Genotype-targeted local therapy of glioma

Translational Research Platform for Malignant Central Nervous System Tumors

Some central nervous system (CNS) malignancies are highly aggressive and urgently need innovative treatment strategies to improve prognosis. A significant concern for therapeutic development is the time-consuming nature of developing treatments for CNS tumors. Therefore, a rapid and efficient translational approach is needed to address this problem. Translational and reverse translational research aims to bridge the gap between laboratory data and clinical applications and has been developed in the field of neuro-oncology. This study presents our translational platform systems for malignant CNS tumors, which combine an intraoperative integrated diagnostic system and comprehensive in vitro and in vivo assay systems. These laboratory systems may contribute to a better understanding of tumor biology and the development of novel therapeutic strategies for the poor prognosis of CNS tumors.

Rapid tumor DNA analysis of cerebrospinal fluid accelerates treatment of central nervous system lymphoma

ABSTRACT

Delays and risks associated with neurosurgical biopsies preclude timely diagnosis and treatment of central nervous system (CNS) lymphoma and other CNS neoplasms. We prospectively integrated targeted rapid genotyping of cerebrospinal fluid (CSF) into the evaluation of 70 patients with CNS lesions of unknown cause. Participants underwent genotyping of CSF-derived DNA using a quantitative polymerase chain reaction-based approach for parallel detection of single-nucleotide variants in the MYD88, TERT promoter, IDH1, IDH2, BRAF, and H3F3A genes within 80 minutes of sample acquisition. Canonical mutations were detected in 42% of patients with neoplasms, including cases of primary and secondary CNS lymphoma, glioblastoma, IDH-mutant brainstem glioma, and H3K27M-mutant diffuse midline glioma. Genotyping results eliminated the need for surgical biopsies in 7 of 33 cases (21.2%) of newly diagnosed neoplasms, resulting in significantly accelerated initiation of disease-directed treatment (median, 3 vs 12 days; P = .027). This assay was then implemented in a Clinical Laboratory Improvement Amendments environment, with 2-day median turnaround for diagnosis of CNS lymphoma from 66 patients across 4 clinical sites. Our study prospectively demonstrates that targeted rapid CSF genotyping influences oncologic management for suspected CNS tumors.

Exploiting Metabolic Defects in Glioma with Nanoparticle-Encapsulated NAMPT Inhibitors

The treatment of primary central nervous system tumors is challenging due to the blood-brain barrier and complex mutational profiles, which is associated with low survival rates. However, recent studies have identified common mutations in gliomas [isocitrate dehydrogenase (IDH)-wild-type and mutant, WHO grades II-IV; with grade IV tumors referred to as glioblastomas (GBM)]. These mutations drive epigenetic changes, leading to promoter methylation at the nicotinic acid phosphoribosyl transferase (NAPRT) gene locus, which encodes an enzyme involved in generating NAD+. Importantly, NAPRT silencing introduces a therapeutic vulnerability to inhibitors targeting another NAD+ biogenesis enzyme, nicotinamide phosphoribosyl transferase (NAMPT), rationalizing a treatment for these malignancies. Multiple systemically administered NAMPT inhibitors (NAMPTi) have been developed and tested in clinical trials, but dose-limiting toxicities-including bone marrow suppression and retinal toxicity-have limited their efficacy. Here, we report a novel approach for the treatment of NAPRT-silenced GBMs using nanoparticle (NP)-encapsulated NAMPTis administered by convection-enhanced delivery (CED). We demonstrate that GMX1778 (a NAMPTi) can be formulated in degradable polymer NPs with retention of potency for NAMPT inhibition and anticancer activity in vitro, plus sustained drug release in vitro and in vivo. Direct injection of these drugs via CED into the brain is associated with reduced retinal toxicity compared with systemic administration. Finally, we show that CED of NP-encapsulated GMX1778 to NAPRT-silenced intracranial GBM xenografts in mice exhibit significant tumor growth delay and extends survival. These data support an approach to treat gliomas harboring defects in NAD+ metabolism using CED of NP-encapsulated NAMPTis to greatly improve the therapeutic index and treatment efficacy for this class of drugs.

NAMPT-targeting PROTAC and nicotinic acid co-administration elicit safe and robust anti-tumor efficacy in NAPRT-deficient pan-cancers

Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the biosynthesis of nicotinamide adenine dinucleotide (NAD+), making it a potential target for cancer therapy. Two challenges hinder its translation in the clinic: targeting the extracellular form of NAMPT (eNAMPT) remains insufficient, and side effects are observed in normal tissues. We previously utilized proteolysis-targeting chimera (PROTAC) to develop two compounds capable of simultaneously degrading iNAMPT and eNAMPT. Unfortunately, the pharmacokinetic properties were inadequate, and toxicities similar to those associated with traditional inhibitors arose. We have developed a next-generation PROTAC molecule 632005 to address these challenges, demonstrating exceptional target selectivity and bioavailability, improved in vivo exposure, extended half-life, and reduced clearance rate. When combined with nicotinic acid, 632005 exhibits safety and robust efficacy in treating NAPRT-deficient pan-cancers, including xenograft models with hematologic malignancy and prostate cancer and patient-derived xenograft (PDX) models with liver cancer. Our findings provide clinical references for patient selection and treatment strategies involving NAMPT-targeting PROTACs.

Intraoperative Integrated Diagnostic System for Malignant Central Nervous System Tumors

PURPOSE

The 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors uses an integrated approach involving histopathology and molecular profiling. Because majority of adult malignant brain tumors are gliomas and primary CNS lymphomas (PCNSL), rapid differentiation of these diseases is required for therapeutic decisions. In addition, diffuse gliomas require molecular information on single-nucleotide variants (SNV), such as IDH1/2. Here, we report an intraoperative integrated diagnostic (i-ID) system to classify CNS malignant tumors, which updates legacy frozen-section (FS) diagnosis through incorporation of a qPCR-based genotyping assay.

EXPERIMENTAL DESIGN

FS evaluation, including GFAP and CD20 rapid IHC, was performed on adult malignant CNS tumors. PCNSL was diagnosed through positive CD20 and negative GFAP immunostaining. For suspected glioma, genotyping for IDH1/2, TERT SNV, and CDKN2A copy-number alteration was routinely performed, whereas H3F3A and BRAF SNV were assessed for selected cases. i-ID was determined on the basis of the 2021 WHO classification and compared with the permanent integrated diagnosis (p-ID) to assess its reliability.

RESULTS

After retrospectively analyzing 153 cases, 101 cases were prospectively examined using the i-ID system. Assessment of IDH1/2, TERT, H3F3AK27M, BRAFV600E, and CDKN2A alterations with i-ID and permanent genomic analysis was concordant in 100%, 100%, 100%, 100%, and 96.4%, respectively. Combination with FS and intraoperative genotyping assay improved diagnostic accuracy in gliomas. Overall, i-ID matched with p-ID in 80/82 (97.6%) patients with glioma and 18/19 (94.7%) with PCNSL.

