Updates on management of gliomas in the molecular age

Gliomas are primary brain tumors derived from glial cells of the central nervous system,afflicting both adults and children with distinct characteristics and therapeutic challenges.Recent developments have ushered in novel clinical and molecular prognostic factors,reshaping treatment paradigms based on classi-fication and grading,determined by histological attributes and cellular lineage.This review article delves into the diverse treatment modalities tailored to the specific grades and molecular classifications of gliomas that are currently being discussed and used clinically in the year 2023.For adults,the therapeutic triad typically consists of surgical resection,chemotherapy,and radiotherapy.In contrast,pediatric gliomas,due to their diversity,require a more tailored approach.Although complete tumor excision can be curative based on the location and grade of the glioma,certain non-resectable cases demand a chemotherapy approach usually involving,vincristine and carboplatin.Addi-tionally,if surgery or chemotherapy strategies are unsuccessful,Vinblastine can be used.Despite recent advancements in treatment methodologies,there remains a need of exploration in the literature,particularly concerning the efficacy of treatment regimens for isocitrate dehydrogenase type mutant astrocytomas and fine-tuned therapeutic approaches tailored for pediatric cohorts.This review article explores into the therapeutic modalities employed for both adult and pediatric gliomas in the context of their molecular classification.

The interplay mechanism between IDH mutation, MGMT-promoter methylation, and PRMT5 activity in the progression of grade 4 astrocytoma: unraveling the complex triad theory

Background:The dysregulation of Isocitrate dehydrogenase(IDH)and the subsequent production of 2-Hydroxyglutrate(2HG)may alter the expression of epigenetic proteins in Grade 4 astrocytoma.The interplay mechanism between IDH,O-6-methylguanine-DNA methyltransferase(MGMT)-promoter methylation,and protein methyltransferase proteins-5(PRMT5)activity,with tumor progression has never been described.Methods:A retrospective cohort of 34 patients with G4 astrocytoma is classified into IDH-mutant and IDH-wildtype tumors.Both groups were tested for MGMT-promoter methylation and PRMT5 through methylation-specific and gene expression PCR analysis.Inter-cohort statistical significance was evaluated.Results:Both IDH-mutant WHO grade 4 astrocytomas(n=22,64.7%)and IDH-wildtype glioblastomas(n=12,35.3%)had upregulated PRMT5 gene expression except in one case.Out of the 22 IDH-mutant tumors,10(45.5%)tumors showed MGMT-promoter methylation and 12(54.5%)tumors had unmethylated MGMT.All IDH-wildtype tumors had unmethylated MGMT.There was a statistically significant relationship between MGMT-promoter methylation and IDH in G4 astrocytoma(p-value=0.006).Statistically significant differences in progression-free survival(PFS)were also observed among all G4 astrocytomas that expressed PRMT5 and received either temozolomide(TMZ)or TMZ plus other chemotherapies,regardless of their IDH or MGMT-methylation status(p-value=0.0014).Specifically,IDH-mutant tumors that had upregulated PRMT5 activity and MGMT-promoter methylation,who received only TMZ,have exhibited longer PFS.Conclusions:The relationship between PRMT5,MGMT-promoter,and IDH is not tridirectional.However,accumulation of D2-hydroxyglutarate(2-HG),which partially activates 2-OG-dependent deoxygenase,may not affect their activities.In IDH-wildtype glioblastomas,the 2HG-2OG pathway is typically inactive,leading to PRMT5 upregulation.TMZ alone,compared to TMZ-plus,can increase PFS in upregulated PRMT5 tumors.Thus,using a PRMT5 inhibitor in G4 astrocytomas may help in tumor regression.

A Comparative Study Between Tumor Blood Vessels and Dynamic Contrast-enhanced MRI for Identifying Isocitrate Dehydrogenase Gene 1(IDH1)Mutation Status in Glioma

