneurons in the SOD1 mouse model of amyotrophic lateral sclerosis have shown alterations long before disease onset, including increased dendritic branching, increased persistent Na+ and Ca2+ currents, and impaired axonal transport. In this study dendritic Ca2+ entry was investigated using two photon excitation fluorescence microscopy and whole-cell patch-clamp of juvenile (P4-11) motoneurons. Neurons were filled with both Ca2+ Green-1 and Texas Red dextrans, and line scans performed throughout. Steps were taken to account for different sources of variability, including (1) dye filling and laser penetration, (2) dendritic anatomy, and (3) the time elapsed from the start of recording. First, Ca2+ Green-1 fluorescence was normalized by Texas Red; next, neurons were reconstructed so anatomy could be evaluated; finally, time was recorded. Customized software detected the largest Ca2+ transients (area under the curve) from each line scan and matched it with parameters above. Overall, larger dendritic diameter and shorter path distance from the soma were significant predictors of larger transients, while time was not significant up to 2 h (data thereafter was dropped). However, Ca2+ transients showed additional variability. Controlling for previous factors, significant variation was found between Ca2+ signals from different processes of the same neuron in 3/7 neurons. This could reflect differential expression of Ca2+ channels, local neuromodulation or other variations. Finally, Ca2+ transients in SOD1G93A motoneurons were significantly smaller than in non-transgenic motoneurons. In conclusion, motoneuron processes show highly variable Ca2+ transients, but these transients are smaller overall in SOD1G93A motoneurons.

Vaccine Therapies in Malignant Glioma

Glioblastoma is a grade IV astrocytoma that is widely accepted in clinical neurosurgery as being an extremely lethal diagnosis. Long-term survival rates remain dismal, and even when tumors undergo gross resection with confirmation of total removal on neuroimaging, they invariably recur with even greater virulence. Standard therapeutic modalities as well as more contemporary treatments have largely resulted in disappointing improvements. However, the therapeutic potential of vaccine immunotherapy for malignant glioma should not be underestimated. In contrast to many of the available treatments, vaccine immunotherapy is unique because it offers the means of delivering treatment that is highly specific to both the patient and the tumor. Peptide, heat-shock proteins, and dendritic cell vaccines collectively encapsulate the majority of research efforts involving vaccine-based treatment modalities. In this review, important recent findings for these vaccine types are discussed in the context of ongoing clinical trials. Broad challenges to immunotherapy are also considered.

Force characterization of intracranial endovascular embolization: coil type, microcatheter placement, and insertion rate.

BACKGROUND Intraoperative rupture (IOR) is a rare, but potentially morbid complication of endovascular aneurysm coil embolization. Yet, IOR predictors have remained relatively uninvestigated in relation to coil design. OBJECTIVE To develop a novel in vitro aneurysm model to characterize forces exerted by coils of different design on the aneurysm during endovascular embolization that are hypothesized to contribute to IOR. METHODS A 3-mm saccular aneurysm model was developed with flat latex membrane at the dome apex. Membrane deflection was observed throughout simulated embolization and converted to force measurement. Simultaneous coil insertion and force measurement were accomplished with a compression strength-testing machine. Membrane and insertion forces across coil type, microcatheter tip placement, and insertion rate were evaluated. RESULTS Insertion force and force directly on the aneurysm wall exhibited a difference, with framing coils exerting greatest force, followed by filling and finishing coils. Regarding microcatheter placement, a similar graded response in membrane and insertion forces was observed with positioning in the top-third of the aneurysm generating the greatest force compared with central and bottom-third placement. Insertion rate was also a factor with the slowest rate (10 mm/min) exhibiting the greatest membrane force, followed by lower forces at 30 and 50 mm/min. A multiple linear regression model was created to assess the contributions of each factor toward aneurysm forces. CONCLUSION Increased force on the aneurysm is associated with framing coil use, microcatheter placement proximal to aneurysm dome, and slow insertion rate. Further characterization remains necessary to reduce IOR risk, especially concerning the contributions of insertion rate.

Semi-automated counting of axon regeneration in poly(lactide co-glycolide) spinal cord bridges

BACKGROUND Spinal cord injury (SCI) is a debilitating event with multiple mechanisms of degeneration leading to life-long paralysis. Biomaterial strategies, including bridges that span the injury and provide a pathway to reconnect severed regions of the spinal cord, can promote partial restoration of motor function following SCI. Axon growth through the bridge is essential to characterizing regeneration, as recovery can occur via other mechanisms such as plasticity. Quantitative analysis of axons by manual counting of histological sections can be slow, which can limit the number of bridge designs evaluated. In this study, we report a semi-automated process to resolve axon numbers in histological sections, which allows for efficient analysis of large data sets. NEW METHOD Axon numbers were estimated in SCI cross-sections from animals implanted with poly(lactide co-glycolide) (PLG) bridges with multiple channels for guiding axons. Immunofluorescence images of histological sections were filtered using a Hessian-based approach prior to threshold detection to improve the signal-to-noise ratio and filter out background staining associated with PLG polymer. RESULTS Semi-automated counting successfully recapitulated average axon densities and myelination in a blinded PLG bridge implantation study. COMPARISON WITH EXISTING METHODS Axon counts obtained with the semi-automated technique correlated well with manual axon counts from blinded independent observers across sections with a wide range of total axons. CONCLUSIONS This semi-automated detection of Hessian-filtered axons provides an accurate and significantly faster alternative to manual counting of axons for quantitative analysis of regeneration following SCI.

The immune checkpoint protein PD-L1 induces and maintains regulatory T cells in glioblastoma

ABSTRACT Glioblastoma (GBM) promotes immunosuppression through upregulation of PD-L1 and regulatory T cell (Treg) expansion, but the association of these suppressive factors has not been well elucidated. Here, we investigate a role of PD-L1 in expanding Tregs and the value of targeting the PD-1 receptor to inhibit Treg expansion. Quantitative RNA sequencing data from The Cancer Genome Atlas were evaluated for an association between CD274 and FOXP3 transcript expressions and impact of FOXP3 on clinical outcomes. Peripheral leukocytes from patients with newly diagnosed GBM were profiled for PD-L1+ myeloid expressions and Treg abundance. Healthy lymphocytes were assessed for impact of recombinant PD-L1 on expansion of the inducible Treg (iTreg) population. iTreg function was evaluated by the capacity to suppress effector T cell proliferation. Specificity of responses were confirmed by pharmacologic inhibition of the PD-1 receptor. Increased PD-L1 mRNA expression in GBM corresponded to increased FOXP3 mRNA (p = 0.028). FOXP3 elevation had a negative impact on overall survival (HR = 2.0; p < 0.001). Peripheral PD-L1 positivity was associated with an increased Treg fraction (p = 0.008). Lymphocyte activation with PD-L1 co-stimulation resulted in greater iTreg expansion compared to activation alone (18.3% vs. 6.5%; p < 0.001) and improved preservation of the Treg phenotype. Suppressive capacity on naïve T cell proliferation was sustained. Nivolumab inhibited PD-L1-induced Treg expansion (p < 0.001). These results suggest that PD-L1 may expand and maintain immunosuppressive Tregs, which are associated with decreased survival in glioma patients. Blockade of the PD-L1/PD-1 axis may reduce Treg expansion and further improve T cell function beyond the direct impact on effector cells.