IDH1 mutation is prognostic for diffuse astrocytoma but not low-grade oligodendrogliomas in patients not treated with early radiotherapy

Congress of Neurological Surgeons systematic review and evidence‑based guidelines on the management of recurrent diffuse low-grade glioma: update

Target population These recommendations apply to adult patients with recurrent WHO grade 2 infiltrative diffuse glioma (oligodendroglioma, astrocytoma).Questions and Recommendations:Imaging Q1: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, do advanced imaging techniques using magnetic resonance spectroscopy, perfusion weighted imaging, diffusion weighted imaging or PET provide superior assessment of tumor recurrence and histologic progression compared to standard MRI neuroimaging?Recommendation Level III: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, advanced imaging techniques using magnetic resonance spectroscopy, perfusion weighted imaging, diffusion weighted imaging or PET are suggested for identification of tumor recurrence or histologic progression.Pathology Q1: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, is molecular testing for IDH-1, IDH-2, and TP53 Mutations and MGMT promotor methylation mutation warranted for predicting survival and formulating treatment recommendations?Recommendation Level III: It is suggested that IDH mutation status be determined for diagnostic purposes. TP53 mutations occur early in WHO grade 2 diffuse glioma pathogenesis, remain stable, and are not suggested as a marker of predisposition to malignant transformation at recurrence or other measures of prognosis. Assessment of MGMT status is suggested as an adjunct to assessing prognosis. Assessment of CDK2NA status is suggested since this is associated with malignant progression of WHO grade 2 diffuse gliomas.Q2: In adult patients with suspected recurrence of histologically proven WHO Grade 2 diffuse glioma, is testing of proliferation indices (MIB-1 and/or BUdR) warranted for predicting survival and formulating treatment recommendations?Recommendation Level III: It is suggested that proliferative indices (MIB-1 or BUdR) be measured in WHO grade 2 diffuse glioma as higher proliferation indices are associated with increased likelihood of recurrence and shorter progression free and overall survival.Chemotherapy Q1: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, does addition of temozolomide (TMZ), other cytotoxic agents or targeted agents to their treatment regimen improve PFS and/or OS?Recommendation Level III: Temozolomide is suggested in the therapy of recurrent WHO grade 2 diffuse glioma as it may improve clinical symptoms. PCV is suggested in the therapy of WHO grade 2 diffuse glioma at recurrence as it may improve clinical symptoms with the strongest evidence being for oligodendrogliomas. TMZ is suggested as the initial choice for recurrent WHO grade 2 diffuse glioma. Carboplatin is not suggested as there is no significant benefit from carboplatin as single agent therapy for recurrent WHO grade 2 diffuse gliomas. There is insufficient evidence to make any recommendations regarding other agents in the management of recurrent WHO grade 2 diffuse glioma.Radiotherapy Q1: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, does addition of radiotherapy to treatment regimen improve PFS and/or OS?Recommendation Level III: Radiation is suggested at recurrence if there was no previous radiation treatment. Q2: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma after previous radiotherapy, does addition of re-irradiation or proton therapy to the treatment regimen improve PFS and/or OS?Recommendation Level III: It is suggested that re-irradiation be considered in the setting of WHO grade 2 diffuse glioma recurrence as it may provide benefit in PFS and OS.Surgery Q1: In adult patients with suspected recurrence of histologically proven WHO grade 2 diffuse glioma, does surgical resection improve PFS and/or OS?. There is insufficient evidence to make any new specific recommendations regarding the value of surgery or extent of resection in relationship to survival for recurrent WHO grade 2 diffuse glioma.

Malignant Progression of Diffuse Low-grade Gliomas: A Systematic Review and Meta-analysis on Incidence and Related Factors

Malignant progression of diffuse low-grade glioma (LGG) is a critical event affecting patient survival; however, the incidence and related factors have been inconsistent in literature. According to the PRISMA guidelines, we systematically reviewed articles from 2009, meta-analyzed the incidence of malignant progression, and clarified factors related to the transformation. Forty-one articles were included in this study (n = 7,122; n, number of patients). We identified two definitions of malignant progression: histologically proven (Htrans) and clinically defined (Ctrans). The malignant progression rate curves of Htrans and Ctrans were almost in parallel when constructed from the results of meta-regression by the mean follow-up time. The true transformation rate was supposed to lie between the two curves, approximately 40% at the 10-year mean follow-up. Risk of malignant progression was evaluated using hazard ratio (HR). Pooled HRs were significantly higher in tumors with a larger pre- and postoperative tumor volume, lower degree of resection, and notable preoperative contrast enhancement on magnetic resonance imaging than in others. Oligodendroglial histology and IDH mutation (IDHm) with 1p/19q codeletion (Codel) also significantly reduced the HRs. Using Kaplan-Meier curves from eight studies with molecular data, we extracted data and calculated the 10-year malignant progression-free survival (10yMPFS). The 10yMPFS in patients with IDHm without Codel was 30.4% (95% confidence interval [95% CI]: 22.2-39.0) in Htrans and 38.3% (95% CI: 32.3-44.3) in Ctrans, and that with IDHm with Codel was 71.7% (95% CI: 61.7-79.5) in Htrans and 62.5% (95% CI: 55.9-68.5) in Ctrans. The effect of adjuvant radiotherapy or chemotherapy could not be determined.