CONCLUSIONS

The i-ID system provides reliable integrated diagnosis of adult malignant CNS tumors.

Development of Zika Virus E Variants for Pseudotyping Retroviral Vectors Targeting Glioblastoma Cells

A fundamental idea for targeting glioblastoma cells is to exploit the neurotropic properties of Zika virus (ZIKV) through its two outer envelope proteins, prM and E. This study aimed to develop envelope glycoproteins for pseudotyping retroviral vectors that can be used for efficient tumor cell infection. Firstly, the retroviral vector pNLlucAM was packaged using wild-type ZIKV E to generate an E-HIVluc pseudotype. E-HIVluc infection rates for tumor cells were higher than those of normal prME pseudotyped particles and the traditionally used vesicular stomatitis virus G (VSV-G) pseudotypes, indicating that protein E alone was sufficient for the formation of infectious pseudotyped particles. Secondly, two envelope chimeras, E41.1 and E41.2, with the E wild-type transmembrane domain replaced by the gp41 transmembrane and cytoplasmic domains, were constructed; pNLlucAM or pNLgfpAM packaged with E41.1 or E41.2 constructs showed infectivity for tumor cells, with the highest rates observed for E41.2. This envelope construct can be used not only as a tool to further develop oncolytic pseudotyped viruses for therapy, but also as a new research tool to study changes in tumor cells after the transfer of genes that might have therapeutic potential.

Recent advances of targeting nicotinamide phosphoribosyltransferase (NAMPT) for cancer drug discovery

Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme for the biosynthesis of NAD⁺ in the salvage pathway. NAMPT is overexpressed in various cancers, associating with a poor prognosis and tumor progression. Beyond cancer metabolism, recent evidence unravels additional roles of NAMPT in cancer biology, including DNA repair machinery, crosstalk with oncogenic signaling pathways, cancer cell stemness, and immune responses. NAMPT is a promising therapeutic target for cancer. However, first-generation NAMPT inhibitors exhibited limited efficacy and dose-limiting toxicities in clinical trials. Multiple strategies are being exploited to improve their efficacy and minimize toxic-side effects. This review discusses the biomarkers predictive of response to NAMPT inhibitors, and summarizes the most significant advances in the evolution of structurally distinct NAMPT inhibitors, the manipulation of targeted delivery technologies via antibody-drug conjugates (ADCs), PhotoActivated ChemoTherapy (PACT) and the intratumoral delivery system, as well as the development and pharmacological outcomes of NAMPT degraders. Finally, a discussion of future perspectives and challenges in this area is also included.

Isolation of Cells from Glioblastoma Multiforme Grade 4 Tumors for Infection with Zika Virus prME and ME Pseudotyped HIV-1

This study aimed to isolate cells from grade 4 glioblastoma multiforme tumors for infection experiments with Zika virus (ZIKV) prME or ME enveloped HIV-1 pseudotypes. The cells obtained from tumor tissue were successfully cultured in human cerebrospinal fluid (hCSF) or a mixture of hCSF/DMEM in cell culture flasks with polar and hydrophilic surfaces. The isolated tumor cells as well as the U87, U138, and U343 cells tested positive for ZIKV receptors Axl and Integrin αvβ5. Pseudotype entry was detected by the expression of firefly luciferase or green fluorescent protein (gfp). In prME and ME pseudotype infections, luciferase expression in U-cell lines was 2.5 to 3.5 logarithms above the background, but still two logarithms lower than in the VSV-G pseudotype control. Infection of single cells was successfully detected in U-cell lines and isolated tumor cells by gfp detection. Even though prME and ME pseudotypes had low infection rates, pseudotypes with ZIKV envelopes are promising candidates for the treatment of glioblastoma.

Graphene Oxide Nanoscale Platform Enhances the Anti-Cancer Properties of Bortezomib in Glioblastoma Models

Graphene-based 2D nanomaterials possess unique physicochemical characteristics which can be utilized in various biomedical applications, including the transport and presentation of chemotherapeutic agents. In glioblastoma multiforme (GBM), intratumorally administered thin graphene oxide (GO) nanosheets demonstrate a widespread distribution throughout the tumor volume without impact on tumor growth, nor spread into normal brain tissue. Such intratumoral localization and distribution can offer multiple opportunities for treatment and modulation of the GBM microenvironment. Here, the kinetics of GO nanosheet distribution in orthotopic GBM mouse models is described and a novel nano-chemotherapeutic approach utilizing thin GO sheets as platforms to non-covalently complex a proteasome inhibitor, bortezomib (BTZ), is rationally designed. Through the characterization of the GO:BTZ complexes, a high loading capacity of the small molecule on the GO surface with sustained BTZ biological activity in vitro is demonstrated. In vivo, a single low-volume intratumoral administration of GO:BTZ complex shows an enhanced cytotoxic effect compared to free drug in two orthotopic GBM mouse models. This study provides evidence of the potential that thin and small GO sheets hold as flat nanoscale platforms for GBM treatment by increasing the bioavailable drug concentration locally, leading to an enhanced therapeutic effect.

Interfering with CALCRL expression inhibits glioma proliferation, promotes apoptosis, and predicts prognosis in low-grade gliomas

Background

CALCRL is involved in a variety of key biological processes, including cell proliferation, apoptosis, angiogenesis, and inflammation. However, the role of CALCRL in glioma remains unknown. The purpose of this study was to investigate the effect of differential CALCRL expression on the malignant progression of glioma and its value in glioma prognosis.

Methods

Sequencing data from glioma and normal tissues were downloaded from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, and the downloaded data were statistically analyzed using bioinformatics tools and the corresponding R package. The expression of CALCRL in normal brain tissue and different grades of glioma tissue was detected by pathological and immunohistochemical staining of clinical glioma specimens. The expression of CALCRL in different glioma cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the U87 cell line with high expression was selected to construct the CALCRL knockdown model by transfection with short hairpin (shRNA). The cell proliferation ability was detected by Celigo assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the ability of cell clone formation was detected by clone formation assay, and the level of apoptosis was detected by flow cytometry.

Results

The expression of CALCRL in glioma was significantly upregulated compared with that of normal tissue, especially in low-grade glioma (LGG) compared to glioblastoma, and the differential expression of CALCRL correlated significantly with the prognosis of LGG. Clinical pathology and immunohistochemistry showed that the expression of CALCRL was related to the pathological grade of glioma, and the highest expression was found in World Health Organization (WHO) grade Ⅲ glioma. The results of qRT-PCR showed that CALCRL expression was highest in the U87 cell line. After knockdown of CALCRL expression, the proliferation and clonogenic ability of U87 cells were significantly decreased, and the apoptosis rate was significantly increased.

Conclusions

CALCRL is highly expressed in LGG. Interfering with CALCRL expression inhibits glioma cell proliferation and promotes apoptosis, and thus has potential as a biomarker and therapeutic target for the prognosis of those with LGGs.