Objective Isocitrate dehydrogenase gene(IDH)mutations are associated with tumor angiogenesis and therefore play an important role in glioma management.This study compared the performance of tumor blood vessels counted from contrast-enhanced 3D brain volume(3D-BRAVO)sequence and dynamic contrast-enhanced(DCE)MRI in differentiating IDH1 status in gliomas.Methods Forty-four glioma patients[16 with IDH1 mutant-type(IDH1-MT),28 with IDH1 wild-type(IDH1-WT)]were retrospectively analyzed.A blood vessel entering a tumor was defined as an intratumoral vessel;a blood vessel adjacent to the edge of a tumor was defined as a peritumoral vessel.Combined vessels were defined as the sum of the intratumoral and peritumoral vessels.DCE-derived metrics of tumor were normalized to the contralateral normal-appearing white matter.Results Intratumoral,peritumoral,and combined tumor blood vessels were all significantly different between IDH1-MT and IDH1-WT gliomas,and the range of area under curves(AUCs)was 0.816–0.855.For DCE-derived parameters,cerebral blood volume,cerebral blood flow,mean transit time,and volume transfer constant were significantly different between IDH1-MT and IDH1-WT gliomas,and the range of AUCs was 0.703–0.756.Combined vessels possessed the best performance for identifying IDH1 mutations in gliomas(AUC:0.855,sensitivity:0.857,specificity:0.812,P<0.001).Conclusion The number of tumor blood vessels has comparable diagnostic performance with DCE-derived parameters for differentiating IDH1 mutations and can serve as a potential imaging biomarker to reflect IDH1 mutations in gliomas.

Paradigm shift of chemotherapy and systemic treatment for biliary tract cancer

Biliary tract cancers(BTC)are frequently identified at late stages and have a poor prognosis due to limited systemic treatment regimens.For more than a decade,the combination of gemcitabine and cis-platin has served as the first-line standard treatment.There are few choices for second-line chemo-therapy.Targeted treatment with fibroblast growth factor receptor 2 inhibitors,neurotrophic tyrosine receptor kinase inhibitors,and isocitrate dehydrogenase 1 inhibitors has had important results.Immune checkpoint inhibitors(ICI)such as pembrolizumab are only used in first-line treatment for microsatellite instability high patients.The TOPAZ-1 trial's outcome is encouraging,and there are several trials underway that might soon put targeted treatment and ICI combos into first-line options.Newer targets and agents for existing goals are being studied,which may represent a paradigm shift in BTC management.Due to a scarcity of targetable mutations and the higher toxicity profile of the current medications,the new category of drugs may occupy a significant role in BTC therapies.

Molecular mechanisms of ＂off-on switch＂ of activities of human IDH1 by tumor-associated mutation R132H

Human cytosolic NADP-1DH （IDH1） has recently been found to be involved in tumorigenesis. Notably, the tumorderived IDH1 mutations identified so far mainly occur at Arg132, and mutation R132H is the most prevalent one. This mutation impairs the oxidative IDH activity of the enzyme, but renders a new reduction function of converting a-ketoglutarate （aKG） to 2-hydroxyglutarate. Here, we report the structures of the R132H mutant IDH1 with and without isocitrate OCT） bound. The structural data together with mutagenesis and biochemical data reveal a previ- ously undefined initial ICT-binding state and demonstrate that IDH activity requires a conformational change to a closed pre-transition state. Arg132 plays multiple functional roles in the catalytic reaction; in particular, the R132H mutation hinders the conformational changes from the initial ICT-binding state to the pre-transition state, leading to the impairment of the IDH activity. Our results describe for the first time that there is an intermediate conformation that corresponds to an initial ICT-binding state and that the R132H mutation can trap the enzyme in this conforma- tion, therefore shedding fight on the molecular mechanism of the ＂off switch＂ of the potentially tumor-suppressive IDH activity. Furthermore, we proved the necessity of Tyr139 for the gained aKG reduction activity and propose that Tyr139 may play a vital role by compensating the increased negative charge on the C2 atom of aKG during the trans- fer of a hydride anion from NADPH to aKG, which provides new insights into the mechanism of the ＂on switch＂ of the hypothetically oncogenic reduction activity of IDH1 by this mutation.

Predictive value of MGMT promoter methylation on the survival of TMZ treated IDH-mutant glioblastoma

Objective:O6 methylguanine-DNA methyltransferase(MGMT)promoter methylation is a biomarker widely used to predict the sensitivity of IDH-wildtype glioblastoma to temozolomide therapy.Given that the IDH status has critical effects on the survival and epigenetic features of glioblastoma,we aimed to assess the role of MGMT promoter methylation in IDH-mutant glioblastoma.Methods:This study included 187 IDH-mutant glioblastomas and used 173 IDH-wildtype glioblastomas for comparison.KaplanMeier curves and multivariate Cox regression were used to study the predictive effects.Results:Compared with IDH-wildtype glioblastomas,IDH-mutant glioblastomas showed significantly higher(P<0.0001)MGMT promoter methylation.We demonstrated that MGMT promoter methylation status,as determined by a high cutoff value(≥30%)in pyrosequencing,could be used to significantly stratify the survival of 50 IDH-mutant glioblastomas receiving temozolomide therapy(cohort A);this result was validated in another cohort of 25 IDH-mutant glioblastomas(cohort B).The median progression-free survival and median overall survival in cohort A were 9.33 and 13.76 months for unmethylated cases,and 18.37 and 41.61 months for methylated cases,and in cohort B were 6.97 and 9.10 months for unmethylated cases,and 23.40 and 26.40 months for methylated cases.In addition,we confirmed that the MGMT promoter methylation was significantly(P=0.0001)correlated with longer OS in IDH-mutant patients with GBM,independently of age,gender distribution,tumor type(primary or recurrent/secondary),and the extent of resection.Conclusions:MGMT promoter methylation has predictive value in IDH-mutant glioblastoma,but its cutoff value should be higher than that for IDH-wildtype glioblastoma.