Chaperonin-containing tailless complex polypeptide 1 subunit 6A correlates with increased World Health Organization grade, less isocitrate dehydrogenase mutation, and deteriorative survival of astrocytoma patients

Objective

Chaperonin‐containing tailless complex polypeptide 1 subunit 6A (CCT6A) is reported to be an efficient prognostic biomarker in various cancers, but it is rarely reported in astrocytoma. Thus, this study aimed to evaluate the expression of CCT6A and its correlation with disease features and prognosis in astrocytoma patients.

Methods

Totally, 198 astrocytoma patients who received surgery treatment were enrolled. CCT6A protein expression was determined in the tumor tissues fixed in formalin and embedded in paraffin (FFEP) by immunohistochemistry (IHC) assay. In addition, 133 out of 198 astrocytoma patients had fresh tumor tissues frozen in the liquid nitrogen for the determination of CCT6A mRNA expression by reverse transcription‐quantitative polymerase chain reaction.

Results

Sixty‐nine (34.8%), 70 (35.4%), 46 (23.2%), and 13 (6.6%) astrocytoma patients had the CCT6A immunohistochemistry (IHC) score of 0–3, 4–6, 7–9, and 10–12, respectively. CCT6A protein expression was correlated with increased World Health Organization (WHO) grade (P < 0.001) and less isocitrate dehydrogenase (IDH) mutation (P = 0.002); meanwhile, CCT6A mRNA expression was only related to elevated WHO grade (P = 0.001). However, CCT6A protein and mRNA expression were not correlated with other clinical features and subsequent treatment modalities (all P > 0.05). Moreover, CCT6A protein high and CCT6A mRNA high were related to shorter accumulating overall survival (OS; both P < 0.05). CCT6A protein high was an independent factor for predicting the worse OS (hazard ratio: 1.821, P = 0.012).

Conclusion

Chaperonin‐containing tailless complex polypeptide 1 subunit 6A correlates with elevated WHO grade and less IDH mutation; besides, CCT6A high expression is independently associated with unfavorable accumulating OS of astrocytoma patients.

Consequences of IDH1/2 Mutations in Gliomas and an Assessment of Inhibitors Targeting Mutated IDH Proteins

Isocitrate dehydrogenases (IDH) 1 and 2 are key metabolic enzymes that generate reduced nicotinamide adenine dinucleotide phosphate (NADPH) to maintain a pool of reduced glutathione and peroxiredoxin, and produce α-ketoglutarate, a co-factor of numerous enzymes. IDH1/2 is mutated in ~70–80% of lower-grade gliomas and the majority of secondary glioblastomas. The mutant IDH1 (R132H), in addition to losing its normal catalytic activity, gains the function of producing the d-(R)-2-hydroxyglutarate (2-HG). Overproduction of 2-HG in cancer cells interferes with cellular metabolism and inhibits histone and DNA demethylases, which results in histone and DNA hypermethylation and the blockade of cellular differentiation. We summarize recent findings characterizing molecular mechanisms underlying oncogenic alterations associated with mutated IDH1/2, and their impact on tumor microenvironment and antitumor immunity. Isoform-selective IDH inhibitors which suppress 2-HG production and induce antitumor responses in cells with IDH1 and IDH2 mutations were developed and validated in preclinical settings. Inhibitors of mutated IDH1/2 enzymes entered clinical trials and represent a novel drug class for targeted therapy of gliomas. We describe the development of small-molecule compounds and peptide vaccines targeting IDH-mutant gliomas and the results of their testing in preclinical and clinical studies. All those results support the translational potential of strategies targeting gliomas carrying IDH1 mutations.

IDH wild-type WHO grade II diffuse low-grade gliomas. A heterogeneous family with different outcomes. Systematic review and meta-analysis