Establishment and validation of a novel prognostic model for lower-grade glioma based on senescence-related genes

Objective

Increasing studies have indicated that senescence was associated with tumorigenesis and progression. Lower-grade glioma (LGG) presented a less invasive nature, however, its treatment efficacy and prognosis prediction remained challenging due to the intrinsic heterogeneity. Therefore, we established a senescence-related signature and investigated its prognostic role in LGGs.

Methods

The gene expression data and clinicopathologic features were from The Cancer Genome Atlas (TCGA) database. The experimentally validated senescence genes (SnGs) from the CellAge database were obtained. Then LASSO regression has been performed to build a prognostic model. Cox regression and Kaplan-Meier survival curves were performed to investigate the prognostic value of the SnG-risk score. A nomogram model has been constructed for outcome prediction. Immunological analyses were further performed. Data from the Chinese Glioma Genome Atlas (CGGA), Repository of Molecular Brain Neoplasia Data (REMBRANDT), and GSE16011 were used for validation.

Results

The 6-SnG signature has been established. The results showed SnG-risk score could be considered as an independent predictor for LGG patients (HR=2.763, 95%CI=1.660-4.599, P<0.001). The high SnG-risk score indicated a worse outcome in LGG (P<0.001). Immune analysis showed a positive correlation between the SnG-risk score and immune infiltration level, and the expression of immune checkpoints. The CGGA datasets confirmed the prognostic role of the SnG-risk score. And Kaplan-Meier analyses in the additional datasets (CGGA, REMBRANDT, and GSE16011) validated the prognostic role of the SnG-signature (P<0.001 for all).

Conclusion

The SnG-related prognostic model could predict the survival of LGG accurately. This study proposed a novel indicator for predicting the prognosis of LGG and provided potential therapeutic targets.

Recent Advances in Glioma Cancer Treatment: Conventional and Epigenetic Realms

Glioblastoma (GBM) is the most typical and aggressive form of primary brain tumor in adults, with a poor prognosis. Successful glioma treatment is hampered by ineffective medication distribution across the blood-brain barrier (BBB) and the emergence of drug resistance. Although a few FDA-approved multimodal treatments are available for glioblastoma, most patients still have poor prognoses. Targeting epigenetic variables, immunotherapy, gene therapy, and different vaccine- and peptide-based treatments are some innovative approaches to improve anti-glioma treatment efficacy. Following the identification of lymphatics in the central nervous system, immunotherapy offers a potential method with the potency to permeate the blood-brain barrier. This review will discuss the rationale, tactics, benefits, and drawbacks of current glioma therapy options in clinical and preclinical investigations.

Mechanism research and treatment progress of NAD pathway related molecules in tumor immune microenvironment

Nicotinamide adenine dinucleotide (NAD) is the core of cellular energy metabolism. NAMPT, Sirtuins, PARP, CD38, and other molecules in this classic metabolic pathway affect many key cellular functions and are closely related to the occurrence and development of many diseases. In recent years, several studies have found that these molecules can regulate cell energy metabolism, promote the release of related cytokines, induce the expression of neoantigens, change the tumor immune microenvironment (TIME), and then play an anticancer role. Drugs targeting these molecules are under development or approved for clinical use. Although there are some side effects and drug resistance, the discovery of novel drugs, the development of combination therapies, and the application of new technologies provide solutions to these challenges and improve efficacy. This review presents the mechanisms of action of NAD  pathway-related molecules in tumor immunity, advances in drug research, combination therapies, and some new technology-related therapies.

Prognostic biomarker SGSM1 and its correlation with immune infiltration in gliomas

Objective

Glioma was the most common type of intracranial malignant tumor. Even after standard treatment, the recurrence and malignant progression of lower-grade gliomas (LGGs) were almost inevitable. The overall survival (OS) of patients with LGG varied widely, making it critical for prognostic prediction. Small G Protein Signaling Modulator 1 (SGSM1) has hardly been studied in gliomas. Therefore, we aimed to investigate the prognostic role of SGSM1 and its relationship with immune infiltration in LGGs.

Methods

We obtained RNA sequencing data from The Cancer Genome Atlas (TCGA) to analyze SGSM1 expression. Functional enrichment analyses, immune infiltration analyses, immune checkpoint analyses, and clinicopathology analyses were performed. Univariate and multivariate Cox regression analyses were used to identify independent prognostic factors. And nomogram model has been developed. Kaplan–Meier survival analysis and log-rank test were used to estimate the relationship between OS and SGSM1 expression. The survival analyses and Cox regression were validated in datasets from the Chinese Glioma Genome Atlas (CGGA).

Results

SGSM1 was significantly down-regulated in LGGs. Functional enrichment analyses revealed SGSM1 was correlated with immune response. Most immune cells and immune checkpoints were negatively correlated with SGSM1 expression. The Kaplan–Meier analyses showed that low SGSM1 expression was associated with a poor outcome in LGG and its subtypes. The Cox regression showed SGSM1 was an independent prognostic factor in patients with LGG (HR = 0.494, 95%CI = 0.311–0.784, P = 0.003).

Conclusion

SGSM1 was considered to be a new prognostic biomarker for patients with LGG. And our study provided a potential therapeutic target for LGG treatment.

Molecular characteristics of single patient-derived glioma stem-like cells from primary and recurrent glioblastoma

Glioblastoma has high recurrence, while the sensitivity of recurrent glioblastoma to chemotherapy is lower than that of primary glioblastoma. Moreover, there is no standardized treatment for recurrent glioblastoma. Unfortunately, the biological mechanism of recurrent glioblastoma is still unclear, and there are few related studies. We compared the phenotypes of clinical glioblastoma specimens, in-vitro cultured glioma stem-like cells (GSCs) and patient-derived xenograft tumor (PDX) models to explore the molecular genetic characteristics of primary and recurrent glioblastoma from the same patient. In vitro, SU5-2, GSCs derived from recurrent glioblastoma specimens, had stronger proliferative activity and self-renewal ability. Meanwhile, SU5-2 was more resistant to temozolomide and invasive than SU5-1, which derived from primary glioblastoma specimens. Further analysis of the expression of costimulatory molecules showed that the expression of B7-H1, B7-H2 and B7-H3 of SU5-2 were upregulated. In vivo, Kaplan-Meier survival curve analysis showed that the median survival of the recurrent PDX group was worse. The results of gene detection in vitro, PDX model and clinical samples were consistent. Our results showed that the GSCs based on glioblastoma specimens and the PDX models could replicate the main molecular genetic characteristics of original tumors, which provided a reliable experimental platform for both tumor translation kinds of research and screening of molecular therapeutic targets.