Virtual mutagenesis of isocitrate dehydrogenase 1 involved in glioblastoma multiforme

Background Site A132Arg mutations potentially impair the affinity of isocitrate dehydrogenase 1 （IDH1） for its substrate isocitrate （ICT）, consequently reducing the production of a-ketoglutarate and leading to tumor growth through the induction of the hypoxia-inducible factor-1 （HIF-1） pathway. However, given that the roles of other active sites in IDH1 substrate binding remain unclear, we aimed to investigate IDH1 mutation pattern and its influence on enzyme function. Methods Fifteen IDH1 catalytic active site candidates were selected for in silico mutagenesis and protein homology modeling. Binding free energy of the IDH1/ICT complexes with single-site mutations was compared with that of the wild type. The affinity of 10 IDH1 catalytic active sites for the ICT substrate was further calculated. Results The IDH1 active site included seven residues from chain A （A77Thr, A94Ser, A100Arg, A132Arg, A109Arg, A275Asp, and A279Asp） and three residues from chain B （B214Thr, B212Lys, and B252Asp） that constituted the substrate ICT-binding site. These residues were located within 0.5 nm of ICT, indicating a potential interaction with the substrate. IDH1 changes of binding free energy （AE） suggested that the A132Arg residue from chain A contributes three hydrogen bonds to the ICT a-carboxyl and 13-carboxyl groups, while the other nine residues involved in ICT binding form only one or two hydrogen bonds. Amino acid substitutes at A132Arg, A109Arg, and B212Lys sites, had the greatest effect on enzyme affinity for its substrate. Conclusions Mutations at sites A132Arg, A109Arg, and B212Lys reduced IDH1 affinity for ICT, indicating these active sites may play a central role in substrate binding. Mutations at sites A77Thr, A94Ser, and A275Asp increased the affinity of IDH1 for ICT, which may enhance IDN1 catalytic activity. Mutant IDH1 proteins with higher catalytic activity than the wild-tvDe IDH1 could potentially be used as a novel qene therapy for qlioblastoma multiforme.

Deep Learning‑Assisted Quantitative Susceptibility Mapping as a Tool for Grading and Molecular Subtyping of Gliomas

This study aimed to explore the value of deep learning(DL)-assisted quantitative susceptibility mapping(QSM)in glioma grading and molecular subtyping.Forty-two patients with gliomas,who underwent preoperative T2 fluid-attenuated inversion recovery(T2 FLAIR),contrast-enhanced T1-weighted imaging(T1WI+C),and QSM scanning at 3.0T magnetic resonance imaging(MRI)were included in this study.Histopathology and immunohistochemistry staining were used to determine glioma grades,and isocitrate dehydrogenase(IDH)1 and alpha thalassemia/mental retardation syndrome X-linked gene(ATRX)subtypes.Tumor segmentation was performed manually using Insight Toolkit-SNAP program(www.itksnap.org).An inception convolutional neural network(CNN)with a subsequent linear layer was employed as the training encoder to capture multi-scale features from MRI slices.Fivefold cross-validation was utilized as the training strategy(seven samples for each fold),and the ratio of sample size of the training,validation,and test dataset was 4:1:1.The performance was evalu-ated by the accuracy and area under the curve(AUC).With the inception CNN,single modal of QSM showed better perfor-mance in differentiating glioblastomas(GBM)and other grade gliomas(OGG,grade II–III),and predicting IDH1 mutation and ATRX loss(accuracy:0.80,0.77,0.60)than either T2 FLAIR(0.69,0.57,0.54)or T1WI+C(0.74,0.57,0.46).When combining three modalities,compared with any single modality,the best AUC/accuracy/F1-scores were reached in grading gliomas(OGG and GBM:0.91/0.89/0.87,low-grade and high-grade gliomas:0.83/0.86/0.81),predicting IDH1 mutation(0.88/0.89/0.85),and predicting ATRX loss(0.78/0.71/0.67).As a supplement to conventional MRI,DL-assisted QSM is a promising molecular imaging method to evaluate glioma grades,IDH1 mutation,and ATRX loss.