WHO grade II diffuse low-grade gliomas (DLGGs) were recently divided into sub-groups on the basis of their molecular profiles. IDH wild-type (IDH-wt) tumors seem to be associated with unfavorable prognoses due to biological similarities to glioblastomas. The authors performed a systematic review and meta-analysis of literature examining epidemiology, clinical characteristics, management, and the outcome of IDH-wt grade II DLGGs. According to PRISMA guidelines, a comprehensive review of studies published from January 2009 to October 2017 was carried out. The authors identified series that examined the prevalence rate, clinical and radiological characteristics, treatment, and outcome of IDH-wt DLGGs. Variables influencing outcomes were analyzed using a random-effects meta-analysis model. Finally, a meta-regression analysis was performed to examine the impact of therapeutic strategies on the effect-size. Twenty-two studies were included in this systematic review. The IDH-wt prevalence rate was 22.9% (95% CI 18.4-27.4%). The hazard ratio for this molecular subgroup in the DLGGs population was 3.46 (95% CI 2.24-5.36; p < 0.001), and the heterogeneity was significant (I² = 85%, τ² = 0.88) (HR range 1.28-376). Nonetheless, publication bias did not affect the analysis (p = 0.176). The meta-regression revealed that the extent of resection and post-operative chemotherapy affected the outcome in the IDH-wt subgroup (p < 0.001 and 0.015, respectively), with no significant association of the HR with the rate of RT or RT + CHT. The prevalence of IDH-wt tumors is approximately 23% of DLGGs. The absence of IDH mutation is associated with a heterogeneous outcome, and its therapeutic relevance for postoperative management remains unclear. Maximal surgical resection improves the overall survival in the DLGGs population, beyond molecular status. Further molecular stratification is needed to better understand IDH-wt behavior and therapeutic response.

[IDH1- and IDH2-mutations in brain glial tumors - the new antioncogenic mechanism]

Mutant forms of the gene IDH1 progress significantly slower, have a lower risk of neoplastic transformation, and generally, mutations of this gene have a pronounced anti-oncogenic effect. At the same time, almost all mutations are quite stereotyped (98,9%) and occur in the same region of the gene - R132H mutations. IDH1 gene mutations is a complex multi-layered process, which is a completely new, not previously described anti-oncogene activation mechanism of intracellular protection. The reason that there is a mutation in the tumor cells is associated with de novo blocking differentiation processes and development of brain cells in the development process, as evidenced by severe cerebral hypoplasia in patients with congenital forms of this mutation. A completely new mechanism of antitumor protection has been described - stereotypical IDH1 gene mutation is a gene, in fact, is a key event, causing a cascade of further anti-oncogenic mechanisms in brain gliomas.

IDH1 R132H Mutation Is Accompanied with Malignant Progression of Paired Primary-Recurrent Astrocytic Tumours

IDH1 R132H mutation is an important marker of survival in patients with gliomas. Although there are many changes of genes in tumour malignant progression, IDH1 R132H mutation status in glioma progression remained unclear. Here, an in-depth characterization of IDH1 R132H mutations were assessed by immunohistochemistry in 55 paired primary-recurrent astrocytomas tissues, including 5 paired primary pilocytic astrocytoma (pPA, WHO grade I), 35 paired primary low grade astrocytoma (pLGA, WHO grade II and III) and 15 paired primary high grade astrocytoma (pHGA/ Glioblastoma, WHO grade IV). Meanwhile, the DNA was isolated from paired samples, and PCR amplification was used for IDH1 exon4 sequencing. Nonparametric test, KM and Cox models were used to examine the statistical difference and survival function. We found that the percent of IDH1 R132H mutation was 68.6% (24/35) in pLGA group, but no IDH1 mutation was found in pPA and pHGA groups. Meanwhile, the results from immunohistochemistry and DNA sequencing showed that, compared with primary astrocytoma, there was no change of IDH1 status in recurrent astrocytoma whatever tumour pathological grade raise or indolent. The pPA group has the longest recurrence-free period (RFP) and overall survival (OS) in three groups (p<0.01), while the pHGA group has the shortest ones (p<0.01). In pLGA group, the IDH1 R132H mutation subgroup has longer RFP than IDH1 wild type subgroup (p<0.01), but the OS has no statistical difference between two subgroups (p>0.6). Additionally, IDH1 R132H mutation independently predicted a long RFP in patients with pLGA (HR 1.073, 95% CI 0.151-0.775, p<0.01).

5-hydroxymethylcytosine loss is associated with poor prognosis for patients with WHO grade II diffuse astrocytomas

Currently, the reliable prognostic biomarkers for WHO grade II diffuse astrocytomas (DA) are still limited. We investigated the relations between the level of 5-Hydroxymethylcytosine (5hmC), an oxidated production of 5-methylcytosine (5mC) by the ten eleven translocated (TET) enzymes, and clinicopathological features of glioma patients. With an identified anti-5hmC antibody, we performed immunohistochemistry in 287 glioma cases. We detected that 5hmC variably reduced in most gliomas and 5hmC reduction was closely associated with higher pathological grades and shortened survival of glioma patients. In multivariate analysis, 5hmC had no independent prognostic value in the entire patient cohort. However, multivariate analysis within subtypes of gliomas revealed that 5hmC was still a prognostic marker confined to DA. In addition, we detected that IDH1 mutation by DNA sequencing was associated with favorable survival within DA. Lastly, we detected that the combination of 5hmC/KI67 was a useful prognostic marker for restratification of DA.