Surface-fill hydrogel attenuates the oncogenic signature of complex anatomical surface cancer in a single application

Tumours growing in a sheet-like manner on the surface of organs and tissues with complex topologies represent a difficult-to-treat clinical scenario. Their complete surgical resection is difficult due to the complicated anatomy of the diseased tissue. Residual cancer often responds poorly to systemic therapy and locoregional treatment is hindered by the limited accessibility to microscopic tumour foci. Here we engineered a peptide-based surface-fill hydrogel (SFH) that can be syringe- or spray-delivered to surface cancers during surgery or used as a primary therapy. Once applied, SFH can shape change in response to alterations in tissue morphology that may occur during surgery. Implanted SFH releases nanoparticles composed of microRNA and intrinsically disordered peptides that enter cancer cells attenuating their oncogenic signature. With a single application, SFH shows efficacy in four preclinical models of mesothelioma, demonstrating the therapeutic impact of the local application of tumour-specific microRNA, which might change the treatment paradigm for mesothelioma and possibly other surface cancers.

Raman Spectroscopy and Machine Learning for IDH Genotyping of Unprocessed Glioma Biopsies

Simple Summary

Isocitrate dehydrogenase (IDH) mutation is one of the most important prognostic markers in glioma tumors. Raman spectroscopy (RS) is an optical technique with great potential in intraoperative molecular diagnosis and surgical guidance. We analyzed RS’s ability to detect the IDH mutation onto unprocessed glioma biopsies. A total of 2073 Raman spectra were extracted from 38 tumor specimens. From the 103 Raman shifts screened, we identified 52 shifts (related to lipids, collagen, DNA and cholesterol/phospholipids) with the highest performance in the distinction of the two groups. We described 18 shifts never used before for IDH detection with RS in fresh or frozen samples. We were able to distinguish between IDH-mutated and IDH-wild-type tumors with an accuracy and precision of 87%. RS showed optimal accuracy and precision in discriminating IDH-mutated glioma from IDH-wild-type tumors ex-vivo onto fresh surgical specimens.

Abstract

Isocitrate dehydrogenase (IDH) mutational status is pivotal in the management of gliomas. Patients with IDH-mutated (IDH-MUT) tumors have a better prognosis and benefit more from extended surgical resection than IDH wild-type (IDH-WT). Raman spectroscopy (RS) is a minimally invasive optical technique with great potential for intraoperative diagnosis. We evaluated the RS’s ability to characterize the IDH mutational status onto unprocessed glioma biopsies. We extracted 2073 Raman spectra from thirty-eight unprocessed samples. The classification performance was assessed using the eXtreme Gradient Boosted trees (XGB) and Support Vector Machine with Radial Basis Function kernel (RBF-SVM). Measured Raman spectra displayed differences between IDH-MUT and IDH-WT tumor tissue. From the 103 Raman shifts screened as input features, the cross-validation loop identified 52 shifts with the highest performance in the distinction of the two groups. Raman analysis showed differences in spectral features of lipids, collagen, DNA and cholesterol/phospholipids. We were able to distinguish between IDH-MUT and IDH-WT tumors with an accuracy and precision of 87%. RS is a valuable and accurate tool for characterizing the mutational status of IDH mutation in unprocessed glioma samples. This study improves RS knowledge for future personalized surgical strategy or in situ target therapies for glioma tumors.

A rapid genotyping panel for detection of primary central nervous system lymphoma

Diagnosing primary central nervous system lymphoma (PCNSL) frequently requires neurosurgical biopsy due to nonspecific radiologic features and the low yield of cerebrospinal fluid (CSF) studies. We characterized the clinical evaluation of suspected PCNSL (N = 1007 patients) and designed a rapid multiplexed genotyping assay for MYD88, TERT promoter, IDH1/2, H3F3A, and BRAF mutations to facilitate the diagnosis of PCNSL from CSF and detect other neoplasms in the differential diagnosis. Among 159 patients with confirmed PCNSL, the median time to secure a diagnosis of PCNSL was 10 days, with a range of 0 to 617 days. Permanent histopathology confirmed PCNSL in 142 of 152 biopsies (93.4%), whereas CSF analyses were diagnostic in only 15/113 samplings (13.3%). Among 86 archived clinical specimens, our targeted genotyping assay accurately detected hematologic malignancies with 57.6% sensitivity and 100% specificity (95% confidence interval [CI]: 44.1% to 70.4% and 87.2% to 100%, respectively). MYD88 and TERT promoter mutations were prospectively identified in DNA extracts of CSF obtained from patients with PCNSL and glioblastoma, respectively, within 80 minutes. Across 132 specimens, hallmark mutations indicating the presence of malignancy were detected with 65.8% sensitivity and 100% specificity (95% CI: 56.2%-74.5% and 83.9%-100%, respectively). This targeted genotyping approach offers a rapid, scalable adjunct to reduce diagnostic and treatment delays in PCNSL.

An Evaluation of the Tolerability and Feasibility of Combining 5-Amino-Levulinic Acid (5-ALA) with BCNU Wafers in the Surgical Management of Primary Glioblastoma

Simple Summary

This reseach explored the safety and feasibility of combining local chemotherapy with fluorescence-guided resection in patients with a brain cancer, glioblastoma. The aim was to determine if the combination of fluorescence-guided surgery using 5-aminolevulinic acid and BCNU wafers left in the tumour cavity at the end of the operation was safe and did not prevent patients getting subsequent chemo-radiotherapy. The results showed that combining local chemotherapy with fluorescence-guided resection was tolerable in terms of surgical morbidity and overall toxicity. However, any potential therapeutic benefit requires further investigation, preferably with improved local delivery technologies.

Abstract

Background Glioblastoma (GBM) is the commonest primary malignant brain tumour in adults and effective treatment options are limited. Combining local chemotherapy with enhanced surgical resection using 5-aminolevulinic acid (5-ALA) could improve outcomes. Here we assess the safety and feasibility of combining BCNU wafers with 5-ALA-guided surgery. Methods We conducted a multicentre feasibility study of 5-ALA with BCNU wafers followed by standard-of-care chemoradiotherapy (chemoRT) in patients with suspected GBM. Patients judged suitable for radical resection were administered 5-ALA pre-operatively and BCNU wafers at the end resection. Post-operative treatment continued as per routine clinical practice. The primary objective was to establish if combining 5-ALA and BCNU wafers is safe without compromising patients from receiving standard chemoRT. Results Seventy-two patients were recruited, sixty-four (88.9%) received BCNU wafer implants, and fifty-nine (81.9%) patients remained eligible following formal histological diagnosis. Seven (11.9%) eligible patients suffered surgical complications but only two (3.4%) were not able to begin chemoRT, four (6.8%) additional patients did not begin chemoRT within 6 weeks of surgery due to surgical complications. Eleven (18.6%) patients did not begin chemoRT for other reasons (other toxicity (n = 3), death (n = 3), lost to follow-up/withdrew (n = 3), clinical decision (n = 1), poor performance status (n = 1)). Median progression-free survival was 8.7 months (95% CI: 6.4–9.8) and median overall survival was 14.7 months (95% CI: 11.7–16.8). Conclusions Combining BCNU wafers with 5-ALA-guided surgery in newly diagnosed GBM patients is both feasible and tolerable in terms of surgical morbidity and overall toxicity. Any potential therapeutic benefit for the sequential use of 5-ALA and BCNU with chemoRT requires further investigation with improved local delivery technologies.