Preclinical efficacy against acute myeloid leukaemia of SH1573, a novel mutant IDH2 inhibitor approved for clinical trials in China

Acute myeloid leukaemia(AML) is the most common form of acute leukaemia in adults,with increasing incidence with age and a generally poor prognosis.Almost 20% of AML patients express mutant isocitrate dehydrogenase 2(mIDH2),which leads to the accumulation of the carcinogenic metabolite 2-hydroxyglutarate(2-HG),resulting in poor prognosis.Thus,global institutions have been working to develop mIDH2 inhibitors.SH1573 is a novel mIDH2 inhibitor that we independently designed and synthesised.We have conducted a comprehensive study on its pharmacodynamics,pharmacokinetics and safety.First,SH1573 exhibited a strong selective inhibition of mIDH2 R140 Q protein,which could effectively reduce the production of 2-HG in cell lines,serum and tumors of an animal model.It could also promote the differentiation of mutant AML cell lines and granulocytes in PDX models.Then,it was confirmed that SH1573 possessed characteristics of high bioavailability,good metabolic stability and wide tissue distribution.Finally,toxicological data showed that SH1573 had no effects on the respiratory system,cardiovascular system and nervous system,and was genetically safe.This research successfully promoted the approval of SH1573 for clinical trials(CTR20200247).All experiments demonstrated that,as a potential drug against mIDH2 R140 Q acute myeloid leukaemia,SH1573 was effective and safe.

A potential role of karyopherin a2 in the impaired maturation of dendritic cells observed in glioblastoma patients

Aim:Patients with glioblastomas demonstrate well‑documented immunological impairments including decreased numbers of mature dendritic cells(DCs).Recent data identified karyopherin a2(KPNA2),a nucleocytoplasmic shuttling receptor,as diagnostic and prognostic biomarker for gliomas.The aim of this ongoing study is to correlate parameters of immunity and nucleocytoplasmic transport in glioblastoma patients.Methods:We preoperatively collected serum from 17 patients with glioblastomas and determined DC subsets(HLA DR+Lin-,CD34-,CD45+,CD123+,CD11+were analyzed)using a 6‑color flow cytometry panel.Expression levels of KPNA2 and nuclear accumulation of p53 were evaluated semi‑quantitatively by immunohistochemistry.O6‑methylguanine DNA methyltransferase(MGMT)and isocitrate dehydrogenase‑1(IDH‑1)status were assessed by pyrosequencing and immunohistochemistry,respectively.Results:Median expression levels for both KPNA2 and p53 were 5-10%.IDH‑1‑R132H mutation and MGMT promoter hypermethylation was detected in 3/16 and 1/9 patients,respectively.Mean counts of total mature DCs,myeloid DCs and plasmacytoid DCs were 9.6,2.1,3.4 cells/μL.A preliminary analysis suggests an association between low KPNA2 nuclear expression and increased numbers of mature DCs.However,this correlation did not reach statistical significance so far(P=0.077).Conclusion:Our preliminary data may indicate a role of KPNA2 in the impaired maturation of DCs observed in glioblastoma patients.

Systemic therapy for advanced cholangiocarcinoma:new options on the horizon

Patients with unresectable cholangiocarcinoma(CCA)face a poor prognosis,and there are few effective treatment options for the disease.The standard of care for patients with locally advanced or metastatic CCA is chemotherapy with a gemcitabine-based doublet.Unfortunately,the clinical benefit obtained with these regimens is modest,with a median overall survival of about one year.For CCA that is chemotherapy-refractory or recurs after first-line chemotherapy,the treatment options are even more limited,and no relevant randomized controlled data are available.In recent years,molecular profiling has shed light on the molecular basis of CCA and identified subgroups of patients that might benefit from a personalized treatment approach.These efforts resulted in the recent FDA approval of the fibroblast growth factor receptor(FGFR)inhibitor,pemigatinib,as a second-line treatment for patients with advanced CCA harboring an FGFR2-fusion or rearrangement.Several other targeted agents also are under evaluation in patients with CCA,of which the isocitrate dehydrogenase inhibitor has had the most promising results.Finally,immunotherapy is being explored as a new treatment approach for advanced CCA patients;indeed,the immune checkpoint inhibitor pembrolizumab can already be used to treat CCAs that are mismatch repair deficient.This review is a comprehensive overview of the treatment options for CCA and offers a glimpse into what the future could hold for these patients.