Development of a Rapid and Sensitive IDH1/2 Mutation Detection Method for Glial Tumors and a Comparative Mutation Analysis of 236 Glial Tumor Samples

BACKGROUND

The presence of mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1/2) in glioma tumors is correlated with good prognosis upon standard-of-care treatment. Therefore, information on whether the glioma tumor has IDH1/2 mutations could be used in the correct diagnosis and management of glial tumors. The two most common techniques used to detect IDH1/2 mutations, immunohistochemistry (IHC) and Sanger sequencing, are prone to missing these mutations, especially if the tumor cells that carry the mutations constitute a small minority of the tumor itself.

OBJECTIVES

We developed and validated a rapid method (3-mismatch-amplification refractory mutation system [3m-ARMS]) that can be used for pre-, intra- and postoperative detection of the most common IDH1/2 mutations in glial tumors with high specificity and sensitivity. We also conducted a comprehensive IDH1/2 mutation analysis in 236 glial tumor samples comparing 3m-ARMS, IHC and Sanger sequencing.

METHODS

3m-ARMS was optimized and validated for the specific and sensitive detection of the most common IDH1 and IDH2 mutations. We then analyzed 236 glial tumor samples for the presence of IDH1/2 mutations using 3m-ARMS, Sanger sequencing and IHC techniques. We then analyzed and compared the results, evaluating the diagnostic and screening potential of 3m-ARMS.

RESULTS

Comparison of the three techniques used in the mutation analysis showed that 3m-ARMS-based IDH1/2 mutation detection was superior to IHC and Sanger sequencing-based IDH1/2 mutation detection in terms of accuracy, specificity and sensitivity, especially for tumor samples in which only a small minority of the cell population carried the mutation. 3m-ARMS could detect the presence of femtogram levels of IDH1/2 mutant DNA in DNA samples in which the mutant DNA-to-wild-type DNA ratio was as low as 1:100,000.

CONCLUSION

Sanger sequencing and IHC-based methods have shortcomings when detecting mutations in glial tumors so can miss IDH1/2 mutations in glial tumors when used alone without proper modifications. 3m-ARMS-based mutation detection is fast and simple with potential for use as a diagnostic test for the majority of hot spot mutations in IDH1/2 genes. It can detect IDH1/2 mutations within an hour so can be adapted for intraoperative diagnosis.

Generative adversarial network for glioblastoma ensures morphologic variations and improves diagnostic model for isocitrate dehydrogenase mutant type

Generative adversarial network (GAN) creates synthetic images to increase data quantity, but whether GAN ensures meaningful morphologic variations is still unknown. We investigated whether GAN-based synthetic images provide sufficient morphologic variations to improve molecular-based prediction, as a rare disease of isocitrate dehydrogenase (IDH)-mutant glioblastomas. GAN was initially trained on 500 normal brains and 110 IDH-mutant high-grade astocytomas, and paired contrast-enhanced T1-weighted and FLAIR MRI data were generated. Diagnostic models were developed from real IDH-wild type (n = 80) with real IDH-mutant glioblastomas (n = 38), or with synthetic IDH-mutant glioblastomas, or augmented by adding both real and synthetic IDH-mutant glioblastomas. Turing tests showed synthetic data showed reality (classification rate of 55%). Both the real and synthetic data showed that a more frontal or insular location (odds ratio [OR] 1.34 vs. 1.52; P = 0.04) and distinct non-enhancing tumor margins (OR 2.68 vs. 3.88; P < 0.001), which become significant predictors of IDH-mutation. In an independent validation set, diagnostic accuracy was higher for the augmented model (90.9% [40/44] and 93.2% [41/44] for each reader, respectively) than for the real model (84.1% [37/44] and 86.4% [38/44] for each reader, respectively). The GAN-based synthetic images yield morphologically variable, realistic-seeming IDH-mutant glioblastomas. GAN will be useful to create a realistic training set in terms of morphologic variations and quality, thereby improving diagnostic performance in a clinical model.

ELF1 Transcription Factor Enhances the Progression of Glioma via ATF5 promoter

A key transcriptional activator, activating transcription factor 5 (ATF5), is aberrantly overexpressed in glioma and supports both poor prognosis and antiapototic potential. Unfortunately, data on ATF5 is largely based on its regulatory mechanism. Further investigation of the upstream regulatory factor for ATF5 transcription in glioma is required. Clinical data for patients with diagnosed glioma were obtained from The Cancer Genome Atlas (TCGA). Additionally, transcription factors potentially regulating the ATF5 promoter in glioma were screened with bioinformatics. A further experimental study was performed to investigate both the role of E74-like factor 1 (ELF1) and the binding of ELF1 and the ATF5 promoter in glioma. We show that ATF5 expression is upregulated in glioma tissues and associated with tumor malignancy and worse prognosis. As a putative upstream regulator, silencing ELF1 inhibits glioma cell growth and migration with ATF5 involvement. Moreover, ELF1 upregulation is also associated with poor prognosis in glioma. Importantly, the luciferase assay and chromatin immunoprecipitation (ChIP) reveal that the ATF5 gene promoter is essential for ELF1-dependent activation of ATF5 gene transcription. These results indicate that a high expression of ELF1 may be related to the malignant behavior of human glioma and ELF1 promotes glioma development mediated by transactivation of the ATF5 gene.

Local Targeting of NAD+ Salvage Pathway Alters the Immune Tumor Microenvironment and Enhances Checkpoint Immunotherapy in Glioblastoma

The aggressive primary brain tumor glioblastoma (GBM) is characterized by aberrant metabolism that fuels its malignant phenotype. Diverse genetic subtypes of malignant glioma are sensitive to selective inhibition of the NAD⁺ salvage pathway enzyme nicotinamide phosphoribosyltransferase (NAMPT). However, the potential impact of NAD⁺ depletion on the brain tumor microenvironment has not been elaborated. In addition, systemic toxicity of NAMPT inhibition remains a significant concern. Here we show that microparticle-mediated intratumoral delivery of NAMPT inhibitor GMX1778 induces specific immunologic changes in the tumor microenvironment of murine GBM, characterized by upregulation of immune checkpoint PD-L1, recruitment of CD3⁺, CD4⁺, and CD8⁺ T cells, and reduction of M2-polarized immunosuppressive macrophages. NAD⁺ depletion and autophagy induced by NAMPT inhibitors mediated the upregulation of PD-L1 transcripts and cell surface protein levels in GBM cells. NAMPT inhibitor modulation of the tumor immune microenvironment was therefore combined with PD-1 checkpoint blockade in vivo, significantly increasing the survival of GBM-bearing animals. Thus, the therapeutic impacts of NAMPT inhibition extended beyond neoplastic cells, shaping surrounding immune effectors. Microparticle delivery and release of NAMPT inhibitor at the tumor site offers a safe and robust means to alter an immune tumor microenvironment that could potentiate checkpoint immunotherapy for glioblastoma. SIGNIFICANCE: Microparticle-mediated local inhibition of NAMPT modulates the tumor immune microenvironment and acts cooperatively with anti-PD-1 checkpoint blockade, offering a combination immunotherapy strategy for the treatment of GBM.

Recent developments and future directions in adult lower-grade gliomas: Society for Neuro-Oncology (SNO) and European Association of Neuro-Oncology (EANO) consensus

The finding that most grades II and III gliomas harbor isocitrate dehydrogenase (IDH) mutations conveying a relatively favorable and fairly similar prognosis in both tumor grades highlights that these tumors represent a fundamentally different entity from IDH wild-type gliomas exemplified in most glioblastoma. Herein we review the most recent developments in molecular neuropathology leading to reclassification of these tumors based upon IDH and 1p/19q status, as well as the potential roles of methylation profiling and deletional analysis of cyclin-dependent kinase inhibitor 2A and 2B. We discuss the epidemiology, clinical manifestations, benefit of surgical resection, and neuroimaging features of lower-grade gliomas as they relate to molecular subtype, including advanced imaging techniques such as 2-hydroxyglutarate magnetic resonance spectroscopy and amino acid PET scanning. Recent, ongoing, and planned studies of radiation therapy and both cytotoxic and targeted chemotherapies are summarized, including both small molecule and immunotherapy approaches specifically targeting the mutant IDH protein.

Multivariate analysis reveals differentially expressed genes among distinct subtypes of diffuse astrocytic gliomas: diagnostic implications

Diagnosis and classification of gliomas mostly relies on histopathology and a few genetic markers. Here we interrogated microarray gene expression profiles (GEP) of 268 diffuse astrocytic gliomas-33 diffuse astrocytomas (DA), 52 anaplastic astrocytomas (AA) and 183 primary glioblastoma (GBM)-based on multivariate analysis, to identify discriminatory GEP that might support precise histopathological tumor stratification, particularly among inconclusive cases with II-III grade diagnosed, which have different prognosis and treatment strategies. Microarrays based GEP was analyzed on 155 diffuse astrocytic gliomas (discovery cohort) and validated in another 113 tumors (validation set) via sequential univariate analysis (pairwise comparison) for discriminatory gene selection, followed by nonnegative matrix factorization and canonical biplot for identification of discriminatory GEP among the distinct histological tumor subtypes. GEP data analysis identified a set of 27 genes capable of differentiating among distinct subtypes of gliomas that might support current histological classification. DA + AA showed similar molecular profiles with only a few discriminatory genes overexpressed (FSTL5 and SFRP2) and underexpressed (XIST, TOP2A and SHOX2) in DA vs AA and GBM. Compared to DA + AA, GBM displayed underexpression of ETNPPL, SH3GL2, GABRG2, SPX, DPP10, GABRB2 and CNTN3 and overexpression of CHI3L1, IGFBP3, COL1A1 and VEGFA, among other differentially expressed genes.

Large-Scale Drug Screening in Patient-Derived IDHmut Glioma Stem Cells Identifies Several Efficient Drugs among FDA-Approved Antineoplastic Agents

The discovery of the isocitrate dehydrogenase (IDH) mutation in glioma led to a paradigm shift on how we see glioma biology. Difficulties in cultivating IDH mutant glioma stem cells (IDH^mut GSCs) resulted in a paucity of preclinical models in IDH^mut glioma, limiting the discovery of new effective chemotherapeutic agents. To fill this gap, we used six recently developed patient-derived IDH^mut GSC lines and performed a large-scale drug screening with 147 Food and Drug Administration (FDA)-approved anticancer drugs. GSCs were subjected to the test compounds for 72 h in concentrations ranging from 0.0001 to 1 µM. Cell viability was assessed by CellTiterGlo and the induction of apoptosis by flow cytometry with Annexin V/propidium iodide staining. The initial screen was performed with two IDH^mut GSC lines and identified seven drugs (bortezomib, carfilzomib, daunorubicin, doxorubicin, epirubicin, omacetaxine, plicamycin) with a substantial antiproliferative activity, as reflected by half maximal inhibitory concentrations (IC₅₀) below 1 µM and maximum inhibitory effects (E_max) below 25%. These findings were validated in an additional four IDH^mut GSC lines. The candidate drugs, of which plicamycin and omacetaxine are known to cross the blood brain barrier, were used for subsequent cell death analyses. A significant induction of apoptosis was observed at IC₅₀ values of the respective drugs. In summary, we were able to identify seven FDA-approved drugs that should be further taken into clinical investigations for the treatment of IDH^mut gliomas.

Isocitrate dehydrogenase (IDH) status prediction in histopathology images of gliomas using deep learning

Mutations in isocitrate dehydrogenase genes IDH1 and IDH2 are frequently found in diffuse and anaplastic astrocytic and oligodendroglial tumours as well as in secondary glioblastomas. As IDH is a very important prognostic, diagnostic and therapeutic biomarker for glioma, it is of paramount importance to determine its mutational status. The haematoxylin and eosin (H&E) staining is a valuable tool in precision oncology as it guides histopathology-based diagnosis and proceeding patient's treatment. However, H&E staining alone does not determine the IDH mutational status of a tumour. Deep learning methods applied to MRI data have been demonstrated to be a useful tool in IDH status prediction, however the effectiveness of deep learning on H&E slides in the clinical setting has not been investigated so far. Furthermore, the performance of deep learning methods in medical imaging has been practically limited by small sample sizes currently available. Here we propose a data augmentation method based on the Generative Adversarial Networks (GAN) deep learning methodology, to improve the prediction performance of IDH mutational status using H&E slides. The H&E slides were acquired from 266 grade II-IV glioma patients from a mixture of public and private databases, including 130 IDH-wildtype and 136 IDH-mutant patients. A baseline deep learning model without data augmentation achieved an accuracy of 0.794 (AUC = 0.920). With GAN-based data augmentation, the accuracy of the IDH mutational status prediction was improved to 0.853 (AUC = 0.927) when the 3,000 GAN generated training samples were added to the original training set (24,000 samples). By integrating also patients' age into the model, the accuracy improved further to 0.882 (AUC = 0.931). Our findings show that deep learning methodology, enhanced by GAN data augmentation, can support physicians in gliomas' IDH status prediction.

Receptor tyrosine kinase gene amplification is predictive of intraoperative seizures during glioma resection with functional mapping

OBJECTIVE

Intraoperative seizures during craniotomy with functional mapping is a common complication that impedes optimal tumor resection and results in significant morbidity. The relationship between genetic mutations in gliomas and the incidence of intraoperative seizures has not been well characterized. Here, the authors performed a retrospective study of patients treated at their institution over the last 12 years to determine whether molecular data can be used to predict the incidence of this complication.

METHODS

The authors queried their institutional database for patients with brain tumors who underwent resection with intraoperative functional mapping between 2005 and 2017. Basic clinicopathological characteristics, including the status of the following genes, were recorded: IDH1/2, PIK3CA, BRAF, KRAS, AKT1, EGFR, PDGFRA, MET, MGMT, and 1p/19q. Relationships between gene alterations and intraoperative seizures were evaluated using chi-square and two-sample t-test univariate analysis. When considering multiple predictive factors, a logistic multivariate approach was taken.

RESULTS

Overall, 416 patients met criteria for inclusion; of these patients, 98 (24%) experienced an intraoperative seizure. Patients with a history of preoperative seizure and those treated with antiepileptic drugs prior to surgery were less likely to have intraoperative seizures (history: OR 0.61 [95% CI 0.38-0.96], chi-square = 4.65, p = 0.03; AED load: OR 0.46 [95% CI 0.26-0.80], chi-square = 7.64, p = 0.01). In a univariate analysis of genetic markers, amplification of genes encoding receptor tyrosine kinases (RTKs) was specifically identified as a positive predictor of seizures (OR 5.47 [95% CI 1.22-24.47], chi-square = 5.98, p = 0.01). In multivariate analyses considering RTK status, AED use, and either 2007 WHO tumor grade or modern 2016 WHO tumor groups, the authors found that amplification of the RTK proto-oncogene, MET, was most predictive of intraoperative seizure (p < 0.05).

CONCLUSIONS

This study describes a previously unreported association between genetic alterations in RTKs and the occurrence of intraoperative seizures during glioma resection with functional mapping. Future models estimating intraoperative seizure risk may be enhanced by inclusion of genetic criteria.

Prospects of biological and synthetic pharmacotherapies for glioblastoma

Introduction: The field of neuro-oncology has experienced significant advances in recent years. More is known now about the molecular and genetic characteristics of glioma than ever before. This knowledge leads to the understanding of glioma biology and pathogenesis, guiding the development of targeted therapeutics and clinical trials. The goal of this review is to describe the state of basic, translational, and clinical research as it pertains to biological and synthetic pharmacotherapy for gliomas.Areas covered: Challenges remain in designing accurate preclinical models and identifying patients that are likely to respond to a particular targeted therapy. Preclinical models for therapeutic assessment are critical to identify the most promising treatment approaches.Expert opinion: Despite promising new therapeutics, there have been no significant breakthroughs in glioma treatment and patient outcomes. Thus, there is an urgent need to better understand the mechanisms of treatment resistance and to design effective clinical trials.

Beyond Energy Metabolism: Exploiting the Additional Roles of NAMPT for Cancer Therapy

Tumor cells have increased requirements for NAD⁺. Thus, many cancers exhibit an increased reliance on NAD⁺ production pathways. This dependence may be exploited therapeutically through pharmacological targeting of NAMPT, the rate-limiting enzyme in the NAD⁺ salvage pathway. Despite promising preclinical data using NAMPT inhibitors in cancer models, early NAMPT inhibitors showed limited efficacy in several early phase clinical trials, necessitating the identification of strategies, such as drug combinations, to enhance their efficacy. While the effect of NAMPT inhibitors on impairment of energy metabolism in cancer cells has been well-described, more recent insights have uncovered a number of additional targetable cellular processes that are impacted by inhibition of NAMPT. These include sirtuin function, DNA repair machinery, redox homeostasis, molecular signaling, cellular stemness, and immune processes. This review highlights the recent findings describing the effects of NAMPT inhibitors on the non-metabolic functions of malignant cells, with a focus on how this information can be leveraged clinically. Combining NAMPT inhibitors with other therapies that target NAD⁺-dependent processes or selecting tumors with specific vulnerabilities that can be co-targeted with NAMPT inhibitors may represent opportunities to exploit the multiple functions of this enzyme for greater therapeutic benefit.

Updates in prognostic markers for gliomas

Gliomas are the most common primary malignant brain tumor in adults. The traditional classification of gliomas has been based on histologic features and tumor grade. The advent of sophisticated molecular diagnostic techniques has led to a deeper understanding of genomic drivers implicated in gliomagenesis, some of which have important prognostic implications. These advances have led to an extensive revision of the World Health Organization classification of diffuse gliomas to include molecular markers such as isocitrate dehydrogenase mutation, 1p/19q codeletion, and histone mutations as integral components of brain tumor classification. Here, we report a comprehensive analysis of molecular prognostic factors for patients with gliomas, including those mentioned above, but also extending to others such as telomerase reverse transcriptase promoter mutations, O6-methylguanine-DNA methyltransferase promoter methylation, glioma cytosine-phosphate-guanine island methylator phenotype DNA methylation, and epidermal growth factor receptor alterations.

Cancer-associated mutation and beyond: The emerging biology of isocitrate dehydrogenases in human disease

Isocitrate dehydrogenases (IDHs) are critical metabolic enzymes that catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (αKG), NAD(P)H, and CO₂. IDHs epigenetically control gene expression through effects on αKG-dependent dioxygenases, maintain redox balance and promote anaplerosis by providing cells with NADPH and precursor substrates for macromolecular synthesis, and regulate respiration and energy production through generation of NADH. Cancer-associated mutations in IDH1 and IDH2 represent one of the most comprehensively studied mechanisms of IDH pathogenic effect. Mutant enzymes produce (R)-2-hydroxyglutarate, which in turn inhibits αKG-dependent dioxygenase function, resulting in a global hypermethylation phenotype, increased tumor cell multipotency, and malignancy. Recent studies identified wild-type IDHs as critical regulators of normal organ physiology and, when transcriptionally induced or down-regulated, as contributing to cancer and neurodegeneration, respectively. We describe how mutant and wild-type enzymes contribute on molecular levels to disease pathogenesis, and discuss efforts to pharmacologically target IDH-controlled metabolic rewiring.

PI3K/AKT/mTOR Pathway Alterations Promote Malignant Progression and Xenograft Formation in Oligodendroglial Tumors

PURPOSE

Oligodendroglioma has a relatively favorable prognosis, however, often undergoes malignant progression. We hypothesized that preclinical models of oligodendroglioma could facilitate identification of therapeutic targets in progressive oligodendroglioma. We established multiple oligodendroglioma xenografts to determine if the PI3K/AKT/mTOR signaling pathway drives tumor progression.

EXPERIMENTAL DESIGN

Two anatomically distinct tumor samples from a patient who developed progressive anaplastic oligodendroglioma (AOD) were collected for orthotopic transplantation in mice. We additionally implanted 13 tumors to investigate the relationship between PI3K/AKT/mTOR pathway alterations and oligodendroglioma xenograft formation. Pharmacologic vulnerabilities were tested in newly developed AOD models in vitro and in vivo.

RESULTS

A specimen from the tumor site that subsequently manifested rapid clinical progression contained a PIK3CA mutation E542K, and yielded propagating xenografts that retained the OD/AOD-defining genomic alterations (IDH1 ^R132H and 1p/19q codeletion) and PIK3CA ^E542K, and displayed characteristic sensitivity to alkylating chemotherapeutic agents. In contrast, a xenograft did not engraft from the region that was clinically stable and had wild-type PIK3CA. In our panel of OD/AOD xenografts, the presence of activating mutations in the PI3K/AKT/mTOR pathway was consistently associated with xenograft establishment (6/6, 100%). OD/AOD that failed to generate xenografts did not have activating PI3K/AKT/mTOR alterations (0/9, P < 0.0001). Importantly, mutant PIK3CA oligodendroglioma xenografts were vulnerable to PI3K/AKT/mTOR pathway inhibitors in vitro and in vivo-evidence that mutant PIK3CA is a tumorigenic driver in oligodendroglioma.

CONCLUSIONS

Activation of the PI3K/AKT/mTOR pathway is an oncogenic driver and is associated with xenograft formation in oligodendrogliomas. These findings have implications for therapeutic targeting of PI3K/AKT/mTOR pathway activation in progressive oligodendrogliomas.

Sensitive and rapid detection of TERT promoter and IDH mutations in diffuse gliomas

BACKGROUND

Mutations in telomerase reverse transcriptase promoter (TERTp) and isocitrate dehydrogenase 1 and 2 (IDH) offer objective markers to assist in classifying diffuse gliomas into genetic subgroups. However, traditional mutation detection techniques lack sensitivity or have long turnaround times or high costs. We developed GliomaDx, an allele-specific, locked nucleic acid-based quantitative PCR assay to overcome these limitations and sensitively detect TERTp and IDH mutations.

METHODS

We evaluated the performance of GliomaDx on cell line DNA and frozen tissue diffuse glioma samples with variable tumor percentage to mimic use in clinical settings and validated low percentage variants using sensitive techniques including droplet digital PCR (ddPCR) and next-generation sequencing. We also developed GliomaDx Nest, which incorporates a high-fidelity multiplex pre-amplification step prior to allele-specific PCR for low-input formalin-fixed paraffin embedded (FFPE) samples.

RESULTS

GliomaDx detects the TERTp and IDH1 alterations at an analytical sensitivity of 0.1% mutant allele fraction, corresponding to 0.2% tumor cellularity. GliomaDx identified TERTp/IDH1 alterations in a cohort of frozen tissue samples with variable tumor percentage of all major diffuse glioma histologic types. GliomaDx Nest is able to detect these hotspot mutations with similar sensitivity from pre-amplified samples and was successfully tested on a cohort of clinical FFPE samples. Testing of a cohort of previously identified TERTpWT-IDHWT gliomas (by Sanger sequencing) revealed that 26.3% harbored low-percentage mutations. Analysis by ddPCR and whole exome sequencing of these tumors confirmed the low mutant fraction of these alterations and overall mutation-based tumor purity.

CONCLUSIONS

Our results show that GliomaDx can rapidly detect TERTp/IDH mutations with high sensitivity, identifying cases that might be missed due to the lack of sensitivity of other techniques. This approach may facilitate more objective classification of diffuse glioma samples in clinical settings such as intraoperative diagnosis or in testing cases with low tumor purity.

High-Density Lipoprotein-Mimicking Nanodiscs for Chemo-immunotherapy against Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor, for which there is no cure. Treatment effectiveness for GBM has been limited due to tumor heterogeneity, an immunosuppressive tumor microenvironment (TME), and the presence of the blood-brain barrier, which hampers the transport of chemotherapeutic compounds to the central nervous system (CNS). High-density lipoprotein (HDL)-mimicking nanodiscs hold considerable promise to achieve delivery of bioactive compounds into tumors. Herein, we tested the ability of synthetic HDL nanodiscs to deliver chemotherapeutic agents to the GBM microenvironment and elicit tumor regression. To this end, we developed chemo-immunotherapy delivery vehicles based on sHDL nanodiscs loaded with CpG, a Toll-like receptor 9 (TLR9) agonist, together with docetaxel (DTX), a chemotherapeutic agent, for targeting GBM. Our data show that delivery of DTX-sHDL-CpG nanodiscs into the tumor mass elicited tumor regression and antitumor CD8+ T cell responses in the brain TME. We did not observe any overt off-target side effects. Furthermore, the combination of DTX-sHDL-CpG treatment with radiation (IR), which is the standard of care for GBM, resulted in tumor regression and long-term survival in 80% of GBM-bearing animals. Mice remained tumor-free upon tumor cell rechallenge in the contralateral hemisphere, indicating the development of anti-GBM immunological memory. Collectively, these data indicate that sHDL nanodiscs constitute an effective drug delivery platform for the treatment of GBM, resulting in tumor regression, long-term survival, and immunological memory when used in combination with IR. The proposed delivery platform has significant potential for clinical translation.

NAD Metabolism in Cancer Therapeutics

Cancer cells have a unique energy metabolism for sustaining rapid proliferation. The preference for anaerobic glycolysis under normal oxygen conditions is a unique trait of cancer metabolism and is designated as the Warburg effect. Enhanced glycolysis also supports the generation of nucleotides, amino acids, lipids, and folic acid as the building blocks for cancer cell division. Nicotinamide adenine dinucleotide (NAD) is a co-enzyme that mediates redox reactions in a number of metabolic pathways, including glycolysis. Increased NAD levels enhance glycolysis and fuel cancer cells. In fact, nicotinamide phosphoribosyltransferase (Nampt), a rate-limiting enzyme for NAD synthesis in mammalian cells, is frequently amplified in several cancer cells. In addition, Nampt-specific inhibitors significantly deplete NAD levels and subsequently suppress cancer cell proliferation through inhibition of energy production pathways, such as glycolysis, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. NAD also serves as a substrate for poly(ADP-ribose) polymerase (PARP), sirtuin, and NAD gylycohydrolase (CD38 and CD157); thus, NAD regulates DNA repair, gene expression, and stress response through these enzymes. Thus, NAD metabolism is implicated in cancer pathogenesis beyond energy metabolism and considered a promising therapeutic target for cancer treatment. In this review, we present recent findings with respect to NAD metabolism and cancer pathogenesis. We also discuss the current and future perspectives regarding the therapeutics that target NAD metabolic pathways.

Long noncoding RNA GACAT3 promotes glioma progression by sponging miR-135a

The long noncoding RNA (lncRNA) gastric cancer associated transcript 3 (GACAT3) has been reported to play important roles in human tumorigenesis. However, its expression pattern, functions, and underlying mechanism in glioma remain unclear. In the present study, we showed that GACAT3 is upregulated in glioma tissues and cell lines. Through online databases, luciferase reporter assays and RNA immunoprecipitation (RIP) assays, we determined that GACAT3 acts as a competing endogenous RNA (ceRNA) for microRNA (miR)-135a, which was downregulated and performed as a tumor inhibitor in glioma. Further, nicotinamide phosphoribosyl transferase (NAMPT) was confirmed as a target gene of miR-135a by a series of gain- and loss-of-function assays. Overall, the present study was the first to show that GACAT3 regulates the expression of NAMPT to promote glioma progression by sponging miR-135a. These findings provide a promising therapy strategy for glioma.